Performance of a fourth-power envelope detector for symbol-rate tone generation

The use of a fourth-law envelope detector followed by a bandpass filter for detection of the symbol rate of a digitally modulated signal is investigated. The detector output spectrum is found and the output SNR is then used as a measure of performance. The effect of signal pulse shape, i.e. bandlimiting, on performance is studied. The performance of the fourth-law circuit, compared to that of a square-law device, is better for small excess bandwidth and high input SNR. However, it has a null in performance which depends on the pulse shape and the input SNR.<>