Noise Problems; Determine The Noise Source - Siemens HydroRanger 200 Instruction Manual

Noise Problems

Incorrect readings can be the result of noise problems, either acoustic or electrical, in the
application.
The noise present at the input to the ultrasonic receiver can be determined by viewing
parameter P807. The display reads ##:##, where the first number is the average noise and
the second is the peak noise. In general, the most useful value is the average noise.
With no transducer attached the noise is under 5 dB. This is often called the noise floor. If
the value with a transducer attached is greater than 5 dB, then signal processing
problems can occur. High noise decreases the maximum distance that can be measured.
The exact relationship between noise and maximum distance is dependent on the
transducer type and the material being measured. Any average noise level greater than
20 dB is probably cause for concern unless the distance is much shorter than the
maximum for the transducer.

Determine the Noise Source

Disconnect the transducer from the HydroRanger 200. If the measured noise is below 5
dB, then continue here. If the measured noise is above 5 dB go to
Sources
below.
1. Connect only the shield wire of the transducer to the HydroRanger 200. If the
measured noise is below 5 dB, continue with the next step. If the noise is above 5
dB, go to Common Wiring Problems.
2. Connect the white and black transducer wires to the HydroRanger 200. Record the
average noise.
3. Remove the positive wire of the transducer. Record the average noise.
4. Re-connect the positive wire and remove the negative wire. Record the average
noise.
Using the table below, determine the appropriate next step. The terms higher, lower and
unchanged refer to the noise recorded in the previous steps.
These are guidelines only. If the suggested solution does not solve the problem, try the
other options also.
- removed
higher
unchanged
lower
Acoustical Noise
To confirm that the problem is acoustical, place several layers of cardboard over the face
of the transducer. If the noise is reduced, the noise is definitely acoustical.
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+ removed
higher
unchanged
lower
higher
unchanged
lower
higher
unchanged
lower
HydroRanger 200 – INSTRUCTION MANUAL
Non-Transducer Noise
Go to:
Reducing Electrical Noise
Common Wiring Problems
Reducing Acoustical Noise
Reducing Electrical Noise
Contact Siemens Milltronics
Reducing Acoustical Noise
Common Wiring Problems
Common Wiring Problems
Reducing Acoustical Noise
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