| 摘要 |
This invention relates to a radio receiver for receiving frequency shift keyed radio signals. The receiver has a mixer 2 which receives the transmitted signals, a local oscillator 3 which feeds a mixing signal to the mixer 2 and a detector 7 which is fed from the mixer 2 through a single receiving channel. A chopper 8 applies a chopping signal to the local oscillator 3 to change the frequency of the oscillator between two values none of which lies midway between the two frequencies, the chopping signal being fed also to the detector 7 in synchronism with that applied to the local oscillator 3 to logically compare the chopper signal with the mixer output so that the detector detects the transmitted binary bits. The invention is useful in the fields of paging, telemetry and communication systems. <IMAGE> |
