The present invention provides a radio frequency ("RF") activation system
with improved operating capability and ease of installation. Improved
responsiveness is provided by the receiver which determines the frame
timing of incoming signals and calculates the estimated time of arrival
for ensuing frames thus minimizing loss of frame synchronization
problems. In one embodiment, this is accomplished by determining the time
span of the frame start sequence and using this to determine the frame
timing of an incoming RF signal. The receiver also makes corrections for
timing errors between the receiver and transmitter by re-synchronizing
the receiver with the incoming RF signal.