TM 1-1520-238-10 4-78 Change 5 4.39 AN/AVR-2 (V)1 LASER DETECTING SET 4.39.1 AN/AVR-2A(V)1 Laser Detecting Set (LDS) Sys- tem Description. The AN/AVR-2A(V)1 Laser Detecting Set (LDS) is a passive electronic warfare system that de- tects, locates, and identifies hostile laser-aided weapon threats fired from both airborne and ground-based plat- forms. The LDS is a frequency extension of the Radar Warning (RW) system and interfaces with the RW receiv- ers and processor to function as an integrated Radar La- ser Warning Receiver (RLWR). The system detects opti- cal radiation illuminating the helicopter, processes this laser data into laser threat messages, and sends these messages to the RW digital processor. The digital proces- sor processes these inputs to provide for both visual and aural threat indications for the system. The LDS can also be used with both the RW and the Air-to-Ground Engage- ment Systems (AGES) to provide an engagement simula- tion system, in the operational training mode. The system is composed of five components: four laser sensor units and an Interface Unit Comparator (IFU). The four sensor units are strategically located around the helicopter with two mounted forward, facing forward and two mounted aft, facing aft. Each sensor unit provides a 1005 Field-Of- View (FOV) and +/– 455 of coverage in elevation. This configuration provides for 3605 coverage in azimuth and +/– 455 in elevation about the helicopter with substantial overlap. Each sensor unit contains four separate laser de- tectors. They are located under a special optical window and supply coverage of three different spectral regions: Electro-Optical (EO) bands I, II, and III. Two detectors are employed in the band III region, the band IIIA and band IIIB detectors, to provide the required band III detection coverage. 4.39.2 System Operation. The sensor units perform the actual laser detection function for the system and contain the necessary electronics to process detected laser sig- nals. If a valid laser signal is detected, a threat message containing the laser type (band I, II, or III) is sent to the IFU for processing. Each sensor unit contains optical and electrical Built-In Test (BIT) electronics to perform a self- test upon command from the IFU. When a self-test com- mand is received, the sensor unit disables detection of all externally generated signals and performs a self-test. When the self-test is completed, the appropriate pass or fail message is sent to the IFU for processing and normal operation is resumed. The IFU is located in the LH aft avionics bay. It is mounted just forward of the RW digital processor with which it directly interfaces. The IFU pro- vides the control and timing necessary for the interface with the sensor units. It also provides the interface with the RW system. The LDS was designed to operate in con- junction with the RW system, therefore, being an integral part of the RW system. The IFU provides the majority of the wiring interface between the RW system and the asso- ciated helicopter systems. If the IFU is removed from the helicopter, a jumper box must be installed in the system or an alternate connector configuration employed to permit the RW system to operate. The LDS employs a removable User Data Module (UDM) which is mounted in the face of the IFU. The UDM contains the classified operational soft- ware required for tactical operation of the system. This software gets downloaded into volatile memory within the sensor units during system power-up and initialization, and the sensor units then become classified. When sys- tem power is removed, the sensor units zeroize the classi- fied software and become unclassified components. The removal of system power and the UDM for the IFU effec- tively declassifies the system. The LDS has the capability to operate in two modes, training and tactical. In the train- ing mode, the system operates with AGES in the Multiple Integrated Laser Engagement System (MILES) to provide the crewmembers with a realistic combat tactical training system that closely simulates the effect of weapon en- gagements. a. Training. During training operation, the LDS oper- ates as a detecting system in a MILES environment and the operating software within the LDS does not recognize .904 micron gallium arsenide (GaAs) MILES laser hits as actual laser threats. b. Tactical. During tactical operation, the LDS de- tects, identifies, and characterizes three different types of optical signals. Each sensor unit provides laser threat detection in three different spectral bands; band I, band II, and band III. When a sensor unit detects optical, coherent radiation within its FOV, it provides band and pulse char- acteristics as laser threat data to the IFU. The IFU further processes this threat data, thus comparing received sig- nal characteristics with stored parameters. It then deter- mines the existence of a laser threat, threat type, and Angle-Of-Arrival (AOA) (quadrant resolution only). This threat data is sent as laser threat messages to the RW digital processor for manipulation to provide visual threat indications on the RW display and aural voice threat mes- sages over the helicopter ICS. Both the visual and aural threat indications provide threat type and relative position information to the crewmembers. c. Operating Procedures. Refer to para. 4.38.1.