Maximum entropy estimation of Doppler shift and spectral width of VHF radar signals
Article first published online: 7 DEC 2012
Copyright 1989 by the American Geophysical Union.
Volume 24, Issue 1, pages 47–63, January-February 1989
How to Cite
1989), Maximum entropy estimation of Doppler shift and spectral width of VHF radar signals, Radio Sci., 24(1), 47–63, doi:10.1029/RS024i001p00047.(
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 18 OCT 1988
- Manuscript Received: 10 MAR 1988
Empirical investigations show that at low and moderate signal-to-noise ratios, maximum entropy (ME) Doppler shift and spectral width estimates of VHF radar signals have significantly higher accuracies than conventional periodogram estimates with noise thresholding. The variances of the ME estimates decrease with decreasing spectral width and clearly indicate a limiting signal-to-noise ratio below which the Doppler shift estimates are dominated by cosmic and instrumental noise rather than fluctuating radar signals. Two criteria are derived empirically that yield estimates of the optimum ME prediction error filter lengths for computing the Doppler shift and spectral width of individual radar signals. At small signal-to-noise ratios the Doppler shift criterion produces variances that are close to the minimum variance bounds of spectral methods. Fast ME algorithms for computing signal power, Doppler shift, and spectral width are described. At large signal-to-noise ratios the ME Doppler shift estimator is faster than the corresponding periodogram estimator based on a fast Fourier tranform, whereas at low signal-to-noise ratios, it is slower. For computing a typical height profile of the mean radial velocity in the troposphere and lower stratosphere, the ME estimator is as fast as the periodogram estimator, whereas for a height profile of the mean spectral width, it needs approximately 3 times as much computation time as the periodogram estimator.