DUAL-MODE SATELLITE/CELLULAR PHONE WITH A FREQUENCY SYNTHESIZER

摘要

A radio telephone which is capable of switching between operating through a land based cellular network and an orbiting satellite system is disclosed. First antenna and radio frequency circuits receive transmitted signals from the land-based network and form first conditioned signals for subsequent numerical decoding. Second antenna and radio frequency circuits receive transmitted signals from the orbiting satellite system and form second condition signals for subsequent numerical decoding. Numerical decoders process either the first condition signals or the second conditioned signals to provide an automatic frequency control signal. Reference frequency oscillators controlled by the automatic frequency control signal provide a reference frequency signal. Radio frequency synthesizers using the reference frequency signal and having a frist output at a first programmable frequency connected to the first radio frequency circuits determine reception of a channel frequency of the land-based network and a second output at a second programmable frequency connected to the second radio frequency circuits determines reception of a channel frequency of the orbiting satellite system.