Tvg - Interphase Vista Operation Manual

vistman1
page 28
manual adjustments will often be required to get the
optimum picture - especially when looking far ahead in
shallow water.
TVG (Time Variable Gain)
As the acoustic signal travels through the water it is
attenuated in strength and also loses strength because the
signal is being spread over a larger and larger area. For
this reason, distant targets appear weaker than close
targets - even if both targets are of identical size.
The Vista's receiver circuit includes a Time Variable
Gain (TVG) feature where the receiver's gain is
controlled by the microprocessor and increases in value
as the depth or forward range increases. This feature
tends to compensate for the weakening of the signal at
Bottom Getting
longer distances as the receiver's gain will be increased
as the signal gets smaller.
Deeper to port
(left) of boat.
Sides of
Underwater
Trench
Bottom
Under Boat
28
Tuesday, July 06, 1999 10:15