GB2249696A - A radio system interface coupling network terminals to individual subscriber stations - Google Patents

Description

A RADIO SYSTEM INTERFACE UNIT FOR COUPLING DIALLING NETWORK INPUT/OUTPUT PORTS TO INDIVIDUAL SUBSCRIBER STATIONS: The invention relates to radio systems having interface units for coupling dialling network input/output ports to individual subscriber stations.

In radio systems, transfer devices of this type are of particular significance in the context of tactical applications in the military field, where systems based on cable or radio relay logistics may be used. The transfer device, also referred to as radio concentrator or radio access point (RAP) serves to connect mobile radio subscribers to a zone covered by the transfer device to a higher-regional, wired dialling network via the interface input/output port. In addition to speech and text information, all forms of data items may be transmitted.

In addition to good transmission properties, radio systems for tactical use are also required to meet stringent secrecy and interference immunity requirements. Therefore, one of the procedures used in information transmission is the so-called frequency jump procedure, as described in detail in the took entitled "Principles of Military Communication Systems" by Don. J. Torrieri, 1981, Artech House.

A bbck schematic circuit diagram shown in Figure 1 illustrates one known interface device already conceived for a tactical radio system. The transfer device comprises a switching device VE which forms the interface to a higher-regional, wired dialling network. For example, the switching device VE possesses four subscriber terminals TL1 to TILL, each connected to a respective radio station control unit, FS1 to FS4. Items of transmitted or received data SED are passed between the subscriber terminals TL1 to TL4 and the radio station control units FS1 to FS4, the term "transmitted-received data" SED being understood as the digitallised items of speech and text information and items of data already referred to.

The radio station control units FS1 to FS4, each cooperate with one of the radio stations, FG1 to FG4 respectively.

These each contain a transmitter S, a frequency generator F and a receiver E. Items of transmitted data SD and received data ED are exchanged between the transmitters S and receivers E of the radio stations FG1 to FG4 and the associated radio station control units FS1 to FS. .By applying a frequency address FA to the frequency generators S, the radio station control unit FS1 to FS4 set the transmitting and receiving frequency of the respective transmitters S and receivers E of the associated radio stations FG1 to FG. The sequence of the emitted frequency addresses FA is determined by a frequency code text stored in the radio station control units FS1 to FS. For purposes of synchronisation the radio station control units FS1 to FS4 are connected to a common clock pulse generator TG.

At their output end the transmitters S of the radio stations FG1 to FG4 are connected via a connection network, consisting of three switching stages K1 to K3, to a common antenna switch AS of an antenna A. A switching stage combination, K1 to K3, consists of so-called 3 D.B.-couplers. Here the transmitters S of the radio stations FG1 and FG2 are connected to the two inputs of the switching stage K1, the transmitters S of the radio stations FG3 and FG4 are connected to the two inputs of the switching stage K2, and the outputs of the switching stages K1 and K2 are connected to the inputs of the switching stage K3.

The output of the switching stage K3 is connected to the antenna switch AS, to which the antenna A is connected.

When there are more radio stations FG than those illustrated, there is an increase in the number of switching stages K via which the transmitters are coupled in accordance with Figure 1. Consequently there is also an increase in the power loss on the path from a transmitter S to the antenna A The antenna switch AS provides for the selective connection of the antenna A to the switching stage K3 and to a receiving distributor EV. A transmitting-receiving change-over stage SE, pulsed by the clock pulse generator TG, is provided for the switching-over of the antenna switch AS. Non-specifically designated outputs of the receiving distributor EV are connected to the receiver E of the radio stations FG1 to FGA.

During T.D.M. operation the antenna A is connected via the antenna switch AS in periodic alternation to the switching stage K3 and the receivin.g distributor EV. It is also conceivable to use a frequency filter in place of the antenna switch AS during frequency multiplex operation. During frequency multiplex operation the transmitters S and receivers E of the radio stations FGl to FG4 are then assigned separate, non-overlapping frequency ranges.

The mode of operation of the known unit illustrated in Figure 1 will now be described.

For example, if a connection is to be established between the subscriber terminal TL1 of the switching device VE and an external radio subscriber, the item of information is transmitted by a frequency jump procedure, for which purpose the radio station control unit FS1 consecutively emits frequency addresses FA to the frequency generator F of the radio station FG1 on the basis of a predetermined frequency code text. The item of information or items of data from the subscriber terminal TL1 are thus consecutively modulated by the radio station FG1 to various carrier frequencies and are transmitted via the antenna A. The same applies for the reverse direction, in the case of reception.

The frequency jump procedure is better resistant to interference the greater the available frequency range, i.e. the greater the number of available carrier frequencies. Each transmitter S of the radio stations FG1 to FG4 is capable of emitting one of the carrier frequencies within this frequency range.

During the transmitting operation of the transfer device a transmitting power loss of 3 D.B. occurs in respect of each coupler in the connection network composed of 3 D.B.-couplers. For example, if eight or more transmitters are coupled via the connection network, half or more of the transmitting power in the connection network is lost.

One object of the present invention is to provide a radio system construction in which this disadvantage is avoided.

The invention comprises the features of the exemplary embodiment, wherein there is provided a radio system interface unit for coupling dialling network input/output ports to individual subscriber stations, in which radio stations contain transmitters, frequency generators and/or receivers, the transmitters being connected via a switching network and a common antenna, and radio station control units connected between the switching device and the radio stations, which store frequency addresses required for a frequency jump procedure and control the data flow between individual subscriber terminals of the switching device and the radio stations, in which the radio stations are mutually assigned delimited, non-overlapping frequency bands, a switching network being provided which is connected between the respective radio -station control units and the radio stations and via which connections can be switched through for the data flows between the radio station control units and the radio stations.

Advantagecusly first and second radio station control units are provided, so that only connections for transmittedreceived data are switched by the switching network.

Preferably the transmitting switching network should contain transmitting filters and a 3 D.B.-coupler, wherein the transmitters of the radio stations are coupled in such manner that a frequency range is covered without gaps by the frequency bands assigned to the tr nsmitters.

The invention will now be described with reference to the drawings, in which Figure 1 represents one known embodiment already discussed; Figure 2 represents one exemplary embodiment of an interface unit construction in accordance with the present invention; Figures 3 and 4 represent two alternative embodiments of a transmitter switching network suitable for use in the proposed invention; and Figure 5 represents a further exemplary embodiment of a unit in accordance with the proposed invention.

The exemplary embodiment in accordance with the invention illustrated in Figure 2, for a system having a like number of radio stations to that in accordance with Figure 1 likewise comprises the switching device VE with (for example) four subscriber terminals TL1 to TL, the clock pulse generator TG, the antenna switch AS with the antenna A, the transmitting-receiving switch-over stage SE, a receiving distributor EV, radio stations FG1 to FG, and radio station control units FS1 to FS.

In contrast to the arrangement shown in Figure 1, here the transmitters S and the radio stations FG1 to FG4 are assigned non-overlapping frequency bands which are delimited relative to one another.

As in the arrangement shown in Figure 1, in the device illustrated in Figure 2 items of transmitted or received data SED are exchanged between the radio station control units FS1 to FSL and the switching device VE, but in accordance with the invention, the switching network is switched between the radio station control units FS1 to FS4 and the radio stations FG1 to FGL. The switching network KF consists for example of modules 4066.

The radio station control units, FS1 to FUSS, emit items of transmitted data SD and receive items of received data ED from the respective terminals 11 to 41, and 13 to 43 of the switching network KF. In addition the radio station control units FS1 to FSL emit frequency addresses FA to terminals 12 to 42 and to first control inputs Sll to S14 of the switching network KF. In the case of the parallel transmission of the frequency addresses FA, the terminals 12 to 42 have a plurality of poles.

The transmitters S of the radio stations FG1 to FGL receive items of transmitted data SD from terminals 14 to 44, or feed terminals 16 to 46 of the switching network KF, as the case may be, the receivers E passing received data ED to said terminals. The frequency generators F of the radio stations FG1 to FG4 receive frequency addresses FA from terminals 15 to 45 of the switching network KF. A control unit ST emits control addresses SA to second control inputs S21 to 524 of the switching network KF.

The principle on which the device in accordance with the invention is based will now be described.

The frequency range required for the frequency jump procedure is divided into delimited, non-overlapping frequency bands. The carrier frequencies of the frequency bands are each assigned a transmitter S of one of the radio stations FG1 to FG4. In accordance with the number of existing radio stations, the frequency range is divided into frequency bands which are assigned an equal number of transmitters S. Gaps can exist between the frequency bands or the frequency bands can cover the frequency range without gaps. The use of these transmitters S which are assigned to different frequency ranges means that the number of 3 D.B.-couplers can be reduced to a maximum of one since here low-loss frequency filters can be provided in place of 3 D.B.-couplers for the coupling of the transmitters S.

In each case the switching network KF establishes connections between the transmitter S and receiver E and the frequency generator F of one of the radio stations FG1 to FG4, and one of the radio station control units FS1 to FS4. This is achieved by applying a frequency address FA to one of the first control inputs S11 to S14 and a control address SA, corresponding to this frequency address FA, to one of the second control inputs S21 to S24. The control addresses SA ensure that only transmitted data SD with an associated carrier frequency, contained in the frequency band of the radio station FG, are switched through to this associated radio station FG. The control addresses FA are permanently set.A carrier frequency is determined by the frequency addresses FA emitted by one of the radio station control units FS1 to FS4. Having been set via the associated frequency generator F, this carrier frequency is transmitted by the transmitter S of one of the radio stations FG1 to FG4. From the switching network KF the frequency addresses FA and the associated items of transmitted data SD are switched through to the corresponding radio station FG.

For example, the radio station control unit FS1 emits a frequency address FA, which serves to determine a carrier frequency transmitted from the transmitter S of the radio station FG3. On the basis of this frequency address FA and the permanently set control address'SA the terminals 11 and 34 of the switching network KF are connected.

For example, only the first two binary values of the frequency address FA are applied to one of the first control inputs S11 to 514. From the switching network KF, the connection is then established to the terminals to which the same two binary values are applied, as a control address SA.

The receivers E of the radio stations FG1 to FGL are described in Figure 1 in association with a receiving distributor EV. The transmitters S of the radio stations FG5 to FG8 (e.g.

Figure 5) are connected to a transmitter switching network SK which is connected to the antenna switch AS. In the aforegoing only the transmitting operation has been described, but similar conditions apply to the receiving operation.

Figure 3 illustrates one exemplary embodiment of a transmitter switching network SK1, which contains three transmitting filters SW1 to SW3 via which, in a manner known per se, the transmitters of the radio stations FG5 to FG8 are interconnected and connected to the antenna switch AS. In this embodiment of the transmitter switching network SK, the transmitters S of the radio stations FG5 to FG8 cannot cover a frequency range without gaps, since the transmitting filters SW require an unavoidable frequency spacing for the filter transition to separate two adjacent frequency bands.

The second transmitter switching network SK2, illustrated in Figure 4 contains two transmitting filters, SW4 and SW5, together with a switching stage K4. The transmitters of the radio stations FG5 and FG6 are switched by the switching stage K4 and connected to the antenna switch AS. In this embodiment of the transmitter switching network SK, gap-free cover of the frequency range is possible if the transmitters S are assigned to the transmitter filters SW1 and SW2, or if more than four transmitters S are provided, are assigned to the two frequency filter arrangements composed of transmitter filters in such manner that transmitters S for mutually adjacent frequency bands are assigned to different frequency filter arrangments.

Figure 5 illustrates an advantageous variant of the embodiment shown in Figure 2, in which the radio stations FG5 to FG8 are shown, which differ from the radio stations FG1 to FG4 known from Figure 2 by virtue of the provision of an additional fine-frequency generator FF. The transmitting and receiving frequencies of the transmitters S and receivers E of the radio stations FG5 to FG8 are commonly set by the frequency generator F and a fine-frequency generator FF. The frequency band, i.e.

the transmitter S, is addressed by the frequency address FA, and a carrier frequency in the frequency band is addressed by the finefrequency address FFA.

Similarly to the radio station control units FS1 to FS4 as shown in Figure 2, Figure 5 represents first radio station control units FS11 to FS1fl which are connected to the subscriber terminals TL1 to TL4 of the switching device VE.

The switching network KF illustrated in Figure 5 differs from that shown in Figure 2 by virtue of a smaller number of connectable terminals. The frequency address FA is no longer switched through to the radio stations ,FG1 to FG4.

On the opposite side cf the switching network KF are arranged two radio station control units FS21 to FS24, each of which receive items of transmitted data SD from the switching network KF, which they forward t-o the transmitters S of the radio stations FG5 to FG8, and each of which receive items of received data ED from the receivers of the radio stations FG5 to FG8, which they forward to the switching network KF. The items of transmitted data SD can be obtained from the terminals 14 to 44, whereas the items of received data ED occur at the terminals 16 to 46. The second radio station control units FS21 to FS24 each emit frequency addresses FA to the second control inputs S21 to S24 of the switching network KF and to frequency generators F of the radio stations FG5 to FG8.In addition, the two radio station control units FS21 to FS24 each emit fine-frequency addresses FFA to the finefrequency generators FF cf the radio stations FG5 to FG8. The first and second radio station control units FS11 to FSl4, FS21 to FS24 are synchronised by the clock pulse generator TG. The frequency addresses FA and the fine-freuency addresses FFA are obtained in the first and second radio station control units FS11 to FS14, and FS21 to FS24 from the frequency code texts stored therein.

The switching network KF in each case establishes ccnnec:ions between one of the first radio station control units FS11 to FS14 and one of the second radio station control units FS21 to FS2L. This is effected by means of identical frequency addresses FA which occur at the first and second control inputs S11 to 514 and S21 to S24 of the switching network.

As four second radio station control units FS21 to FS2fl, i.e. four transmitters S of the radio stations FG1 to FG4 can be driven by four different frequency bands, the first radio station control units FS11 to FS14 can emit four different frequency addresses FA.

For example, a connection is established between the first radio station control unit FS12 and the second radio station control unit FS24 when the same frequency address FA occurs at the first control input S12 and the second control input 524 of the switching network KF.

As described with reference to Figure 1, the receivers E of the radio stations FG5 and FG8 are connected to the receiving distributor EV. The transmitters S of the radio stations FG5 to FG8 are connected to a transmitter switching network SK which is connected to the antenna switch AS.

The transmitters S of the radio stations FG5 to FG8 are permanently set at predetermined frequency bands on the basis of the frequency addresses FA emitted from the two radio station control units FS21 to Fas24 Within these frequency bands specific channels and carrier frequencies can be selected by the fine-frequency addresses FFA emitted from the second frequency (FIC) control units FS21 to FS24. For example, if a connection is now established between the subscriber terminal TL1 of the switching device VE and an external radio subscriber, the item of information is transmitted in the frequency jump procedure.For this purpose, on the basis of the predetermined frequency code text, the first radio station control unit FS11 consecutively emits frequency addresses FA to the first control input S11 of the switching network KF. As a result, the subscriber terminal TL1 is consecutively connected to the transmitters S of the radio stations FG5 to FG8 to whose frequency generators F the same frequency address FA is connected. Thus the item of information or the items of data from the subscriber terminal TLl are consecutively transmitted via the antenna A from one of the radio stations FG5 to FG8 in which they are modulated to different carrier frequencies.

In the device constructed in accordance with the invention, the connection element between the antenna A and the radio stations FG5 to FG8, the transmitter switching network SK, SK1 or SK2 primarily consists of transmitter filters SW1 to SW5 whose switching function is subject to low losses. This is possible since the transmitters S of the radio stations FG5 to FGS are assigned mutually delimited, non-overlapping frequency bands.

The number of parallel radio connections, i.e. of the radio stations FG is limited by the frequency allocation, but not by the switching network KF. The greater the number of parallel radio connections, the greater is the deign in transmitting power of the device in accordance with the invention (Figures 2 to 5) in relation to the conventional device (Figure 1).

Claims (6)

CLAIMS:

1. A radio system interface unit for coupling dialling network input/output ports to individual subscriber stations, in which radio stations contain transmitters, frequency generators and/or receivers, the transmitters being connected via a switching network and a common antenna, and radio station control units connected between the switching device and the radio stations, which store frequency addresses required for a frequency jump procedure and control the data flow between individual subscriber terminals of the switching device and the radio stations, in which the radio stations are mutually assigned delimited, non-overlapping frequency bands, a switching network being provided which is connected between the respective radio station control units and the radio stations and via which connections can be switched through for the data flows between the radio station control units and the radio stations.

2. A unit as claimed in Claim 1, in which the switching network possesses both first and second control inputs and terminals on the side of the radio stations and on the side of the radio station control units, for items of transmitted data and/ or received data, where those terminals which are assigned to a first control input are connected to those assigned to a second control input when the same frequency address occurs at both of the control inputs.

3. A system as claimed in Claim 2, in which further radio station control units are provided between the switching network and the radio stations, the radio stations having additional finefrequency generators, where the frequency generator and finefrequency generator together determine the transmitting and/or receiving frequency, and the radio station control units emit frequency addresses to the first control inputs, whereas the further radio station control units emit frequency addresses to the second control inputs of the switching network and emit frequency addresses at fine-frequency addresses to the radio stations.

4. A system as claimed in any preceding Claim, in which the transmitter switching network is provided with a frequency filter arrangement which consists of a set of transmitting filters possessing frequency gaps, required for unavoidable filter transitions between frequency bands assigned to the transmitters.

5. A system as claimed in any preceding Claim, in which the transmitter switching network has two frequency filter arrangements which consist of transmitter filters connected at their output end via a 3 D.B.-coupler to the antenna and a gap-free cover of the frequency range is obtained by the transmitters of the radio sets being distributed amongst the two frequency filter arrangements in such manner that transmitters for mutually adjacent frequency bands are assigned to different frequency filter arrangements.

6. A radio system interface unit substantially as described with reference to any one of Figures 2 to 5.

6. A radio system interface unit substantially as described with reference to any one of Figures 2 to 5. AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS.

1. A radio system interface unit for coupling dialling network terminals to individual subscriber stations, in which radio stations contain transmitters, frequency generators and receivers, the transmitters being connected via a switching network to a common antenna, and radio station control units connected between a switching device and the radio stations, which store frequency addresses required for a frequency jump procedure and control the data flow between individual subscriber terminals of the switching .device and the radio stations, in which the radio stations are assigned delimited, non-overlapping frequency bands, a switching network being provided which is connected between the respective radio station control units and the radio stations and via which selective connections can be switched through in accordance with the frequency jump procedure for the data flows between the radio station control units and the radio stations.

2. A unit as claimed in Claim 1, in which the switching network possesses both first and second control inputs and terminals on the side of the radio stations and on the side of the radio station control units, for items of transmitted data and/ or received data, where those terminals which are assigned to a first control input are connected to those assigned to a second control input when the same frequency address occurs at both of the control inputs.

3. A system as claimed in Claim 2, in which further radio station control units are provided between the switching network and the radio stations, the radio stations having additional finefrequency generators, where the frequency generator and finefrequency generator together determine the transmitting and/or receiving frequency, and the radio station control units emit frequency addresses to the first control inputs, whereas the further radio station control units emit frequency addresses to the second control inputs of the switching network and emit frequency addresses at fine-frequency addresses to the radio stations.

4. A system as claimed in any preceding Claim, in which the transmitter switching network is provided with a frequency filter arrangement which consists of a set of transmitting filters possessing frequency gaps, required for unavoidable filter transitions between frequency bands assigned to the transmitters.

5. A system as claimed in any preceding Claim, in which the transmitter switching network has two frequency filter arrangements which consist of transmitter filters connected at their output end via a 3 D.B.-coupler to the antenna and a gap-free cover of the frequency range is obtained by the transmitters of the radio sets being distributed amongst the two frequency filter arrangements in such manner that transmitters for mutually adjacent frequency bands are assigned to different frequency filter arrangements.