NARROW BAND SCANNING RF RECEIVER

摘要

The narrow band scanning RF receiver (12) includes a ph ase-locked loop radio frequency stage having a reference oscillator (38) for receiving a radio frequency signal. The radio frequency stage has a frequency which may be selected by a controller via a selectable frequency signal supplied to the reference oscillator (38). The controller tests for the presence of a legitimate radio frequency signal and also temporarily inhibits the tuned radio frequency stage when changing from a first selected frequency to a second selected frequency. The receiver (12) produces an output for controlling an electric motor (100) for operating a barrier.