Abstract: A mobile communication system with a portable telephone capable of automatically switching between a ground communication system and a satellite communication system, in which when the ground satellite system is not available and the portable telephone is in a place where a satellite from the satellite communication system cannot be observed, a signal process operation is switched in such a manner that an RF signal is processed by the ground communication system, and both of an IF signal and a baseband signal are processed by the satellite communication system; and a relaying apparatus for performing a converting operation of the RF signal in the satellite communication system and the RF signal in the ground communication system. The ground communication system and the satellite communication system can be automatically switched to be used without replacing the antenna/radio frequency units.

Abstract: A voice transmitting apparatus and a voice receiving apparatus using voice activation techniques. The voice transmitting apparatus is provided with a UW2 burst generator 8 for generating, in the absence of voice, second unique word pattern (UW2) differing from first unique word pattern (UW) used in the presence of voice. Also, the voice receiving apparatus is provided with a UW2 detection circuit which makes it silent upon the detection of the second unique word pattern (UW2), thus preventing the occurrence of unwanted sounds while positively maintaining the frame timing.

Abstract: A method and apparatus for pointing a tracking antenna to a communication satellite in the initial stage of satellite tracking by means of frequency shifting, upon reception of a carrier wave having deviation from the accepted standards of frequency, the antenna initial pointing apparatus including a downconverter for converting a signal received at a directive antenna to an IF signal, a synthesizer for providing the downconverter with a local signal for the IF signal conversion, a power detector for detecting the power of the IF signal, and a controller for controlling the synthesizer to generate the local signal and also for controlling the rotation of the directtive antenna. Based on a detected result from the power detector, a downconverted IF signal having deviation from the accepted standards of frequency is further converted to be included within a limited bandwidth of the power detector by means of frequency shifting.