GB2069261A

GB2069261A - Fibre optic signalling

Info

Publication number: GB2069261A
Application number: GB7917424A
Authority: GB
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1979-05-18
Filing date: 1979-05-18
Publication date: 1981-08-19
Also published as: GB2069261B

Abstract

A radio transceiver (12) controlled from a central station (11) via a fibre optic link (13) includes circuitry for indicating a power failure to the central station. In the event of a power failure a delay circuit (27, Figure 2, not shown) enables a signal generator (28) which sends a signal back along the fibre (13) to the central station (11). The latter recognises the power failure condition by the cessation of normal return signals followed, after the recognised delay, by the fault signal. Power for this signaling function is provided via a storage capacitor charge from the transmitter power supply. <IMAGE>

Description

SPECIFICATION Fibre optic signalling This invention relates to fibre optic remote control systems.

Fibre optictechniques are finding increasing use in remote control and signalling applications. In many such applications the equipment or device remotely controlled is so constructed as to send return signals along the control fibre to provide an indication to the control station that the equipment or device is functioning correctly. Such an arrangement has the disadvantage that, in the even of a sudden loss of the return signal at the sensing station, it is not immediately apparent whether such loss is due to damage or fracture of the control fibre or to failure of the controlled equipment. In the even of such a failur it is at present necessary either to employ somewhat complex fibre break detection techniques ortho inspect the fibre andlorthe equipment.Such a procedure is of course time consuming.

The object of the invention is to minimise or to overcome this disadvantage.

According to one aspect of the invention there is provided an optical signalling arrangementforan apparatus controllable from a remote station via an optical fibre, the arrangement including a delay circuitm, a signal generator coupled to the delay circuit, and optical transmitting means coupled to the signal generator, wherein the delay circit is adapted to respond, after a predetermined delay period, to a predetermined change in the condition or mode of operation of the apparatus, and wherein, after said delay period, the delay means enables the signal generator so as to transmit an optical signal indicative of said change via the optical fibre to the remote station.

According to another aspect of the invention there is provided a remote control radio transmission arrangement, including a radio transceiver, and a central control station coupled to the transceiver via a fibre optic link, and wherein the transceiver is.

provided with delay and signalling means whereby, in the even of a power failure of the transceiver, an optical signal indicative of said failure is transmitted via the fibre to the control station after a predetermined delay.

In the event of a change in the condition of the controlled apparatus, typically a power failure, a signal is transmitted, after a delay, to the control station indicating both that the controller equipment has failed and that the optical fibre link is still in working order.

An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a block schematic diagram of a remotely controlled radio signalling arrangement; and Figure2 shows a fault indication and signalling circuit for use in the arrangement of Figure 1.

Referring to Figure 1, the radio communication arrangement includes a central control station 11 coupled e.g. to a radio transceiver 12 via an optical fibre link 13. Information to be transmitted is relayed from the control station 11 in the form of coded optical signals via the fibre link 13, which comprises separate 'go' and 'return' fibres 13a, 13b Figure 2, and return signals indicating correct functioning of the transceiver 12 together with signals representative of receiver radio transmissions, are returned via the fibre link 13 to the control station. In a typical arrangement one control station may be coupled to a plurality of transceivers.

As shown in Figure 2, optical signals from the fibre 13a are received by a photo detector 24 which feeds a corresponding electrical signal to the radio transceiver output/input circuitry 25. The transceiver is powered from a power supply 26, which typically comprises a storage battery.

The radio transceiver also includes a delay circuit 27, a signal generator 28, an optical drive circuit 29 and a light emitting device 30 all powered from the supply 26 via a diode 31 and a storage capacitor 32.

A further optical drive circuit 34 feeds received signals from the transceiver via a blocking diode 35 to the light emitting device 30 for transmission via the fibre 13b. In the event of a power failure the detector and transceiver output/input circuits 24 and 25 respectively and the drive circuit 34, all cease to operate and the voltage across the capacitor 32 falls at a rate determined by the value of its capacitance and the impedance of the circuits fed via the capacitor. At the same time the supply voltage applied to the sensing input 33 of the delay circuit 27 falls substantially to zero thus causing the delay circuit to transmit an enabling signal to the signal generator 28 after a predetermined period.The signal generator output is then fed via the optical drive circuit 29 and blocking diode 36 to the light emitting device 30, typically a solid state laser, which latter transmits a corresponding optical signal via the fibre 13b to the control station 11. At the control station the return signals from the fibre link are seen to cease, followed, after a recognised delay period by a further optical signal thus indicating to the control station that the transceiver and not the fibre link has failed.

In an alternative embodiment the delay circuit may respond to an applied supply voltage and switch when this voltage falls below a preset value. This dispenses with the voltage sensing input.

The signal generator 28 may be a simple oscillator or it may be so constructed as to transmit a digital code signal. Such a coded signal can then be used to trigger an alarm at the control station.

1. An optical signalling arrangement for an apparatus controllable from a remote station via an optical fibre, the arrangement including a delay circuit, a signal generator coupled to the delay circuit, and optical transmitting means coupled to the signal generator, wherein the delay circuit is adopted to respond, after a predetermined delay period, to a predetermined change in the condition or mode of operation of the apparatus, and wherein,

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fibre optic signalling This invention relates to fibre optic remote control systems. Fibre optictechniques are finding increasing use in remote control and signalling applications. In many such applications the equipment or device remotely controlled is so constructed as to send return signals along the control fibre to provide an indication to the control station that the equipment or device is functioning correctly. Such an arrangement has the disadvantage that, in the even of a sudden loss of the return signal at the sensing station, it is not immediately apparent whether such loss is due to damage or fracture of the control fibre or to failure of the controlled equipment. In the even of such a failur it is at present necessary either to employ somewhat complex fibre break detection techniques ortho inspect the fibre andlorthe equipment.Such a procedure is of course time consuming. The object of the invention is to minimise or to overcome this disadvantage. According to one aspect of the invention there is provided an optical signalling arrangementforan apparatus controllable from a remote station via an optical fibre, the arrangement including a delay circuitm, a signal generator coupled to the delay circuit, and optical transmitting means coupled to the signal generator, wherein the delay circit is adapted to respond, after a predetermined delay period, to a predetermined change in the condition or mode of operation of the apparatus, and wherein, after said delay period, the delay means enables the signal generator so as to transmit an optical signal indicative of said change via the optical fibre to the remote station. According to another aspect of the invention there is provided a remote control radio transmission arrangement, including a radio transceiver, and a central control station coupled to the transceiver via a fibre optic link, and wherein the transceiver is. provided with delay and signalling means whereby, in the even of a power failure of the transceiver, an optical signal indicative of said failure is transmitted via the fibre to the control station after a predetermined delay. In the event of a change in the condition of the controlled apparatus, typically a power failure, a signal is transmitted, after a delay, to the control station indicating both that the controller equipment has failed and that the optical fibre link is still in working order. An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a block schematic diagram of a remotely controlled radio signalling arrangement; and Figure2 shows a fault indication and signalling circuit for use in the arrangement of Figure 1. Referring to Figure 1, the radio communication arrangement includes a central control station 11 coupled e.g. to a radio transceiver 12 via an optical fibre link 13. Information to be transmitted is relayed from the control station 11 in the form of coded optical signals via the fibre link 13, which comprises separate 'go' and 'return' fibres 13a, 13b Figure 2, and return signals indicating correct functioning of the transceiver 12 together with signals representative of receiver radio transmissions, are returned via the fibre link 13 to the control station. In a typical arrangement one control station may be coupled to a plurality of transceivers. As shown in Figure 2, optical signals from the fibre 13a are received by a photo detector 24 which feeds a corresponding electrical signal to the radio transceiver output/input circuitry 25. The transceiver is powered from a power supply 26, which typically comprises a storage battery. The radio transceiver also includes a delay circuit 27, a signal generator 28, an optical drive circuit 29 and a light emitting device 30 all powered from the supply 26 via a diode 31 and a storage capacitor 32. A further optical drive circuit 34 feeds received signals from the transceiver via a blocking diode 35 to the light emitting device 30 for transmission via the fibre 13b. In the event of a power failure the detector and transceiver output/input circuits 24 and 25 respectively and the drive circuit 34, all cease to operate and the voltage across the capacitor 32 falls at a rate determined by the value of its capacitance and the impedance of the circuits fed via the capacitor. At the same time the supply voltage applied to the sensing input 33 of the delay circuit 27 falls substantially to zero thus causing the delay circuit to transmit an enabling signal to the signal generator 28 after a predetermined period.The signal generator output is then fed via the optical drive circuit 29 and blocking diode 36 to the light emitting device 30, typically a solid state laser, which latter transmits a corresponding optical signal via the fibre 13b to the control station 11. At the control station the return signals from the fibre link are seen to cease, followed, after a recognised delay period by a further optical signal thus indicating to the control station that the transceiver and not the fibre link has failed. In an alternative embodiment the delay circuit may respond to an applied supply voltage and switch when this voltage falls below a preset value. This dispenses with the voltage sensing input. The signal generator 28 may be a simple oscillator or it may be so constructed as to transmit a digital code signal. Such a coded signal can then be used to trigger an alarm at the control station. CLAIMS

1. An optical signalling arrangement for an apparatus controllable from a remote station via an optical fibre, the arrangement including a delay circuit, a signal generator coupled to the delay circuit, and optical transmitting means coupled to the signal generator, wherein the delay circuit is adopted to respond, after a predetermined delay period, to a predetermined change in the condition or mode of operation of the apparatus, and wherein, after said delay period the delay means enables the signal generator so as to transmit an optical signal indicative of said change via the optical fibre to the remote station.

2. A remote control radio transmission arrangement, including a radio transceiver, and a central control station coupled to the transceiver via a fibre optic link, and wherein the transceiver is provided with delay and signalling means whereby, in the event of a power failure of the transceiver, an optical signal indicative of said failure is transmitted via the fibre to the control station after a predetermined delay.

3. An arrangement as claimed in claim 2, and in which the delay and signalling means are operated from the transceiver power supply via a blocking diode and storage capacitor

4. An arrangement as claimed in claim 2 or 3, and in which the signalling means includes an oscillator.

5. An arrangement as claimed in claim 2 or 3, and in which the signalling means includes a pulse code generator circuit.

6. A remote signalling arrangement substantially as described herein with reference to the accompanying drawings.

7. A method of remote signalling substantially as described herein with reference to the accompanying drawings.

8. A radio communication system provided with one or more remote signalling arrangements as claimed in any one of claims 1 to 6.