SU1619417A2 - Device for locating damaged point of fibre-optics cable - Google Patents

Abstract

The invention relates to telecommunications and provides an increase in the accuracy of determining the distance to the damage site by eliminating the ambiguity of the deformation site. The device contains a master oscillator 1, a driver 2, a source of optical radiation 3, a translucent mirror 4, a photodetector 5, a two-bit binary counter 6, DRS triggers 7 and 8, an element OR 9, a generator of 10 counting pulses, counters 11 and 12, a decision unit 13, element 14, the sensor 15 of the deforming signals mounted on the fiber optic cable 16. The goal is achieved by using the element OR 9, which adds the measurement interval from the translucent mirror 4 to the point of damage of the reference time second interval and time interval of the transmitter 15 to the point of damage to the fiber-optic cable 16. 3 Il. J6 S (Л С & 5 Јъ

Description

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The invention relates to telecommunications, can be used in monitoring information transmission systems via a fiber optic cable or optical fiber with unknown wave impedances, and is an improvement on the author. K ° 1234978.

The purpose of the invention is to improve the accuracy of determining the distance to the damage site by eliminating the ambiguity of the deformation site.

Fig. 1 shows the structural electrical circuit of the device for determining the location of damage to the fiber optic cable; 2 and 3 are timing diagrams explaining the operation of the device.

A device for detecting a fiber optic cable fault location contains a master oscillator 1, a probe pulse shaper 2, an optical radiation source 3, a translucent mirror 4, a photoreceiver — a peak 5, a two-digit binary counter 6, the first DRS trigger 7, the second DRS trigger 8 , element OR 9, generator 10 counting pulses, auxiliary counter And, the main counter 12, the resolving unit 13, the element And 14 and the sensor 15 deforming signals mounted on an optical fiber cable 16

The device works as follows

With the arrival of each control pulse from the master oscillator 1 to the input of the imager 2, an electrical pulse is generated at its output, which is fed to the source of optical radiation 3. Source 3 converts an electrical pulse into an optical one. The translucent mirror 4 allows a probe pulse to be introduced into the fiber-optic cable under study 16. At the same time, a part of its power reflected from the input end of the fiber-optic cable 16 using the same translucent mirror 4 reaches the photodetector. After some time, a pulse arrives here reflected by the sensor 15 from the deformation point of the fiber-optic cable 16, reflected from the place of damage. These signals are converted by a photodetector 5, into electrical signals, and fed to the input of a two-bit binary counter 6 (lig.2a). In the initial state at the outputs of a two-bit binary counter 6, the combination 00 G fig. 26, c), with the arrival of a pulse amplified by the photo-receiver 5, reflected from the input end of the fiber-optic cable 16 (FIG. 2a), the double-bit binary counter 6 goes to state 01 (fig.2b, century. The pulse reflected from the place of deformation (fig. 2a) sends the binary two-digit counter 6 to the state 10 (fig. 2b, c). With the appearance of a pulse reflected from the place of damage of the fiber-optic cable 16 (Fig. 2a) at the outputs of a two-bit binary counter 6 in a combination of 11 (fig.2b, c), which, arriving at the input of the element 14, generates a signal at its output (fig.2g), resets a two-bit binary counter 6 and sets the output of the second DRS trigger 8 to a logical signal zero

Thus, at the output of the lower bit of the two-bit binary counter 6, an exemplary time interval is formed (Fig. 2b), equal to the transit time of the optical probe pulse from the input end of the fiber-optic cable 16 to the deformation point and back. In this case, since the probing periodically repeats with the frequency of the master oscillator 1, then with the same frequency at the output of the low bit of the two-bit binary counter 6 there appears also an exemplary time interval (Fig. 3a). Similarly, at the output of the higher bit of a two-bit binary counter b, a time interval t occurs, starting from the sensor of deforming signals 15 and to the point of damage to the fiber-optic cable 16 Fig. 2b), which also periodically repeats in time (Fig. 3b). To obtain the measurement interval from the translucent mirror to the damage site (c2d), it is necessary to add an exemplary time interval (Fig 2b) with the time interval t starting from the deforming signal sensor 15 and to the location of the fiber-optic cable 16 (), for this addition and the additionally introduced element OR 9 is used.

The measurement process of sample t and time interval ty is carried out over several periods.

516194:

their repetition, the measurement cycle begins with a reference auxiliary and main counters 11 and 12 of the model time interval t. For this, the signal of the periodically repeating sample time interval tfl from the low-bit output of the two-bit binary counter 6 (Fig.A) is simultaneously fed to the D input of the first JQ ELM trigger 7 and through the OR element 9 to the D input of the second DRS trigger 8 Lyg.Zv). Since the frequency of the generator 10 counting pulses differs from the repetition frequency of the sample time intervals t0 by a small amount, filling starts when the leading edge of the pulse of the counting sequence (Fig. 3g) coincides (ty) interval t0 (fig.Za), and ends when the leading edge of the pulse of the counting sequence coincides (t) with the rear edge of the sample time interval t 25 (fig.Zd), And during the time interval in the auxiliary and main counters And 12 Respectively, the pulses come from the outputs of DRS-flip-flops 7 and 8, and their number is 30 defined by the length of the sample time interval tfl. generator 10 by the value of Ј. As can be seen from fig.Za, b, c, d, the following relationship holds:

tK-tu mQ + te m (0 + $),

where m is an integer, 40

where it is easy to get, i.e. in auxiliary and main counters 11 and 12 for a time,. the number of pulses arrives, which is equal to the length of the reference interval tc, 45 measured with discreteness C.

At the time tc (fig. 3d), the sample time interval t ends with an auxiliary counter 11, and the main counter 12 50 continues to count the time interval starting from the sensor 15 of deforming signals and to the point of damage to the optical fiber

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cable 16 (yy.Ze). The next counting pulse coincides with the time interval tu on the D input of the second DRS trigger 8, since the end of the model S. and the beginning of the time interval t are formed simultaneously (t., fig.26, c, d ) During the entire measurement time, until the counting pulses, shifting relative to the time interval ty5 go beyond its limits, the coincidence pulses from the output of the second DRS trigger 8 continue to flow into counter 12. This process is similar to the described filling process of counter 11. If the duration measured time interval va + t, and the magnitude of the shift of the counting pulse for a period relative to this interval is Ј, as previously accepted, the number of pulses entering the main counter 12 during the measurement time is equal to

to + t-C

t

t m -f -

The decision block 15 divides the number M recorded during the measurement cycle by the main counter 12 by the number t recorded in the auxiliary counter 11. As a result, the length of the measured time interval is expressed in units of the length of the reference interval:

K T “O T tft + tu

ish

I

Claims (1)

Invention Formula A device for determining the place of damage of an optical fiber cable according to the author. St. No. 1234978, characterized in that, in order to improve the accuracy of determining the distance to the damage site by eliminating the ambiguity of the deformation site, the output of the lower section of the two-digit binary counter is connected to the D input and the R output of the second DRS trigger through an input of the OR element and the element I, whose second inputs are connected to the output of the higher bit of a two-digit binary counter, the reset input of which is connected to the output of the element I. FIG. 2 but Editor N. Yatsola FIG. Compiled by V. Smirnova Tehred M. Didyk Order 55 Circulation INFLUENCED by the State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR PZOZ, Moscow, F-35, Raushsk nab. 4/5 Production - h, c, ich-1ye combine Patent, Uzhgorod, st. Gagarin, 101 Corrector To Malets Subscription