Radio receiver receiving voice and data signals

Abstract From the Canadian patent

A radio receiver having a frequency converter which frequency converts an RF signal into an IF signal. An IF filter filters the IF signal to provide the filtered output to a frequency discriminator. The discriminator frequency discriminates the filtered IF signal to produce a baseband signal. From the baseband signal a voice signal is recovered and a data signal is extracted. Using the IF signal a field detector, detects an electromagnetic field strength of RF signal and outputs a signal detect signal when the field strength is higher than a predetermined level. A sync detector detects a sync signal in the extracted data signal to produce a sync detect signal. In response to the signal and …