Kongsberg Simrad SN90 Reference Manual page 612

Simrad SN90 Reference Manual
Description
Each Inspection view offered by
the SN90 system can show you a
different echogram type. Which type
to see is chosen on this
page. The page also allows you to
select which TVG curve to use for
the chosen echogram.
The changes you make are by default
only valid for the active Inspection view. Click in the Inspection view to activate it. The
active view is identified with a thicker border.
Tip
You can also select TVG setting with the
function is located on the
Details
TVG (Time Variable Gain)
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 Variable 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.
Select the TVG (Time Variable Gain) setting you want to use. Several TVG
compensation settings are available.
No TVG
TVG compensation is not implemented. This option is hardly ever used.
School (20 log R)
This 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.
Fish (40 log R)
This setting offers larger amplification closer to the bottom. It has been
designed to provide the best echoes from single fish.
Targets (40 log R)
This setting uses the same TVG compensation as Fish (40 log R), but
additional filtering and compensation is implemented.
610
Echogram
TVG
menu.
Active
function. The (Time Variable Gain)
TVG
381294/E