Kongsberg Simrad CS90, Reference Manual

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Tip
• Frequency modulated transmissions may provide a more stable echo presentation. You
may see an increase in target detection because noise and reverberation are reduced.
• HFM (Hyperbolic Frequency Modulation) pulses are less sensitive to Doppler. These
pulses may be a better choice for fast moving targets.
• With CW transmissions, increasing the duration of the transmitted pulse increases its
energy and improves target detection capability. However, this will also reduce the range
resolution. Small targets may then be harder to detect. CW pulses with long duration are
also sensitive to Doppler.
• Decreasing the duration of the transmitted CW pulse increases the range resolution.
• When you operate with frequency modulated pulses, the range resolution is independent
of the pulse duration. You can increase the pulse duration without decreasing the
resolution.
• If you wish to investigate targets close to the bottom, a short pulse duration is always
recommended.
• We recommend that you use Auto or a CW setting during normal operation.
Details
Auto
Select Auto to make the CS90 system choose pulse type and duration for you. The
resulting setting is based on the current range. By default, the Auto setting will use
LFM Medium on shorter ranges, and then automatically switch to LFM Long when
the range is increased.
CW (Continuous Wave)
In CW transmissions the frequency is fixed during the entire duration of the pulse.
Tip
If you select different centre frequency for each view, you will reduce the risk of
interference between them. If you operate in the close vicinity of other vessels that
are also using a CS90 system - or another sonar system operating within the same
frequency range – set each system to use different centre frequency.
Simrad CS90 Reference Manual