SIS-1500 Seafloor Imaging System 4-7SECTION 4 Theory of Operation Topside Processor ElectronicsFigure 4-2 Chirplink II Digital Multiplexer Chassisthe tow vehicle; D2, which is TELEM LOCK and flashes when the uplink anddownlink FSK telemetry is being established just after turning on the highvoltage power and is extinguished when the link is established; and D3, whichis DATA LOCK and flashes when the uplink T1 telemetry is being establishedand is illuminated continuously when the link is established.The Cable Interface on the Multiplexer board combines the high voltagepower with the downlink commands and the sonar and responder keys. Thedownlink commands are input to the Microcontroller board on the Multiplexerboard from the workstation’s TELEM serial port in RS-232 format. TheMicrocontroller board outputs the data to the Modem, which converts the datainto an FSK format that is centered at 35 kHz. The data are transmitted atDC POWERSUPPLY (3) MULTIPLEXERBOARDRELAY K1+/-12 VDC & +5 VCDPOWER SUPPLYCIRCUITBREAKERCB1VOLTMETER AMMETERKEY SWITCH S1LAMP LP1FILTER FL1
