RADIO SYSTEM

摘要

1497789 Relaying arrangements SIEMENS AG 31 Aug 1972 [25 Feb 1972] 40514/72 Heading H4L In operation of a radio-telecommunications system (Fig. 2) in which any one of a number of subscribers associated with a first station can be connected to a selected subscriber associated with a second station not directly accessible from the first, the connection is established via a relay station by making a transmission which is radiated to all adjacent accessible stations and receiving such transmission at the receiving stations via respective directional antenna. Thus, when a subscriber A associated with station I dials a subscriber B associated with station VI, a call signal is transmitted on a service channel from station I. The signal is received at station III and, after adding to the signal a code which identifies station I as the original, station III transmits the signal non-directionally. Stations II, IV and V receive and retransmit the signal (with further coding to establish station III as the caller) and station VI receives the signal simultaneously from stations IV and V. One of these signals is rejected and, using the coding of the other, a return transmission from station VI on its service channel is received by the directional antennµ of the relevant relay stations and relayed back to the original station I. Thus, in establishing the return link, individual stations withdraw only information intended for them. The subscribers are connected to their associated stations by radio or by line and vocoders preferably are included to reduce bandwidth. Speech channel information, which is transmitted in digital form, can be pulse code modulated or pulse delta modulated. The service and other priority channels are always open. In the transmitter stage of the station (Fig. 4) a random generator ZG, whose output is similar to a normal speech noise spectrum, is connected to any channel modulator KM not in use at a given time to hinder analysis of the transmission by unauthorized parties. Each station has a number of different directional antennµ, one for each adjacent accessible station, and each antenna EA1-EA4 is associated with a respective receiver RFE1-RFE4. The stations can be mobile (Fig. 1, not shown). Resistance of the system to jamming can be increased by reducing the mesh size (i.e. using an increased number of stations. In special cases, some stations can be interconnected by line, conventional narrow band relay equipment or scatter equipment.