Simrad ES80 Reference Manual page 427

Description
Each separate echogram view offered
by the ES80 can show you a different
echogram type. Which type to see is
chosen on this
Echogram
page also allows you to select which
TVG curve to use for the chosen
echogram.
The setting(s) you choose will only
be valid for the currently "active"
echogram. Click in any echogram
view to make it "active". The
"active" echogram view is identified
with a thicker border. Select
if you wish to use the chosen settings on all the echograms of the same type.
All
Tip
You can also select TVG setting with the
function is located on the
Details
TVG
When an acoustic pulse is sent through the water, it will gradually lose its energy.
The greater the distance between the transducer and the target(s), the greater the
loss of energy.
The TVG (Time Varible Gain) compensation is designed to counteract the natural
phenomena of geometric spread and absorption loss.
The TVG compensation is expressed as a logarithmic curve. You can choose
from a selection of curves. Each curve has a different slope creating a different
gain compensation. Each curve is identified with the equation X log TVG. The
coefficient "X" is an integer. Typical values for "X" are 10 to 40.
Select the
TVG
available.
•
No TVG
TVG compensation is not implemented. This setting is hardly ever used.
•
School (20 log R)
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.
406273/C
page. The
Apply to
TVG
menu.
Active
setting you want to use. Several TVG compensation settings are
Functions and dialog boxes
function. The (Time Varied Gain)
TVG
425