Symbol-rate detection by a power-series-nonlinear envelope detector receiver

The use of a nonlinear envelope detector followed by a bandpass filter for detection of the symbol rate of a digitally modulated signal (AM) is investigated. The intent is to give a better approximation to the maximum-likelihood symbol rate estimator than that of the delay-and-multiply receiver. The case of low input signal-to-noise ratio (SNR) is considered. Under this assumption, the detector output spectrum is found and the output SNR is then used as a measure of detectability, The effect of signal pulse shape. i.e. bandlimiting, on performance is studied