Simrad SC90, Руководство по установке

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419050/B
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Measuring the Echo level in Passive mode
Low noise is a key factor for high quality and reliable measurements. The performance
of the SC90 will always be limited by different noise sources. A high noise level will
mask the echoes and make them difficult to read and interpret. The noise is measured
while the SC90 operates in
Passive mode with the transmit pulses disabled.
Prerequisites
The SC90 is installed as specified in this manual. The vessel is at sea. The SC90 is
turned on, and it is working normally. Neither tools nor instruments are required. In
order to do this test, the ship must be "silent".
• The water must be as deep as possible. Recommended minimum depth is 100 metres.
• There must be no other vessels in the vicinity.
• The vessel must lie still in the water.
• As much machinery as possible must be switched off. It is particularly important to
switch off electrical motors, as well as cooling systems and hydraulic pumps that
may cause electric noise.
• To prevent interference, all other hydroacoustic instruments must be switched off.
This test must be considered as indicative. With the vessel in port, the environmental
conditions are not satisfactory. In the shallow waters of the port, noise from other
vessels, dockyard workers or machinery will cause unreliable test results. If you do
this tests in a busy harbour, or with noise sources present, the sensitive receivers will
detect all the noise in the nearby waters.
Context
This task allows you to check the noise conditions. To measure the noise level, observe
the value presented by the
Echo Level
button in the
System Test
menu.
Procedure
1 Make sure that the transducer is retracted to its upper position.
2 Set
Mode
to Bow Up .
3 Set
TX Power
to Off .
4 Make the following preparations.
a Select the
Horizontal
tab to open the menu.
b Set
Range
to: 1200 m
c Set the
Frequency
to: 82.5 kHz
d Select the
Setup
tab to open the menu.
e Select
Test
on the
Setup
menu to open the
System Test
menu.
Setting to work