Simrad EK15 Reference Manual page 213

Parameters
1
TVG
This field allows you to define the Time Variable Gain (TVG) curve applied to the
received echoes.
The following TVG settings are available:
a
Power (No TVG)
TVG gain is not implemented. This setting is hardly ever used.
b
School (20 log TVG)
This gain setting offers weaker amplification close to the bottom. It has been
designed to provide the best echoes for schools. The physical size of a school
allows you to detect it even with reduced gain.
c
Fish (40 log TVG)
This gain setting provides larger amplification close to the bottom. It has been
designed to provide the best echoes from single fish.
d
Targets (40 log TVG)
Basically, this setting uses the same TVG amplification as
filtering and compensation is implemented. Only echoes detected and
interpreted as single fish are shown. The echoes are compensated for their
physical position in the beam (beam compensation). This means that fish in
the outer region of the beam are adjusted to correct size even though their
echoes are weaker.
Note that this
transducers.
e
Target Mix (40 log TVG)
Basically, this setting uses the same TVG amplification as
beam compensation is implemented. Echoes detected and interpreted as single
fish are adjusted to their correct size according to their physical position in
the beam.
Note that this
transducers.
f
User (Variable TVG)
This setting allows you to define your own TVG setting.
Note that you can also select TVG by means of the
2
Echogram Type
Use this field to select what kind of echogram you wish to see.
a
Surface
The echogram is related to the sea surface. Start depth (upper echogram
boundary) and vertical range (across echogram) are manually selected by the
Start Depth
351718/C
Targets (40 log TVG)
Target Mix (40 log TVG)
and buttons on the
Range
Functions and dialog boxes
setting is only functional with split beam
setting is only functional with split beam
button on the
TVG
menu.
Main
, but additional
Fish
, but additional
Fish
menu.
Active
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