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.
|Date of Award||31 Dec 2019|
- The University of Manchester
|Supervisor||Simon Watson (Supervisor) & Barry Lennox (Supervisor)|