An adaptive threshold detector and channel parameter estimator for deep space optical communications

A method for optimal adaptive setting of pulse-position-modulation pulse detection thresholds, which minimizes the total probability of error for the dynamically fading optical free space channel, is presented. The threshold's adaptive setting, in response to varying channel conditions, results in orders of magnitude improvement in probability of error, as compared to use of a fixed threshold. The adaptive threshold system itself is based on a robust channel identification system that uses average signal strengths to estimate the degree of fade and total attenuation in the channel, and a radial basis function network for estimating pulse spreads, all with excellent accuracy.