Signal sensing and measuring in fibre optic systems with light pulse width detecting

Claim 2

A fibre optic sensor control system, comprising: means for generating a pulsed source electrical signal; electro-optical converter means for converting the source electrical signal into an optical signal; optical fibre means for transmitting the optical signal with a variable transmittance; opto-electrical converter means for converting an optical signal received from the fibre into an electrical signal; and detector means for detecting the pulse width of the received electrical signal.

Claim 3

A system as claimed in claim 1, wherein the detector means is operable to detect a time-related parameter of the received electrical signal.

Claim 4

A system as claimed in claim 1, wherein the source electrical signal is a substantially rectangular wave pulsed signal.

Claim 5

A system as claimed in claim 1, further comprising means causing microbending of the optical fibre in response to an applied external force.

Claim 6

A signal detector system comprising: opto-electrical convertor means for converting a pulsed optical signal received from an optical fibre into an electrical signal; and detector means for detecting the pulse width of the electrical signal.

Claim 7

A signal detector system comprising: opto-electrical convertor means for converting a pulsed optical signal received from an optical fibre into an electrical signal; and detector means for detecting the pulse width of the electrical signal.

Claim 8

A system as claimed in claim 1 or 3 or 4, wherein the detector means comprises a timer which is triggered by the received electrical signal.

Claim 9

A system according to claim 6 further comprising a logic element which is triggered by a combination of the received electrical signal and timing-out of the timer.

Claim 10

A system as claimed in claim 6 wherein the timer is arranged to time-out after a predetermined period which is less than the expected pulse-width of the received electrical signal.

Claim 11

A system as claimed in claim 7, wherein the logic element comprises a further timer which is disabled by an output from the first-mentioned timer and which is triggered by the received electrical signal.

Claim 12

A system as claimed in claim 9, wherein the further timer is triggered by an attenuated form of the received electrical signal.

Claim 13

A fibre-optic sensor system comprising: means for generating a pulsed optical signal, optical fibre means for receiving the optical signal, means for varying an optical property of the fibre in dependance upon an external condition, signal detector means including timing means for timing the duration of a predetermined portion of the pulses of the signal, and means for indicating the value of the external condition in dependence upon the timed signal portion.

Claim 14

A fibre-optic sensor system comprising: means for generating a pulsed optical signal, optical fibre means for receiving the optical signal, means for varying an optical property of the fibre in dependance upon an external condition, signal detector means including timing means for timing the duration of a predetermined portion of the pulses of the signal, and means for indicating the value of the external condition in dependence upon the timed signal portion.

Claim 15

A system according to claim 11 in which the pulsed optical signal is controlled in dependence upon an electrical signal corresponding to an optical signal transmitted through said optical fibre means.

Claim 16

A system as claimed in claim 11 and including a further such detector means for detecting the optical signal, and means for comparing the outputs of the two detector means and for determining whether the outputs of the two detector means are consistent with each other.

Claim 17

A fibre-optic sensor control system comprising: pulsed optical source means for producing optical pulses, optical fibre means for receiving optical pulses form the source means, and detector means for detecting pulses received via the fibre means and for generating a corresponding pulsed electrical signal to control the optical source so as to maintain the pulse width of the pulsed electrical signal substantially constant.

Claim 18

A fibre-optic sensor control system comprising: pulsed optical source means for producing optical pulses, optical fibre means for receiving optical pulses form the source means, and detector means for detecting pulses received via the fibre means and for generating a corresponding pulsed electrical signal to control the optical source so as to maintain the pulse width of the pulsed electrical signal substantially constant.

Claim 19

A system according to claim 14 comprising means for indicating the value of an external condition affecting the optical properties of the fibre means, in response to variations in the optical pulses generated by the source means.

Claim 20

A system according to claim 15 in which the indicating means is responsive to the source pulse width.

Claim 21

A system according to claim 15 in which the indicating means is responsive to the source rise time.

Claim 22

A system as claimed in claim 14 and including a further such detector means for detecting the optical pulses, and means for comparing the outputs of the two detector means and for determining whether the outputs of the two detector means are consistent with each other.

Claim 23

A detector system for a fail-to-safe control system comprising: opto-electrical converter means for converting a pulsed optical signal received from an optical fibre into an electrical signal, and detector means for detecting the pulse width of the electrical signal, the detector means being operable not to respond to an electrical pulse having less than a predetermined pulse width.

Claim 24

A detector system for a fail-to-safe control system comprising: opto-electrical converter means for converting a pulsed optical signal received from an optical fibre into an electrical signal, and detector means for detecting the pulse width of the electrical signal, the detector means being operable not to respond to an electrical pulse having less than a predetermined pulse width.

Claim 25

A system as claimed in claim 1 or 5 or 19 and including a further such detector means for detecting the received electrical signal, and means for comparing the outputs of the two detector means and for determining whether the outputs of the two detector means are consistent with each other.

Claim 26

A system as claimed in claim 19 and including a further such detector means for detecting the received electrical signal, and means for comparing the outputs of the two detector means and for determining whether the outputs of the two detector means are consistent with each other, and wherein the logic element comprises a further timer which is disabled by an output from the first-mentioned timer and which is triggered by the electrical signal, wherein each further timer has an output and a complementary output, the comparing means comprising a transistor bridge having transistors with control electrodes, with the control electrodes of the transistors connected to the outputs and complementary outputs of the timers, and the bridge providing outputs to a latch device.

Claim 31

In an optical fibre sensing method comprising the steps of launching a pulsed optical signal into said optical fibre at a first end thereof and detecting a corresponding signal at a second end thereof, the steps of timing the duration of received signals, and of rejecting received pulses of shorter than a predetermined duration.

Claim 32

In an optical fibre sensing method comprising the steps of launching a pulsed optical signal into said optical fibre at a first end thereof and detecting a corresponding signal at a second end thereof, the steps of timing the duration of received signals, and of rejecting received pulses of shorter than a predetermined duration.