Received signal decision apparatus for digital modulated signal receiver

Abstract

A received signal strength detector detects a received signal strength corresponding to an envelope of a received signal and outputs a received strength signal corresponding to the strength level. A DC component extracting filter extracts a DC component from the received strength signal and outputs an extracted DC component signal corresponding to the level of the DC component. A modulation rate component extracting filter extracts a line spectrum component corresponding to a modulation rate from the received strength signal and outputs an extracted modulation rate component signal corresponding to the level of the modulation rate component. A decision circuit compares the extracted DC component signal and the extracted modulation rate component signal to respective threshold levels set therefor and decides, when the levels of the two signals are higher than the respective threshold levels, that the received signal is an optimum signal. The decision may otherwise be based on comparison of a ratio between the two extracted signals with a threshold level set therefor.

Dependencies are inferred from the claim text.