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Chapter 5: Using the Fishfinder 117
TVG (Time Varied Gain)
The TVG (Time Variable Gain) reduces the clutter by varying the gain throughout the
water column. This function is useful for reducing the appearance of ‘noise’. Increasing
the TVG value increases the maximum depth to which TVG is applied. Decreasing it
reduces the maximum depth. A low TVG value has little effect on gain in shallow
water; a high value decreases the gain in shallow water so that only the strongest
echoes are displayed. TVG has no effect in Fishfinder Simulator Mode.
Gain adjust (200/50)
When the SELECTED FREQ is set to BOTH (see
page 115
), the GAIN ADJUST soft key is
enabled to allow you to select the frequency that the gain controls affect.
To adjust this gain setting:
Note:
Gain adjustment for individual frequencies is only available when the selected
frequency is set to BOTH.
Adjusting the power setting
The Power control provides adjustment of the transducer signal.
Auto
This is the default setting. When it is selected the DSM automatically determines the
required power setting based on the current depth, speed, and (bottom) signal
strength.
Manual
If you wish to manually adjust the power to suit current conditions, you can adjust the
power level between 0 and 100%, in 10% increments. Lower power levels are
normally used in depth ranges less than 8 ft. (2.4 m) and higher power levels are
typically selected for depths greater than 12 ft. (3.7 m).
Note:
When the power level setting is changed there is a short delay while the new
setting takes effect.
FISHFINDER
SETTINGS...
D7359-2
GAIN...
TVG
100
TVG
adjust setting
Press to highlight
soft key
Toggle to manual and
MA
N
AU
T
O
FISHFINDER
SETTINGS...
D8457-1
GAIN ADJUST
200 50
GAIN...
Toggle to the
required frequency
81221_4.book Page 117 Tuesday, February 28, 2006 5:24 PM