Performance of time-delay estimators

Geophysics ◽  
2005 ◽  
Vol 70 (4) ◽  
pp. V109-V120 ◽  
Author(s):  
Claudio Bagaini
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Signal To Noise Ratio ◽  
Linear Equations ◽  
Reference Signal ◽  
Synthetic Data ◽  
Original Data ◽  
Small Time ◽  
Time Delay Estimation ◽  
Estimation Accuracy

I analyze the problem of estimating differences in the arrival times of a seismic wavefront recorded by an array of sensors. The two-sensor problem is tackled first, showing that even an approximate knowledge of the wavelet, such as its power spectrum, can substantially increase the accuracy of the time-delay estimate and reduce the signal-to-noise ratio (S/N) threshold for reliable time-delay estimation. The use of the complex trace, although beneficial for time-delay estimates in the presence of frequency-independent phase shifts, reduces the estimation accuracy in poor S/N conditions. I compare the performance of five time-delay estimators for arrays of sensors. Four of five estimators are based on crosscorrelation with a reference signal derived according to one of the following criteria: one trace in the array randomly selected, the stack of all array traces, the stack of all array traces iteratively updated, and (possible only for synthetic data) the noise-free wavelet. Another method, which is referred to as integration of differential delays, is based on the solution of an overdetermined system of linear equations built using the time delays between each pair of sensors. In all the situations considered, the performance of crosscorrelation with a trace of the array randomly selected is significantly worse than the other methods. Integration of differential delays proved to be the best-performing method for a large range of S/N conditions, particularly in the presence of large fluctuations in time delays and large bandwidth. However, for small time delays with respect to the wavelet duration, or if a priori knowledge of the moveout can be used to detrend the original data, crosscorrelation with a stacked trace performs similarly to integration of differential delays.

scholarly journals Methods for broadband signals mutual time delays estimating enhancement

2019 ◽  
Vol 30 ◽  
pp. 03012
Author(s):  
Ilya Grin ◽  
Oleg Morozov
Keyword(s):  
Time Delay ◽  
Computational Efficiency ◽  
Radiation Source ◽  
Time Delays ◽  
Time Delay Estimation ◽  
Ambiguity Function ◽  
Delay Estimation ◽  
Reliability Criterion ◽  
Optimal Processing ◽  
Narrowband Channels

This paper considers methods for estimating the mutual time delay of broadband signals recorded by satellites based multi-position systems for determining the location of a radiation source. All methods considered are based on modified algorithms for calculating the ambiguity function. The presented algorithms are based on the extraction of narrowband channels from the studied signals and their further optimal processing. The reliability criterion for mutual time delay estimation by the presented methods was evaluated. Based on the results and analysis of computational efficiency, viability of methods considered and their modifications was determined.

scholarly journals Methods for mutual time delay estimation of wideband signals based on nonlinear digital filtering

2019 ◽  
Vol 30 ◽  
pp. 03008
Author(s):  
Roman Ershov ◽  
Oleg Morozov
Keyword(s):  
Time Delay ◽  
Communication Systems ◽  
Satellite Communication ◽  
Signal To Noise Ratio ◽  
Digital Filtering ◽  
Time Delay Estimation ◽  
Delay Estimation ◽  
Wideband Signals ◽  
Correlation Processing

Methods for mutual time delay estimation of wideband signals propagating in satellite communication systems are proposed. The signals are propagated in different channels and received with low signal-to-noise ratio. A characteristic feature of satellite channel is the presence of the Doppler Effect, which leads to a shift and scaling the signal spectrums. The proposed approaches are based on the separation of narrow-band channels from the studied signals, using non-linear digital filtering algorithms in each channel, and subsequent optimal (correlation) processing. The accuracy of the proposed methods and the reliability of the determination of time delay are investigated.

Root-Cause Analysis Based on Time Delay Estimation for Alarm Systems in Power Grids

2011 ◽  
Vol 354-355 ◽  
pp. 943-946
Author(s):  
Yi Shu Zhao ◽  
Xi Nong Li ◽  
Ke Jun Li
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Estimation Method ◽  
Root Cause Analysis ◽  
Time Delay Estimation ◽  
Power Grids ◽  
Delay Estimation ◽  
Consistency Check ◽  
Cause Analysis ◽  
Root Cause

This paper studies the root-cause analysis based on the time delays among various signals, for reducing nuisance alarms in modern industrial systems including power grids. Time delays are estimated via the revised nearest neighbor imputation method, and are validated via the subsequent consistency check. Numerical examples including the IEEE 5-node system as a prototype power grid are provided to demonstrate the effectiveness of the proposed time delay estimation method and the subsequent consistency check.

A Biologically Inspired Coupled Microphone Array for Sound Source Bearing Estimation

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Yaqiong Zhang ◽  
Ming Yang ◽  
Xinlei Zhu ◽  
Na Ta ◽  
Zhushi Rao
Keyword(s):  
Time Delay ◽  
Sound Source ◽  
Microphone Array ◽  
Time Delay Estimation ◽  
Estimation Accuracy ◽  
Coupling Mechanism ◽  
Mechanical Coupling ◽  
Bearing Estimation ◽  
Localization Ability ◽  
Output Filter

The Ormia ochracea, a species of parasitic fly, has a remarkable localization ability despite the tiny interaural distance compared with the incoming wavelength. The mechanical coupling between its ears enhances the differences of the two received signals, the main cues to locate the source. Inspired by the coupling mechanism, we present a miniature coupled two-microphone array for estimating sound source horizontal bearing. The coupled array consists of a standard two-microphone array and a two-input, two-output filter which implements the coupling. The relationship between filter parameters and time delay magnification is investigated to provide theoretical support for array design. With appropriate parameters, the time delay of received signals can be linearly magnified. Based on the linear magnification, we present a method for estimating source direction using the coupled array. The influence of time delay magnification on time delay estimation accuracy is explored through the general cross-correlation (GCC) method. Experiments are conducted to verify the coupled array and demonstrate its advantages on improving the resolution of estimation of time delay and accuracy of bearing estimation compared with the standard array with the same element spacing.

Investigation of the Statistical Method of Time Delay Estimation Based on Conditional Averaging of Delayed Signal

2011 ◽  
Vol 18 (2) ◽  
pp. 335-342 ◽  
Author(s):  
Adam Kowalczyk ◽  
Robert Hanus ◽  
Anna Szlachta
Keyword(s):  
Time Delay ◽  
Statistical Method ◽  
Signal To Noise Ratio ◽  
Extreme Points ◽  
Time Delay Estimation ◽  
Delay Estimation ◽  
Experimental Investigations ◽  
Average Value ◽  
Standard Deviations ◽  
Conditional Averaging

Investigation of the Statistical Method of Time Delay Estimation Based on Conditional Averaging of Delayed Signal This paper presents the results of the theoretical and practical analysis of selected features of the function of conditional average value of the absolute value of delayed signal (CAAV). The results obtained with the CAAV method have been compared with the results obtained by method of cross correlation (CCF), which is often used at the measurements of random signal time delay. The paper is divided into five sections. The first is devoted to a short introduction to the subject of the paper. The model of measured stochastic signals is described in Section 2. The fundamentals of time delay estimation using CCF and CAAV are presented in Section 3. The standard deviations of both functions in their extreme points are evaluated and compared. The results of experimental investigations are discussed in Section 4. Computer simulations were used to evaluate the performance of the CAAV and CCF methods. The signal and the noise were Gaussian random variables, produced by a pseudorandom noise generator. The experimental standard deviations of both functions for the chosen signal to noise ratio (SNR) were obtained and compared. All simulation results were averaged for 1000 independent runs. It should be noted that the experimental results were close to the theoretical values. The conclusions and final remarks were included in Section 5. The authors conclude that the CAAV method described in this paper has less standard deviation in the extreme point than CCF and can be applied to time delay measurement of random signals.

MICROPHONE ARRAY SYSTEM IN ACOUSTICAL SOURCE LOCALIZATION USING LEAST SQUARE ESTIMATION

1996 ◽  
Vol 06 (06) ◽  
pp. 581-591
Author(s):  
MING JIAN ◽  
ALEX C. KOT ◽  
MENG H. ER
Keyword(s):  
Source Localization ◽  
Time Delays ◽  
Signal To Noise Ratio ◽  
Microphone Array ◽  
Time Delay Estimation ◽  
Least Square ◽  
Delay Estimation ◽  
Signal To Noise ◽  
Least Square Estimation ◽  
Five Elements

In this paper, we address the problem of acoustical source localization using a five-elements microphone array system. The time delay estimation of signal arrival for any given pair of microphones using least square technique is proposed. These estimated time delays are used in the geometric location method to determine the location of the acoustical source which, in our case, is the position of talker of interest. Computer simulations are carried out in a teleconferencing room scenario. It is shown that the location of the acoustical source can be estimated effectively as signal-to-noise ratio is larger than 20 dB in a high reverberation environment.

scholarly journals Envelope and Wavelet Transform for Sound Localisation at Low Sampling Rates in Wireless Sensor Networks

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
O. M. Bouzid ◽  
G. Y. Tian ◽  
J. Neasham ◽  
B. Sharif
Keyword(s):  
Wavelet Transform ◽  
Time Delay ◽  
Sampling Rate ◽  
Time Delay Estimation ◽  
Wireless Sensor ◽  
Estimation Accuracy ◽  
Memory Space ◽  
Time Frequency ◽  
Sound Localisation ◽  
Huge Data

High sampling frequencies in acoustic wireless sensor network (AWSN) are required to achieve precise sound localisation. But they are also mean analysis time and memory intensive (i.e., huge data to be processed and more memory space to be occupied which form a burden on the nodes limited resources). Decreasing sampling rates below Nyquist criterion in acoustic source localisation (ASL) applications requires development of the existing time delay estimation techniques in order to overcome the challenge of low time resolution. This work proposes using envelope and wavelet transform to enhance the resolution of the received signals through the combination of different time-frequency contents. Enhanced signals are processed using cross-correlation in conjunction with a parabolic fit interpolation to calculate the time delay accurately. Experimental results show that using this technique, estimation accuracy was improved by almost a factor of 5 in the case of using 4.8 kHz sampling rate. Such a conclusion is useful for developing precise ASL without the need of any excessive sensor resources, particularly for structural health monitoring applications.

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