Distributed Low-Power Electronic Units for Sensing and Communication in Water Pipeline Monitoring

Sets of metal electrodes applied along pipelines can serve both for detecting leaks of water, as well as to bring power and transmit data among remote monitoring units. We present a modular electronic system developed to demonstrate this versatile hybrid wired and wireless sensing network concept applied to monitoring water distribution for agricultural applications. The system provides km-scale granularity, submeter spatial resolution and a selectable temporal resolution from seconds to hours. The central unit communicates with the gateway via a LoRa radio and contains the readout of water sensors (pressure, temperature, and flow rate by means of ultrasounds), while the remote unit detects water leakage by a novel sensing concept based on multiplexed differential impedance measurements. The latter is achieved with a 2 MHz analog lock-in circuit sequentially connected to the four electrodes. A small-scale hydraulic loop was built to experimentally validate the system. All parameters are tracked with 1% resolution. The total power consumption was minimized to only 10 mWh/day, easily provided by a compact solar panel for energetic autonomy.