Title :
The relation between range sampling rate, system bandwidth, and variance reduction in spectral averaging for meteorological radar
Author :
Urkowitz, Harry ; Katz, Sheldon L.
Author_Institution :
Gov. Electron. Syst., Moorestown, NJ, USA
fDate :
5/1/1996 12:00:00 AM
Abstract :
Periodograms are frequently used in radar meteorology to get spectral moments of weather echo. Each range trace is sampled and the set of samples at each of the specific ranges is used to obtain a pulse-to-pulse periodogram from which the spectral moments are estimated. Over some range interval, the separate periodograms would be averaged to get smoother estimates to be reported. The averaging will reduce the variance of the spectral estimates but the resulting variance is not quite inversely proportional to the number of periodograms because of the correlation introduced by a sampling rate that preserves range resolution. The authors derive the equivalent number Meq of uncorrelated range-samples when M range samples are actually averaged. The factors involved are the 3-dB system half-bandwidth W, the number M, and the range sampling frequency fs . The formula is Meq=M[1+2Σ(r=1)M-1 (1-r/M)exp(-28.48r2W2/fs2 )]-1. A table is provided of Meq versus M
Keywords :
geophysical signal processing; meteorological radar; radar applications; radar signal processing; remote sensing by radar; atmosphere; formula; measurement technique; meteorological radar; pulse-to-pulse periodogram; radar meteorology; radar remote sensing; radar signal processing; range sampling rate; range trace; spectral averaging; spectral moment; spectrogram; system bandwidth; variance reduction; weather echo; weather radar; Bandwidth; Discrete Fourier transforms; Filters; Fourier transforms; Frequency; Meteorological radar; Pulse compression methods; Sampling methods; Spectral analysis; Transfer functions;
Journal_Title :
Geoscience and Remote Sensing, IEEE Transactions on