CFAR Processing by Converting Weibull to Rayleigh Distributions

Abstract

I have observed sea clutter containing a target (ship) using an X-band radar with a frequency of 9.41GHz, a beamwidth of 1.0°, a pulsewidth of 0.5µs, and a pulse-repetition frequency of 1,600Hz. To investigate the sea clutter amplitude statistics, I introduce the Akaike Information Criterion (AIC). I have found that the sea clutter amplitudes obey the Weibull distribution with the shape parameter of c=2.83 for entire data and the log-normal, Weibull, and log-Weibull distributions with the shape parameters of σ=0.439, c=2.76 to 4.59, and c=8.09 to 10.42, respectively, for data within the beam width of an antenna. The number of the smallest AIC (MAIC) of the log-normal, Weibull, and log-Weibull distributions to data are 1, 18, and 2, respectively, from 21 range sweep numbers. I have used a circuit to convert Weibull to Rayleigh distributions and a Cell-Averaging (CA) LOG/CFAR circuit. It is found that ship is detected and sea clutter is suppressed with improvement of 31.43dB by CFAR processing.