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Customized 2-in-1 Colorful Metal USB Flash Drive: Featured Customization, Showing Corporate Quality最先出现在XingFei Technology Co., Ltd.。

“UAV” redirects here. For other uses, see UAV (disambiguation).

An unmanned aerial vehicle (UAV) or unmanned aircraft system (UAS), commonly known as a drone, is an aircraft with no human pilot, crew, or passengers onboard, but rather is controlled remotely or is autonomous.^[1][2] UAVs were originally developed through the twentieth century for military missions too “dull, dirty or dangerous”^[3] for humans, and by the twenty-first, they had become essential assets to most militaries. As control technologies improved and costs fell, their use expanded to many non-military applications.^[4] These include aerial photography, area coverage,^[5] precision agriculture, forest fire monitoring,^[6] river monitoring,^[7][8] environmental monitoring,^{[9][10][11][12]} weather observation, policing and surveillance, infrastructure inspections, smuggling,^[13] product deliveries, entertainment, drone racing, and combat.

目录

• 1Terminology
• 2Classification types
  • 2.1Range and endurance
  • 2.2Size
  • 2.3Weight
  • 2.4Degree of autonomy
  • 2.5Altitude
  • 2.6Composite criteria
  • 2.7Power sources
• 3History
  • 3.1Early drones
  • 3.2World War II
  • 3.3Postwar period
  • 3.4Modern UAVs
• 4Design
  • 4.1Aircraft configuration
  • 4.2Propulsion
  • 4.3Ornithopters – wing propulsion
• 5Computer control systems
  • 5.1Architecture
  • 5.2Autonomy
• 6Performance considerations
  • 6.1Flight envelope
  • 6.2Endurance
  • 6.3Reliability
• 7Applications
  • 7.1Warfare
  • 7.2Civil applications
• 8Safety and security
  • 8.1Threats
  • 8.2Countermeasures
  • 8.3Regulation
• 9See also
• 10References
  • 10.1Citations
  • 10.2Bibliography
• 11Further reading
• 12External links

Terminology

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Many terms are used for aircraft which fly without any persons onboard.

The term drone has been used from the early days of aviation, some being applied to remotely flown target aircraft used for practice firing of a battleship’s guns, such as the 1920s Fairey Queen and 1930s de Havilland Queen Bee. Later examples included the Airspeed Queen Wasp and Miles Queen Martinet, before ultimate replacement by the GAF Jindivik.^[14] The term remains in common use. In addition to the software, autonomous drones also employ a host of advanced technologies that allow them to carry out their missions without human intervention, such as cloud computing, computer vision, artificial intelligence, machine learning, deep learning, and thermal sensors.^[15] For recreational uses, an aerial photography drone is an aircraft that has first-person video, autonomous capabilities, or both.^[16]

An unmanned aerial vehicle (UAV) is defined as a “powered, aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry a lethal or nonlethal payload”.^[17] UAV is a term that is commonly applied to military use cases.^[18] Missiles with warheads are generally not considered UAVs because the vehicle itself is a munition, but certain types of propeller-based missile are often called “kamikaze drones” by the public and media. Also, the relation of UAVs to remote controlled model aircraft is unclear in some jurisdictions. The US FAA now defines any unmanned flying craft as a UAV regardless of weight.^[19] A similar term is remotely piloted aerial vehicle (RPAV).

UAVs or RPAVs can also be seen as a component of an unmanned aircraft system (UAS), which also includes a ground-based controller and a system of communications with the aircraft.^[6] The term UAS was adopted by the United States Department of Defense (DoD) and the United States Federal Aviation Administration (FAA) in 2005 according to their Unmanned Aircraft System Roadmap 2005–2030.^[20] The International Civil Aviation Organization (ICAO) and the British Civil Aviation Authority adopted this term, also used in the European Union’s Single European Sky (SES) Air Traffic Management (ATM) Research (SESAR Joint Undertaking) roadmap for 2020.^[21] This term emphasizes the importance of elements other than the aircraft. It includes elements such as ground control stations, data links and other support equipment. Similar terms are unmanned aircraft vehicle system (UAVS) and remotely piloted aircraft system (RPAS).^[22] Many similar terms are in use. Under new regulations which came into effect 1 June 2019, the term RPAS has been adopted by the Canadian Government to mean “a set of configurable elements consisting of a remotely piloted aircraft, its control station, the command and control links and any other system elements required during flight operation”.^[23]

“Uncrewed” is sometimes used rather than “Unmanned”.^[24][25][26]

Classification types

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UAVs may be classified like any other aircraft, according to design configuration such as weight or engine type, maximum flight altitude, degree of operational autonomy, operational role, etc. According to the United States Department of Defense, UAVs are classified into five categories below:^[27][28]

Other classifications of UAVs include:^[27]

Range and endurance

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There are usually five categories when UAVs are classified by range and endurance:^[27]

Size

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There are usually four categories when UAVs are classified by size, with at least one of the dimensions (length or wingspan) meet the following respective limits:^[27]

Weight

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Based on their weight, drones can be classified into five categories:

NATO uses a similar classification shown below:^[1]

Degree of autonomy

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Drones can also be classified based on the degree of autonomy in their flight operations. ICAO classifies unmanned aircraft as either remotely piloted aircraft or fully autonomous.^[30] Some UAVs offer intermediate degrees of autonomy. For example, a vehicle may be remotely piloted in most contexts but have an autonomous return-to-base operation. Some aircraft types may optionally fly manned or as UAVs, which may include manned aircraft transformed into manned or Optionally Piloted UAVs (OPVs). The flight of UAVs may operate under remote control by a human operator, as remotely piloted aircraft (RPA), or with various degrees of autonomy, such as autopilot assistance, up to fully autonomous aircraft that have no provision for human intervention.^[31][32]

Altitude

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Based on the altitude, the following UAV classifications have been used at industry events such as ParcAberporth Unmanned Systems forum:

• Hand-held 2,000 ft (600 m) altitude, about 2 km range
• Close 5,000 ft (1,500 m) altitude, up to 10 km range
• NATO type 10,000 ft (3,000 m) altitude, up to 50 km range
• Tactical 18,000 ft (5,500 m) altitude, about 160 km range
• MALE (medium altitude, long endurance) up to 30,000 ft (9,000 m) and range over 200 km
• HALE (high altitude, long endurance) over 30,000 ft (9,100 m) and indefinite range
• Hypersonic high-speed, supersonic (Mach 1–5) or hypersonic (Mach 5+) 50,000 ft (15,200 m) or suborbital altitude, range over 200 km
• Orbital low Earth orbit (Mach 25+)
• CIS Lunar Earth-Moon transfer
• Computer Assisted Carrier Guidance System (CACGS) for UAVs

Composite criteria

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An example of classification based on the composite criteria is U.S. Military’s unmanned aerial systems (UAS) classification of UAVs based on weight, maximum altitude and speed of the UAV component.

Power sources

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UAVs can be classified based on their power or energy source, which significantly impacts their flight duration, range, and environmental impact. The main categories include:

• Battery-powered (electric): These UAVs use rechargeable batteries, offering quiet operation and lower maintenance but potentially limited flight times. The reduced noise levels make them suitable for urban environments and sensitive operations.^[33]
• Fuel-powered (internal combustion): Utilizing traditional fuels like gasoline or diesel, these UAVs often have longer flight times but may be noisier and require more maintenance. They are typically used for applications requiring extended endurance or heavy payload capacity.^[34]
• Hybrid: Combining electric and fuel power sources, hybrid UAVs aim to balance the benefits of both systems for improved performance and efficiency. This configuration could allow for versatility in mission profiles and adaptability to different operational requirements.^[35]
• Hydrogen fuel cell: hydrogen fuel cells offer the potential for longer flight times than batteries yet stealthier (no heat signature) operation than combustion engines.^[36] The high energy density of hydrogen makes it a promising option for future UAV propulsion systems.^[37]
• Solar-powered: Equipped with solar panels, these UAVs can potentially achieve extended flight times by harnessing solar energy, especially at high altitudes. Solar-powered UAVs may be particularly suited for long-endurance missions and environmental monitoring applications.^[38]
• Nuclear-powered: While nuclear power has been explored for larger aircraft, its application in UAVs remains largely theoretical due to safety concerns and regulatory challenges. Research in this area is ongoing but faces significant hurdles before practical implementation.^[39]

History

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Main article: History of unmanned aerial vehicles

Early drones

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The earliest recorded use of an unmanned aerial vehicle for warfighting occurred in July 1849,^[41] with a balloon carrier (the precursor to the aircraft carrier)^[42] in the first offensive use of air power in naval aviation.^[43][44][45] Austrian forces besieging Venice attempted to launch some 200 incendiary balloons at the besieged city. The balloons were launched mainly from land; however, some were also launched from the Austrian ship SMS Vulcano. At least one bomb fell in the city; however, due to the wind changing after launch, most of the balloons missed their target, and some drifted back over Austrian lines and the launching ship Vulcano.^[46][47][48]

The Spanish engineer Leonardo Torres Quevedo introduced a radio-based control-system called the Telekino^[49] at the Paris Academy of Science in 1903, as a way of testing airships without risking human life.^[50][51][52]

Significant development of drones started in the 1900s, and originally focused on providing practice targets for training military personnel. The earliest attempt at a powered UAV was A. M. Low‘s “Aerial Target” in 1916.^[53] Low confirmed that Geoffrey de Havilland’s monoplane was the one that flew under control on 21 March 1917 using his radio system.^[54] Following this successful demonstration in the spring of 1917 Low was transferred to develop aircraft controlled fast motor launches D.C.B.s with the Royal Navy in 1918 intended to attack shipping and port installations and he also assisted Wing Commander Brock in preparations for the Zeebrugge Raid. Other British unmanned developments followed, leading to the fleet of over 400 de Havilland 82 Queen Bee aerial targets that went into service in 1935.

Nikola Tesla described a fleet of uncrewed aerial combat vehicles in 1915.^[55] These developments also inspired the construction of the Kettering Bug by Charles Kettering from Dayton, Ohio and the Hewitt-Sperry Automatic Airplane – initially meant as an uncrewed plane that would carry an explosive payload to a predetermined target. Development continued during World War I, when the Dayton-Wright Airplane Company invented a pilotless aerial torpedo that would explode at a preset time.^[56]

The film star and model-airplane enthusiast Reginald Denny developed the first scaled remote piloted vehicle in 1935.^[53]

Soviet researchers experimented with controlling Tupolev TB-1 bombers remotely in the late 1930s.^[57]

World War II

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In 1940, Denny started the Radioplane Company and more models emerged during World War II – used both to train antiaircraft gunners and to fly attack-missions. Nazi Germany produced and used various UAV aircraft during the war, like the Argus As 292 and the V-1 flying bomb with a jet engine. Fascist Italy developed a specialised drone version of the Savoia-Marchetti SM.79 flown by remote control, although the Armistice with Italy was enacted prior to any operational deployment.^[58]

Postwar period

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After World War II development continued in vehicles such as the American JB-4 (using television/radio-command guidance), the Australian GAF Jindivik and Teledyne Ryan Firebee I of 1951, while companies like Beechcraft offered their Model 1001 for the U.S. Navy in 1955.^[53] Nevertheless, they were little more than remote-controlled airplanes until the Vietnam War. In 1959, the U.S. Air Force, concerned about losing pilots over hostile territory, began planning for the use of uncrewed aircraft.^[59] Planning intensified after the Soviet Union shot down a U-2 in 1960. Within days, a highly classified UAV program started under the code name of “Red Wagon”.^[60] The August 1964 clash in the Tonkin Gulf between naval units of the U.S. and the North Vietnamese Navy initiated America’s highly classified UAVs (Ryan Model 147, Ryan AQM-91 Firefly, Lockheed D-21) into their first combat missions of the Vietnam War.^[61] When the Chinese government^[62] showed photographs of downed U.S. UAVs via Wide World Photos,^[63] the official U.S. response was “no comment”.

During the War of Attrition (1967–1970) in the Middle East, Israeli intelligence tested the first tactical UAVs installed with reconnaissance cameras, which successfully returned photos from across the Suez Canal. This was the first time that tactical UAVs that could be launched and landed on any short runway (unlike the heavier jet-based UAVs) were developed and tested in battle.^[64]

In the 1973 Yom Kippur War, Israel used UAVs as decoys to spur opposing forces into wasting expensive anti-aircraft missiles.^[65] After the 1973 Yom Kippur War, a few key people from the team that developed this early UAV joined a small startup company that aimed to develop UAVs into a commercial product, eventually purchased by Tadiran and leading to the development of the first Israeli UAV.^{[66][pages needed]}

In 1973, the U.S. military officially confirmed that they had been using UAVs in Southeast Asia (Vietnam).^[67] Over 5,000 U.S. airmen had been killed and over 1,000 more were missing or captured. The USAF 100th Strategic Reconnaissance Wing flew about 3,435 UAV missions during the war^[68] at a cost of about 554 UAVs lost to all causes. In the words of USAF General George S. Brown, Commander, Air Force Systems Command, in 1972, “The only reason we need (UAVs) is that we don’t want to needlessly expend the man in the cockpit.”^[69] Later that year, General John C. Meyer, Commander in Chief, Strategic Air Command, stated, “we let the drone do the high-risk flying … the loss rate is high, but we are willing to risk more of them …they save lives!”^[69]

During the 1973 Yom Kippur War, Soviet-supplied surface-to-air missile-batteries in Egypt and Syria caused heavy damage to Israeli fighter jets. As a result, Israel developed the IAI Scout as the first UAV with real-time surveillance.^[70][71][72] The images and radar decoys provided by these UAVs helped Israel to completely neutralize the Syrian air defenses at the start of the 1982 Lebanon War, resulting in no pilots downed.^[73] In Israel in 1987, UAVs were first used as proof-of-concept of super-agility, post-stall controlled flight in combat-flight simulations that involved tailless, stealth-technology-based, three-dimensional thrust vectoring flight-control, and jet-steering.^[74]

Modern UAVs

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With the maturing and miniaturization of applicable technologies in the 1980s and 1990s, interest in UAVs grew within the higher echelons of the U.S. military. The U.S. funded the Counterterrorism Center (CTC) within the CIA, which sought to fight terrorism with the aid of modernized drone technology.^[75] In the 1990s, the U.S. DoD gave a contract to AAI Corporation along with Israeli company Malat. The U.S. Navy bought the AAI Pioneer UAV that AAI and Malat developed jointly. Many of these UAVs saw service in the 1991 Gulf War. UAVs demonstrated the possibility of cheaper, more capable fighting-machines, deployable without risk to aircrews. Initial generations primarily involved surveillance aircraft, but some carried armaments, such as the General Atomics MQ-1 Predator, that launched AGM-114 Hellfire air-to-ground missiles.

CAPECON, a European Union project to develop UAVs,^[76] ran from 1 May 2002 to 31 December 2005.^[77]

As of 2012, the United States Air Force (USAF) employed 7,494 UAVs – almost one in three USAF aircraft.^[78][79] The Central Intelligence Agency also operated UAVs.^[80] By 2013 at least 50 countries used UAVs. China, Iran, Israel, Pakistan, Turkey, and others designed and built their own varieties. The use of drones has continued to increase.^[81] Due to their wide proliferation, no comprehensive list of UAV systems exists.^[79][82]

The development of smart technologies and improved electrical-power systems led to a parallel increase in the use of drones for consumer and general aviation activities. As of 2021, quadcopter drones exemplify the widespread popularity of hobby radio-controlled aircraft and toys, but the use of UAVs in commercial and general aviation is limited by a lack of autonomy^{[clarification needed]} and by new regulatory environments which require line-of-sight contact with the pilot.^{[citation needed]}

In 2020, a Kargu 2 drone hunted down and attacked a human target in Libya, according to a report from the UN Security Council‘s Panel of Experts on Libya, published in March 2021. This may have been the first time an autonomous killer-robot armed with lethal weaponry attacked human beings.^[83]

Superior drone technology, specifically the Turkish Bayraktar TB2, played a role in Azerbaijan’s successes in the 2020 Nagorno-Karabakh war against Armenia.^[84]

UAVs are also used in NASA missions. The Ingenuity helicopter is an autonomous UAV that operated on Mars from 2021 to 2024. As of 2024 the Dragonfly spacecraft is being developed, and is aiming to reach and examine Saturn‘s moon Titan. Its primary goal is to roam around the surface, expanding the amount of area to be researched previously seen by landers. As a UAV, Dragonfly allows examination of potentially diverse types of soil. The drone is set to launch in 2027, and is estimated to take seven more years to reach the Saturnian system.

Miniaturization is also supporting the development of small UAVs which can be used as individual system or in a fleet offering the possibility to survey large areas, in a relatively small amount of time.^[85]

According to data from GlobalData, the global military uncrewed aerial systems (UAS) market, which forms a significant part of the UAV industry, is projected to experience a compound annual growth rate of 4.8% over the next decade. This represents a near doubling in market size, from $12.5 billion in 2024 to an estimated $20 billion by 2034.^[86]

Design

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Crewed and uncrewed aircraft of the same type generally have recognizably similar physical components. The main exceptions are the cockpit and environmental control system or life support systems. Some UAVs carry payloads (such as a camera) that weigh considerably less than an adult human, and as a result, can be considerably smaller. Though they carry heavy payloads, weaponized military UAVs are lighter than their crewed counterparts with comparable armaments.

Small civilian UAVs have no life-critical systems, and can thus be built out of lighter but less sturdy materials and shapes, and can use less robustly tested electronic control systems. For small UAVs, the quadcopter design has become popular, though this layout is rarely used for crewed aircraft. Miniaturization means that less-powerful propulsion technologies can be used that are not feasible for crewed aircraft, such as small electric motors and batteries.

Control systems for UAVs are often different from crewed craft. For remote human control, a camera and video link almost always replace the cockpit windows; radio-transmitted digital commands replace physical cockpit controls. Autopilot software is used on both crewed and uncrewed aircraft, with varying feature sets.^[87][88][89]

Aircraft configuration

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UAVs can be designed in different configurations than manned aircraft both because there is no need for a cockpit and its windows, and there is no need to optimize for human comfort, although some UAVs are adapted from piloted examples, or are designed for optionally piloted modes. Air safety is also less of a critical requirement for unmanned aircraft, allowing the designer greater freedom to experiment. Instead, UAVs are typically designed around their onboard payloads and their ground equipment. These factors have led to a great variety of airframe and motor configurations in UAVs.

For conventional flight the flying wing and blended wing body offer light weight combined with low drag and stealth, and are popular configurations for many use cases. Larger types which carry a variable payload are more likely to feature a distinct fuselage with a tail for stability, control and trim, although the wing configurations in use vary widely.

For uses that require vertical flight or hovering, the tailless quadcopter requires a relatively simple control system and is common for smaller UAVs. Multirotor designs with 6 or more rotors is more common with larger UAVs, where redundancy is prioritized.^[90][91]

Propulsion

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Traditional internal combustion and jet engines remain in use for drones requiring long range. However, for shorter-range missions electric power has almost entirely taken over. The distance record for a UAV (built from balsa wood and mylar skin) across the North Atlantic Ocean is held by a gasoline model airplane or UAV. Manard Hill “in 2003 when one of his creations flew 1,882 miles across the Atlantic Ocean on less than a gallon of fuel” holds this record.^[92]

Besides the traditional piston engine, the Wankel rotary engine is used by some drones. This type offers high power output for lower weight, with quieter and more vibration-free running. Claims have also been made for improved reliability and greater range.^{[citation needed]}

Small drones mostly use lithium-polymer batteries (Li-Po), while some larger vehicles have adopted the hydrogen fuel cell.^[93][94][95] Hydrogen-fueled proton-exchange membrane fuel cells for UAVs have the advantages of longer flight duration than rechargeable lithium-ion batteries, of lower total cost of ownership than primary lithium metal batteries and of better stealth than heat engines.^[96]

The energy density of modern Li-Po batteries is far less than gasoline or hydrogen. However electric motors are cheaper, lighter and quieter. Complex multi-engine, multi-propeller installations are under development with the goal of improving aerodynamic and propulsive efficiency. For such complex power installations, battery elimination circuitry (BEC) may be used to centralize power distribution and minimize heating, under the control of a microcontroller unit (MCU).

Ornithopters – wing propulsion

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Flapping-wing ornithopters, imitating birds or insects, have been flown as microUAVs. Their inherent stealth recommends them for spy missions.

Sub-1g microUAVs inspired by flies, albeit using a power tether, have been able to “land” on vertical surfaces.^[97] Other projects mimic the flight of beetles and other insects.^[98]

Computer control systems

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UAV computing capability followed the advances of computing technology, beginning with analog controls and evolving into microcontrollers, then system-on-a-chip (SOC) and single-board computers (SBC).

Modern system hardware for UAV control is often called the flight controller (FC), flight controller board (FCB) or autopilot. Common UAV-systems control hardware typically incorporate a primary microprocessor, a secondary or failsafe processor, and sensors such as accelerometers, gyroscopes, magnetometers, and barometers into a single module.

In 2024 EASA agreed on the first certification basis for a UAV flight controller in compliance with the ETSO-C198 for Embention’s autopilot. The certification of the UAV flight control systems aims to facilitate the integration of UAVs within the airspace and the operation of drones in critical areas.^[99]

Architecture

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Sensors

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Position and movement sensors give information about the aircraft state. Exteroceptive sensors deal with external information like distance measurements, while exproprioceptive ones correlate internal and external states.^[100]

Non-cooperative sensors are able to detect targets autonomously so they are used for separation assurance and collision avoidance.^[101]

Degrees of freedom (DOF) refers to both the amount and quality of onboard sensors: 6 DOF implies 3-axis gyroscopes and accelerometers (a typical inertial measurement unit – IMU), 9 DOF refers to an IMU plus a compass, 10 DOF adds a barometer and 11 DOF usually adds a GPS receiver.^[102]

In addition to the navigation sensors, the UAV (or UAS) can be also equipped with monitoring devices such as: RGB, multispectral, hyper-spectral cameras or LiDAR, which may allow providing specific measurements or observations.^[103]

Actuators

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UAV actuators include digital electronic speed controllers (which control the RPM of the motors) linked to motors/engines and propellers, servomotors (for planes and helicopters mostly), weapons, payload actuators, LEDs and speakers.

Software

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Modern UAVs run a software stack that ranges from low-level firmware that directly controls actuators, to high level flight planning. At the lowest level, firmware directly controls reading from sensors such as an IMU^[104] and commanding actuators such as motors. Control software (often referred to as an autopilot) is responsible for computing actuator speeds given desired vehicle velocity. Due to its direct interaction with hardware, this software is time-critical and may run on microcontrollers. This software may also handle radio communications, in the case of UAVs that are not autonomous. One popular example is the PX4 autopilot.

At the next level, autonomy algorithms compute the desired velocity given higher level goals. For example, trajectory optimization^[105] may be used to calculate a flight trajectory given a desired goal location. This software is not necessarily time-critical, and can often run on a single board computer running an operating system such as Linux with relaxed time constraints.

Loop principles

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UAVs employ open-loop, closed-loop or hybrid control architectures.

• Open loop – This type provides a positive control signal (faster, slower, left, right, up, down) without incorporating feedback from sensor data.
• Closed loop – This type incorporates sensor feedback to adjust behavior (reduce speed to reflect tailwind, move to altitude 300 feet). The PID controller is common. Sometimes, feedforward is employed, transferring the need to close the loop further.^[106]

Communications

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UAVs use a radio for control and exchange of video and other data. Early UAVs had only narrowband uplink. Downlinks came later. These bi-directional narrowband radio links carried command and control (C&C) and telemetry data about the status of aircraft systems to the remote operator.

In most modern UAV applications, video transmission is required. So instead of having separate links for C&C, telemetry and video traffic, a broadband link is used to carry all types of data. These broadband links can leverage quality of service techniques and carry TCP/IP traffic that can be routed over the internet.

The radio signal from the operator side can be issued from either:

• Ground control – a human operating a radio transmitter/receiver, a smartphone, a tablet, a computer, or the original meaning of a military ground control station (GCS).
• Remote network system, such as satellite duplex data links for some military powers. Downstream digital video over mobile networks has also entered consumer markets, while direct UAV control uplink over the cellular mesh and LTE have been demonstrated and are in trials.^[107]
• Another aircraft, serving as a relay or mobile control station – military manned-unmanned teaming (MUM-T).^[108]

Modern networking standards have explicitly considered drones and therefore include optimizations. The 5G standard has mandated reduced user plane latency to 1ms while using ultra-reliable and low-latency communications.^[109]

UAV-to-UAV coordination supported by Remote ID communication technology. Remote ID messages (containing the UAV coordinates) are broadcast and can be used for collision-free navigation.^[110]

Autonomy

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Main article: Autonomous aircraft

The level of autonomy in UAVs varies widely. UAV manufacturers often build in specific autonomous operations, such as:^[111]

• Self-level: attitude stabilization on the pitch and roll axes.
• Altitude hold: The aircraft maintains its altitude using barometric pressure and/or GPS data.
• Hover/position hold: Keep level pitch and roll, stable yaw heading and altitude while maintaining position using GNSS or inertial sensors.
• Headless mode: Pitch control relative to the position of the pilot rather than relative to the vehicle’s axes.
• Care-free: automatic roll and yaw control while moving horizontally
• Takeoff and landing (using a variety of aircraft or ground-based sensors and systems; see also “autoland“)
• Failsafe: automatic landing or return-to-home upon loss of control signal
• Return-to-home: Fly back to the point of takeoff (often gaining altitude first to avoid possible intervening obstructions such as trees or buildings).
• Follow-me: Maintain relative position to a moving pilot or other object using GNSS, image recognition or homing beacon.
• GPS waypoint navigation: Using GNSS to navigate to an intermediate location on a travel path.
• Orbit around an object: Similar to Follow-me but continuously circle a target.
• Pre-programmed aerobatics (such as rolls and loops)
• Pre-programmed delivery (delivery drones)

One approach to quantifying autonomous capabilities is based on OODA terminology, as suggested by a 2002 US Air Force Research Laboratory report, and used in the table on the right.^[112]

Full autonomy is available for specific tasks, such as airborne refueling^[113] or ground-based battery switching.

Other functions available or under development include; collective flight, real-time collision avoidance, wall following, corridor centring, simultaneous localization and mapping and swarming,^[114] cognitive radio, and machine learning. In this context, computer vision can play an important role for automatically ensuring flight safety.

Performance considerations

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Flight envelope

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UAVs can be programmed to perform aggressive maneuvers or landing/perching on inclined surfaces,^[115] and then to climb toward better communication spots.^[116] Some UAVs can control flight with varying flight modelisation,^[117][118] such as VTOL designs.

UAVs can also implement perching on a flat vertical surface.^[119]

Endurance

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UAV endurance is not constrained by the physiological capabilities of a human pilot.

Because of their small size, low weight, low vibration and high power to weight ratio, Wankel rotary engines are used in many large UAVs. Their engine rotors cannot seize; the engine is not susceptible to shock-cooling during descent and it does not require an enriched fuel mixture for cooling at high power. These attributes reduce fuel usage, increasing range or payload.

Proper drone cooling is essential for long-term drone endurance. Overheating and subsequent engine failure is the most common cause of drone failure.^[120]

Hydrogen fuel cells, using hydrogen power, may be able to extend the endurance of small UAVs, up to several hours.^[121][122]

Micro air vehicles endurance is so far best achieved with flapping-wing UAVs, followed by planes and multirotors standing last, due to lower Reynolds number.^[100]

Solar-electric UAVs, a concept originally championed by the AstroFlight Sunrise in 1974, have achieved flight times of several weeks.

Solar-powered atmospheric satellites (“atmosats”) designed for operating at altitudes exceeding 20 km (12 miles, or 60,000 feet) for as long as five years could potentially perform duties more economically and with more versatility than low Earth orbit satellites. Likely applications include weather drones for weather monitoring, disaster recovery, Earth imaging and communications.

Electric UAVs powered by microwave power transmission or laser power beaming are other potential endurance solutions.^[123]

Another application for a high endurance UAV would be to “stare” at a battlefield for a long interval (ARGUS-IS, Gorgon Stare, Integrated Sensor Is Structure) to record events that could then be played backwards to track battlefield activities.

The delicacy of the British PHASA-35 military drone (at a late stage of development) is such that traversing the first turbulent twelve miles of atmosphere is a hazardous endeavor. It has, however, remained on station at 65,000 feet for 24 hours. Airbus’ Zephyr in 2023 has attained 70,000 feet and flown for 64 days; 200 days aimed at. This is sufficiently close enough to near-space for them to be regarded in “pseudo-satellites” as regards to their operational capabilities.^[133]

Reliability

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Reliability improvements target all aspects of UAV systems, using resilience engineering and fault tolerance techniques.

Individual reliability covers robustness of flight controllers, to ensure safety without excessive redundancy to minimize cost and weight.^[134] Besides, dynamic assessment of flight envelope allows damage-resilient UAVs, using non-linear analysis with ad hoc designed loops or neural networks.^[135] UAV software liability is bending toward the design and certifications of crewed avionics software.^[136]

Swarm resilience involves maintaining operational capabilities and reconfiguring tasks given unit failures.^[137]

Applications

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Main article: List of unmanned aerial vehicle applications

In recent years, autonomous drones have begun to transform various application areas as they can fly beyond visual line of sight (BVLOS)^[138] while maximizing production, reducing costs and risks, ensuring site safety, security and regulatory compliance,^[139] and protecting the human workforce in times of a pandemic.^[140] They can also be used for consumer-related missions like package delivery, as demonstrated by Amazon Prime Air, and critical deliveries of health supplies.

There are numerous civilian, commercial, military, and aerospace applications for UAVs.^[4] These include:GeneralRecreation, disaster relief, archeology, conservation of biodiversity and habitat,^[141]law enforcement, crime, and terrorism.CommercialAerial surveillance, filmmaking,^[142]journalism, scientific research, surveying, cargo transport, mining, manufacturing, forestry, solar farming, thermal energy, ports and agriculture.

Warfare

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Main articles: Unmanned combat aerial vehicle, Drone warfare, Loitering munition, Unmanned surveillance and reconnaissance aerial vehicle, Miniature UAV, Micro air vehicle, and Target drone

As of 2020, seventeen countries have armed UAVs, and more than 100 countries use UAVs in a military capacity.^[143] The first five countries producing domestic UAV designs are the United States, China, Israel, Iran and Turkey.^{[144][145][146][147]} Top military UAV manufactures are including General Atomics, Lockheed Martin, Northrop Grumman, Boeing, Baykar,^[148][145] TAI, IAIO, CASC and CAIG.^[147] China has established and expanded its presence in military UAV market^[147] since 2010. In the early 2020s, Turkey also established and expanded its presence in the military UAV market.^{[144][147][145][148]}

In the early 2010s, Israeli companies mainly focused on small surveillance UAV systems, and by the number of drones, Israel exported 60.7% (2014) of UAVs on the market while the United States exported 23.9% (2014).^[149] Between 2010 and 2014, there were 439 drones exchanged compared to 322 in the five years previous to that, among these only small fraction of overall trade – just 11 (2.5%) of the 439 are armed drones.^[149] The US alone operated over 9,000 military UAVs in 2014; among them more than 7000 are RQ-11 Raven miniature UAVs.^[150] Since 2010, Chinese drone companies have begun to export large quantities of drones to the global military market. Of the 18 countries that are known to have received military drones between 2010 and 2019, the top 12 all purchased their drones from China.^[147][151] The shift accelerated in the 2020s due to China’s advancement in drone technologies and manufacturing, compounded by market demand from the Russian invasion of Ukraine and the Israel-Gaza conflict.^{[152][153][154][155]}

For intelligence and reconnaissance missions, the inherent stealth of micro UAV flapping-wing ornithopters, imitating birds or insects, offers potential for covert surveillance and makes them difficult targets to bring down.

Unmanned surveillance and reconnaissance aerial vehicle are used for reconnaissance, attack, demining, and target practice.

Following the 2022 Russian invasion of Ukraine a dramatic increase in UAV development took place with Ukraine creating the Brave1 platform to promote rapid development of innovative systems.

Civil applications

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The civilian (commercial and general) drone market is dominated by Chinese companies. Chinese manufacturer DJI alone had 74% of the civil market share in 2018, with no other company accounting for more than 5%.^[156] The companies continue to hold over 70% of global market share by 2023, despite under increasing scrutinies and sanctions from the United States.^[157] The US Interior Department grounded its fleet of DJI drones in 2020, while the Justice Department prohibited the use of federal funds for the purchase of DJI and other foreign-made UAVs.^[158][159] DJI is followed by American company 3D Robotics, Chinese company Yuneec, Autel Robotics, and French company Parrot.^[160][161]

As of May 2021, 873,576 UAVs had been registered with the US FAA, of which 42% were categorized as commercial and 58% as recreational.^[162] 2018 NPD point to consumers increasingly purchasing drones with more advanced features with 33 percent growth in both the $500+ and $1000+ market segments.^[163]

The civil UAV market is relatively new compared to the military one. Companies are emerging in both developed and developing nations at the same time. Many early-stage startups have received support and funding from investors, as is the case in the United States, and from government agencies, as is the case in India.^[164] Some universities offer research and training programs or degrees.^[165] Private entities also provide online and in-person training programs for both recreational and commercial UAV use.^[166]

Consumer drones are widely used by police and military organizations worldwide because of the cost-effective nature of consumer products. Since 2018, the Israeli military have used DJI UAVs for light reconnaissance missions.^{[167][168][153]} DJI drones have been used by Chinese police in Xinjiang since 2017^[169][170] and American police departments nationwide since 2018.^[171][172] Both Ukraine and Russia used commercial DJI drones extensively during the Russian invasion of Ukraine.^[173] These civilian DJI drones were sourced by governments, hobbyists, international donations to Ukraine and Russia to support each side on the battlefield, and were often flown by drone hobbyists recruited by the armed forces. The prevalence of DJI drones was attributable to their market dominance, affordability, high performance, and reliability.^[174]

Entertainment

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See also: Drone art and Drone racing

Drones are also used in nighttime displays for artistic and advertising purposes with the main benefits are that they are safer, quieter and better for the environment than fireworks. They can replace or be an adjunct for fireworks displays to reduce the financial burden of festivals. In addition they can complement fireworks due to the ability for drones to carry them, creating new forms of artwork in the process.^{[175][176][177]}

Drones can also be used for racing, either with or without VR functionality.

Aerial photography

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See also: Drone journalism

Drones are ideally suited to capturing aerial shots in photography and cinematography, and are widely used for this purpose.^[142] Small drones avoid the need for precise coordination between pilot and cameraman, with the same person taking on both roles. Big drones with professional cine cameras usually have a drone pilot and a camera operator who controls camera angle and lens. For example, the AERIGON cinema drone, used in film production, is operated by two people.^{[178][full citation needed]} Drones provide access to dangerous, remote or otherwise inaccessible sites.

Environmental monitoring

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UASs or UAVs offer the great advantage for environmental monitoring to generate a new generation of survey at very-high or ultra-high resolution both in space and time.^[179] This gives the opportunity to bridge the existing gap between satellite data and field monitoring. This has stimulated a huge number of activities in order to enhance the description of natural and agricultural ecosystems. Most common applications are:

• Topographic surveys^[180] for the production of orthomosaics, digital surface models and 3D models;
• Monitoring of natural ecosystems for biodiversity monitoring,^[181] habitat mapping,^[182] detection of invasive alien species^[183] and study of ecosystem degradation due to invasive species or disturbances;
• Precision agriculture^[184] which exploits all available technologies including UAV in order to produce more with less (e.g., optimisation of fertilizers, pesticides, irrigation);
• River monitoring several methods have been developed to perform flow monitoring using image velocimetry methods which allow to properly describe the 2D flow velocity fields.^[185]
• Structural integrity of any type of structure whether it be a dam, railway or other dangerous, inaccessible or massive locations for building monitoring.^[186]
• Mineral detection for acid mine drainage using UAVs and hyperspectral cameras can produce detailed maps of proxy minerals (e.g. goethite, jarosite) for certain pH-values in natural, mining and post-mining environments, such as remediated sites.^[187][188]

These activities can be completed with different measurements, such as photogrammetry, thermography, multispectral images, 3D field scanning, and normalized difference vegetation index maps.

Geological hazards

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UAVs have become a widely used tool for studying geohazards such as landslides.^[189] Various sensors, including radar, optical, and thermal, can be mounted on UAVs to monitor different properties. UAVs enable the capture of images of various landslide features, such as transverse, radial, and longitudinal cracks, ridges, scarps, and surfaces of rupture, even in inaccessible areas of the sliding mass.^[190][191] Moreover, processing the optical images captured by UAVs also allows for the creation of point clouds and 3D models, from which these properties can be derived.^[192] Comparing point clouds obtained at different times allows for the detection of changes caused by landslide deformation.^[193][194]

Mineral exploration

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UAVs may help in the discovery of new or reevaluation of known mineral deposits to meet the demand for raw materials such as critical raw metals (e.g. cobalt, nickel), rare earths and battery minerals. By employing a suite of sensors (e.g. spectral imaging, Lidar, magnetics, gamma-ray spectroscopy),^[195][196] and similar to those used in environmental monitoring, UAV-based data can produce maps of geological surface and subsurface features, contributing to more efficient and targeted mineral exploration.^[197][198]

Agriculture, forestry and environmental studies

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Main article: Agricultural drone

As global demand for food production grows exponentially, resources are depleted, farmland is reduced, and agricultural labor is increasingly in short supply, there is an urgent need for more convenient and smarter agricultural solutions than traditional methods, and the agricultural drone and robotics industry is expected to make progress.^[199] Agricultural drones have been used to help build sustainable agriculture all over the world leading to a new generation of agriculture.^[200] In this context, there is a proliferation of innovations in both tools and methodologies which allow precise description of vegetation state and also may help to precisely distribute nutrients, pesticides or seeds over a field.^[7]

The use of UAVs is also being investigated to help detect and fight wildfires, whether through observation or launching pyrotechnic devices to start backfires.^[201]

UAVs are also now widely used to survey wildlife such as nesting seabirds, seals and even wombat burrows.^[202]

Law enforcement

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Main article: Use of UAVs in law enforcement

Police can use drones for applications such as search and rescue and traffic monitoring.^[203]

Humanitarian aid

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See also: Delivery drone

Drones are increasingly finding their application in humanitarian aid and disaster relief, where they are used for a wide range of applications such as delivering food, medicine and essential items to remote areas or image mapping before and following disasters.^[204]

Safety and security

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See also: List of UAV-related incidents and Unmanned combat aerial vehicle

Threats

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Nuisance

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UAVs can threaten airspace security in numerous ways, including unintentional collisions or other interference with other aircraft, deliberate attacks or by distracting pilots or flight controllers. The first incident of a drone-airplane collision occurred in mid-October 2017 in Quebec City, Canada.^[205] The first recorded instance of a drone collision with a hot air balloon occurred on 10 August 2018 in Driggs, Idaho, United States; although there was no significant damage to the balloon nor any injuries to its 3 occupants, the balloon pilot reported the incident to the National Transportation Safety Board, stating that “I hope this incident helps create a conversation of respect for nature, the airspace, and rules and regulations”.^[206] Unauthorized UAV flights into or near major airports have prompted extended shutdowns of commercial flights.^[207]

Drones caused significant disruption at Gatwick Airport during December 2018, needing the deployment of the British Army.^[208][209]

In the United States, flying close to a wildfire is punishable by a maximum $25,000 fine. Nonetheless, in 2014 and 2015, firefighting air support in California was hindered on several occasions, including at the Lake Fire^[210] and the North Fire.^[211][212] In response, California legislators introduced a bill that would allow firefighters to disable UAVs which invaded restricted airspace.^[213] The FAA later required registration of most UAVs.

Security vulnerabilities

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By 2017, drones were being used to drop contraband into prisons.^[214]

The interest in UAVs cybersecurity has been raised greatly after the Predator UAV video stream hijacking incident in 2009,^[215] where Islamic militants used cheap, off-the-shelf equipment to stream video feeds from a UAV. Another risk is the possibility of hijacking or jamming a UAV in flight. Several security researchers have made public some vulnerabilities in commercial UAVs, in some cases even providing full source code or tools to reproduce their attacks.^[216] At a workshop on UAVs and privacy in October 2016, researchers from the Federal Trade Commission showed they were able to hack into three different consumer quadcopters and noted that UAV manufacturers can make their UAVs more secure by the basic security measures of encrypting the Wi-Fi signal and adding password protection.^[217]

Aggression

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Many UAVs have been loaded with dangerous payloads, and/or crashed into targets. Payloads have included or could include explosives, chemical, radiological or biological hazards. UAVs with generally non-lethal payloads could possibly be hacked and put to malicious purposes. Counter-UAV systems (C-UAS), from detection to electronic warfare to UAVs designed to destroy other UAVs, are in development and being deployed by states to counter this threat.

Such developments have occurred despite the difficulties. As J. Rogers stated in a 2017 interview to A&T, “There is a big debate out there at the moment about what the best way is to counter these small UAVs, whether they are used by hobbyists causing a bit of a nuisance or in a more sinister manner by a terrorist actor”.^[218]

Countermeasures

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Counter unmanned air system

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Further information: Electronic warfare

The malicious use of UAVs has led to the development of counter unmanned air system (C-UAS) technologies. Automatic tracking and detection of UAVs from commercial cameras have become accurate thanks to the development of deep learning based machine learning algorithms.^[219] It is also possible to automatically identify UAVs across different cameras with different viewpoints and hardware specification with re-identification methods.^[220] Commercial systems such as the Aaronia AARTOS have been installed on major international airports.^[221][222] Once a UAV is detected, it can be countered with kinetic force (missiles, projectiles or another UAV) or by non-kinetic force (laser, microwaves, communications jamming).^[223] Anti-aircraft missile systems such as the Iron Dome are also being enhanced with C-UAS technologies. Utilising a smart UAV swarm to counter one or more hostile UAVs is also proposed.^[224]

Regulation

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Main article: Regulation of unmanned aerial vehicles

Regulatory bodies around the world are developing unmanned aircraft system traffic management solutions to better integrate UAVs into airspace.^[225]

The use of unmanned aerial vehicles is becoming increasingly regulated by the civil aviation authorities of individual countries. Regulatory regimes can differ significantly according to drone size and use. The International Civil Aviation Organization (ICAO) began exploring the use of drone technology as far back as 2005, which resulted in a 2011 report.^[226] France was among the first countries to set a national framework based on this report and larger aviation bodies such as the FAA and the EASA quickly followed suit.^[227] In 2021, the FAA published a rule requiring all commercially used UAVs and all UAVs regardless of intent weighing 250 g or more to participate in Remote ID, which makes drone locations, controller locations, and other information public from takeoff to shutdown; this rule has since been challenged in the pending federal lawsuit RaceDayQuads v. FAA.^[228][229]

EU Drone Certification – Class Identification Label

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The implementation of the Class Identification Label serves a crucial purpose in the regulation and operation of drones.^[230] The label is a verification mechanism designed to confirm that drones within a specific class meet the rigorous standards set by administrations for design and manufacturing.^[231] These standards are necessary to ensure the safety and reliability of drones in various industries and applications.

By providing this assurance to customers, the Class Identification Label helps to increase confidence in drone technology and encourages wider adoption across industries. This, in turn, contributes to the growth and development of the drone industry and supports the integration of drones into society.

Export controls

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The export of UAVs or technology capable of carrying a 500 kg payload at least 300 km is restricted in many countries by the Missile Technology Control Regime.

Unmanned aerial vehicle (UAV, Drone)最先出现在XingFei Technology Co., Ltd.。

“Consumer Electronics” redirects here. For the electronic music group, see Philip Best.

Consumer electronics or home electronics are electronic (analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. These products are usually referred to as black goods in American English, due to many products being housed in black or dark casings. This term is used to distinguish them from “white goods“, which are meant for housekeeping tasks, such as washing machines and refrigerators.^[1][2] In British English, they are often called brown goods by producers and sellers.^{[3][n 1]} In the 2010s, this distinction is absent in large big box consumer electronics stores, which sell entertainment, communication and home office devices, light fixtures and appliances, including the bathroom type.

Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver. Later products included telephones, televisions, and calculators, then audio and video recorders and players, video game consoles, mobile phones, personal computers and MP3 players. In the 2010s, consumer electronics stores often sell GPS, automotive electronics (vehicle audio), video game consoles, electronic musical instruments (e.g., synthesizer keyboards), karaoke machines, digital cameras, and video players (VCRs in the 1980s and 1990s, followed by DVD players and Blu-ray players). Stores also sell smart light fixtures and appliances, digital cameras, camcorders, mobile phones, and smartphones. Some of the newer products sold include virtual reality head-mounted display goggles, smart home devices that connect home devices to the Internet, streaming devices, and wearable technology.

In the 2010s, most consumer electronics have become based on digital technologies. They have essentially merged with the computer industry in what is increasingly referred to as the consumerization of information technology. Some consumer electronics stores have also begun selling office and baby furniture. Consumer electronics stores may be “brick and mortar” physical retail stores, online stores, or combinations of both. Annual consumer electronics sales are expected to reach $2.9 trillion by 2020.^[5] It is part of the wider electronics industry. In turn, the driving force behind the electronics industry is the semiconductor industry.^[6]

目录

• 1History
  • 1.1White Goods
• 2Products
  • 2.1Trends
  • 2.2Business competition
• 3Industries
  • 3.1Manufacturing
    • 3.1.1Electronic component
    • 3.1.2Software development
    • 3.1.3Standardization
  • 3.2Trade shows
  • 3.3IEEE initiatives
  • 3.4Retailing
  • 3.5Service and repair
  • 3.6Mobile phone industry
    • 3.6.1By country
• 4Environmental impact
  • 4.1Rare metals and rare earth elements
  • 4.2Energy consumption
  • 4.3Standby power
  • 4.4Electronic waste
    • 4.4.1Reuse and repair
• 5Health impact
• 6See also
• 7References
• 8Notes
• 9Further reading

History

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Main article: History of electronic engineering

For its first fifty years, the phonograph turntable did not use electronics; the needle and sound horn were purely mechanical technologies. However, in the 1920s, radio broadcasting became the basis of mass production of radio receivers. The vacuum tubes that had made radios practical were used with record players as well, to amplify the sound so that it could be played through a loudspeaker. Television was soon invented but remained insignificant in the consumer market until the 1950s.

The first working transistor, a point-contact transistor, was invented by John Bardeen and Walter Houser Brattain at Bell Labs in 1947, which led to significant research in the field of solid-state semiconductors in the early-1950s.^[7] The invention and development of the earliest transistors at Bell led to transistor radios. This led to the emergence of the home entertainment consumer electronics industry starting in the 1950s, largely due to the efforts of Tokyo Tsushin Kogyo (now Sony) in successfully commercializing transistor technology for a mass market, with affordable transistor radios and then transistorized television sets.^[8]

Integrated circuits (ICs) followed when manufacturers built circuits (usually for military purposes) on a single substrate using electrical connections between circuits within the chip itself. IC technology led to more advanced and cheaper consumer electronics, such as transistorized televisions, pocket calculators, and by the 1980s, affordable video game consoles and personal computers that regular middle-class families could buy.

Starting in the 1980s with the compact disc and the introduction of personal computers, and until the early 2000s, many consumer electronics devices such as televisions and stereo systems, were digitized: digital computer technology, and thus digital signals, were integrated into the operation of consumer electronics devices, drastically changing their operation but with improved results such as improved image quality in televisions. This was made possible by Moore’s law.^[9]

In 2004, the consumer electronics industry was worth US$240 billion annually worldwide comprising visual equipment, audio equipment, and games consoles. It was truly global with Asia Pacific having 35% market share, Europe having 31.5%, the US having 23%, and the rest of the world having the rest. Major players in this industry are household names like Sony, Samsung, Philips, Sanyo, and Sharp.^[10]

White Goods

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The increase in popularity of such domestic appliances as ‘white goods‘ is a characteristic element of consumption patterns during the golden age of the Western economy.^[11] Europe’s White Goods industry has evolved over the past 40 years, first by changing tariff barriers, and later by technical and demand shifts. ^[12] The spending on domestic appliances has claimed only a tiny fraction of disposable income, rising from 0.5 percent in the US in 1920, to about 2 percent in 1980. Yet the sequence of electrical and mechanical durables have altered the activities and experiences of households in America and Britain in the twentieth century. With the expansion of cookers, vacuum cleaners, refrigerators, washing machines, radios, televisions, air conditioning, and microwave ovens, households have gained an escalating number of appliances. Despite the ubiquity of these goods, their diffusion is not well understood. Some types of appliances diffuse more frequently than others. In particular, home entertainment appliances such as radio and television have diffused much faster than household and kitchen machines.”^[13]

Products

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See also: List of electronics brands, Category:Consumer electronics, and Electronics industry

Consumer electronics devices include those used for ^[14]

• entertainment (flatscreen TVs, television sets, MP3 players, video recorders, DVD players, radio receivers, etc.)
• communications (telephones, mobile phones, email-capable personal computers, desktop computers, laptops, printers, paper shredders, etc.)
• recreation (digital cameras, camcorders, video game consoles, ROM cartridges, radio-controlled cars, robot kits, etc.).

Increasingly consumer electronics products such as digital distribution of video games have become based on the internet and digital technologies. The consumer electronics industry has primarily merged with the software industry in what is increasingly referred to as the consumerization of information technology.

Trends

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One overriding characteristic of consumer electronic products is the trend of ever-falling prices. This is driven by gains in manufacturing efficiency and automation, lower labor costs as manufacturing has moved to lower-wage countries, and improvements in semiconductor design.^[23] Semiconductor components benefit from Moore’s law, an observed principle which states that, for a given price, semiconductor functionality doubles every two years.

While consumer electronics continues in its trend of convergence, combining elements of many products, consumers face different purchasing decisions. There is an ever-increasing need to keep product information updated and comparable for the consumer to make an informed choice. Style, price, specification, and performance are all relevant. There are a gradual shift towards e-commerce web-storefronts.

Many products include Internet access using technologies such as Wi-Fi, Bluetooth, EDGE, or Ethernet. Products not traditionally associated with computer use (such as TVs or hi-fi equipment) now provide options to connect to the Internet or to a computer using a home network to provide access to digital content. The desire for high-definition (HD) content has led the industry to develop a number of technologies, such as WirelessHD or ITU-T G.hn, which are optimized for distribution of HD content between consumer electronic devices in a home.

Business competition

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The consumer electronics industry faces consumers with unpredictable tastes on the demand side, supplier-related delays or disruptions on the supply side, and production challenges occurring in the process. The high rate of technology evolution or revolution requires large investments without any guarantee of profitable returns. As a result, the big players rely on global markets to achieve economies of scale. Even these companies sometimes have to cooperate with each other, for instance on standards, to reduce the risk of their investments.^[24] In supply chain management, there is much discussion on risks related to such aspects of supply chains as short product life cycles, high competition combined with cooperation, and globalization. The consumer electronics industry is the very embodiment of these aspects of supply chain management and related risks. While some of the supply and demand related risks are similar to such industries as the toy industry, the consumer electronics industry faces additional risks due to its vertically integrated supply chains.^[24] There are also numerous supply-chain-wide contextual risks that cut across the supply chain especially impacting companies with global supply chains. These include cultural differences in multinational operations, environmental risk, regulations risk, and exchange rate risk across multiple countries.^[25] Whether or not demand is comparable across countries affects the extent of the gains from international integration. In addition, consumer preferences change over time to disturb existing patterns of behavior. A feature of some industries is that demand for variety increases as the market moves from first-time buying to replacement demand.^[26] A resource to further understand this idea of consumer preferences can be observed through Lizabeth Cohen’s book titled, “A Consumers’ Republic”, “Only if we have large demands can we expect large production”.^[27]

Industries

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Main article: Electronics industry

See also: Electronics industry in Japan, Electronics industry in China, and Electronics industry in Bangladesh

The electronics industry, especially consumer electronics, emerged in the 20th century and has become a global industry worth billions of dollars. Contemporary society uses all manner of electronic devices built-in automated or semi-automated factories operated by the industry.

Manufacturing

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Main article: Electronics industry

See also: Electronic packaging

Most consumer electronics are built in China, due to maintenance cost, availability of materials, quality, and speed as opposed to other countries such as the United States.^[28] Cities such as Shenzhen have become important production centres for the industry, attracting many consumer electronics companies such as Apple Inc.^[29]

Electronic component

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Main article: Electronic component

An electronic component is any essential discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form, and are not to be confused with electrical elements, conceptual abstractions representing idealized electronic components.

Software development

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See also: Software development

Consumer electronics such as personal computers use various types of software. Embedded software is used within some consumer electronics, such as mobile phones.^[30] This type of software may be embedded within the hardware of electronic devices.^[31] Some consumer electronics include software that is used on a personal computer in conjunction with electronic devices, such as camcorders and digital cameras, and third-party software for such devices also exists.

Standardization

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Some consumer electronics adhere to protocols, such as connection protocols “to high speed bi-directional signals”.^[32] In telecommunications, a communications protocol is a system of digital rules for data exchange within or between computers.

Trade shows

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The Consumer Electronics Show (CES) trade show has taken place yearly in Las Vegas, Nevada since its foundation in 1973. The event, which grew from having 100 exhibitors in its inaugural year to more than 4,500 exhibiting companies in its 2020 edition, features the latest in consumer electronics, speeches by industry experts and innovation awards.^[33]

The IFA Berlin trade show has taken place in Berlin, Germany since its foundation in 1924. The event features new consumer electronics and speeches by industry pioneers.

IEEE initiatives

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Institute of Electrical and Electronics Engineers (IEEE), the world’s largest professional society, has many initiatives to advance the state of the art of consumer electronics. IEEE has a dedicated society of thousands of professionals to promote CE, called the Consumer Electronics Society (CESoc).^[34] IEEE has multiple periodicals and international conferences to promote CE and encourage collaborative research and development in CE. The flagship conference of CESoc, called IEEE International Conference on Consumer Electronics (ICCE), is in its 35th year.

• IEEE Transactions on Consumer Electronics^[35]
• IEEE Consumer Electronics Magazine^[36]
• IEEE International Conference on Consumer Electronics (ICCE)^[37]

Institute of Electrical and Electronics Engineers (IEEE) Computer Society also have initiated a conference to research on next generation consumer electronics as Smart Electronics. ^[38] The conference named IEEE Symposium on Smart Electronics Systems (IEEE-iSES) is on its 9th year.^[39]

Retailing

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See also: Consumer electronics store

Electronics retailing is a significant part of the retail industry in many countries. In the United States, dedicated consumer electronics stores have mostly given way to big-box stores such as Best Buy, the largest consumer electronics retailer in the country,^[40] although smaller dedicated stores include Apple Stores, and specialist stores that serve, for example, audiophiles and exceptions, such as the single-branch B&H Photo store in New York City. Broad-based retailers, such as Walmart and Target, also sell consumer electronics in many of their stores.^[40] In April 2014, retail e-commerce sales were the highest in the consumer electronic and computer categories as well.^[41] Some consumer electronics retailers offer extended warranties on products with programs such as SquareTrade.^[42]

See also: Category:Consumer electronics retailers

An electronics district is an area of commerce with a high density of retail stores that sell consumer electronics.^[43]

See also: Category:Electronics districts

Service and repair

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See also: Electronics technician

Consumer electronic service can refer to the maintenance of said products. When consumer electronics have malfunctions, they may sometimes be repaired.

In 2013, in Pittsburgh, Pennsylvania, the increased popularity in listening to sound from analog audio devices, such as phonographs, as opposed to digital sound, has sparked a noticeable increase of business for the electronic repair industry there.^[44]

Mobile phone industry

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A mobile phone, cellular phone, cell phone, cellphone, handphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Modern mobile telephone services use a cellular network architecture and, therefore, mobile telephones are called cellular telephones or cell phones in North America. In addition to telephony, digital mobile phones (2G) support a variety of other services, such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, video games and digital photography. Mobile phones offering only those capabilities are known as feature phones; mobile phones which offer greatly advanced computing capabilities are referred to as smartphones.^[45]

A smartphone is a portable device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which facilitate wider software, internet (including web navigation over mobile broadband), and multimedia functionality (including music, video, cameras, and gaming), alongside core phone functions such as voice calls and text messaging. Smartphones typically contain a number of MOSFET integrated circuit (IC) chips, include various sensors that can be leveraged by pre-included and third-party software (such as a magnetometer, proximity sensors, barometer, gyroscope, accelerometer and more), and support wireless communications protocols (such as Bluetooth, Wi-Fi, or satellite navigation).

By country

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Main articles: Mobile phone industry in India, Mobile phone industry in Japan, Mobile phone industry in Russia, and Mobile phone industry in South Korea

Environmental impact

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In 2017, Greenpeace USA published a study of 17 of the world’s leading consumer electronics companies about their energy and resource consumption and the use of chemicals.^[46]

Rare metals and rare earth elements

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Electronic devices use thousands rare metals and rare earth elements (40 on average for a smartphone), these material are extracted and refined using water and energy-intensive processes. These metals are also used in the renewable energy industry meaning that consumer electronics are directly competing for the raw materials.^[47][48]

Energy consumption

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The energy consumption of consumer electronics and their environmental impact, either from their production processes or the disposal of the devices, is increasing steadily. EIA estimates that electronic devices and gadgets account for about 10%–15% of the energy use in American homes – largely because of their number; the average house has dozens of electronic devices.^[49] The energy consumption of consumer electronics increases – in America and Europe – to about 50% of household consumption if the term is redefined to include home appliances such as refrigerators, dryers, clothes washers and dishwashers.

Standby power

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Standby power – used by consumer electronics and appliances while they are turned off – accounts for 5–10% of total household energy consumption, costing $100 annually to the average household in the United States.^[50] A study by United States Department of Energy‘s Berkeley Lab found that a videocassette recorders (VCRs) consume more electricity during the course of a year in standby mode than when they are used to record or playback videos. Similar findings were obtained concerning satellite boxes, which consume almost the same amount of energy in “on” and “off” modes.^[51]

A 2012 study in the United Kingdom, carried out by the Energy Saving Trust, found that the devices using the most power on standby mode included televisions, satellite boxes, and other video and audio equipment. The study concluded that UK households could save up to £86 per year by switching devices off instead of using standby mode.^[52] A report from the International Energy Agency in 2014 found that $80 billion of power is wasted globally per year due to inefficiency of electronic devices.^[53] Consumers can reduce unwanted use of standby power by unplugging their devices, using power strips with switches, or by buying devices that are standardized for better energy management, particularly Energy Star-marked products.^[50]

Electronic waste

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A high number of different metals and low concentration rates in electronics means that recycling is limited and energy intensive.^[47] Electronic waste describes discarded electrical or electronic devices. Many consumer electronics may contain toxic minerals and elements,^[54] and many electronic scrap components, such as CRTs, may contain contaminants such as lead, cadmium, beryllium, mercury, dioxins, or brominated flame retardants. Electronic waste recycling may involve significant risk to workers and communities and great care must be taken to avoid unsafe exposure in recycling operations and leaking of materials such as heavy metals from landfills and incinerator ashes. However, large amounts of the produced electronic waste from developed countries is exported, and handled by the informal sector in countries like India, despite the fact that exporting electronic waste to them is illegal. Strong informal sector can be a problem for the safe and clean recycling.^[55]

Reuse and repair

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E-waste policy has gone through various incarnations since the 1970s, with emphases changing as the decades passed. More weight was gradually placed on the need to dispose of e-waste more carefully due to the toxic materials it may contain. There has also been recognition that various valuable metals and plastics from waste electrical equipment can be recycled for other uses. More recently, the desirability of reusing whole appliances has been foregrounded in the ‘preparation for reuse’ guidelines. The policy focus is slowly moving towards a potential shift in attitudes to reuse and repair.

With turnover of small household appliances high and costs relatively low, many consumers will throw unwanted electric goods in the normal dustbin, meaning that items of potentially high reuse or recycling value go to landfills. While more oversized items such as washing machines are usually collected, it has been estimated that the 160,000 tonnes of EEE in regular waste collections were worth £220 million. And 23% of EEE taken to Household Waste Recycling Centres was immediately resaleable – or would be with minor repairs or refurbishment. This indicates a lack of awareness among consumers about where and how to dispose of EEE and the potential value of things that are going in the bin.

For the reuse and repair of electrical goods to increase substantially in the UK, some barriers must be overcome. These include people’s mistrust of used equipment in terms of whether it will be functional, safe and the stigma for some of owning second-hand goods. But the benefits of reuse could allow lower-income households access to previously unaffordable technology while helping the environment at the same time.^[56]

Health impact

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Desktop monitors and laptops produce major physical health concerns for humans when bodies are forced into unhealthy and uncomfortable positions to see the screen better. From this, neck and back pains and problems increase, commonly referred to as repetitive strain injuries. Using electronics before going to bed makes it difficult for people to fall asleep, hurting human health. Sleeping less prevents people from performing to their full potential physically and mentally and can also “increase rates of obesity and diabetes”, which are “long-term health consequences”.^[57] Obesity and diabetes are more commonly seen in students and in youth because they tend to be the ones using electronics the most. “People who frequently use their thumbs to type text messages on cell phones can develop a painful affliction called De Quervain syndrome that affects their tendons on their hands. The best-known disease in this category is called carpal tunnel syndrome, which results from pressure on the median nerve in the wrist”.^[57]

Consumer electronics最先出现在XingFei Technology Co., Ltd.。

From wikipedia: https://en.wikipedia.org/wiki/USB

This article is about the computer bus standard. For other uses, see USB (disambiguation).

Universal Serial Bus (USB) is an industry standard, developed by USB Implementers Forum (USB-IF), for digital data transmission and power delivery between many types of electronics. It specifies the architecture, in particular the physical interfaces, and communication protocols to and from hosts, such as personal computers, to and from peripheral devices, e.g. displays, keyboards, and mass storage devices, and to and from intermediate hubs, which multiply the number of a host’s ports.^[2]

Introduced in 1996, USB was originally designed to standardize the connection of peripherals to computers, replacing various interfaces such as serial ports, parallel ports, game ports, and Apple Desktop Bus (ADB) ports.^[3] Early versions of USB became commonplace on a wide range of devices, such as keyboards, mice, cameras, printers, scanners, flash drives, smartphones, game consoles, and power banks.^[4] USB has since evolved into a standard to replace virtually all common ports on computers, mobile devices, peripherals, power supplies, and manifold other small electronics.

In the latest standard, the USB-C connector replaces many types of connectors for power (up to 240 W), displays (e.g. DisplayPort, HDMI), and many other uses, as well as all previous USB connectors.

As of 2024, USB consists of four generations of specifications: USB 1.x, USB 2.0, USB 3.x, and USB4. The USB4 specification enhances the data transfer and power delivery functionality with “a connection-oriented tunneling architecture designed to combine multiple protocols onto a single physical interface so that the total speed and performance of the USB4 Fabric can be dynamically shared.”^[2] In particular, USB4 supports the tunneling of the Thunderbolt 3 protocols, namely PCI Express (PCIe, load/store interface) and DisplayPort (display interface). USB4 also adds host-to-host interfaces.^[2]

Each specification sub-version supports different signaling rates from 1.5 and 12 Mbit/s half-duplex in USB 1.0/1.1 to 80 Gbit/s full-duplex in USB4 2.0.^[5][6][7][2] USB also provides power to peripheral devices; the latest versions of the standard extend the power delivery limits for battery charging and devices requiring up to 240 watts as defined in USB Power Delivery (USB-PD) Rev. V3.1.^[8] Over the years, USB(-PD) has been adopted as the standard power supply and charging format for many mobile devices, such as mobile phones, reducing the need for proprietary chargers.^[9]

目录

• 1Overview
  • 1.1Connector type quick reference
  • 1.2Objectives
  • 1.3Limitations
• 2History
  • 2.1USB 1.x
  • 2.2USB 2.0
  • 2.3USB 3.x
    • 2.3.1Naming scheme
  • 2.4USB4
    • 2.4.1September 2022 naming scheme
  • 2.5Version history
    • 2.5.1Release versions
    • 2.5.2Power-related standards
• 3System design
• 4Device classes
  • 4.1USB mass storage / USB drive
  • 4.2Media Transfer Protocol
  • 4.3Human interface devices
  • 4.4Device Firmware Upgrade mechanism
  • 4.5Audio streaming
• 5Connectors
• 6Cabling
  • 6.1USB bridge cables
    • 6.1.1Dual-role USB connections
• 7Power
  • 7.1Low-power and high-power devices
• 8Signaling
• 9Protocol layer
• 10Transactions
• 11Related standards
  • 11.1Media Agnostic USB
  • 11.2InterChip USB
  • 11.3USB-C
  • 11.4DisplayLink
• 12Comparisons with other connection methods
  • 12.1FireWire (IEEE 1394)
  • 12.2Ethernet
  • 12.3MIDI
  • 12.4eSATA/eSATAp
  • 12.5Thunderbolt
• 13Interoperability
• 14Security threats
• 15See also
  • 15.1USB
  • 15.2Derived and related standards
• 16References
• 17Further reading
• 18External links
  • 18.1General overview
  • 18.2Technical documents

Overview

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USB was designed to standardize the connection of peripherals to personal computers, both to exchange data and to supply electric power. It has largely replaced interfaces such as serial ports and parallel ports and has become commonplace on various devices. Peripherals connected via USB include computer keyboards and mice, video cameras, printers, portable media players, mobile (portable) digital telephones, disk drives, and network adapters.

USB connectors have been increasingly replacing other types of charging cables for portable devices.^[10][11][12]

USB connector interfaces are classified into three types: the many various legacy Type-A (upstream) and Type-B (downstream) connectors found on hosts, hubs, and peripheral devices, and the modern Type-C (USB-C) connector, which replaces the many legacy connectors as the only applicable connector for USB4.

The Type-A and Type-B connectors came in Standard, Mini, and Micro sizes. The standard format was the largest and was mainly used for desktop and larger peripheral equipment. The Mini-USB connectors (Mini-A, Mini-B, Mini-AB) were introduced for mobile devices. Still, they were quickly replaced by the thinner Micro-USB connectors (Micro-A, Micro-B, Micro-AB). The Type-C connector, also known as USB-C, is not exclusive to USB, is the only current standard for USB, is required for USB4, and is required by other standards, including modern DisplayPort and Thunderbolt. It is reversible and can support various functionalities and protocols, including USB; some are mandatory, and many are optional, depending on the type of hardware: host, peripheral device, or hub.^[13][14]

USB specifications provide backward compatibility, usually resulting in decreased signaling rates, maximal power offered, and other capabilities. The USB 1.1 specification replaces USB 1.0. The USB 2.0 specification is backward-compatible with USB 1.0/1.1. The USB 3.2 specification replaces USB 3.1 (and USB 3.0) while including the USB 2.0 specification. USB4 “functionally replaces” USB 3.2 while retaining the USB 2.0 bus operating in parallel.^[5][6][7][2]

The USB 3.0 specification defined a new architecture and protocol named SuperSpeed (aka SuperSpeed USB, marketed as SS), which included a new lane for a new signal coding scheme (8b/10b symbols, 5 Gbit/s; later also known as Gen 1) providing full-duplex data transfers that physically required five additional wires and pins, while preserving the USB 2.0 architecture and protocols and therefore keeping the original four pins/wires for the USB 2.0 backward-compatibility resulting in 9 wires (with 9 or 10 pins at connector interfaces; ID-pin is not wired) in total.

The USB 3.1 specification introduced an Enhanced SuperSpeed System – while preserving the SuperSpeed architecture and protocol (SuperSpeed USB) – with an additional SuperSpeedPlus architecture and protocol (aka SuperSpeedPlus USB) adding a new coding schema (128b/132b symbols, 10 Gbit/s; also known as Gen 2); for some time marketed as SuperSpeed+ (SS+).

The USB 3.2 specification^[15] added a second lane to the Enhanced SuperSpeed System besides other enhancements so that the SuperSpeedPlus USB system part implements the Gen 1×2, Gen 2×1, and Gen 2×2 operation modes. However, the SuperSpeed USB part of the system still implements the one-lane Gen 1×1 operation mode. Therefore, two-lane operations, namely USB 3.2 Gen 1×2 (10 Gbit/s) and Gen 2×2 (20 Gbit/s), are only possible with Full-Featured USB-C. As of 2023, they are somewhat rarely implemented; Intel, however, started to include them in its 11th-generation SoC processor models, but Apple never provided them. On the other hand, USB 3.2 Gen 1(×1) (5 Gbit/s) and Gen 2(×1) (10 Gbit/s) have been quite common for some years.

Connector type quick reference

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Main article: USB hardware § Connectors

Each USB connection is made using two connectors: a receptacle and a plug. Pictures show only receptacles:

Objectives

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The Universal Serial Bus was developed to simplify and improve the interface between personal computers and peripheral devices, such as cell phones, computer accessories, and monitors, when compared with previously existing standard or ad hoc proprietary interfaces.^[17]

From the computer user’s perspective, the USB interface improves ease of use in several ways:

• The USB interface is self-configuring, eliminating the need for the user to adjust the device’s settings for speed or data format, or configure interrupts, input/output addresses, or direct memory access channels.^[18]
• USB connectors are standardized at the host, so any peripheral can use most available receptacles.
• USB takes full advantage of the additional processing power that can be economically put into peripheral devices so that they can manage themselves. As such, USB devices often do not have user-adjustable interface settings.
• The USB interface is hot-swappable (devices can be exchanged without shutting the host computer down).
• Small devices can be powered directly from the USB interface, eliminating the need for additional power supply cables.
• Because the use of the USB logo is only permitted after compliance testing, the user can have confidence that a USB device will work as expected without extensive interaction with settings and configuration.
• The USB interface defines protocols for recovery from common errors, improving reliability over previous interfaces.^[17]
• Installing a device that relies on the USB standard requires minimal operator action. When a user plugs a device into a port on a running computer, it either entirely automatically configures using existing device drivers, or the system prompts the user to locate a driver, which it then installs and configures automatically.

The USB standard also provides multiple benefits for hardware manufacturers and software developers, specifically in the relative ease of implementation:

• The USB standard eliminates the requirement to develop proprietary interfaces to new peripherals.
• The wide range of transfer speeds available from a USB interface suits devices ranging from keyboards and mice up to streaming video interfaces.
• A USB interface can be designed to provide the best available latency for time-critical functions or can be set up to do background transfers of bulk data with little impact on system resources.
• The USB interface is generalized with no signal lines dedicated to only one function of one device.^[17]

Limitations

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As with all standards, USB possesses multiple limitations to its design:

• USB cables are limited in length, as the standard was intended for peripherals on the same tabletop, not between rooms or buildings. However, a USB port can be connected to a gateway that accesses distant devices.
• USB data transfer rates are slower than those of other interconnects such as 100 Gigabit Ethernet.
• USB has a strict tree network topology and master/slave protocol for addressing peripheral devices; slave devices cannot interact with one another except via the host, and two hosts cannot communicate over their USB ports directly. Some extension to this limitation is possible through USB On-The-Go, Dual-Role-Devices^[19] and protocol bridge.
• A host cannot broadcast signals to all peripherals at once; each must be addressed individually.
• While converters exist between certain legacy interfaces and USB, they might not provide a full implementation of the legacy hardware. For example, a USB-to-parallel-port converter might work well with a printer, but not with a scanner that requires bidirectional use of the data pins.

For a product developer, using USB requires the implementation of a complex protocol and implies an “intelligent” controller in the peripheral device. Developers of USB devices intended for public sale generally must obtain a USB ID, which requires that they pay a fee to the USB Implementers Forum (USB-IF). Developers of products that use the USB specification must sign an agreement with the USB-IF. Use of the USB logos on the product requires annual fees and membership in the organization.^[17]

History

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A group of seven companies began the development of USB in 1995:^[21] Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel. The goal was to make it fundamentally easier to connect external devices to PCs by replacing the multitude of connectors at the back of PCs, addressing the usability issues of existing interfaces, and simplifying software configuration of all devices connected to USB, as well as permitting greater data transfer rates for external devices and plug and play features.^[22] Concepts of the 1979 Atari SIO serial bus, of the 8-bit Atari computers, and the 1980 IEEE-488 derived Commodore bus, and Hewlett Packard’s HP-IL bus pioneered this approach.^[23][24] A consortium lead by Apple, and containing Sony, Panasonic (Matsushita), LG, Toshiba, Hitachi, Cannon, Philips Electronics, Compaq, Thomson and Texas Instruments, would develop the concept further, from 1986, as the IEEE 1394 firewire standard and patent pool.^[25] Joseph C. Decuir, originally of Atari, then Commodore, and a designer of the Atari SIO common bus, would work on the USB project, for Microsoft, obtaining one of the related US patents.^[26] Ajay Bhatt and his team^[a] worked on the standard at Intel;^[28][29] the first integrated circuits supporting USB were produced by Intel in 1995.^[30]

USB 1.x 

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Released in January 1996, USB 1.0 specified signaling rates of 1.5 Mbit/s (Low Bandwidth or Low Speed) and 12 Mbit/s (Full Speed).^[31] It did not allow for extension cables, due to timing and power limitations. Few USB devices made it to the market until USB 1.1 was released in August 1998. USB 1.1 was the earliest revision that was widely adopted and led to what Microsoft designated the “Legacy-free PC“.^[32][33][34]

Neither USB 1.0 nor 1.1 specified a design for any connector smaller than the standard type A or type B. Though many designs for a miniaturized type B connector appeared on many peripherals, conformity to the USB 1.x standard was hampered by treating peripherals that had miniature connectors as though they had a tethered connection (that is: no plug or receptacle at the peripheral end). There was no known miniature type A connector until USB 2.0 (revision 1.01) introduced one.

USB 2.0 

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USB 2.0 was released in April 2000, adding a higher maximum signaling rate of 480 Mbit/s (maximum theoretical data throughput 53 MByte/s^[35]) named High Speed or High Bandwidth, in addition to the USB 1.x Full Speed signaling rate of 12 Mbit/s (maximum theoretical data throughput 1.2 MByte/s).^[36]

Modifications to the USB specification have been made via engineering change notices (ECNs). The most important of these ECNs are included into the USB 2.0 specification package available from USB.org:^[37]

• Mini-A and Mini-B Connector
• Micro-USB Cables and Connectors Specification 1.01
• InterChip USB Supplement
• On-The-Go Supplement 1.3 USB On-The-Go makes it possible for two USB devices to communicate with each other without requiring a separate USB host
• Battery Charging Specification 1.1 Added support for dedicated chargers, host chargers behavior for devices with dead batteries
• Battery Charging Specification 1.2:^[38] with increased current of 1.5 A on charging ports for unconfigured devices, allowing high-speed communication while having a current up to 1.5 A
• Link Power Management Addendum ECN, which adds a sleep power state

USB 3.x 

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Main article: USB 3.0

The USB 3.0 specification was released on 12 November 2008, with its management transferring from USB 3.0 Promoter Group to the USB Implementers Forum (USB-IF) and announced on 17 November 2008 at the SuperSpeed USB Developers Conference.^[39]

USB 3.0 adds a new architecture and protocol named SuperSpeed, with associated backward-compatible plugs, receptacles, and cables. SuperSpeed plugs and receptacles are identified with a distinct logo and blue inserts in standard format receptacles.

The SuperSpeed architecture provides for an operation mode at a rate of 5.0 Gbit/s, in addition to the three existing operation modes. Its efficiency is dependent on a number of factors including physical symbol encoding and link-level overhead. At a 5 Gbit/s signaling rate with 8b/10b encoding, each byte needs 10 bits to transmit, so the raw throughput is 500 MB/s. When flow control, packet framing and protocol overhead are considered, it is realistic for about two-thirds of the raw throughput, or 330 MB/s to transmit to an application.^{[40]: 4–19} SuperSpeed’s architecture is full-duplex; all earlier implementations, USB 1.0-2.0, are all half-duplex, arbitrated by the host.^[41]

Low-power and high-power devices remain operational with this standard, but devices implementing SuperSpeed can provide an increased current of between 150 mA and 900 mA, by discrete steps of 150 mA.^{[40]: 9–9}

USB 3.0 also introduced the USB Attached SCSI Protocol (UASP), which provides generally faster transfer speeds than the BOT (Bulk-Only-Transfer) protocol.

USB 3.1,^[5] released in July 2013 has two variants. The first one preserves USB 3.0’s SuperSpeed architecture and protocol and its operation mode is newly named USB 3.1 Gen 1,^{[42] [43][44]} and the second version introduces a distinctively new SuperSpeedPlus architecture and protocol with a second operation mode named as USB 3.1 Gen 2 (marketed as SuperSpeed+ USB). SuperSpeed+ doubles the maximum signaling rate to 10 Gbit/s (later marketed as SuperSpeed USB 10 Gbps by the USB 3.2 specification), while reducing line encoding overhead to just 3% by changing the encoding scheme to 128b/132b.^[42][45]

USB 3.2, released in September 2017,^[15] preserves existing USB 3.1 SuperSpeed and SuperSpeedPlus architectures and protocols and their respective operation modes, but introduces two additional SuperSpeedPlus operation modes (USB 3.2 Gen 1×2 and USB 3.2 Gen 2×2) with the new USB-C Fabric with signaling rates of 10 and 20 Gbit/s (raw data rates of 1212 and 2424 MB/s). The increase in bandwidth is a result of two-lane operation over existing wires that were originally intended for flip-flop capabilities of the USB-C connector.^[46]

Naming scheme

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Starting with the USB 3.2 specification, USB-IF introduced a new naming scheme.^[47] To help companies with the branding of the different operation modes, USB-IF recommended branding the 5, 10, and 20 Gbit/s capabilities as SuperSpeed USB 5Gbps, SuperSpeed USB 10 Gbps, and SuperSpeed USB 20 Gbps, respectively.^[48]

In 2023, they were replaced again,^[49] removing “SuperSpeed”, with USB 5Gbps, USB 10Gbps, and USB 20Gbps. With new Packaging and Port logos.^[50]

USB4

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This section needs to be updated. The reason given is: Incomplete, erroneous and not up-to-date; e.g. lacks differences between USB4 first version and 2.0. Applies also to main article.. Please help update this article to reflect recent events or newly available information. (August 2024)

Main article: USB4

The USB4 specification was released on 29 August 2019 by the USB Implementers Forum.^[51]

The USB4 2.0 specification was released on 1 September 2022 by the USB Implementers Forum.^[52]

USB4 is based on the Thunderbolt 3 protocol.^[53] It supports 40 Gbit/s throughput, is compatible with Thunderbolt 3, and backward compatible with USB 3.2 and USB 2.0.^[54][55] The architecture defines a method to share a single high-speed link with multiple end device types dynamically that best serves the transfer of data by type and application.

During CES 2020, USB-IF and Intel stated their intention to allow USB4 products that support all the optional functionality as Thunderbolt 4 products.

USB4 2.0 with 80 Gbit/s speeds was to be revealed in November 2022.^[56][57] Further technical details were to be released at two USB developer days scheduled for November 2022.^{[58][needs update]}

The USB4 specification states that the following technologies shall be supported by USB4:^[2]

September 2022 naming scheme

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Because of the previous confusing naming schemes, USB-IF decided to change it once again. As of 2 September 2022, marketing names follow the syntax “USB xGbps”, where x is the speed of transfer in Gbit/s.^[59] Overview of the updated names and logos can be seen in the adjacent table.

The operation modes USB 3.2 Gen 2×2 and USB4 Gen 2×2 – or: USB 3.2 Gen 2×1 and USB4 Gen 2×1 – are not interchangeable or compatible; all participating controllers must operate with the same mode.

Version history 

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Release versions

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Power-related standards 

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System design 

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A USB system consists of a host with one or more downstream facing ports (DFP),^[67] and multiple peripherals, forming a tiered-star topology. Additional USB hubs may be included, allowing up to five tiers. A USB host may have multiple controllers, each with one or more ports. Up to 127 devices may be connected to a single host controller.^{[68][40]: 8–29} USB devices are linked in series through hubs. The hub built into the host controller is called the root hub.

A USB device may consist of several logical sub-devices that are referred to as device functions. A composite device may provide several functions, for example, a webcam (video device function) with a built-in microphone (audio device function). An alternative to this is a compound device, in which the host assigns each logical device a distinct address and all logical devices connect to a built-in hub that connects to the physical USB cable.

USB device communication is based on pipes (logical channels). A pipe connects the host controller to a logical entity within a device, called an endpoint. Because pipes correspond to endpoints, the terms are sometimes used interchangeably. Each USB device can have up to 32 endpoints (16 in and 16 out), though it is rare to have so many. Endpoints are defined and numbered by the device during initialization (the period after physical connection called enumeration) and so are relatively permanent, whereas pipes may be opened and closed.

There are two types of pipe: stream and message.

• A message pipe is bi-directional and is used for control transfers. Message pipes are typically used for short, simple commands to the device, and for status responses from the device, used, for example, by the bus control pipe number 0.
• A stream pipe is a uni-directional pipe connected to a uni-directional endpoint that transfers data using an isochronous,^[69] interrupt, or bulk transfer:Isochronous transfersAt some guaranteed data rate (for fixed-bandwidth streaming data) but with possible data loss (e.g., realtime audio or video)Interrupt transfersDevices that need guaranteed quick responses (bounded latency) such as pointing devices, mice, and keyboardsBulk transfersLarge sporadic transfers using all remaining available bandwidth, but with no guarantees on bandwidth or latency (e.g., file transfers)

When a host starts a data transfer, it sends a TOKEN packet containing an endpoint specified with a tuple of (device_address, endpoint_number). If the transfer is from the host to the endpoint, the host sends an OUT packet (a specialization of a TOKEN packet) with the desired device address and endpoint number. If the data transfer is from the device to the host, the host sends an IN packet instead. If the destination endpoint is a uni-directional endpoint whose manufacturer’s designated direction does not match the TOKEN packet (e.g. the manufacturer’s designated direction is IN while the TOKEN packet is an OUT packet), the TOKEN packet is ignored. Otherwise, it is accepted and the data transaction can start. A bi-directional endpoint, on the other hand, accepts both IN and OUT packets.

Endpoints are grouped into interfaces and each interface is associated with a single device function. An exception to this is endpoint zero, which is used for device configuration and is not associated with any interface. A single device function composed of independently controlled interfaces is called a composite device. A composite device only has a single device address because the host only assigns a device address to a function.

When a USB device is first connected to a USB host, the USB device enumeration process is started. The enumeration starts by sending a reset signal to the USB device. The signaling rate of the USB device is determined during the reset signaling. After reset, the USB device’s information is read by the host and the device is assigned a unique 7-bit address. If the device is supported by the host, the device drivers needed for communicating with the device are loaded and the device is set to a configured state. If the USB host is restarted, the enumeration process is repeated for all connected devices.

The host controller directs traffic flow to devices, so no USB device can transfer any data on the bus without an explicit request from the host controller. In USB 2.0, the host controller polls the bus for traffic, usually in a round-robin fashion. The throughput of each USB port is determined by the slower speed of either the USB port or the USB device connected to the port.

High-speed USB 2.0 hubs contain devices called transaction translators that convert between high-speed USB 2.0 buses and full and low speed buses. There may be one translator per hub or per port.

Because there are two separate controllers in each USB 3.0 host, USB 3.0 devices transmit and receive at USB 3.0 signaling rates regardless of USB 2.0 or earlier devices connected to that host. Operating signaling rates for earlier devices are set in the legacy manner.

Device classes 

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The functionality of a USB device is defined by a class code sent to a USB host. This allows the host to load software modules for the device and to support new devices from different manufacturers.

Device classes include:^[70]

USB mass storage / USB drive 

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See also: USB mass storage device class, Disk enclosure, and External hard disk drive

The USB mass storage device class (MSC or UMS) standardizes connections to storage devices. At first intended for magnetic and optical drives, it has been extended to support flash drives and SD card readers. The ability to boot a write-locked SD card with a USB adapter is particularly advantageous for maintaining the integrity and non-corruptible, pristine state of the booting medium.

Though most personal computers since early 2005 can boot from USB mass storage devices, USB is not intended as a primary bus for a computer’s internal storage. However, USB has the advantage of allowing hot-swapping, making it useful for mobile peripherals, including drives of various kinds.

Several manufacturers offer external portable USB hard disk drives, or empty enclosures for disk drives. These offer performance comparable to internal drives, limited by the number and types of attached USB devices, and by the upper limit of the USB interface. Other competing standards for external drive connectivity include eSATA, ExpressCard, FireWire (IEEE 1394), and most recently Thunderbolt.

Another use for USB mass storage devices is the portable execution of software applications (such as web browsers and VoIP clients) with no need to install them on the host computer.^[74][75]

Media Transfer Protocol

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See also: Picture Transfer Protocol

Media Transfer Protocol (MTP) was designed by Microsoft to give higher-level access to a device’s filesystem than USB mass storage, at the level of files rather than disk blocks. It also has optional DRM features. MTP was designed for use with portable media players, but it has since been adopted as the primary storage access protocol of the Android operating system from the version 4.1 Jelly Bean as well as Windows Phone 8 (Windows Phone 7 devices had used the Zune protocol—an evolution of MTP). The primary reason for this is that MTP does not require exclusive access to the storage device the way UMS does, alleviating potential problems should an Android program request the storage while it is attached to a computer. The main drawback is that MTP is not as well supported outside of Windows operating systems.

Human interface devices

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Main article: USB human interface device class

A USB mouse or keyboard can usually be used with older computers that have PS/2 ports with the aid of a small USB-to-PS/2 adapter. For mice and keyboards with dual-protocol support, a passive adapter that contains no logic circuitry may be used: the USB hardware in the keyboard or mouse is designed to detect whether it is connected to a USB or PS/2 port, and communicate using the appropriate protocol.^{[citation needed]} Active converters that connect USB keyboards and mice (usually one of each) to PS/2 ports also exist.^[76]

Device Firmware Upgrade mechanism 

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Device Firmware Upgrade (DFU) is a generic mechanism for upgrading the firmware of USB devices with improved versions provided by their manufacturers, offering (for example) a way to deploy firmware bug fixes. During the firmware upgrade operation, USB devices change their operating mode effectively becoming a PROM programmer. Any class of USB device can implement this capability by following the official DFU specifications. Doing so allows use of DFU-compatible host tools to update the device.^[73][77][78]

DFU is sometimes used as a flash memory programming protocol in microcontrollers with built-in USB bootloader functionality. ^[79]

Audio streaming

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The USB Device Working Group has laid out specifications for audio streaming, and specific standards have been developed and implemented for audio class uses, such as microphones, speakers, headsets, telephones, musical instruments, etc. The working group has published three versions of audio device specifications:^[80][81] USB Audio 1.0, 2.0, and 3.0, referred to as “UAC”^[82] or “ADC”.^[83]

UAC 3.0 primarily introduces improvements for portable devices, such as reduced power usage by bursting the data and staying in low power mode more often, and power domains for different components of the device, allowing them to be shut down when not in use.^[84]

UAC 2.0 introduced support for High Speed USB (in addition to Full Speed), allowing greater bandwidth for multi-channel interfaces, higher sample rates,^[85] lower inherent latency,^[86][82] and 8× improvement in timing resolution in synchronous and adaptive modes.^[82] UAC2 also introduced the concept of clock domains, which provides information to the host about which input and output terminals derive their clocks from the same source, as well as improved support for audio encodings like DSD, audio effects, channel clustering, user controls, and device descriptions.^[82][87]

UAC 1.0 devices are still common, however, due to their cross-platform driverless compatibility,^[85] and also partly due to Microsoft‘s failure to implement UAC 2.0 for over a decade after its publication, having finally added support to Windows 10 through the Creators Update on 20 March 2017.^[88][89][87] UAC 2.0 is also supported by macOS, iOS, and Linux,^[82] however Android only implements a subset of the UAC 1.0 specification.^[90]

USB provides three isochronous (fixed-bandwidth) synchronization types,^[91] all of which are used by audio devices:^[92]

• Asynchronous — The ADC or DAC are not synced to the host computer’s clock at all, operating off a free-running clock local to the device.
• Synchronous — The device’s clock is synced to the USB start-of-frame (SOF) or Bus Interval signals. For instance, this can require syncing an 11.2896 MHz clock to a 1 kHz SOF signal, a large frequency multiplication.^[93][94]
• Adaptive — The device’s clock is synced to the amount of data sent per frame by the host^[95]

While the USB spec originally described asynchronous mode being used in “low cost speakers” and adaptive mode in “high-end digital speakers”,^[96] the opposite perception exists in the hi-fi world, where asynchronous mode is advertised as a feature, and adaptive/synchronous modes have a bad reputation.^[97][98][90] In reality, all types can be high-quality or low-quality, depending on the quality of their engineering and the application.^[94][82][99] Asynchronous has the benefit of being untied from the computer’s clock, but the disadvantage of requiring sample rate conversion when combining multiple sources.

Connectors 

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Main article: USB hardware § Connectors

The connectors the USB committee specifies support a number of USB’s underlying goals, and reflect lessons learned from the many connectors the computer industry has used. The female connector mounted on the host or device is called the receptacle, and the male connector attached to the cable is called the plug.^{[40]: 2-5–2-6} The official USB specification documents also periodically define the term male to represent the plug, and female to represent the receptacle.^[100]

The design is intended to make it difficult to insert a USB plug into its receptacle incorrectly. The USB specification requires that the cable plug and receptacle be marked so the user can recognize the proper orientation.^[40] The USB-C plug however is reversible. USB cables and small USB devices are held in place by the gripping force from the receptacle, with no screws, clips, or thumb-turns as some connectors use.

The different A and B plugs prevent accidentally connecting two power sources. However, some of this directed topology is lost with the advent of multi-purpose USB connections (such as USB On-The-Go in smartphones, and USB-powered Wi-Fi routers), which require A-to-A, B-to-B, and sometimes Y/splitter cables.

USB connector types multiplied as the specification progressed. The original USB specification detailed standard-A and standard-B plugs and receptacles. The connectors were different so that users could not connect one computer receptacle to another. The data pins in the standard plugs are recessed compared to the power pins, so that the device can power up before establishing a data connection. Some devices operate in different modes depending on whether the data connection is made. Charging docks supply power, and do not include a host device or data pins, allowing any capable USB device to charge or operate from a standard USB cable. Charging cables provide power connections but not data. In a charge-only cable, the data wires are shorted at the device end; otherwise, the device may reject the charger as unsuitable.

Cabling 

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Main article: USB hardware § Cabling

The USB 1.1 standard specifies that a standard cable can have a maximum length of 5 meters (16 ft 5 in) with devices operating at full speed (12 Mbit/s), and a maximum length of 3 meters (9 ft 10 in) with devices operating at low speed (1.5 Mbit/s).^{[101][102][103]}

USB 2.0 provides for a maximum cable length of 5 meters (16 ft 5 in) for devices running at high speed (480 Mbit/s).^[103]

The USB 3.0 standard does not directly specify a maximum cable length, requiring only that all cables meet an electrical specification: for copper cabling with AWG 26 wires the maximum practical length is 3 meters (9 ft 10 in).^[104]

USB bridge cables

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USB bridge cables, or data transfer cables can be found within the market, offering direct PC to PC connections. A bridge cable is a special cable with a chip and active electronics in the middle of the cable. The chip in the middle of the cable acts as a peripheral to both computers and allows for peer-to-peer communication between the computers. The USB bridge cables are used to transfer files between two computers via their USB ports.

Popularized by Microsoft as Windows Easy Transfer, the Microsoft utility used a special USB bridge cable to transfer personal files and settings from a computer running an earlier version of Windows to a computer running a newer version. In the context of the use of Windows Easy Transfer software, the bridge cable can sometimes be referenced as Easy Transfer cable.

Many USB bridge / data transfer cables are still USB 2.0, but there are also a number of USB 3.0 transfer cables. Despite USB 3.0 being 10 times faster than USB 2.0, USB 3.0 transfer cables are only 2 to 3 times faster given their design.^{[clarification needed]}

The USB 3.0 specification introduced an A-to-A cross-over cable without power for connecting two PCs. These are not meant for data transfer but are aimed at diagnostic uses.

Dual-role USB connections

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USB bridge cables have become less important with USB dual-role-device capabilities introduced with the USB 3.1 specification. Under the most recent specifications, USB supports most scenarios connecting systems directly with a Type-C cable. For the capability to work, however, connected systems must support role-switching. Dual-role capabilities requires there be two controllers within the system, as well as a role controller. While this can be expected in a mobile platform such as a tablet or a phone, desktop PCs and laptops often will not support dual roles.^[105]

Power 

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Main article: USB hardware § Power

Upstream USB connectors supply power at a nominal 5 V DC via the V_BUS pin to downstream USB devices.

Low-power and high-power devices 

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This section describes the power distribution model of USB that existed before Power-Delivery (USB-PD). On devices that do not use PD, USB provides up to 4.5 W through Type-A and Type-B connectors, and up to 15 W through USB-C. All pre-PD USB power is provided at 5 V.

For a host providing power to devices, USB has a concept of the unit load. Any device may draw power of one unit, and devices may request more power in these discrete steps. It is not required that the host provide requested power, and a device may not draw more power than negotiated.

Devices that draw no more than one unit are said to be low-power devices. All devices must act as low-power devices when starting out as unconfigured. For USB devices up to USB 2.0 a unit load is 100 mA (or 500 mW), while USB 3.0 defines a unit load as 150 mA (750 mW). Full-featured USB-C can support low-power devices with a unit load of 250 mA (or 1250 mW).

Devices that draw more than one unit are high-power devices (such as typical 2.5-inch hard disk drives). USB up to 2.0 allows a host or hub to provide up to 2.5 W to each device, in five discrete steps of 100 mA, and SuperSpeed devices (USB 3.x) allows a host or a hub to provide up to 4.5 W in six steps of 150 mA. USB-C allows for dual-lane operation of USB 3.x with larger unit load (250 mA; up to 7.5 W).^[106] USB-C also allows for Type-C Current as a replacement for USB BC, signaling power availability in a simple way, without needing any data connection.^[107]

To recognize Battery Charging mode, a dedicated charging port places a resistance not exceeding 200 Ω across the D+ and D− terminals. Shorted or near-shorted data lanes with less than 200 Ω of resistance across the D+ and D− terminals signify a dedicated charging port (DCP) with indefinite charging rates.^[108][109]

In addition to standard USB, there is a proprietary high-powered system known as PoweredUSB, developed in the 1990s, and mainly used in point-of-sale terminals such as cash registers.

Signaling

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Main article: USB communications § Signaling (USB PHY)

USB signals are transmitted using differential signaling on twisted-pair data wires with 90 Ω ± 15% characteristic impedance.^[110] USB 2.0 and earlier specifications define a single pair in half-duplex (HDx). USB 3.0 and later specifications define one dedicated pair for USB 2.0 compatibility and two or four pairs for data transfer: two data wire pairs realising full-duplex (FDx) for single lane (×1) variants require at least SuperSpeed (SS) connectors; four pairs realising full-duplex for two lane (×2) variants require USB-C connectors.

USB4 Gen 4 requires the use of all four pairs but allow for asymmetrical pairs configuration.^[111] In this case one data wire pair is used for the upstream data and the other three for the downstream data or vice-versa. USB4 Gen 4 use pulse amplitude modulation on 3 levels, providing a trit of information every baud transmitted, the transmission frequency of 12.8 GHz translate to a transmission rate of 25.6 GBd^[112] and the 11-bit–to–7-trit translation provides a theoretical maximum transmission speed just over 40.2 Gbit/s.^[113]

1. ^ 跳转到：^{a b c d e f g h} USB 2.0 implementation
2. ^ 跳转到：^a b USB4 can use optional Reed–Solomon forward error correction (RS FEC). In this mode, 12 × 16 B (128 bit) symbols are assembled together with 2 B (12 bit + 4 bit reserved) synchronization bits indicating the respective symbol types and 4 B of RS FEC to allow to correct up to 1 B of errors anywhere in the total 198 B block.

• Low-speed (LS) and Full-speed (FS) modes use a single data wire pair, labeled D+ and D−, in half-duplex. Transmitted signal levels are 0.0–0.3 V for logical low, and 2.8–3.6 V for logical high level. The signal lines are not terminated.
• High-speed (HS) uses the same wire pair, but with different electrical conventions. Lower signal voltages of −10 to 10 mV for low and 360 to 440 mV for logical high level, and termination of 45 Ω to ground or 90 Ω differential to match the data cable impedance.
• SuperSpeed (SS) adds two additional pairs of shielded twisted data wires (and new, mostly compatible expanded connectors) besides another grounding wire. These are dedicated to full-duplex SuperSpeed operation. The SuperSpeed link operates independently from the USB 2.0 channel and takes precedence on connection. Link configuration is performed using LFPS (Low Frequency Periodic Signaling, approximately at 20 MHz frequency), and electrical features include voltage de-emphasis at the transmitter side, and adaptive linear equalization on the receiver side to combat electrical losses in transmission lines, and thus the link introduces the concept of link training.
• SuperSpeed+ (SS+) uses a new coding scheme with an increased signaling rate (Gen 2×1 mode) and/or the additional lane of USB-C (Gen 1×2 and Gen 2×2 modes).

A USB connection is always between an A end, either a host or a downstream port of a hub, and a B end, either a peripheral device or the upstream port of a hub. Historically this was made clear by the fact that hosts had only Type-A and peripheral devices had only Type-B ports, and every compatible cable had one Type-A plug and one Type-B plug. USB-C (Type-C) is a single connector that replaces all legacy Type-A and Type-B connectors, so when both sides are equipment with USB Type-C ports they negotiate which is the host and which is the device.

Protocol layer

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Main article: USB (Communications) § Protocol layer

During USB communication, data is transmitted as packets. Initially, all packets are sent from the host via the root hub, and possibly more hubs, to devices. Some of those packets direct a device to send some packets in reply.

Transactions

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Main article: USB (Communications) § Transaction

The basic transactions of USB are:

• OUT transaction
• IN transaction
• SETUP transaction
• Control transfer exchange

Related standards 

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Media Agnostic USB

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The USB Implementers Forum introduced the Media Agnostic USB (MA-USB) v.1.0 wireless communication standard based on the USB protocol on 29 July 2015. Wireless USB is a cable-replacement technology, and uses ultra-wideband wireless technology for data rates of up to 480 Mbit/s.^[114]

The USB-IF used WiGig Serial Extension v1.2 specification as its initial foundation for the MA-USB specification and is compliant with SuperSpeed USB (3.0 and 3.1) and Hi-Speed USB (USB 2.0). Devices that use MA-USB will be branded as “Powered by MA-USB”, provided the product qualifies its certification program.^[115]

InterChip USB

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Main article: InterChip USB

InterChip USB is a chip-to-chip variant that eliminates the conventional transceivers found in normal USB. The HSIC physical layer uses about 50% less power and 75% less board area compared to USB 2.0.^[116] It is an alternative standard to SPI and I2C.

USB-C

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Main article: USB-C

USB-C (officially USB Type-C) is a standard that defines a new connector, and several new connection features. Among them it supports Alternate Mode, which allows transporting other protocols via the USB-C connector and cable. This is commonly used to support the DisplayPort or HDMI protocols, which allows connecting a display, such as a computer monitor or television set, via USB-C.

All other connectors are not capable of two-lane operations (Gen 1×2 and Gen 2×2) in USB 3.2, but can be used for one-lane operations (Gen 1×1 and Gen 2×1).^[117]

DisplayLink

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Main article: DisplayLink

DisplayLink is a technology which allows multiple displays to be connected to a computer via USB. It was introduced around 2006, and before the advent of Alternate Mode over USB-C it was the only way to connect displays via USB. It is a proprietary technology, not standardized by the USB Implementers Forum and typically requires a separate device driver on the computer.

Comparisons with other connection methods

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FireWire (IEEE 1394)

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At first, USB was considered a complement to FireWire (IEEE 1394) technology, which was designed as a high-bandwidth serial bus that efficiently interconnects peripherals such as disk drives, audio interfaces, and video equipment. In the initial design, USB operated at a far lower data rate and used less sophisticated hardware. It was suitable for small peripherals such as keyboards and pointing devices.

The most significant technical differences between FireWire and USB include:

• USB networks use a tiered-star topology, while IEEE 1394 networks use a tree topology.
• USB 1.0, 1.1, and 2.0 use a “speak-when-spoken-to” protocol, meaning that each peripheral communicates with the host when the host specifically requests communication. USB 3.0 allows for device-initiated communications towards the host. A FireWire device can communicate with any other node at any time, subject to network conditions.
• A USB network relies on a single host at the top of the tree to control the network. All communications are between the host and one peripheral. In a FireWire network, any capable node can control the network.
• USB runs with a 5 V power line, while FireWire supplies 12 V and theoretically can supply up to 30 V.
• Standard USB hub ports can provide from the typical 500 mA/2.5 W of current, only 100 mA from non-hub ports. USB 3.0 and USB On-The-Go supply 1.8 A/9.0 W (for dedicated battery charging, 1.5 A/7.5 W full bandwidth or 900 mA/4.5 W high bandwidth), while FireWire can in theory supply up to 60 watts of power, although 10 to 20 watts is more typical.

These and other differences reflect the differing design goals of the two buses: USB was designed for simplicity and low cost, while FireWire was designed for high performance, particularly in time-sensitive applications such as audio and video. Although similar in theoretical maximum signaling rate, FireWire 400 is faster than USB 2.0 high-bandwidth in real-use,^[118] especially in high-bandwidth use such as external hard drives.^{[119][120][121][122]} The newer FireWire 800 standard is twice as fast as FireWire 400 and faster than USB 2.0 high-bandwidth both theoretically and practically.^[123] However, FireWire’s speed advantages rely on low-level techniques such as direct memory access (DMA), which in turn have created opportunities for security exploits such as the DMA attack.

The chipset and drivers used to implement USB and FireWire have a crucial impact on how much of the bandwidth prescribed by the specification is achieved in the real world, along with compatibility with peripherals.^[124]

Ethernet

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The IEEE 802.3af, 802.3at, and 802.3bt Power over Ethernet (PoE) standards specify more elaborate power negotiation schemes than powered USB. They operate at 48 V DC and can supply more power (up to 12.95 W for 802.3af, 25.5 W for 802.3at, a.k.a. PoE+, 71 W for 802.3bt, a.k.a. 4PPoE) over a cable up to 100 meters compared to USB 2.0, which provides 2.5 W with a maximum cable length of 5 meters. This has made PoE popular for Voice over IP telephones, security cameras, wireless access points, and other networked devices within buildings. However, USB is cheaper than PoE provided that the distance is short and power demand is low.

Ethernet standards require electrical isolation between the networked device (computer, phone, etc.) and the network cable up to 1500 V AC or 2250 V DC for 60 seconds.^[125] USB has no such requirement as it was designed for peripherals closely associated with a host computer, and in fact it connects the peripheral and host grounds. This gives Ethernet a significant safety advantage over USB with peripherals such as cable and DSL modems connected to external wiring that can assume hazardous voltages under certain fault conditions.^[126][127]

MIDI

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The USB Device Class Definition for MIDI Devices transmits Music Instrument Digital Interface (MIDI) music data over USB.^[128] The MIDI capability is extended to allow up to sixteen simultaneous virtual MIDI cables, each of which can carry the usual MIDI sixteen channels and clocks.

USB is competitive for low-cost and physically adjacent devices. However, Power over Ethernet and the MIDI plug standard have an advantage in high-end devices that may have long cables. USB can cause ground loop problems between equipment, because it connects ground references on both transceivers. By contrast, the MIDI plug standard and Ethernet have built-in isolation to 500V or more.

eSATA/eSATAp

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The eSATA connector is a more robust SATA connector, intended for connection to external hard drives and SSDs. eSATA’s transfer rate (up to 6 Gbit/s) is similar to that of USB 3.0 (up to 5 Gbit/s) and USB 3.1 (up to 10 Gbit/s). A device connected by eSATA appears as an ordinary SATA device, giving both full performance and full compatibility associated with internal drives.

eSATA does not supply power to external devices. This is an increasing disadvantage compared to USB. Even though USB 3.0’s 4.5 W is sometimes insufficient to power external hard drives, technology is advancing, and external drives gradually need less power, diminishing the eSATA advantage. eSATAp (power over eSATA, a.k.a. ESATA/USB) is a connector introduced in 2009 that supplies power to attached devices using a new, backward compatible, connector. On a notebook eSATAp usually supplies only 5 V to power a 2.5-inch HDD/SSD; on a desktop workstation it can additionally supply 12 V to power larger devices including 3.5-inch HDD/SSD and 5.25-inch optical drives.

eSATAp support can be added to a desktop machine in the form of a bracket connecting the motherboard SATA, power, and USB resources.

eSATA, like USB, supports hot plugging, although this might be limited by OS drivers and device firmware.

Thunderbolt

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Main article: Thunderbolt (interface)

Thunderbolt combines PCI Express and DisplayPort into a new serial data interface. Original Thunderbolt implementations have two channels, each with a transfer speed of 10 Gbit/s, resulting in an aggregate unidirectional bandwidth of 20 Gbit/s.^[129]

Thunderbolt 2 uses link aggregation to combine the two 10 Gbit/s channels into one bidirectional 20 Gbit/s channel.^[130]

Thunderbolt 3 and Thunderbolt 4 use USB-C.^{[131][132][133]} Thunderbolt 3 has two physical 20 Gbit/s bi-directional channels, aggregated to appear as a single logical 40 Gbit/s bi-directional channel. Thunderbolt 3 controllers can incorporate a USB 3.1 Gen 2 controller to provide compatibility with USB devices. They are also capable of providing DisplayPort Alternate Mode as well as DisplayPort over USB4 Fabric, making the function of a Thunderbolt 3 port a superset of that of a USB 3.1 Gen 2 port.

DisplayPort Alternate Mode 2.0: USB4 (requiring USB-C) requires that hubs support DisplayPort 2.0 over a USB-C Alternate Mode. DisplayPort 2.0 can support 8K resolution at 60 Hz with HDR10 color.^[134] DisplayPort 2.0 can use up to 80 Gbit/s, which is double the amount available to USB data, because it sends all the data in one direction (to the monitor) and can thus use all eight data wires at once.^[134]

After the specification was made royalty-free and custodianship of the Thunderbolt protocol was transferred from Intel to the USB Implementers Forum, Thunderbolt 3 has been effectively implemented in the USB4 specification – with compatibility with Thunderbolt 3 optional but encouraged for USB4 products.^[135]

Interoperability

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Main article: USB-to-serial adapter

Various protocol converters are available that convert USB data signals to and from other communications standards.

Security threats

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Due to the prevalency of the USB standard, there are many exploits using the USB standard. One of the biggest instances of this today is known as the USB killer, a device that damages USB devices by sending high voltage pulses across the data lines.

In versions of Microsoft Windows before Windows XP, Windows would automatically run a script (if present) on certain devices via AutoRun, one of which are USB mass storage devices, which may contain malicious software.^[136]

Some information you should know about USB最先出现在XingFei Technology Co., Ltd.。

With the continuous development of the times, people’s working methods are constantly changing. Imagine having a device that can effectively manage the synchronization of phone and computer screens while having a good office environment, how wonderful it would be! However, such a small thing can generate unexpected results. This is a laptop side phone stand that can customize the company brand logo, a new species in social office. By its strong function, team members can conveniently achieve the simultaneous display of the mobile phone and computer during work, elevating efficiency and mood.

Janie Lau, the founder of XingFei once said, “Embrace technology, liberate hands and feet, this will bring us infinite possibilities.” This product not only enhances team collaboration efficiency but also strengthens team cohesion and identification through customizing a company’s logo, really putting people first and promoting a company’s culture.

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Xing-fei tech, Easy Office, Efficient Team – A Smart Device to Promote Team Collaboration最先出现在XingFei Technology Co., Ltd.。

What would happen if a customizable logo portable metal Bluetooth speaker is introduced into the team-building process? It offers an innovative and smart approach to strengthen team connection when everyone experiences music of clear quality and high fidelity from this dustproof and waterproof device. Various colors and styles can be chosen according to company and brand needs, with the option to print a personalized logo, increasing team participation and solidifying their bond.

Can you resist falling in love with this gadget, which is easy to carry, and comes with significant battery life? This long-lasting color does not fade and exhibits superb quality from its frosted metal appearance. This is a smart design incorporated into team building. Every team member feels a common mission and bonding through using this product, thus elevating team cohesion.

“As per Janie Lau, the founder of XingFei, a high-quality custom speaker can not only enhance team cohesion but also present the company’s brand image and cultural significance. Making the company’s essence more seen and felt by others develops a sense of professionalism and unique charm, thereby deepening employees’ identification and belonging to the company.”, says Janie Lau

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Hello world! Empower Team Building with High-quality Portable Bluetooth Speakers, Digging Deeper into Brand Meaning最先出现在XingFei Technology Co., Ltd.。

Growing with the Electronics Industry: Discover XingFei Technology Co., Ltd.

Established in 2011, XingFei Technology Co., Ltd. (XingFei or XF) has grown into a trusted business partner in the manufacturing and trading of electronic products. With over a decade of expertise, XingFei has consistently delivered cutting-edge solutions designed to meet the evolving demands of customers worldwide.

This is our website:

Old website: http://www.xingfeitechnology.com/index.php

New website: https://www.xing-fei.com/

Our Core Offerings

At XingFei, we specialize in a wide range of high-quality electronic products, including:

• Mobile Phones: Sleek designs paired with advanced technology for modern lifestyles.
• Laptops: Reliable and powerful computing devices tailored for work, study, and entertainment.
• MP3 & MP4 Players: Compact and stylish music and media players for on-the-go users.
• Mini Speakers: Portable audio solutions with impressive sound clarity and durability.
• Bluetooth Keyboards: Convenient and versatile keyboards for productivity anytime, anywhere.
• Power Banks: Long-lasting power solutions designed to keep you connected.
• Accessories: A comprehensive range of electronic accessories to complement your devices.

Why Choose XingFei?

1. Factory Expertise: With a fully equipped production facility, we ensure superior quality and cost efficiency.
2. Diverse Product Range: Our extensive lineup caters to both personal and professional needs.
3. Innovation-Driven: We prioritize R&D to stay ahead in the competitive electronics market.
4. Global Reach: XingFei products are trusted by customers in markets across the globe.
5. Customer-Centric Approach: We strive to build long-term partnerships by delivering unparalleled service and support.

Commitment to Quality

Every product that bears the XingFei name goes through rigorous quality control to meet international standards. Our team is dedicated to creating solutions that combine functionality, reliability, and design.

A Vision for the Future

As technology continues to evolve, XingFei remains at the forefront of innovation. Our mission is to empower individuals and businesses with electronics that enhance connectivity, productivity, and entertainment.

Partner With Us

Whether you’re a distributor, retailer, or consumer, XingFei Technology Co., Ltd. is your trusted partner in electronics. Explore our full range of products and see how we can support your needs.

Contact us today to learn more about our offerings or discuss business opportunities:
• Visit our website: https://www.xing-fei.com (Link)
• Email us: service@xing-fei.com (Link)

Join XingFei (XF) and experience the difference a reliable partner in electronics can make. Together, we can create a smarter, more connected world.

Our Mission:  Gift to everywhere,to help you succeed
Our Vision:      To be the most popolar trading partner
OurValues:      Customer first.Top quantity,Truth-seeking,fair and reasonable,Feedback fast

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Hello world! This is XingFei, Your good business partner !最先出现在XingFei Technology Co., Ltd.。