Page 51 - HydrophoneHandbook_eReader_Ed2_20151208
P. 51

10. Troubleshooting

There are many subtleties to correctly make a hydrophone
measurement. Here, an outline is presented to assist in
troubleshooting 2 common issues :
• No Signal Detected
• Anomalous Signal Observed

No Signal Detected
1. Determine where the signal should be by estimating

    distance.
2. Ensure all connections are secure and properly seated;

    make sure there are no damaged cables.
3. If trying to measure a pulse, make sure that triggering is

    properly set-up.
4. Visually inspect the hydrophone tip to ensure the quality of

    the electrode has not been compromised.
5. Use a reference transducer and/or a second hydrophone to

    isolate the issue. If reference devices are not available,
    consider doing a pulse-echo measurement or a
    measurement using a different method (e.g., RFB) for
    comparison.
6. Use a network analyzer to check the hydrophone
    capacitance and compare with the capacitance values done
    as part of the calibration.

Anomalous Signal Observed
1. To isolate the effect of environmental factors, pulse the

    source (even if designed to operate in CW) to separate in
    time the acoustic signal from environmental interference
    (electrical, optical, etc.). Account for the speed of sound in
    water and the number of cycles.

                                                                                                    49

                                                                                                                        0NDA Corporation
   46   47   48   49   50   51   52   53   54   55   56