Aviation Electronics Technician 1 - Historic Naval Ships Association

ATAC/DLC.— The air transportable communication(ATAC) and down-link communication (DLC)buoys are intended for use as a means of communicationbetween an aircraft and a submarine. TheATAC buoy is commendable from the aircraft andprovides up-link and down-link communications by apreselected code. The DLC buoy is not commandableand provides a down-link communicationsonly by a preselected code.ACOUSTIC SYSTEMLearning Objective: Recognize componentsand operating principles of a typical acousticsystem.The AN/UYS-1 single advanced signal processorsystem (SASP) processes sonobuoy acoustic audioand displays the resulting data in a format suitable foroperator evaluation in the P3-C Update III aircraft.SONOBUOY RECEIVERSLearning Objective: Recognize the operatingprinciples and components of a typicalsonobuoy receiver.The sonobuoy receiver set that will be discussedin this chapter is the AN/ARR-75. This set is used onthe H-60 LAMPS helicopter.The radio receiving set (RRS) receives,demodulates, and amplifies sonobuoy transmissionsin the VHF bands, It provides channels A, B, C, andD acoustic data to the data link for transmission to theship via the communications system control group.Channels E, F, G, and H acoustic data is provideddirect to the data link for transmission to the ship.The acoustic data is also routed to the spectrumanalyzer group for processing and display on boardthe aircraft. Simultaneous reception and demodulationof standard sonobuoy RF channels is possible.Any one of the received channels can be selected foraural monitoring. The RRS consists of two radioreceiver groups.The radio receiver groups each consist of fourVHF radio receivers and a power supply. Each of thefour receivers can operate on a separate channel,independent of the others. The RF signals receivedby the sonobuoy antennas are applied to each of thefour receiver modules, where tuned filters select thesignals for each module. The signals then passthrough a series of amplifiers, filters, and mixers toproduce the output audio signals. The output signalsare supplied to the spectrum analyzer group and thedata link system. The spectrum analyzer processesthe signals to allow monitoring by the aircrew.OPERATING PRINCIPLESThe SASP processes sonobuoy audio in activeand passive processing modes to provide long rangesearch, detection, localization, and identification ofsubmarines. The sonobuoys presently in use includethe LOFAR, DIFAR, CASS, DICASS, and BT. TheRF signals from the sonobuoys are received by thesonobuoy receivers and sent to the SASP. Afterprocessing, signals are sent to the displays and therecorders for operator use. The SASP also generatescommand tones for controlling the CASS andDICASS sonobuoys.COMPONENTSThe major components include the TS-4008/UYS-1 spectrum analyzer (SA), PP-7467/UYS-1power supply, and the C-11104/UYS-1 controlindicator(SASP power control).TS-4008/UYS-1 Spectrum AnalyzerThe TS-4008/UYS-1 spectrum analyzer is ahigh-speed signal processor designed to extractacoustic target information from both active andpassive sonobuoy data. The SA determinesfrequency, amplitude, bearing, Doppler, range, andother characteristics for acoustic targets.PP-7467/UYS-1 Power SupplyThe PP-7467/UYS-1 power supply converts 115volts ac into 120 volts dc operating voltages. The120-volt dc power is then converted to low-level dcvoltages for operation of individual circuits. A powerinterrupt unit protects the data against transient powerinterruptions that normally occur during airborneoperations.4-27