Adaptive estimation of transmission distortion in a digital communications channel

An online nondisruptive time-domain technique is proposed for estimating several important types of linear transmission distortion that commonly occur on line-of-sight digital radio communication channels. This approach uses a system that initially estimates the discrete-pulse response of the communications channel. The amount of amplitude and group-delay distortion present in the estimated channel-pulse response is then determined by iteratively adjusting the coefficients (representing the channel distortion) of a polynomial model of the channel, until the difference between a computed version of the channel-pulse response (from the model), and the measured values of the discrete channel pulse response is minimized. The technique is found to work well for most operating regions of practical interest to digital line-of-sight radio links