SCATTERING FUNCTION ESTIMATION.

The estimation of the scattering function of a homogeneous, random, time-variant, linear system is considered. The estimator structure is assumed to be a bank of linear filters, followed by squared-envelope detectors, and another linear operation. The estimator output is shown to be equivalent to a single linear operation on the ambiguity function of the channel output, and expressions for the mean, and - assuming a gaussian channel - for the variance of the estimator output are found. It is shown that for any input signal with time duration and bandwidth greater than the channel correlation time and frequency, and effectively unbiased estimate of the scattering function can always be found. An example is used to show that for a gaussian channel, the variance of the estimate can be made as small as desired by further increasing the time duration and band-width of the transmitted signal. Author 22 for gaussian for a gaussian