GB2260467A

GB2260467A - Repeater

Info

Publication number: GB2260467A
Application number: GB9119589A
Authority: GB
Inventors: Michael George Gloster
Original assignee: BLICK COMMUNICATIONS Ltd
Current assignee: BLICK COMMUNICATIONS Ltd
Priority date: 1991-09-12
Filing date: 1991-09-12
Publication date: 1993-04-14
Also published as: GB9119589D0

Abstract

A repeater 27 for a communication (e.g. radio paging) system comprises a receiver 29, a decoder 45 for decoding a signal received by the receiver 29 in order to determine the source and intended recipient of the signal, and a transmitter 35 for retransmitting the received signal. <IMAGE>

Description

REPEATER The present invention relates to a repeater for a communications system.

The invention is applicable to any kind of broadcast communications system, for example a paging system, a telephone communications system or the like. It may for example work on radio (eg. LF, HF, VHF, UHF), microwave, infrared or optical frequencies.

Whilst being suitable for any of the aforementioned applications or others, the invention is especially suited to use in radio paging systems. Conventionally, such a paging system comprises central site encoding equipment which communicates with local pagers in its own zone by way of a main site transmitter and with remote pagers via local transmitters. Link interfaces are provided between the central site encoding equipment and the remote transmitters. The link interfaces are interconnected e. g. via a land line.

This conventional paging network has problems in that sometimes it is impossible to install land lines to certain remote locations and the rebroadcast to the remote transmitters results in cross-interference between transmissions within the system.

We have now devised a new form of system which overcomes these drawbacks. This uses, in accordance with the present invention, a repeater for a communication system, the repeater comprising receiver, a decoder for decoding a signal received by the receiver in order to determine the source and intended recipient of the signal, and a transmitter for retransmitting the received signal.

The present invention also extends to a method of communication, the method comprising receiving a signal, decoding the signal in order to determine the source and intended recipient of the signal and retransmitting said signal.

It is especially preferred that the repeater should have the ability, after decoding the signal received in a given format, to re-encode it in a different format for retransmission.

Although the signal may be retransmitted at a frequency different from that of the originally received signal, preferably it is retransmitted at the same frequency. Most embodiments are directed to the situation where the original signal comprises "header" information. Header information comprises for example, an indication of the identity of the user, geographical origin, number of transmissions, and identity of the specific transmission (eg to identify the intended recipient zone). For example, a paging system utilising a repeater according to the present invention may transmit to a plurality of zones which contain respective local transmitters. It may transmit to these zones in a predetermined time sequence.For example, in time slot 1, it may transmit to the North East zone, in time slot 2, to the North West zone and to the South West and South East zones in time slots 3 and 4 respectively.

The retransmitted signal from the repeater according to the present invention may communicate direct with pagers, or with a local transmitter, or with another repeater in a chain. To avoid multi-pathing, the retransmission should be made during a time slot when (say) the central transmitter, another repeater, or another local transmitter is broadcasting to another time zone. Therefore, it is especially preferred that after the repeater has received the original signal, the content of that signal should be stored for a predetermined time to be rebroadcast during the appropriate time slot.

It is also preferred that before retransmitting the signal, the repeater should insert its own header information to the signal in place of the original header, this new header, at least containing the repeater' s own identity and/or location. However, the new header may equally be inserted in addition to the original header.

The present invention will now be explained in more detail by reference to the following description of a preferred embodiment in which Figure 1 shows a paging system utilising a repeater according to the present invention; Figure 2 shows a basic block diagram of the repeater appearing in Figure 1; and Figure 3 shows a more detailed circuit block diagram of the repeater of Figure 2.

Figure 1 shows a geographical area 1 for a paging service. Within this area are located, a central or main site 3 and remote zones 5, 7 and 9.

In the main site, there is located a central site encoding equipment 11 connected to a main site transmitter 13. Two of the remote zones 5, 7 are served by respective remote transmitters 15, 17 for communicating with pagers within those zones.

Th central site encoding equipment is connected to a link interface 19 and the remote zone transmitters 15, 17 are connected to respective local link interfaces 21, 23.

The remote zone transmitters receive paging broadcast signals via a land line bearer 25 and the link interfaces. Thus, when it is decided to communicate with pagers in the remote zones 5, 7, appropriate paging information is sent from the central site encoding equipment via the bearer and link interfaces to be broadcast in the respective zones by their local transmitters.

However, the remote zone 9 is in a geographical location unsuitable for land line communication with the main site. Therefore, this zone is provided with a remote repeater device 27. The repeater receives paging information from the main site transmitter 13.

The basic construction of the repeater 27 is shown in Figure 2. It comprises a receiver 29 connected to an aerial 31 for receiving a transmission signal from the central site transmitter. The output of the receiver is connected to a micro-computer system 33 adapted to decode header information in the received signal. The micro-computer system also comprises a memory for storing the information from the received sigr:al prior to retransmission.

The micro-computer is connected to a transmitter 35 of the repeater and the transmitter is connected to a transmitter aerial 37.

More detail of the construction of the repeater is shown in Figure 3.

Optionally, the receiver 29 is connected to the micro-computer system 33 via a filter circuit 39 for removing unwanted noise/inteference. The micro computer system is connected to the transmitter 35 via appropriate control circuitry 41 which optionally may also control an aerial changeover unit 43, eg consisting of appropriately connected relays.

The micro-processor system comprises a central processor unit 45 connected to input/output ports 47. These input/output ports are respectively connected to the aforementioned transmitter control circuitry 41, to a battery backed random access memory (RAM) for back-up memory preservation during a power-down situation, and to links/switches 51. The links/switches enable certain pre-programmed parameters to be input to the micro-processor unit, for example receive and transmit frequencies and site parameters.

The links/switches also can be used to instruct the unit to effect a format charge. Thus, for example, the incoming signal may be recieved in a two-tone code format utilising tones at 665Hz and 1. 3KHz. After decoding, the signal may be re-encoded in (say) the POCSAG or Motorola Two-Tone format prior to retransmission.

The micro-processor unit also contains an eraseable-programmable-read-only-memory (EPROM) 53 containing the main operating program, as well as internal default parameters and the like. The user-specified data input via the links/switches is stored in a random access memory (RAM) 55 (backed-up by the battery powered unit 49).

This preferred embodiment is programmed to receive and transmit on the same frequency.

In use, the signal transmitted by the main site transmitter 13 is received by the repeater's receiver 29 and decoded in the CPU 45. Header information from the original transmission is stored in the RAM 55. The EPROM contains time slot recognition data so that the CPU 45 can determine the appropriate time slot for retransmission The RAM 55 also contains the repeater' s own header information which the CPU inserts in place of the original header during the retransmission time slot. At that time, the original signal with attached repeater header information is output by one of the ports 47 and the transmitter control circuitry 41 to the transmitter 35, whereby it is retransmitted by means of the aerial 37.

The header information in the retransmitted signal enables it to be recognised and received by the appropriate designated pagers/remote zone transmitters/further repeater' s and prevents it from being propagated by devices for which that is not appropriate.

Claims

CLAIMS:-

1. A repeater for a communication system, the repeater comprising a receiver, a decoder for decoding a signal received by the receiver in order to determine the source and intended recipient of the signal, and a transmitter for retransmitting the received signal.

2. A repeater according to claim 1, wherein the repeater can decode the signal received in a given format, and subsequently re-encode it in a different format for retransmission.

3. A repeater according to claim 1 or 2, the said repeater being capable of retransmitting the signal at a frequency different from that of the originally received signal.

4. A repeater according to any preceding claim, the said repeater being capable of retransmitting the signal at the same frequency as the received signal.

5. A repeater according to any preceding claim, the said repeater being particularly adapted and arranged to process a signal which comprises an indication of one or more of: the identity of the user, the geographical origin of the signal, the number of transmissions, and the identity of the specific transmission.

6. A repeater according to claim 5, particularly adapted and arranged to transmit to a plurality of zones which contain respective local transmitters.

7. A repeater according to claim 6, wherein the said repeater can transmit to the said zones in a predetermined time sequence.

8. A paging system incorporating a repeater according to any preceding claim.

9. A method of communication comprising receiving a signal, decoding the signal in order to determine the source and intended recipient of the signal, and retransmitting said signal.

10. A method according to claim 9, wherein the said repeater communicates directly with pagers.

11. A method according to claim 9, wherein the said repeater communicates directly with a local transmitter.

12. A method according to claim 9, wherein the said repeater communicates directly with another repeater in a chain.

13. A method according to any one of claims 9 to 12, wherein the said repeater transmits to a plurality of zones which contain respective local transmitters.

14. A method according to claim 13, wherein the said repeater transmits to the said zones in a predetermined time sequence.

15. A method according to any one of claims 10 to 12 or claims 13 and 14 when dependent on one of claims 10 to 12, wherein retransmission is made during a time slot when the central transmitter, the other repeater, or the local transmitter is broadcasting to another time zone.

16. A method according to claim 13, wherein, after the repeater has received the original signal, the content of that signal is stored for a predetermined time before being rebroadcast during an appropriate time slot.

17. A method according to any one of claims 9 to 16, wherein, before retransmitting the signal, the repeater inserts its own header information into the signal, in place of the original header.

18. A method according to claim 17, wherein the said new header at least contains the repeater' s own identity and/or location.

19. A method according to claim 17, wherein the said new header is inserted in addition to the original header.

20. A repeater substantially as herein described with reference to Figures 2 and 3 of the accompanying drawings.

21. A paging system substantially as herein described with reference to Figure 1 of the accompanying drawings.