A-7
Video Sounder
Clutter
Cruising noise, polluted water or plankton can
clutter the screen with low signal level ech-
oes. This situation can be improved by ad-
justing the CLUTTER function.
Detecting area
The detecting area varies with the main
beamwidth of the transducer. Objects out of
the main beam but close to the beam will be
presented less densely, smaller in size and at
a lower intensity.
Generally, beamwidth depends on Tx fre-
quency; a narrower beamwidth is usually ob-
tained at a higher frequency. The beamwidth
of the 200 kHz is narrow, thus it has the ad-
vantage of higher resolution. On the negative
side, fish at the sides of the boat can be over-
looked because of the narrow beamwidth.
Display color
A color video sounder displays an echo in a
color corresponding to its strength. The GP-
1610CF displays echoes in eight colors: red-
dish brown, red, orange, yellow, green,
light-blue, blue and black.
Frequency
The frequency of the ultrasonic pulse used in
video sounders is between 15 and 200 kHz,
and the GP-1610CF provides both 50 kHz and
200 kHz. The 200 kHz frequency offers a
sharp, clear-cut picture since its beamwidth
is narrow. However its use should be limited
to shallow waters since its pulse is easily at-
tenuated in water. The 50 kHz frequency pro-
vides a longer sounding range since its pulse
it is not as easily attenuated.
Gain
Gain adjusts the sensitivity of the receiver. It
should be set at the point where excessive
noise does not appear on the screen. Usually,
use a high gain setting for deep water; a low
one for shallow water.
Interference, noise
Interference can result from other acoustic
equipment which operates on the same fre-
quency as your own or electrical equipment
on your boat which disturbs the video sounder.
In most cases interference can be suppressed
with the noise limiter.
Picture advance speed
Picture advance speed defines how fast the
video sounder picture moves across the dis-
play screen. Several speeds are available in-
cluding freeze, which lets you stop
advancement to observe the picture more
closely.
Pulselength
Pulselength is the length of time the transmit-
ter in the transducer is turned on each trans-
mitted ultrasonic signal. Pulselength is linked
with range and thus cannot be selected. The
higher the range selected the longer the
pulselength.
Pulse repetition rate
The pulse repetition rate defines the number
of pulses transmitted within a certain period.
The more pulses transmitted the greater the
detection accuracy. The pulse repetition rate
is automatically changed with range.
Resolution
Resolution is the ability of the video sounder
transducer to discriminate returning signals.
The higher the transducer frequency the bet-
ter the resolution.