Kongsberg 1007D, Руководство оператора

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1007D Altimeter Operators Manual 974-72007001/1.0
Theory of Operation Page 5
Kongsberg Mesotech Ltd.
Port Coquitlam, BC - Canada
2 THEORY OF OPERATION
The Model 1007D altimeter measures range as a function of
the two-way acoustic travel time between its transducer and a
reflecting target or sea bottom.
The 1007D range measurement cycle (or ‘ping’) begins by
transmitting an acoustic tone burst from its transducer into a
narrow conical-shaped beam. This beam pattern depends on
the transducer element used, and defines the coverage of the
targets which will be illuminated. The acoustic energy is
reflected back to the transducer by each target at a delay time
proportional to its distance, and at a strength related to its size
and reflectivity.
The signal received by the transducer consists of a series of
pulses or “returns” corresponding to each insonified target,
and is amplified and conditioned by an adjustable gain
receiver. The receiver output is sampled, digitized, and stored
in internal memory over the duration of the ping, as
determined by the altimeter’s current maximum range setting.
The sample data is then analyzed by a Digital Signal
Processor (DSP) to determine time and distance to the most
likely target.
The receiver gain is hardware-controlled by a Time-Varying-
Gain (TVG) characteristic to compensate for acoustic energy
losses that increase with range:
Ro) - 2a(R Log(R/Ro) 20 (dB) Gain
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