FI77553B - RADIOTELEFONANLAEGGNING. - Google Patents

Description

77553

Radio telephony systems

The invention relates to radiotelephone equipment according to the preamble of claim 1.

Such radiotelephone equipment is known from Technischen Mitteilungen AEG-TELEFUNKEN 68, (1978) 6/7, pages 287-296. It is intended to operate, in particular, for the distribution of an urban area or an entire area or even several areas.

The fact that high costs (e.g. line costs) have to be used for synchronization signal connections or frequency filters has proved to be disadvantageous in the distribution of such a large distribution area by means of synchronous common wave radio operation.

Admittedly, these costs would be eliminated if the so-called quasi-synchronous co-wave radio operation described in the journal Elektrizitätswirtschaft, Volume 80 (1981), Booklet 6, pages 187-198 were used instead of synchronous co-wave operation. In this mode of operation, the frequency of each transmitter is ensured by a very stable oscillator (frequency normal). It occurs as an autarchy structural group in each fixed transmitter, and the carrier frequency is thus independent of external reference frequency sources or their availability (e.g., atmospherically disturbed normal frequency reception). But in the case of a large distribution area and thus several transmitters, the cost for the same number of frequency normals at a price of a few thousand D-marks is very considerable.

It is therefore an object of the invention to provide a radiotelephone apparatus for an area larger than a distribution area; this is intended, on the one hand, to reduce the cost of synchronization connections (e.g. wires) or frequency filters 77553, without, on the other hand, requiring a very stable frequency normal for each transmitter in the area.

This object is solved by the features of claim 1. Preferred forms of further development are set out in the subclaims.

The invention is based on the following ideas:

When an area is divided into several distribution areas, in which the transmitters synchronized from the exchange operate in synchronous common radio operation, it is sufficient that the exchanges themselves are not synchronized from the main exchange and thus become independent of their synchronization functionality, but the exchanges can be equipped with , namely in such a way that the distribution areas adjacent to each other and deliberately intersecting at their edges operate in quasi - synchronous common wave radio operation. Thus, a practical compromise has been found between the required reliability on the one hand and the price of this reliability on the other.

A preferred embodiment will be explained in more detail with the aid of the drawing.

The area shown has a plurality of exchanges 1-5 with associated distribution areas, e.g. 6. Each distribution area has a plurality of transmitters, e.g. 7-13, for transmitting radio calls to mobile radio call receivers. Each distribution area 6 operates in synchronous common wave radio operation. In this case, both modulation signals and synchronization signals are transmitted to the transmitters 7-13 via the two-wire or four-wire connections 7a-13a when leaving the exchange 2. After equalizing the propagation time differences in the distribution area, care is taken that these transmitters transmit call 3,77553 signals based on the modulation signals from the exchange 2 simultaneously and that the transmitters 7-13 are precisely synchronized with each other via existing synchronization signal connections with a high frequency transmission frequency. In this case, techniques known in connection with synchronous common wave radio operation are used.

However, this does not work for high-frequency synchronization of exchanges 1-5, but only provides modulation signals via links 15-19 (e.g. two-wire connections or directional radio slots) via exchanges 1-5 to transmitters, e.g. 7-13, largely simultaneously. and for phase rigid transmission. In this case, the travel time differences in the area (and also in several areas) must be compensated. On the other hand, does the high-frequency synchronization of the exchanges 1-5 from the main exchange 14 not take place or at most occasionally, for example daily, weekly or monthly? for the exchanges 1-5 contain long-term highly stable oscillators to achieve quasi-synchronous co-wave radio operation. In this case, in turn, a known technique can be used, for example, as described in Elektrizitätswirtschaft, Volume 80 (1981), Booklet 6, pages 187 ff. It recommends that the frequency standards be made so stable in the exchanges 1-5 that the frequency deviations between the individual distribution ranges are at most 20 Hz for the carrier frequency used therein.

To this end, the relative -8 frequency deviation of each frequency normal should be less than 2 x 10 days in the temperature range of -20 to + δ 5 ° C.

The main exchange 14 is accessed from the public telephone network via a relay station 20, so that the user of the public telephone can access the mobile radiotelephone receiver via the radiotelephone equipment shown.

4,77553

There may be several radiotelephone equipment shown in the telephone network, so that the transmission takes place from the telephone network to one of the main exchanges, namely those where the desired mobile radiotelephone receiver is currently located, or - if the location is not known - to several main exchanges.

Claims (4)

5,77553 1. Radiotelephone equipment with the following features: a frequency standard exchange (2) is provided for transmitting radio calls to a number of radio call receivers (7-13) arranged in the exchange via fixed transmitters (7-13) distributed in the distribution area <6), each having two adjacent distribution areas, the transmitters (7-13) are arranged to operate in synchronous common wave radio operation and transmit substantially simultaneously identical paging signals on the basis of modulation signals coming from the exchange (2) and compensated for travel time, there are synchronization signal connections to the respective synchronization device of the transmitters, characterized in centers (1-5) with their associated distribution areas (6), these centers (1-5) are each provided with a very stable frequency normal, adjacent distribution areas operating in a quasi-synchronous common wave in diode operation, the exchanges (1-5) receive modulation signals from the main exchange (14) via transmitters (7-13) for substantially simultaneous transmission. Radiotelephone equipment according to Claim 1, characterized in that the synchronization signal connections from the main exchange (14) to the exchanges (1 to 5) for post-synchronization are established temporarily when necessary, e.g. daily or monthly. Use of radiotelephone equipment according to one of the preceding claims as an extension of a telephone network, characterized in that the main exchange (14) is accessed via the telephone network. 6 77553 Use of radiotelephone equipment according to Claim 3 as an extension of a telephone network, characterized in that a plurality of main exchanges <14) are arranged in the telephone network.