This invention pertains to the detection of leaks in plastic water distribution pipes by processing the sound or vibration induced in the pipe by water escaping under pressure. Acoustic leak signals are measured at two (or more) contact points with the pipe, e.g., fire hydrants or valves, using vibration sensors or hydrophones.
The signals are digitally recorded using the computer's soundcard. The leak is located using the difference in arrival times of two leak signals as determined from the cross-correlation function traditionally used in leak detection applications or an enhanced impulse response function. The enhanced impulse response function eliminates the need to filter leak signals before processing and hence avoids the uncertainty involved in selecting filter cutoff frequencies for non-experts. Listening to leak sound in plastic pipes is made possible in software by shifting their low-frequency content to an audible higher range. The software implementation of this system can be readily integrated with commercially available RF-based data transmitters and leak sensors - thus providing a complete, flexible, and inexpensive leak detection system.