Evaluation of νth-law devices

Most of the work which has been done in the analysis of a νth-law device is concerned with the statistical properties of the output. Apparently, a general investigation to determine the optimum value of ν for a νth-law device has never been made. Therefore, a simple method of evaluating a νth-law device is necessary. This may be done by choosing the optimum value of ν based on the criterion for masimizing the detector output information capacity. It is shown that when the input of a νth-law detector consists of an amplitude modulated (AM) sine-wave signal and a stationary narrow-band white Gaussian noise, the square-law detector will give maximum output information capacity for very small input signal-to-noise ratio (SNR). In the case of a very large input SNR and a normally distributed signal modulating process on the AM sine wave signal, the linear detector will be considered as an optimum one.