Measuring the BITE noise with the transducer disconnected from the Transceiver Unit
Low noise is a key factor for high quality and reliable measurements. The performance of the CS90 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 CS90 operates in Passive mode with the transducer disconnected.
Prerequisites
The CS90 is installed as specified in this manual. All cables - except the transducer - 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 on the Noise page in the BITE dialog box.
Note
This task must be done with the transducer cable disconnected from the Transceiver Unit.
Procedure
1 Open the Operation menu.
2 Set TX Power to Off.
3 Make the following preparations.
a At the bottom of the CS90 presentation, select a suitable presentation mode, and activate the Horizontal view.
b Set Frequency to 70 kHz.
c Set Range to 1500 m.
d Set Gain to 20.
The Gain setting has no effect on the noise measurement.
e Select BITE to open the BITE (Built-In Test Equipment) dialog box.
f Select Noise to open the page.
4 Select Start Noise Measurements.
a Observe the noise curve.
b Read the maximum and average noise values.
c Repeat for selected frequencies.
d Record the frequencies and the measured values in the result table.
Result
For each transmit frequency (in kHz), write down the measured noise levels (in dB).
Frequency Maximum Average
70 kHz  

 
85 kHz  

 
90 kHz  

 
Requirements Results
Maximum noise level (in dB) shown on the Noise page when the transduceris disconnected is ≤25 dB.
Maximum noise level measured on the Noise page:  

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