Automatic radio telephone system

Claim 1

An automatic radio telephone system having: a plurality of mobile transmitting-receiving stations, a plurality of stationary transmitting-receiving stations which can be coupled through a plurality of duplex speech channels to said mobile transmitting-receiving stations, a common switching station means coupled to said stationary stations for establishing any desired connection between said mobile stations or between said mobile stations and the subscribers of a line-wire telephone network, each one of said stationary transmitting-receiving stations comprising at least a transmitting means for continuously transmitting a signal on an individual call channel frequency which is specific for each stationary station, and furthermore each stationary station having means for using a plurality of duplex speech channels, each one of said mobile transmitting-receiving stations comprising a duplex speech channel selector and a call channel selector means for selecting the call channel frequency which is locally received strongest and which automatically tunes the mobile transmitting receiving station for reception on the selected call channel, wherein the improvement comprises a channel status store, a control means coupled to said store for up-dating in the channel status store of each stationary station the instantaneous occupancy status of duplex speech channels of that stationary station, a separate output register means coupled to each stationary station to the channel status store and controlled by said control means, said output register means providing the channel number of any free duplex speech channel, the transmitter means present in each stationary station continuously transmitting a signal on the call channel frequency which is specific for the stationary station, said call channel frequency signal being modulated by a code which is representative of the channel number provided by said output register, and each mobile station comprising a demodulator means and a storage register means for respectively demodulating and storing in said storage register the channel number transmitted over the received call channel, and a control device means coupled to said duplex speech channel selector for automatically tuning in response to a connection set-up command the transceiver of the mobile station to the duplex speech channel indicated by the channel number stored in said storage register.