DATASONICS SIS-1500, System Manual

Page: 74 / 110

4-6 DATASONICS
Volume I System Manual June 1998
Digital Multiplexer
The main components of the digital multiplexer are the combi5 VDC
and +/- 12 VDC power supply, which powers the multiplexer’s electronics; the
high voltage power supply, which powers the subsea electronics; and the
Multiplexer board, which performs all of the communications functions.
Specifically, the Multiplexer board includes the following functions:
Cable Interface. Combines the high voltage power with the downlink
commands and the sonar and transponder keys and transmits the
combination to the subsea electronics while it simultaneously receives
the sonar data, the tow vehicle status information, and the sensor data
from the subsea electronics.
T1 Receiver. Recovers the sonar data.
Modem. Modulates the downlink commands and demodulates the
uplink vehicle status information and sensor data.
Microcontroller board. Plugs into the Multiplexer board and
generates the sonar and responder keys and provides the downlink
and uplink data telemetry control.
An outline drawing of the digital multiplexer chassis is shown in Figure 4-2.
The digital multiplexer, in addition to functioning as the communications link
between the workstation and the subsea electronics, is also the subsea
electronics power supply. When the front panel circuit breaker CB1 is closed,
100 -125 VAC or 220 - 240 VAC, 50 - 60 Hz power is applied to the
multiplexer’s +/-12 VDC and +5 VDC power supply, which o/- 12 VDC
and +5 VDC to the Multiplexer board. An indicator in the circuit breaker lights.
When the keyswitch S1 is closed, and if the circuit breaker has been closed,
+5 VDC is applied to the solid state relay K1. This closes the relay and applies
100 -125 VAC or 220 - 240 VAC, 50 - 60 Hz power to the three DC power
supplies. The three DC power supplies are wired in series to provide the high
voltage power, which is input to the Multiplexer board and output to the tow
vehicle. All the power supplies are auto sensing and automatically determine
whether the applied power is 100 - 125 VAC or 220 - 240 VAC, 50 to 60 Hz.
The applied power is also filtered with the AC line filter FL1. In addition, when
the keyswitch is closed, the yellow lamp LP1 on the front panel lights, the
front panel voltmeter indicates the voltage being output to the tow vehicle,
and the front panel ammeter indicates the current being output to the tow
vehicle. The front panel of the digital multiplexer also includes three LEDs:
D1, which is XMIT KEY and flashes once every time a sonar key is output to