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2.1 UAV TYPES AND CAPABILITIESThere are two primary types of UAVs: fixed wing and rotocopter, as shown in Figure 2-2. SomeUAVs attempt to combine aspects associated with both types; however, these are lessprevalent. Fixed wing UAVs have a motor(s) and propeller(s) to create propulsion in a roughlyhorizontal direction. The flight path is determined by the manipulation of the flight controlsurfaces on the wings (i.e., ailerons) and tail (i.e., rudder and elevator).Rotocopters may have two or more propellers that generate lift in a roughly verticaldirection. Rotocopters have no wings and their flight path is determined by independentlyadjusting the rotation speed of each of their propellers.Fixed WingRotocopterFigure 2-2 Examples of Small UAS TypesThe available capabilities vary greatly between both types of UAV and makes/models of similartypes. Table 2-1 provides examples of capabilities of commercial sUAS, showing approximatedata for a range of specifications (e.g., range, speed, flight time, etc.).Table 2-1 UAS Capabilities ExamplesSpecificationiiValuesRangeSpeedFlight TimePayloadAltitude4 to 60 miles20 to 50 milesper hour (mph)25 to 120 minutes 0 to 15 pounds3,300 to16,000 feetabove meansea levelDJI Mavic Pro: 4 milesYuneec Breeze: 20 mphParrot Bebop 2: 25 minDJI Spark: 1 poundYuneec Q500: 3,300 feetFlightWave Edge: 120 minDJI S1000: 15 poundsDJI Mavic Pro: 16,000 feetExamplesFlightWave Edge: NMS M600: 60 miles 50 mphTable 2-1 provides examples of sUAS capabilities as of July 2018, based on information gathered from a sample ofmanufacturer websites. Note that the FAA sets operational limitations for UAS flight operations under the Small UASRules (Part 107) for specifications such as speed and altitude (FAA sUAS Part 107: The Small UAS Rules).iiApproved for Public Release8

2.2 UAV COMPONENTS AND ATTRIBUTESUAVs can be further deconstructed into many sub-systems and attributes. For the purposes ofunderstanding the capabilities of C-UAS technologies, we will limit this section to just thepropulsion system, flight controller, payloads and telemetry data.2.2.1 PROPULSION SYSTEMMost small UAVs are propeller driven and powered by one or multiple electric motors. Theenergy is provided by an on-board rechargeable battery. Small UAVs may also be powered byinternal combustion engines, or hybrid gas-electric systems where a generator keeps abattery charged but propulsion is provided by electric motors.2.2.2 FLIGHT CONTROLLERThe flight controller is a small on-board computer that acts as the central hub for directingall inputs and outputs to and from the UAV. Often times the flight controller will includeseveral built-in sensors such as gyroscopes, accelerometers and Global Positioning System(GPS) receivers. The flight controller will direct all operations in the UAV, this includes: Managing the amount of power drawn from the battery and power distribution to thevarious components of the UAVConnecting radio frequency (RF) receivers and transmitters (i.e., GPS receivers,command and control (C2) receivers and telemetry transmitters)Connecting and operating sensors (i.e., thermal sensors, proximity sensors, etc.) andpayloads (i.e., actuators, cameras, etc.)Connecting and operating the flight control surfaces (i.e., wings, propellers, etc.) ofthe UAV.2.2.3 PAYLOADSSmall UAVs can carry payloads which are additional packages added to the UAV. Payloadsmay be innocuous, or may be malicious, including: CamerasSensorsAerosol dispersersMedical suppliesExplosives, chemical, biological or radiological substances, or other weaponsHazardous materialsRadiofrequency transmitters or receiversSurveillance equipmentOther cargo.Some payloads can be manipulated remotely, for example, the movement and zooming of acamera lens. Many UAS come standard with one or more built-in cameras.Approved for Public Release9

2.2.4 TELEMETRY DATATelemetry is the term used to describe information that is transmitted from the UAV to theGCS. This may include: Video and audio dataBattery statusAltitudeSpeedDirection of flightAir temperatureLaunch locationOthers.Telemetry information is generally derived from on-board sensors such as: Inertial measurement unitAccelerometerGyroscopesTemperature sensorsCamerasInfrared sensorsRF receiversSonar sensors.2.3 GROUND-BASED CONTROL SYSTEM COMPONENTSA GCS, or controller, can be a hand controller, laptop, visual display or some combination ofthese items that transmits commands to a UAV and receives telemetry data from the UAV. Thecontroller facilitates the human interface with the UAS.Using a controller, a remote operator can control motor power, flight control surfaces, an onboard camera and other sensors wirelessly. Telemetry, UAV status warnings and notificationscan be presented to the remote pilot using a built-in or attached display. Examples of GCS areshown in Figure 2-3.As shown in Figure 2-3, there are two primary attributes that are associated with the GCS:communication protocols and C2.Figure 2-3 Examples of Ground-Based ControllersApproved for Public Release10

2.3.1 COMMAND AND CONTROLCommand and control (commonly called C2) is the term used to describe the set ofcommands transmitted from the GCS to the UAV, which leads to changes in the operation ofthe UAV, such as: speed, direction of flight and altitude. C2 transmissions may also be usedto manipulate other payloads and sensors on the UAV (e.g., pan, tilt, zoom andrecord/capture of an on-board camera) or to transition between different types of flightnavigation modes.2.3.2 COMMUNICATION PROTOCOLA communication protocol is a system of rules that allows two or more end nodes of anetwork to exchange information. Communication protocols define the rules, syntax,semantics and synchronization of communication data between two or more nodes. It mayalso include information about how data should be compressed, encrypted or recoveredfrom data error issues.For UAS, a protocol defines how the control, telemetry and video data are to be encoded,transmitted and decoded to facilitate communication between the GCS and UAV.Communication between the GCS and UAV may use standard, or proprietary, protocols.Examples of UAS-specific protocols include but are not limited to: LightbridgeOcusyncMAVlink.Communication protocols use special formatting methods to determine message structure.Most protocol messages contain three main parts: Header: The portion of a data frame that precedes the message data. It usuallycontains information such as who the sender and receiver are, protocols governingthe format of the message and any synchronization information allowing the receiverto adapt the way it should process signals. Message Data: Sometimes called the ‘payload,’ it is the actual message or fragmentof a longer message to be transmitted. For example, it can be a command sent fromthe GCS to the UAV, or a video frame from on-board UAV camera back to the GCS. Footer: A portion of the data packet that may contain control and information fields.The footer is often used to verify error-free reception of the information by thereceiving device.Communication protocols are transmitted via a medium. For UAS the medium is the radiospectrum: wireless RF emissions between 3 kHz and 300 GHz in the United States (Office ofSpectrum Management, National Telecommunications and information Administration, U.S.Department of Commerce, 2003).Most consumer UAVs and their GCS use the same radio bands as Wi-Fi compatible devices(2.4 GHz and 5.8 GHz) to both control the UAV and transmit telemetry information from theUAV to the operator. More advanced and hobbyist platforms can be fitted with modems thattransmit and receive data at 433 MHz or 915 MHz.Approved for Public Release11

Three of the four radio bands mentioned: 2.4 GHz, 5.8 GHz, and 915 MHz, are part of theindustrial, scientific and medical (ISM) radio bands, defined by the Federal CommunicationsCommission (FCC), which do not require licenses for use to transmit (FederalCommunications Commission, 2010). The 433 MHz band is considered to be a regulatedband in the United States and is generally reserved for amateur radio operators. Accordingto international standards it is also considered to be part of the ISM radio bands (FederalCommunications Commission, 2018). These are the most common transmission bands forcommercially available UAS, but any other portion of the radio spectrum could theoreticallybe used in a custom system.2.3.3 FLIGHT NAVIGATION MODESThe three common flight navigation modes that are used to remotely operate a UAV are: Manual Navigation: Under the manual navigation mode, the UAV is directly controlledin real time by a remote, human pilot who manipulates joysticks, buttons and/orknobs on a controller. Manual navigation relies on uninterrupted and continuousradio communication between the UAV and controller. Manual navigation cansometimes include first person viewing (FPV), in which a pilot operates the UAV byrelying on a live video feed from the UAV in a display mounted on the remotecontroller or in headset. GPS Navigation: Many UAVs are equipped with GPS receivers that tell them wherethey are in space and time. Relying on the GPS system, UAVs can be pre-programmedto fly autonomously to specified locations (also known as waypoints) or use specifiedflight paths. This navigation mode can be achieved without any radio emissions fromthe UAV or GCS, although many UAVs may emit a “heartbeat” signal that occasionallytransmits telemetry, for safety reasons, back to the controller. This heartbeatfunction is a safety feature that can be turned off to avoid radio emissions. Autonomous Navigation: Some UAVs have the capability of navigating using only theirown on-board sensors, as opposed to relying on received signals from the GPSsystem. These sensors can include, but are not limited to: accelerometers,gyroscopes, magnetometers, video cameras and collision avoidance sensors. In thismode, the UAV can follow moving objects or people, fly towards a stationary object ata distance or navigate by dead reckoning. UAVs relying on autonomous navigationmay not emit any radio signals and may be entirely unaffected by any impediments inradio signal propagation or interference.Approved for Public Release12

3.0 COUNTER-UAS TECHNOLOGIESVarious technologies exist to counter use of UAS. These technologies, collectively referred to asC-UAS technologies, employ a variety of sensors and processes that account for or exploit thephysical components of a UAS and the communications between the UAV and the GCS.Federal law prohibits the operation of certain C-UAS technologies described in this section of thisguide.iii Only the Departments of Homeland Security, Justice, Defense, and Energy have receiveda legislative exception to those Federal laws to conduct C-UAS. This portion of the TechnologyGuide is intended to provide background information about C-UAS technology, and is notintended to imply that any agencies other than those listed above have the lawful authority topurchase, possess or use such systems. Please consult with an attorney experienced with bothfederal and state criminal, surveillance, and communications laws. Entities should conduct theirown legal and technical analysis of each UAS detection or mitigation system and should not relysolely on vendors’ representations of the systems’ legality or functionality. This is particularlyimportant because potential legal prohibitions are not based on broad classifications of systems(e.g., active versus passive, detection versus mitigation), but instead are based on thefunctionality of each system. A thorough understanding of both applicable law and the systems’functionality will ensure that important technologies designed to protect public safety, bydetecting or mitigating UAS threats, are used responsibly and legally.3.1 C-UAS PROCESSING CHAINA C-UAS processing chain (Figure 3-1) is a framework for approaching the potential threatposed by UAS that can be used by technology developers and public safety officials alike.Terms and definitions within this processing chain may be different depending on theaudience (e.g., developers, operators and government agencies), and not all C-UAStechnologies are able to address all of the activities identified by this processing chain, or inthe same Figure 3-1 C-UAS PThis processing chain and description can be used as a reference to understand how differentC-UAS technologies operate. Table 3-1 defines the terms identified in the C-UAS processingchain.See generally, Pen/Trap Statute, 18 U.S.C. §§ 3121-3127, Wiretap Act, 18 U.S.C. § 2510; Aircraft Sabotage Act,18 U.S.C. § 32(a); Computer Fraud and Abuse Act, 18 U.S.C. § 1030; 18 U.S.C. § 1362; 18 U.S.C. § 1367; 47 U.S.C.§ 301; 47 U.S.C. § 302a; and 47 U.S.C. § 333.iiiApproved for Public Release13

Table 3-1 C-UAS Processing Chain StagesDetectA detection is a declaration that a UAS is in the presence of a sensor. Somesystems, depending on how thresholds are configured, may report any objectin its view as a detection (i.e., birds, commercial planes, etc.), or they mayattempt t

Counter-Unmanned Aircraft Systems Technology Guide was prepared by the U.S. Department of Homeland Security, Science and Technology Directorate, National Urban Security Technology Laboratory (NUSTL). Reference herein to any specific commercial p