Simrad SC90, Installation Manual

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419050/B
301
Measuring the Echo level with the transducer disconnected
from the Transceiver Unit
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 transducer disconnected.
Prerequisites
The SC90 is installed as specified in this manual. All cables - except the transducer cable
- are properly connected. Neither tools nor instruments are required.
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.
Note
This task must be done with the transducer cable disconnected from the Transceiver Unit.
Procedure
1 Make sure that the transducer is retracted to its upper position.
2 Disconnect the transceiver plug from the Transceiver Unit output.
3 Set
Mode
to Bow Up .
4 Set
TX Power
to Off .
5 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.
f Select
Test Config
to open the
Test Config
parameter dialog.
g Select
Noise & VR
to select the
Noise test
settings.
h Select the
Horizontal
tab to open the menu.
i Set
Gain
to: 20 – 25
The
Gain
setting has no effect on the noise measurement.
6 Observe the noise on the SC90 presentation.
Setting to work