Acoustic pulse reflectometry for potential industrial applications

• Main Author: Aldughayem, Omar
• Other Authors: Watson, Simon ; Lennox, Barry
• Published: University of Manchester 2019
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.764769

The goal of this thesis was to investigate improvements that could be made to Acoustic Pulse Reflectometry APR for potential industrial uses with an emphasis on natural gas distribution networks. A typical APR system's range is limited by overlap of acoustic signals that is a result of short source tubes. An experimental rig was constructed to perform a comparative study of wave separation techniques and to develop a novel absorbing termination technique to remove overlap effects in real-time. A measure known as separation index (SI) was used to assess the quality of wave separation for two different multi-microphone algorithms. The results indicated that pair selection frequency domain wave separation algorithms, used with 100 coefficient adaptive least mean square (ALMS) identified inter-microphone transfer functions provide a separation quality of up to -62.2dB. Also, results show that time domain wave separation techniques are as robust as established frequency domain techniques. In addition, a novel method termed active absorbing termination was developed to remove source reflections in real-time. This method was presented and tested using a modified version of SI called the Absorption Index. The results showed that source reflections can be removed in real-time within a single measurement which was not possible in previous works.