acoustic-leak-detector: open source, battery-powered, long-range acoustic leak detection

AquaPing is an ultra-low power smart sensor that provides isolated water leak detection, even behind walls. No contact with pipes is required. All signal processing and analysis happens at the edge, so no audio is streamed to the cloud and cannot be eavesdropped. When pressurized water escapes from seams, cracks or loose fittings on pipes, it emits broadband high-frequency acoustics. These signals can travel 30 feet or more in free space and be detected by remote sensors. This demonstrates that this isolation approach to water leakage detection is significantly different compared to traditional contact humidity sensors and various types of smart flow meters installed on or within pipes. Acoustic leak detection combines the principles of glass breakage and smoke detectors. Glass breakage occurs on time scales of seconds or less, requiring continuous data collection at rates approaching 1 kHz or higher. Nearly all pipe leaks are persistent, which allows for sub-hertz sampling rates and extremely long battery life. The advantage of glass breaking is that it is usually louder than the surrounding environment, so detector sensitivity is not an issue. Small leaks, especially when separated from the sensor by a sound barrier such as a wall, may be at or below ambient background. Higher sensitivity and noise reduction are essential. This is addressed through mechanical, electronic and digital filtering as well as judicious use of statistical analysis. The sensor is intended to be deployed as a remote wireless network node. However, there are many wireless protocols, so it was decided to make AquaPing agnostic of host hardware to have the widest possible range of use cases. It works with any controller with I2C interface and 3V3 power bus.