Kongsberg Simrad ST90, Reference Manual

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Related topics
Operating procedures, page 79
Choosing operating mode and key transmit parameters, page 84
Tx Power function, page 433
Selecting the best operating frequency
The
Frequency
function is used to control the centre frequency of the acoustic transmissions
(pings). You can select any operational frequency from 14 to 24 kHz. All types of noise
matter when you wish to find the best operating frequency.
Context
A lower frequency gives you a better detection range because the attenuation loss is smaller.
A higher frequency gives you better range resolution. A higher frequency also gives you
narrower beams and a "sharper" image".
Noise from internal and external sources have an impact on the choice of operating
frequency. One specific frequency may perform better than the others on your vessel. To
measure the noise level, observe the value presented on the
Noise
page in the
BITE
dialog
box.
We recommend that you do this test twice. First, do the test with all other hydroacoustic
systems (echo sounders, ADCP, sonars) turned off. Second, do the test with normal
operating conditions. This allows you to see how the other hydroacoustic systems affect the
operation and performance of your ST90 system.
Procedure
1 On the
Main
menu, select
User Settings
.
a Select
ST90 Factory Defaults
.
b Select
Activate Selected Setting
.
c Select
OK
to apply your changes and close the
User Settings
dialog box.
2 On the
Main
menu, set
Range
to 1000 m .
3 Open the
Operation
menu. Set
Tx Power
to Off .
4 Open the
Active
menu. Set
Pulse Type
to CW Medium .
5 Open the
Setup
menu.
6 Select
BITE
to open the dialog box.
a Select
Noise
to open the page.
Simrad ST90 Reference Manual