Klein Marine Systems, Inc. HYDROCHART 3500, Руководство по эксплуатации и обслуживанию

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Sonar Head Unit
5-7
Receiver board.
The Receiver board includes eight broad band, low power
differential input receivers which input and amplify the sonar signals from
preamplifiers in the transducer arrays. The amplified signals are output to a
high speed 16-bit analog-to-digital converter (ADC), one for each receiver,
and the digitized sonar data are processed, downsampled and output to the CDI
board in accordance with command and control and clock signals from the
CDI board. The Receiver board is powered with 12 VDC from the CDI board
and supplies power and a time varying gain (TVG) trigger to the preamplifiers
in the transducer arrays. The Receiver board also provides an enable signal that
switches on a fixed gain in the preamplifiers. This gain is in addition to the
TVG and is operator selectable.
Receiver Transition board.
The Receiver Transition board provides the
means to connect the large gauge wires from the RX PORT and RX STBD
bulkhead connectors on the electronics housing connector end cap to the
Receiver board with smaller gauge shielded wires, as the Receiver board has
input connectors which require small gauge wires. Wires from the two
bulkhead connectors terminate into four connectors which connect to four
corresponding 12-pin connectors on the Receiver Transition board. Lands on
the circuit board connect the pins of these connectors to four corresponding
16-pin connectors to which four shielded jumper cables from the Receiver
board connect. The shields provide better noise immunity for the input signals.
5.2.2 Transducer Arrays
The transducer arrays contain transducer elements that both transmit and receive
the acoustic signals. They also include two 2-channel embedded preamplifiers
each which are powered from the Receiver board. The preamplifiers provide
filtering and both 12 dB of fixed gain and 48 dB of TVG to the received sonar
signals where the TVG is triggered from the Receiver board. The 12 dB of fixed
gain is on or off operator selectable. Along with the TVG to compensate for the
acoustic spreading loss, the preamplifiers increase the signal-to-noise ratio of the
received signals before they are output to the Receiver board.