PHASELOCK THRESHOLD CORRECTION

摘要

A noise estimator for threshold correction of a receiver includes a low pass filter to remove wideband noise from an input signal that includes a signal component and a noise component. The output of the wideband filter is applied to a square-law power detector having an output applied to an envelope detector. The output of the envelope detector is the instantaneous envelope of the input signal and is applied to a low pass filter to perform time averaging and is also applied to a differential network. The output of the low pass filter is a signal representing a time averaged statistical envelope representing the statistical mean of the instantaneous envelope of the input signal. This signal is also applied to the differential network that generates a signal representing the difference in the instantaneous envelope of the input signal and the time averaged statistical envelope signal. This difference signal is applied to a square-law power detector and then to a low pass filter for time averaging. An output of the low pass filter is a signal representing an estimate of the noise component of the input signal.