GB1602839A

GB1602839A - Telecommunications systems

Info

Publication number: GB1602839A
Application number: GB2967577A
Authority: GB
Original assignee: Sperry Ltd
Current assignee: Unisys Group Services Ltd
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-11-18

Description

(54) IMPROVEMENTS IN OR RELATING TO TELECOMMUNICATION SYSTEMS (71) We, SPERRY LIMITED, formerly SPERRY RAND LIMITED, a British Company, of Sperry House, 78 Portsmouth Road, Cobham, Surrey, KT 11 1JZ, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be perfromed, to be particularly described in and by the following statement This invention relates to telecommunication systems.

According to the present invention a telecommunication system comprises a base station and at least one relay station remote from and in telecommunication with the base station via a duplex link with at least one of the relay stations having a satellite station in telecommunication therewith via a simplex link, each relay station associated with a satellite station being provided with means for storing messages received either from the base station or the satellite station and subsequently forwarding those messages to the satellite station and base station, respectively, when the associated link is free.

The use of a simplex telecommunication link between each satellite station and the associated relay station makes the satellite stations cheaper since the extra components required for a duplex link are avoided. The simplest simplex link is a cable and this is particularly advantageously employed when the satellite station is in the form of a submersible vessel which may be utilised for investigatory work on the sea bed. In this case, the base station will transmit messages in the form of command signals to the submersible vessel, such as throttle and rudder commands, and will require the vessel to transmit data regarding its position, for example.Since the simplex link between the satellite and relay station can only convey data in one direction at a given instant, the provision on the relay station of means for storing messages enables the satellite station to receive all messages in due course even though the simplex link may be engaged at the instant of receipt by the relay station of a message from the base station intended for the satellite station.

A digital telecommunication system in accordance with the present invention will now be described in greater detail, by way of example, with reference to the drawings accompanying the Provisional Specification, in which: Figure 1 is a diagrammatic representation of the telecommunication system, Figure 2 is a block diagram of part of a relay station of the system having a satellite station associated therewith, and Figure 3 is a block diagram of part of the satellite station associated with the relay station of Figure 2.

Referring to Figure 1, the telecommunication system comprises a base station 1 in telecommunication via respective duplex links 2 with tow relay stations 3, 4. The relay station 4 has associated with it a satellite station 5 via a simplex telecommunication link in the form of a cable 6 being provided between the two.

Each relay station 3, 4 comprises a transmitter/receiver 7 connected to a controller 8 operable to control the passing of incoming messages to output data peripherals 9 and the receipt of data from input data peripherals 11 for the construction of messages to be transmitted to the base station 1. Relay station 4 has a store-andforward controller 12 connected to the controller 8, the controller 12 being connected to the cable 6 and operable to store messages intended for the satellite station 5 until such time as the cable 6 is free for transmission purposes. The controller 12 is also operable to store messages from the satellite station 5 for the base station 1 until such time as the associate duplex link 2 is free for transmission purposes.The satellite station 5 has a controller 13, input peripherals 14 and output peripherals 15 generally similar to those of the relay stations 3, 4.

Referring now to Figure 2, this shows the controller 8 and store-and-forward controller 12 of the relay 4 in greater detail.

The controller 8 comprises a deserialiser 16 for messages received from the base station 1. Each message has a five word format as follows: Header Word 1Synchronisation and mess age routing with different codes defining different message destinations and origins.

Header Word 2-Peripheral address for the next two data words.

Data Word 1-A seven bit data word.

Data Word 2-A seven bit data word.

Message or Longitudinal Parity Word-A seven bit parity check for the previous four Words and the Parity Word.

If the deserialiser 16 recognises the code of the Header Word 1, then it will proceed in one of two ways according to the routing indicated in the Header Word 1. If the routing indicates that the message is intended for the relay station itself, then Header Worder 2 is stored in a store 17 and the two Data Words 1 and 2 stored in a buffer 18 under the control of a transmitter/ receiver controller 19. If the Message Parity Word shows there to have been no error in the message, then the Data Words 1 and 2 are outputed to the peripherals 9, again under the control of controller 19, in accordance with the address contained in Header Word 2.If the routing data in Header Word 1 indicates that the message is intended for the satellite station 5, then the whole message is routed to the store-andforward controller 12 and more specifically to a buffer 21 and thence to a serialiser/ deserialiser 22 which is controlled by a further transmitter/receiver controller 23, which components together with a further controller 24, make up the controller 12.

Since the system is designed to handle messages asyncronously (i.e. messages are transmitted at random and the receiving station does not know in detail when a message might be received, sQme timing mechanism is required to ensure that no errors occur as a result of attempted transmission during an existing transmission, for example. This timing function is effected by the controller 24 which minitors all receptions and transmissions and attends to the necessary timing, being connected to the controllers 19 and 23.

When a message is transmitted to the satellite station 5, it is serialised at 22 and sent down the cable 6 via a modem 25. The message is received at a deserialiser 26 (Figure 3) via a modem 27 which form part of the controller 13 of the satellite station 5.

The controller 13 is generally similar to the controller 8 of the relay stations 3,4 and further comprises a store 28 for the Header Word 2 of a received message, a buffer 29 for the Data Words 1 and 2 and a transmitter/receiver controller 31 which has a timing device 32 associated therewith, the latter also being connected to the store 28.

At the appropriate time, the data in the buffer 29 is outputed to the peripherals 15 in accordance with the address data in the Header Word 2.

Considering now outgoing messages from the relay 4, these can be generated either in the relay itself or in the satellite station 5. Taking the latter first, data for a message is taken from the input data peripherals and fed to a serialiser 33, each message having the same format of five Words as described above in relation to received messages. The Message Parity Word is provided by a parity generator 34 and the serialised message is sent through the cable 6 via the modem 27 and is received in the serialiser/deserialiser 22 of the relay 4 via the modem 25. The message is transferred to a buffer 35 and subsequently transmitted to a serialiser 36 under the control of the controllers 23 and 24.

The message is finally transmitted from the relay transmitter receiver 7 under the control of the controllers 19 and 24.

The message transmission portion of the relay controller 8 is generally similar to that of the sub-station 5 and comprises the serialiser 36 and a parity generator 37.

The data input for a given message is obtained from the inpute peripherals 11 and in the case of both the substation 5 and the relay 4, the Header Word 2 of the previously received message is used to dictate the channels from which data is to be obtained for the next transmitted message.

Thus if, for example, channels 1 and 2 of the output data peripherals 9 or 15 are involved in a received message, then the next transmitted message will take data from channels 1 and 2 of the input data peripherals 11 or 14 but the channels 1 and 2 of the output data peripherals may concern information different from those with which channels 1 and 2 of the respective input data peripherals are concerned.

It will be appreciated that the relay station number 3 operates as regards message reception and transmission in a manner similar to that described for relay station 4 given that it has no satellite station associated therewith. Messages transmitted from the transmitters/receivers 7 are received by a transmitter receiver 38 provided at the base station 1. This station also having a controller 39, input data peripherals 41 and output data peripherals 42. Thus, the base station 1 receives and transmits messages in a manner similar to that described in connection with the relay stations 3 and 4.

It will also be appreciated that the number of input and output data peripherals associated with the base, relay and satellite stations can vary in number and the system lends itself well to a modular construction of peripheral, whereby they can be added or subtracted at will without disrupting the overall system. The described embodiment has been used in a marine environment in which the base station has been based either on land or on a vessel, with each relay station being a surface vessel and the satellite station being a submersible vessel.

The system has been found reliable and utilitarian with the provision of the storeand-forward controller 12 which allows the simplex cable 6 to be employed without having to suffer from the inherent limitation thereof by way of being able to transmit in one direction only at a given time. The messages transmitted from the base station 1 to the satellite station 5 will concern in the main throttle and rudder commands so as to position the submersible satellite as required for the work which it is undertaking and these commands will tend to be the subject of repetitive messages so that if an error is detected in a received message resulting in the entire message being discarded, then no great harm is done.The transmitter portion of each of the stations is capable of including an error bit in the Header Word 2 of the next transmitted message if the previously received message has had an error detected therein. Thus, the station transmitting the incorrect message is notified that an error exists and it may be arranged so as to retransmit the message or merely to log the occurrence of an error. An error may occur either at source or be due to a faulty transmission path. A computer may be used to effect basic control of the sysem.

The buffer of each controller and storeand-forward controller may comprise means for displaying visually the existence of an error in a received message. Furthermore, the controller of the base station may comprise a third deserialiser to which received messages are applied, a third buffer for storing the data content of a received message, and a third buffer controller.In addition, the controller of the base station may comprise a sequencher which holds routing and data address information, a serialiser, and a message parity generator, the third buffer controller also being operable to select data either from the input peripherals or the sequencher to construct a message to be transmitted, the message parity generator monitoring the input to the serialiser so as to update the partity word as each Word is transmitted, and inputting the Message Parity Word to the serialiser at the appropriate time. Alternatively, the sequencer may be replaced by a data processing unit.

These possible modifications to the illustrated embodiment are disclosed in more detail in co-pending Patent Application No.

29676/77 (Serial No. 1 602 840) to which reference is made.

WHAT WE CLAIM IS:- 1. A telecommunication system comprising a base station and at least one relay station remote from and in telecommunication with the base station via a duplex link with at least one of the relay stations having a satellite station in telecommunication therewith via a simplex link, each relay station associated with a satellite station being provided with means for storing messages received either from the base station or the satellite station and subsequently forwarding those messages to the satellite station and base station, respectively, when the associated link is free.

2. A system according to claim 1, wherein each message is made up of five Words with each Word containing eleven Bits, namely one start Bit, seven data Bits, one Word Parity Bit and two stop Bits, the first Word being a Header Word for synchronisation and message routing, the second Word being a Header Word giving the peripheral address for Data Words, the third and fourth Words being the Data Words, and the fifth Word being a Message Parity Word for checking for errors between Words of a message.

3. A system according to claim 1 or 2, wherein each relay station comprises a transmitter/receiver connected to a controller operable to pass incoming messages to output data peripherals and to receive data from input peripherals for the construction of messages to be transmitted to the base station.

4. A system according to claim 3 wherein the controller of a relay station having a satellite station associated therewith is connected to a store-and-forward controller operable to store messages to and from the satellite station until the appropriate telecommunication link is free.

5. A system according to claim 3 or 4, wherein each controller comprises a first deserialiser to which received messages are applied, and address store for storing the address content of a received message, a first buffer for storing the data content of a received message, and a first buffer controller.

6. A system according to claim 4, when appended to claim 3, wherein each F.tore-and-forward controller comprises a recond buffer for storing messages intended for the satellite station, a second deserialiser connected to the second buffer and a second buffer controller.

7. A system according to claim 6, wherein messages are transmitted asynchronously and timing means are connected to the first

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Claims

**WARNING** start of CLMS field may overlap end of DESC **.

stations can vary in number and the system lends itself well to a modular construction of peripheral, whereby they can be added or subtracted at will without disrupting the overall system. The described embodiment has been used in a marine environment in which the base station has been based either on land or on a vessel, with each relay station being a surface vessel and the satellite station being a submersible vessel.

The system has been found reliable and utilitarian with the provision of the storeand-forward controller 12 which allows the simplex cable 6 to be employed without having to suffer from the inherent limitation thereof by way of being able to transmit in one direction only at a given time. The messages transmitted from the base station 1 to the satellite station 5 will concern in the main throttle and rudder commands so as to position the submersible satellite as required for the work which it is undertaking and these commands will tend to be the subject of repetitive messages so that if an error is detected in a received message resulting in the entire message being discarded, then no great harm is done.The transmitter portion of each of the stations is capable of including an error bit in the Header Word 2 of the next transmitted message if the previously received message has had an error detected therein. Thus, the station transmitting the incorrect message is notified that an error exists and it may be arranged so as to retransmit the message or merely to log the occurrence of an error. An error may occur either at source or be due to a faulty transmission path. A computer may be used to effect basic control of the sysem.

The buffer of each controller and storeand-forward controller may comprise means for displaying visually the existence of an error in a received message. Furthermore, the controller of the base station may comprise a third deserialiser to which received messages are applied, a third buffer for storing the data content of a received message, and a third buffer controller.In addition, the controller of the base station may comprise a sequencher which holds routing and data address information, a serialiser, and a message parity generator, the third buffer controller also being operable to select data either from the input peripherals or the sequencher to construct a message to be transmitted, the message parity generator monitoring the input to the serialiser so as to update the partity word as each Word is transmitted, and inputting the Message Parity Word to the serialiser at the appropriate time. Alternatively, the sequencer may be replaced by a data processing unit.

These possible modifications to the illustrated embodiment are disclosed in more detail in co-pending Patent Application No.

29676/77 (Serial No. 1 602 840) to which reference is made.

WHAT WE CLAIM IS:- 1. A telecommunication system comprising a base station and at least one relay station remote from and in telecommunication with the base station via a duplex link with at least one of the relay stations having a satellite station in telecommunication therewith via a simplex link, each relay station associated with a satellite station being provided with means for storing messages received either from the base station or the satellite station and subsequently forwarding those messages to the satellite station and base station, respectively, when the associated link is free.
2. A system according to claim 1, wherein each message is made up of five Words with each Word containing eleven Bits, namely one start Bit, seven data Bits, one Word Parity Bit and two stop Bits, the first Word being a Header Word for synchronisation and message routing, the second Word being a Header Word giving the peripheral address for Data Words, the third and fourth Words being the Data Words, and the fifth Word being a Message Parity Word for checking for errors between Words of a message.
3. A system according to claim 1 or 2, wherein each relay station comprises a transmitter/receiver connected to a controller operable to pass incoming messages to output data peripherals and to receive data from input peripherals for the construction of messages to be transmitted to the base station.
4. A system according to claim 3 wherein the controller of a relay station having a satellite station associated therewith is connected to a store-and-forward controller operable to store messages to and from the satellite station until the appropriate telecommunication link is free.
5. A system according to claim 3 or 4, wherein each controller comprises a first deserialiser to which received messages are applied, and address store for storing the address content of a received message, a first buffer for storing the data content of a received message, and a first buffer controller.
6. A system according to claim 4, when appended to claim 3, wherein each F.tore-and-forward controller comprises a recond buffer for storing messages intended for the satellite station, a second deserialiser connected to the second buffer and a second buffer controller.
7. A system according to claim 6, wherein messages are transmitted asynchronously and timing means are connected to the first

buffer controller and to the second buffer controller to ensure that no errors occur as a result of attempted message transmission during an existing transmission.
8. A system according to any of claims 5 to 7, wherein the buffer of each controller and store-and-forward controller comprises means for displaying visually the existence of an error in a received message.
9. A system according to any of the preceding claims, wherein the base station comprises a transmitter/receiver connected to a controller operable to pass incoming messages to output data peripherals and to receive data from input data peripherals for the construction of messages to be transmitted.
10. A system according to claim 9, wherein the controller of the base station comprises a third deserialiser to which received messages are applied, a third buffer for storing the data content of a received message, and a third buffer controller.
11. A system according to claim 10, wherein the controller of the base station further comprises a sequencer which holds routing and data address information, a serialiser, and a message parity generator, the third buffer controller also being operable to select data either from the input peripherals or the sequence to construct a message to be transmitted, the message parity generator monitoring the input to the serialiser so as to update the parity word as each Word is transmitted, and inputting the Message Parity Word to the serialiser at the appropriate time.
12. A system according to claim 11, wherein the sequencer is replaced by a data processing unit.
13. A telecommunication system substantially as herein particularly described with reference to the drawings accompanying the Provisional Specification.