Simrad TV80, Справочное руководство

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Pulse Duration
The
Pulse Duration
setting specifies the current duration ("length") of the transmitted
pulse. The duration ("length") of your transmitted pulse is very important to how
you can detect fish.
• A short pulse duration gives you a very fine vertical resolution.
• A long pulse duration throws a lot more energy into the water, and the digital filters
used by the receiver are narrower.
TVG
The purpose of the TVG compensation is to make targets of the same size produce
echoes of the same size, regardless of the range. Time Variable Gain (TVG) is applied
to the echo signals before they are displayed. The TV80 can work with several
different TVG compensation settings. The default value is shown with an asterisk.
When an acoustic pulse is sent through the water, it will gradually lose its energy. The
greater the distance between the hydrophone and the target(s), the greater the loss of
energy. Signals received from long ranges are amplified to compensate for losses
due to geometric spread and absorption. By means of algorithms, the time variable
gain compensation converts the echo presentation as a function of range. This makes
the targets with the same strength appear with the same intensity independent of
their physical distance from the hydrophone. The TVG compensation is expressed
as a logarithmic curve.
Gain
The purpose of the
Gain
function is to adjust the echo level in the TV80 presentations.
It controls how much amplification that is applied to the received echoes. The default
value is shown with an asterisk.
Offset
Offset can be used if you are more interested on details from, for example, the centre
of the trawl and down to the bottom rather than the whole trawl opening.Instead of
having the echogram starting from the sensor, you make it start from a distance from
the sensor. This will help you focus on the part of the trawl that is most important for
you. The default value is shown with an asterisk.
Simrad TV80 Reference Manual