Kongsberg Simrad ST90, Справочное руководство

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will reduce the voltage level on the output capacitors, and this reduces the source level
on the following transmissions.
Longer pulses will also increase the blind zone close to the transducer and increase
the reverberation level.
For these reasons, the use of long pulse durations may not be the best choice.
For CW (Continuous Wave) transmissions:
• Long pulses provides longer detection range. They make the ST90 system less
sensitive for noise, but offer lower range resolution.
• Short pulses provides shorter detection range. They make the ST90 system more
sensitive for noise, but offer higher range resolution.
For FM (Frequency Modulated) transmissions:
• Long pulses provide longer detection range, and the range resolution is independent
of the pulse duration..
• Short pulses provide shorter detection range, and they make the ST90 system more
sensitive for noise.
Related topics
Functions and dialog boxes, page 416
Active menu; Functions and dialog boxes, page 466
Bandwidth function
The
Bandwidth
function allows you to select the frequency range in the frequency modulated
transmissions (pings).
How to open
You open this function from the
Active
menu.
Description
Each frequency modulated transmission ("ping") from the ST90 system consists of a
frequency sweep around the centre frequency. The difference between the lowest and the
highest frequency in each transmission is referred to as
bandwidth . The centre frequency in
each transmission is chosen with the
Frequency
function. The chosen bandwidth will spread
equally to both sides of the centre frequency.
Functions and dialog boxes