Adding Sensitivity to the MLBF Doppler Centroid Estimator

TitleAdding Sensitivity to the MLBF Doppler Centroid Estimator
Publication TypeJournal Article
Year of Publication2007
AuthorsCumming, I. G., and S. Li
JournalGeoscience and Remote Sensing, IEEE Transactions on
Pagination279 -292
Date Publishedfeb.
Keywordscross beating, Doppler ambiguity, Doppler centroid estimator, Doppler radar, estimation sensitivity, fast Fourier transforms, FFT, Fourier transform, frequency estimation, MLBF algorithm, multilook beat frequency algorithm, radar signal processing, RADARSAT-1, range migration, remote sensing by radar, ScanSAR, sensitivity, synthetic aperture radar, target trajectory

The multilook beat frequency (MLBF) algorithm is the Doppler centroid estimator most commonly used in practice to solve the Doppler ambiguity. However, it still makes errors, notably in medium- or low-contrast scenes. In this paper, we present two ways in which the estimation sensitivity of the MLBF algorithm can be improved. First, we give a more thorough frequency-domain explanation of how the MLBF algorithm works and explain how cross beating and range migration cause estimation difficulties. The first improvement to the algorithm replaces the fast Fourier transform (FFT)-based beat frequency estimator with a more accurate one that uses phase increments. It avoids the FFT limitations of resolution and quantization, especially when the signal is discontinuous in one range cell due to range cell migration or burst mode operation (ScanSAR). A second improvement uses range cell migration correction to straighten the target trajectories before the beat frequency estimator is applied. This has the effect of narrowing the bandwidth of the beat signal and reducing the effect of cross beating. Finally, experiments with RADARSAT-1 data are used to illustrate the improved estimation accuracy of the modified algorithm


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