GB1082734A - Land-to-mobile telephone link - Google Patents

Abstract

1,082,734. Automatic exchange systems. INTERNATIONAL STANDARD ELECTRIC CORPORATION. April 23, 1965 [April 30, 1964], No. 17191/65. Heading H4K. In a system which includes mobile radio stations, a base station 52 connected to a central office 51 is provided with a line circuit 63 for each mobile substation and is further connected to the radio equipment 53, 54 by way of a 2-to-4 wire converter 55 similar to that described in Specification 1,060,138. There may be for example 8 radio channels one of which is pre-allotted as the next to be used, and an idle tone is sent to align all the mobile stations on that channel. When a call is initiated at a mobile station the allotted channel is seized and a guard tone is sent to that station. If no tone indicating a dialling station is received the call is directed to an operator's position, but if such a tone is received the call goes to the switching equipment at the central office and a register is taken into use. Mobile subscribers take priority over normal subscribers. The identity of the mobile station is sent automatically in the form of tone signals which are repeated as D.C. impulses to the register. Dial tone is then sent to tell the mobile subscriber to dial. In both cases a pulse of guard tone is sent between impulses as a parity check. On a call to a mobile station either the operator or the calling subscriber dials the number of the station which is transmitted in the form of code signals over the pre-allotted radio channel. The station required recognizes its own code and when the subscriber replies the ringing is tripped to complete the connection.