Measuring noise in Passive mode
Low noise is a key factor for high quality and reliable measurements. The performance of the MS70 will always be limited by different noise sources. As a part of the Installation Manual, the noise is measured while the MS70 operates in passive mode.
Prerequisites
The MS70 is switched on and working in normal operational mode. You need an open two-way oral communication channel with the bridge. You need the following equipment:
•  Personal computer
•  Spreadsheet program
Context
To read the noise level, use the Numerical view.
The following requirement must be met:
•  The noise level in Passive mode is acceptable.
Note
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. The test is therefore repeated during the Sea Acceptance Test.
Procedure
1 On the Main menu, set Beam Mode to Example 1 Sector Uniform Weighting.
2 Open the Operation menu.
a Select Operation, and set it to Inactive.
b Set Range to: 500 m.
c Set Ping to On.
d Set Ping Mode to Maximum.
e Set TX Mode to Passive
f Set TX Power to Maximum.
3 Open the Active menu.
4 Select Echogram to open the dialog box.
a Set Reference to Surface.
b Set Backscatter to Sv (20 log).
c Select OK to save the chosen setting and close the dialog box.
5 In the Numerical view, read the noise level estimates for beams 12, 212 and 487.
Record the values in the result table.
6 In the Numerical view, estimate the ranges to where the noise becomes visible.
Record the values in the result table.
Result
Test procedure Results
Measuring noise in Passive mode  
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