A Circuit for Peak Location Based on Two-Sample Log-Domain Interpolation

In applications such as digital communication, radar and time domain reflectometry, a digital circuit is required to estimate the time of occurrence of the peak in the analog equivalent of a sampled signal, which could be an analog signal after it has been sampled. This brief proposes a technique that is more accurate than the commonly used three-sample parabolic fit in applications where the distortion introduced by the channel is not too large. The technique approximates the analog signal in the vicinity of its peak with a two parameter function, the logarithm of which is approximated with a straight line. One of the parameters is the location and the other is the amplitude of the peak. Two samples, one on each side of the peak, are used to estimate the location of the peak. Simulation results show that the circuit for the proposed estimator, which is comparable in cost to that of the parabolic fit, is significantly more accurate when the distortion introduced by the channel is modest, as in the case of a DOCSIS channel environment.