Adaptive Time Delay Estimation in the Presence of Multipath Propagation

• Main Author: 黃寶龍
• Other Authors: 陳巽璋
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/13496801212224998088

碩士 === 國立中山大學 === 電機工程研究所 === 81 === 　　The conventional methods for time delay estimation (TDE) used the parametric approach along with adaptive algorithm. Recently, the direct delay estimation formula was proposed and applied to the adaptie first-order moment (FOM) and second-order cumulants (SOC) methods for TDE and has been found very serviceable and practicable. However, when multipath propagations exist, in general, the performance of the delay estimation using the conventional methods will be degraded. Ideally, if we are able to remove the terms of the multipath delays from both sensors, thus the conventional methods with direct formula can be applied for extracting the true time delay. 　　To achieve this goal, the wavelet recovering methods using the so-call cepstrum techniques are employed. Basically, these techniques are found usefully for removing the multiple echoes or multipath effects. In this thesis, we will apply it to the FOM and SOC methods for improving the performance of the TDE in the multipath propagations environment. 　　To demonstrate the merits of the presented methods, the additive noises in both sensors to be uncorrelated with each other are considered. From the simulation results we found that the performance with using the cepstrum techniques outperformed the one without using the cepstrum techniques. Moreover, the SOC method performs superior to the FOM method with the cepstrum techniques. Especially, when the signal-to-noise ratio is relatively low, e.g., SNR=0 dB.