Novel communication system for buried water pipe monitoring using acoustic signal propagation along the pipe

This research presents the design and development of a novel wireless underground communication system for buried water pipe monitoring, using acoustic signal propagation along the pipe. One of the main challenges for wireless underground communication in buried water pipe monitoring is the limitation of reliable data communication range, between an underground transmitter and receiver, to less than 3 metres using radio signal propagation. In this work, an alternative means of enabling data communication within an underground soil environment was investigated by using the water pipe wall as an acoustic communication medium. With acoustic transducers carefully selected from an abundance of commercially available options, a digital communication transmitter was developed alongside a separate digital communication receiver according to the low cost (tens of pounds at most), low power supply requirement (in the order of 1 Watt-hour) and miniature (centimetre scale) size of a wireless communication node. Following the transmitter and receiver design, the developed system was tested in the laboratory along an above ground medium density polyethylene (MDPE) pipe as well as in the field along buried steel and MDPE pipes with reliable digital communication (i.e., 0% bit error rate) successfully achieved at 3.0 and 5.6 m along the buried steel and MDPE pipes respectively with these pipes buried in well or poorly graded SAND (SW or SP). To analyse acoustic signal attenuation along the water pipes (a key requirement for predicting maximum data transmission range within the proposed communication system), three separate approaches were employed, i.e., analytical, numerical, and experimental (laboratory and field) approaches. While the analytical model was based on fundamental acoustic propagation equations, the numerical model was developed using Abaqus software to simulate acoustic propagation along the pipe; and the experimental approach directly measured acoustic signal attenuation along the pipes in the laboratory and field experiments. The analytical model and experimental results were used to validate the acoustic attenuation predictions of the numerical model. For the above ground MDPE pipe, the numerical model and laboratory experiments predicted a maximum data communication range of 18-42 m while for the buried MDPE and steel pipes, the field measurements predicted a maximum data communication range of 14-17 m. The results for the buried water pipes are particularly important as they show the possibility of using low frequency (< 1 kHz) acoustic signal propagation along a buried water pipe for achieving reliable wireless underground communication in soil