Simrad SD570, Руководство оператора

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System familiarization
11
850--160137 / A
3.4 Receiving
A great effort has been made to reduce unwanted noise to get
a clean and stable echo presentation. To achieve this goal the
sonar receiver has the following filtering possibilities:
BANDPASS FILTER
One hardware filter for each preamplifier with a bandwidth of
1500 Hz to reduce interference and noise from signals outside
the sonar frequency.
FM CORRELATION FILTER
See description in paragraph 3.3.
AGC (Automatic Gain Control)
This control will automatically adjust the gain in the
preamplifier, dependent on the strength of the incoming echo
signals. The strength of the filtering can be selected in the
menu: OFF, WEAK, MEDIUM and STRONG. Note that the
AGC is sensing the echo strength in the audio channel, and use
this as a basis for adjusting all the receiver beams.
RCG (Reverberation Controlled Gain)
RCG is sensing the noise level (reverberation, propeller noise,
etc.), adjusting the gain individually for each of the 64 receiver
beams to eliminate the noise on the display. The strength of the
filtering can be selected in the menu: OFF, WEAK, MEDIUM
and STRONG.
Note that scattered fish can be perceived as reverberation, so
therefore RCG should be used with care if scattered schools are
to be detected.
PP FILTER
The sonar is equipped with a ping--to--ping filter which gives a
clean and steady presentation by reducing the interference and
noise. This filter compares the echoes from a selected amount
of transmissions (pings), and an echo has to be present in the
selected amount of pings in order to be presented on the display.
The selection is made in the menu, with the following
possibilities:
OFF - filter switched off
WEAK - compares 2 pings
MEDIUM - compares 4 pings
STRONG - compares 8 pings
Note that in rough seas, when the beam easily can miss the
target in several pings, the PP filter should be used with care.