Estimation of subsample time delay differences in narrowband ultrasonic echoes using the Hilbert correlation
1994 (English)Report (Other academic)
In many areas the time delay of arrival (TDOA) is desired. Conventional estimators usually have the property of breaking down for low SNR. In the case of narrowbanded signals we propose a fast and simple method to estimate the small time delays. The method is shown to have the same accuracy as conventional methods for small delays and high SNR while it performs better for low SNR. It is based on using the Hilbert transform in correlation between two signals. Apart from using it for better resolution in TDOA, it may also be used in applications with narrowbanded signals where the measurements are repeatable, such as ultrasonic imaging and ECG. In ultrasonic applications, due to fluctuations in the insonified media, a small random time shift may be present causing the signals to be misaligned in time. Averaging signals under these conditions will result in a distortion of the signal shape. We propose an averaging method to avoid this and to accomplish a higher SNR without the distortion. Simulations and experiments from ultrasonic applications are presented.
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 1994. , 21 p.
Research report / Luleå University of Technology1 jan 1974 → 31 dec 1996, ISSN 0347-0881 ; 1994:29
Research subject Signal Processing
IdentifiersURN: urn:nbn:se:ltu:diva-22603Local ID: 378869c0-df8a-11dc-9e29-000ea68e967bOAI: oai:DiVA.org:ltu-22603DiVA: diva2:995652
Godkänd; 1994; 20080220 (ysko)2016-09-292016-09-29Bibliographically approved