SU1233630A1 - Multiplex fibre-optics system for monitoring physical values - Google Patents

Description

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The invention relates to an experimental technique and can be used to remotely measure physical quantities (force, pressure, temperature, acceleration, etc.) simultaneously from many fiber-optic sensors of specified physical quantities.

The aim of the invention is to expand the dynamic range and decrease the measurement error by compensating for the effect of destabilizing factors on the transmission coefficient of the measuring path,

The drawing shows a block diagram of a multiplex fiber-optic system for monitoring physical quantities.

The system includes a pulse generator 1, an optical radiation source 2, an optical connector 3, a fiber optic transmitting path 4, an optical coupler 5, a fiber optic measuring transducer 6 containing a feed fiber 7 with an optical connector 8, an optical power divider 9, reference optical channel 10, parallel to it an optical delay line 11 and a sensitive element 12, an optical power adder 13, an output optical fiber 14 with an optical connector 15, an optical the coupler 16, the receiving fiber-optical path 17 with the optical connector 18, the photodetector unit 19, the output of which;) is electrically connected to the electrical delay line 20 and the first control key 21. The output of the electrical delay line 20 is connected to the selector 22 of the reference signal and via another delay line 23 to the second control key 24. The output of the reference signal detector is connected to the first and second control switches 21 and 2, to the riHKOBoro input of the control channel detector 25. The outputs of the controlled keys are connected to the pulse reading unit 26, Vb. 25 peak detector Kaii; iJia Lenil is connected to the subtractor (Zpoku 27, to which the station is connected 28 onopHOj o voltage, the output of the reading unit 26 is connected to the paired amplifier, which is connected to. input D € mulg-, tig |. 30, to iiTopi: MV input KO i ojrr i and rc-iv :(

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chen impulse generator 1. The output channels of the demultiplexer 30 are connected to peak amplification detectors 31.

2 The system works as follows. From a pulse generator 1, a short pulse (10 ns) is fed to a radiation source 2 (laser diode), from which an optical pulse is introduced through optical connector 3 into transmitting optical fiber path 4, from which optical power spans optical fiber coupler 5 - optical measuring transducer 6 (sensors). The optical pulse after the optical coupler 5 passes through the optical connector 8 through the feed fiber light 20 to 7 optical fiber power divider 9, from which the pulse passed through the reference optical channel 10 is fed to the optical power adder 13 through the outgoing fiber

25 to the light guide 14, to the optical connector 15, the optical coupler 16, and to the receiving optical fiber path 17 and then through the optical connector 18 to the photoreceiver unit 19. Another optical pulse from the optical power divider 9 passes through the optical delay line 11, the sensitive element 12, wherein — the pulse is modulated by the amplitude of the measured physical quantity, supplied to the optical power adder 13 and further along the same path as the first optical pulse, goes to the photodetector unit 19. Amplitude of the reference impulse It depends on path losses, connectors, couplers, optical fibers. Such a measurement pulse suffers, but the effect of sensing element 12 is added to this. Therefore, subtracting one signal from another in the subtracting unit, a signal is obtained, the value of which depends only on the value of the measured value and does not depend on the indicated destabilizing factors in the connectors, fiber paths and optical fibers. Electrical signals from the photodetector unit 19 in the form of successive pulses (reference signal and delayed

 5 by the optical delay line of the measuring signal) are sent to the Utem1.E-keys 21 and 24, closed before the arrival of the pulses, the first

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the pulse of the reference signal cannot pass through the closed controlled key, 21, but passes through the electric delay lines 20, 23. After the delay line 20, a small portion of the power of the reference pulse branches to the selector 22 of the reference signal, the output of which opens: controlled keys 21 and 2A. At this point, the measuring pulse comes to the key 21, and the reference pulse to the key 24. The delay time of the optical delay line 11 and the total time delay of the electrical delay lines 20 and 23 are the same. The delay time on line 23 is equal to the time for the signal to pass in the selector 22 of the reference pulse and the time required for opening the keys 21 and 24. After passing by the pulses of keys 21 and 24, they close before the arrival of a new pair of pulses (reference and measurement signals) from another measuring signal. converter Past pulses go to the impulse subtraction unit 26, the output signal of which is proportional to the measured physical quantity sensed by the sensing element 12 of the measuring transducer. In this case, the instability of the optical connectors 3, 8, 15, 18 in the transmitting and receiving paths 4 and 17 in the supply and output fibers of the KOHHbijc optical fibers 7 and 14 is compensated in the subtractor unit. Thus, measurement measurements associated with the influence of various destabilizing factors in optical paths and connectors are eliminated. To support a certain of us

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stacking the level of the measuring signal from various measuring transducers included in the fiber-optic system for monitoring physical quantities, is a controlled amplifier 29, the input of which receives a signal from the output of the pulse subtractive unit 27. The control voltage to the amplifier 29 comes from the output of the subtracting unit 27 , one of the inputs of which is supplied with the comparison voltage from the source 28 of the reference voltage, and the input voltage is supplied from the output of the peak detector 25 of the control channel, the input of which is Wow connected to the output of the selector 22 of the reference signal. When the level of the reference signal changes, the voltage at the output of the peak detector 25 also changes. As a result of comparing the voltage from the peak detector 25 with a predetermined voltage of the source 28 of the reference voltage, the error signal from the output of the subtracting unit 27 goes to the controlled amplifier 29 by maintaining the required scale of each of the measuring transducers. From the output of the controlled amplifier 29, the measuring pulses are fed to the demultiplexer 30, in which each of the pulses of the measuring transducers is distributed over the corresponding channels that are connected to the peak amplifying detectors

35 31. At the output of each of the peak amplification detectors, there is a voltage corresponding to the measured physical quantity in each of the fiber-optic measuring

 converters.

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/ Compiled by H. Mikhalev

Editor E. Kravtsov Tehred L. Oleinik

Order 2560 Circulation 358, Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d.

Production and printing enterprise, Uzhgorod Project Project, 4

Proofreader S. Shekmar

Claims (2)

1. MULTIPLEX BOJIOKOHHOOPTICAL SYSTEM OF PHYSICAL VALUES CONTROL, which contains a pulse generator, a radiation source and a transmitting fiber-optic path in series, to the outputs of which are connected transducers that include a sensing element, the outputs of which are connected to the inputs of the receiving fiber-optic path, the output of which is connected a unit connected in series to a demultiplexer, the controlled input of which is connected to the second output of the pulse generator, peak detector, wherein the measurement transducers are connected between the transmitting. fiber optic paths and receiving paths using optical couplers located at fixed distances from each other along the paths, characterized in that, in order to expand the dynamic range and reduce the measurement error, the first controlled key is introduced into it, the first and second electrically connected in series delay lines, a second controlled key, a pulse subtracting unit and a controlled amplifier, series-connected reference signal selector, a peak detector of the control channel and a subtracting unit, as well as a reference voltage source, the output of which is connected to the second input of the subtracting unit, the output of which is connected to the control input of a controlled amplifier, the output of which is connected to the second input of the demultiplexer, while the input of the reference signal selector is connected to the output of the first electrical delay line, and the output is to the control inputs of the first and second controlled keys, the output of the photodetector unit is connected to the inputs of the first electric delay line and the first controlled key, the output of which is It is connected to the second input of the pulse subtracting block. 2. The device according to π. 1, characterized in that the measuring transducer contains an optical power divider, the input of which is the input of the transducer, the first output is connected through the reference optical channel to the first input of the optical power adder, and the second output is connected through the optical delay line and the sensing element in series. the second input of the optical power adder, the output of which is the output of the converter. SU ,,, 1233 630 ί