A Novel Approach to Predict the End-of-Life of a Hydrophone Due to Low Insulation Resistance

Insulation resistance and capacitance are used as indicators of the health of hydrophones used for sonar applications on naval platforms. It is found that an increase in capacitance of the hydrophone indicates a very low value of insulation resistance. The reduction in insulation resistance and increase in capacitance leads to adverse effects in sonar systems, such as increased self-noise of the system and limited low-frequency operation. A very low value of insulation resistance indicates the end-of-life of the hydrophone. Sonar systems usually employ a charge amplifier for amplifying the hydrophone output. As the gain of the charge amplifier depends on the input capacitance, an increase in capacitance leads to the rise in preamplifier gain beyond the expected level, which may further lead to clipping of output signal. However, this opens a new way to test the health of the hydrophone without relying on external instruments. Determining the gain of the amplifier regularly using the reference transducer available in the platform helps determine the end-of-life on the hydrophone.