Doppler Frequency Estimation of Point Targets in the Single-Channel SAR Image by Linear Least Squares

This paper presents a method and results for the estimation of residual Doppler frequency, and consequently the range velocity component of point targets in single-channel synthetic aperture radar (SAR) focused single-look complex (SLC) data. It is still a challenging task to precisely retrieve the radial velocity of small and slow-moving objects, which requires an approach providing precise estimates from only a limited number of samples within a few range bins. The proposed method utilizes linear least squares, along with the estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm, to provide optimum estimates from sets of azimuth subsamples that have different azimuth temporal distances. The ratio of estimated Doppler frequency to root-mean square error (RMSE) is suggested for determining a critical threshold, optimally selecting a number of azimuth subsample sets to be involved in the estimation. The proposed method was applied to TerraSAR-X and KOMPSAT-5 X-band SAR SLC data for on-land and coastal sea estimation, with speed-controlled, truck-mounted corner reflectors and ships, respectively. The results demonstrate its performance of the method, with percent errors of less than 5%, in retrieved range velocity for both on-land and in the sea. It is also robust, even for weak targets with low peak-to-sidelobe ratios (PSLRs) and signal-to-clutter ratios (RCSs). Since the characteristics of targets and clutter on land and in the sea are different, it is recommended that the method is applied separately with different thresholds. The limitations of the approach are also discussed.

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Joint 2D-DOA and Frequency Estimation for L-Shaped Array Using Iterative Least Squares Method

International Journal of Antennas and Propagation ◽

10.1155/2012/983092 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Ling-yun Xu ◽

Xiao-fei Zhang ◽

Zong-ze Xu ◽

Miao Yu

Keyword(s):

Least Squares ◽

Least Squares Method ◽

Frequency Estimation ◽

Spectral Peak ◽

Propagator Method ◽

Esprit Algorithm ◽

Delay Matrix

We introduce an iterative least squares method (ILS) for estimating the 2D-DOA and frequency based on L-shaped array. The ILS iteratively finds direction matrix and delay matrix, then 2D-DOA and frequency can be obtained by the least squares method. Without spectral peak searching and pairing, this algorithm works well and pairs the parameters automatically. Moreover, our algorithm has better performance than conventional ESPRIT algorithm and propagator method. The useful behavior of the proposed algorithm is verified by simulations.

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Multi-sensor Doppler radar for machine tool collision detection

Advances in Radio Science ◽

10.5194/ars-12-35-2014 ◽

2014 ◽

Vol 12 ◽

pp. 35-41 ◽

Cited By ~ 6

Author(s):

T. J. Wächter ◽

U. Siart ◽

T. F. Eibert ◽

S. Bonerz

Keyword(s):

Moving Objects ◽

Continuous Wave ◽

Doppler Radar ◽

Frequency Estimation ◽

Control Unit ◽

Doppler Frequency ◽

Low Complexity ◽

Abstract Machine ◽

Human Errors ◽

Spatially Distributed

Abstract. Machine damage due to tool collisions is a widespread issue in milling production. These collisions are typically caused by human errors. A solution for this problem is proposed based on a low-complexity 24 GHz continuous wave (CW) radar system. The developed monitoring system is able to detect moving objects by evaluating the Doppler shift. It combines incoherent information from several spatially distributed Doppler sensors and estimates the distance between an object and the sensors. The specially designed compact prototype contains up to five radar sensor modules and amplifiers yet fits into the limited available space. In this first approach we concentrate on the Doppler-based positioning of a single moving target. The recorded signals are preprocessed in order to remove noise and interference from the machinery hall. We conducted and processed system measurements with this prototype. The Doppler frequency estimation and the object position obtained after signal conditioning and processing with the developed algorithm were in good agreement with the reference coordinates provided by the machine's control unit.

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Iteratively Reweighted Linear Least Squares for Frequency Estimation in Unbalanced Three-phase Power System

ICASSP 2019 - 2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) ◽

10.1109/icassp.2019.8682364 ◽

2019 ◽

Author(s):

Yuan Chen ◽

Weize Sun ◽

Long-Ting Huang ◽

Hing Cheung So

Keyword(s):

Power System ◽

Least Squares ◽

Frequency Estimation ◽

Linear Least Squares ◽

Three Phase

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Acceleration Compensation for Estimation of Along-Track Velocity of Ground Moving Target from Single-Channel SAR SLC Data

Remote Sensing ◽

10.3390/rs12101609 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1609

Author(s):

Sang-Wan Kim ◽

Joong-Sun Won

Keyword(s):

Single Channel ◽

Estimation Error ◽

Doppler Frequency ◽

Moving Target ◽

Complex Data ◽

X Band ◽

Irregular Motion ◽

Velocity Jump ◽

Moving Direction ◽

Along Track

Across-track acceleration is a major source of estimation error of along-track velocity in synthetic-aperture radar (SAR) ground moving-target indication (GMTI). This paper presents the theory and a method of compensating across-track acceleration to improve the accuracy of along-track velocity estimated from single-channel SAR single-look complex data. A unique feature of the proposed method is the utilisation of phase derivatives in the Doppler frequency domain, which is effective for azimuth-compressed signals. The performance of the method was evaluated through experimental data acquired by TerraSAR-X and speed-controlled and measured vehicles. The application results demonstrate a notable improvement in along-track velocity estimates. The amount of along-track velocity correction is particularly significant when a target has irregular motion with a low signal-to-clutter ratio. A discontinuous velocity jump rather than a constant acceleration was also observed and verified through comparison between actual data and simulations. By applying this method, the capability of single-channel SAR GMTI could be substantially improved in terms of accuracy of velocity, and moving direction. However, the method is effective only if the correlation between the actual Doppler phase derivatives and a model derived from the residual Doppler rate is sufficiently high. The proposed method will be applied to X-band SAR systems of KOMPSAT-5 and -6.

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