A radio communication apparatus comprises a detecting circuit for detecting a change of a received frequency of a radio communication channel during a communication and outputting a digital detection signal, a pulse width modulating circuit, and a smoothing circuit. The pulse width modulating circuit...http://www.google.ca/patents/US5444736?utm_source=gb-gplus-sharePatent US5444736 - Radio communication apparatus having an automatic frequency control circuit for controlling a transmission frequency on the basis of a reception frequency
