| 摘要 |
A radio system includes a fairly large number of transmitting-receiving stations which are spatially distributed over an area to be covered. Each of the stations preferably serves a fairly large number of individual subscribers in such a way that the individual subscriber can reach a subscriber who may be connected to another transmitting-receiving station. Radio frequency channels with different frequencies are provided at least for the speech channels of adjacent exchanges and positioned in a frequency range which is fixed for the system. The transmission of the individual speech channel is provided in accordance with digital methods, preferably by means of converting the signals of the individual speech channel into a PCM or a pulse delta modulation signal. Preferably, the bandwidth for the individual signal is reduced through the use of a Vocoder. The transmitter of an exchange transmits its information toward the other exchanges, through which a connection is to be established to the called party, by way of an omnidirectional antenna which effects little grouping in the plane spatially determined by the exchange. Directional antennas are provided for receiving the radio frequency signals and preferably provide a relatively high degree of grouping in the horizontal plane and in the vertical plane. The transmitter therefore covers all exchanges which must be reached by way of one antenna while the receiver in each exchange will respectively receive the transmitters of the other exchanges by way of its associated directional antenna.
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