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1-5
Theory of Operation
Figure 1-4:
Sonar Electronics Block Diagram
The Transmitter board produces a transmit pulse, at the
Transmitter board.
start of a swath, that ensonifies the sea floor over a defined footprint. The
Transmitter board is composed of two individual transmitting channels, one
connected to the port array and the other connected to the starboard array. The
transmitters operate at a center frequency of 455 kHz and support both CW and
chirp waveform transmission. The Transmitter board also contains transmit
and receive circuitry for the downward looking altimeter.
The Receiver boards process the backscatter information
Receiver boards.
by applying fixed gain, time varied gain (TVG) and frequency filtering to the
input voltage signals received from the individual sub-arrays in the transducer
arrays. There are two Receiver boards, one for the port array and one for the
starboard array.
Each of the receiver channels is bandpass filtered with tightly matched filters
providing a -3dB bandwidth of 20 kHz, centered at 455 kHz. The filtered
signal is then output to the Multiplexer board for subsequent sampling.
The Sensor Interface board conditions sensor data
Sensor Interface board.
from the compass board, depth pressure sensor, altimeter, and optional devices
for subsequent multiplexing and transmission to the TPU.
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