Kongsberg Maritime AS
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KONGSBERG PROPRIETARY – see Statement of Proprietary Information
401925 / D / 2021-08-17 / Page 8 of 15
2.3.6
Noise measurements
To fully utilize the system’s capabilities, it is important to achieve the best possible Signal to
Noise ratio (SNR) for the installation. The first step is to follow the guidelines given in the
installation manual.
For a ship installation, there are other systems and noise sources that inevitably will influence
the SNR, but still, it is important to optimize the installation and keep the influence at a
minimum. KM can provide a report showing the achievable noise levels under ideal conditions.
During the tests, the vessel should have the generators operational and not be running on shore
power. It is important to have the conditions as realistic as possible so that they reflect the
normal operation as close as possible.
Note!
Be aware that the lower frequencies can be affected by noise caused by construction
work in the port or background noise in the sea and the surroundings.
2.3.6.1
Setup of system for noise checks
Note!
The EC150-3C must be configured in ES mode during the noise measurements.
Set up all the frequencies with the following pulse configurations and settings:
•
LFM, passive mode, pulse length 2.048ms, max power, fast ramping
•
For frequencies where LFM is not available:
o
CW, passive mode, pulse length 1.024ms, max power, fast ramping
•
For EC150-3C in ES mode:
o
LFM, passive mode, depth cell size 2, max velocity 10m/s, max power
•
Echogram range 2000 meters
•
Ping mode maximum. Bottom detection should be turned off
•
Select TVG to Sv (20 log) and echogram threshold -70 dB
Record data for 5 minutes.
2.3.6.2
Collecting and checking noise data
2.3.6.2.1
Noise data with transducer
Activate all the systems and log data for 5 minutes.
Check the noise estimate value for all the systems in the
Diagnostics -> Noise
menu. The values
will vary from ping to ping. Do an average over 10 pings and enter the value in the checklist.
2.3.6.2.2
Noise data with dummy load
Note!
This section does not apply to the EC150-3C.
Disconnect the transducer cables from all the WBTs and connect the shielded dummy load (P/N
453635). Activate the system(s) with the dummy load connected and log data for 5 minutes.
