CN116015516A - Phase synchronization circuit, optical fiber vibration monitoring equipment and phase synchronization method - Google Patents

Abstract

The application provides a phase synchronization circuit, an optical fiber vibration monitoring device and a phase synchronization method. The phase synchronization circuit includes a clock signal generation circuit, a frequency multiplication circuit, and an acousto-optic modulation driving circuit. The clock signal generation circuit is used for generating a standard clock signal. The frequency doubling circuit is used for processing the standard clock signal when the trigger signal is received to obtain a first frequency doubling signal and a second frequency doubling signal. The acousto-optic modulation circuit is used for generating a driving signal according to the first frequency multiplication signal. The data acquisition circuit is used for receiving the second frequency multiplication signal and sampling the electric signal output by the balanced photoelectric detector according to the second frequency multiplication signal to generate a sampling signal. According to the method, the standard clock signal is provided through the clock signal generating circuit, the first frequency multiplication signal and the second frequency multiplication signal are output through the frequency multiplication circuit, so that the oscillation starting phase of the detection light signal is synchronous with the phase of the sampling signal of the data acquisition circuit, the phase error is reduced, and the phase identification precision is improved.

Description

Phase synchronization circuit, optical fiber vibration monitoring equipment and phase synchronization method

Technical Field

The application relates to the field of optical fibers, in particular to a phase synchronization circuit, optical fiber vibration monitoring equipment and a phase synchronization method.

Background

Distributed optical fiber vibration monitoring equipment based on phi OTDR (optical time domain reflectometer) technology is already a conventional vibration monitoring equipment, and the technology is expanded in application to sound restoration at present. The sound restoration not only illustrates that the device has high-precision phase precision control, but also has high-reliability restoration to vibration events.

For phi OTDR systems, the accuracy of the phase measurement can significantly affect the accuracy of the vibration measurement of the system. Currently, limited to industry-wide developments, suppliers of phi OTDR devices and suppliers of data acquisition cards are different suppliers, and as a result, both are physically different, a phase oscillation asynchronous situation occurs, as shown in fig. 1. Each time the AOM end modulates an optical signal, the phase of a starting point is random, and a random phase term is added to the optical signal after interference, so that the phase error cannot be eliminated.

Disclosure of Invention

In order to solve the problems in the prior art, the application provides a phase synchronization circuit, optical fiber vibration monitoring equipment and a phase synchronization method, so that phase errors are reduced, and phase identification accuracy is improved.

The application provides a phase synchronization circuit is applied to optical fiber vibration monitoring equipment, optical fiber vibration monitoring equipment includes balanced photoelectric detector, phase synchronization circuit includes:

A clock signal generation circuit for generating a standard clock signal;

the input end of the frequency doubling circuit is electrically connected with the clock signal generating circuit; the frequency doubling circuit is used for carrying out first frequency doubling processing on the standard clock signal to obtain a first frequency doubling signal when receiving the trigger signal, and carrying out second frequency doubling processing on the standard clock signal to obtain a second frequency doubling signal;

the input end of the acousto-optic modulation driving circuit is electrically connected with the first output end of the frequency doubling circuit; the acousto-optic modulation circuit is used for receiving the first frequency multiplication signal and generating a driving signal according to the first frequency multiplication signal;

the input end of the data acquisition circuit is electrically connected with the second output end of the frequency doubling circuit, and the acquisition end of the data acquisition circuit is electrically connected with the balance photoelectric detector; the data acquisition circuit is used for receiving the second frequency multiplication signal and sampling the electric signal output by the balance photoelectric detector according to the second frequency multiplication signal to generate a sampling signal.

In one embodiment, the frequency doubling circuit comprises:

The input end of the phase-locked circuit is the input end of the frequency doubling circuit; the phase-locking circuit is used for phase-locking the standard clock signal;

the input end of the first frequency multiplier is electrically connected with the output end of the phase-locked circuit, and the output end of the first frequency multiplier is a first output end of the frequency multiplication circuit; the first frequency multiplier is used for performing first frequency multiplication processing on the standard clock signal;

the input end of the second frequency multiplier is electrically connected with the output end of the phase-locked circuit, and the output end of the first frequency multiplier is a second output end of the frequency multiplication circuit; the second frequency multiplier is used for performing second frequency multiplication processing on the standard clock signal.

In one embodiment, the acousto-optic modulation driving circuit includes:

the input end of the first delay circuit is electrically connected with the first output end of the frequency doubling circuit; the first delay circuit is further used for detecting the phase of the first frequency multiplication signal and delaying the first frequency multiplication signal when detecting that the phase of the first frequency multiplication signal is not a preset phase; and outputting the first frequency multiplied signal when detecting that the phase of the first frequency multiplied signal is a preset phase;

The input end of the first amplifying circuit is electrically connected with the output end of the first delay circuit; the first amplifying circuit is used for amplifying the received first frequency multiplication signal according to preset amplification factors to generate a driving signal.

In an embodiment, the acousto-optic modulation driving circuit further includes:

the input end of the second amplifying circuit is electrically connected with the first output end of the frequency doubling circuit, and the output end of the second amplifying circuit is electrically connected with the input end of the first delay circuit; the second amplifying circuit is used for amplifying the driving signal output by the phase-locked circuit and outputting the driving signal;

the input end of the shaping circuit is electrically connected with the output end of the first amplifying circuit; the shaping circuit is used for shaping and outputting the driving signal output by the first amplifying circuit.

In one embodiment, the data acquisition circuit comprises:

the input end of the second delay circuit is the input end of the data acquisition circuit, and the controlled end of the second delay circuit is electrically connected with the output end of the first delay circuit; the second delay circuit is used for delaying the second frequency multiplication signal;

The first delay circuit is further used for outputting a phase signal when the phase of the driving signal is detected to be a preset phase, and the second delay circuit is further used for delaying the second frequency multiplication signal when the phase signal is not received; and outputting the second multiplied signal upon receiving the phase signal;

the input end of the data acquisition card is electrically connected with the input end of the second delay circuit, and the acquisition end of the data acquisition card is the acquisition end of the data acquisition circuit; the data acquisition card is used for sampling the electric signals output by the balance photoelectric detector according to the second frequency multiplication signal to generate the sampling signals.

The application also proposes an optical fiber vibration monitoring device, the optical fiber vibration monitoring device includes:

the phase synchronization circuit described above;

the acousto-optic modulation circuit is electrically connected with the phase synchronization circuit; the acousto-optic modulation circuit is used for receiving the driving signal output by the phase synchronization circuit and outputting a detection light signal under the control of the driving signal;

the balance photoelectric detector is electrically connected with the phase synchronization circuit; the balanced photoelectric detector is used for receiving the feedback optical signal, converting the feedback optical signal into a corresponding electric signal and outputting the corresponding electric signal to the phase synchronization circuit;

The phase synchronization circuit is also used for sampling the electric signals output by the balance photoelectric detector to generate sampling signals.

In an embodiment, the fiber optic vibration monitoring device further comprises:

the control circuit is electrically connected with the phase synchronization circuit; the control circuit is used for outputting a trigger signal to the phase synchronization circuit; the phase synchronization circuit is also used for generating the driving signal according to the trigger signal;

the control circuit is also used for receiving the sampling signal output by the phase synchronization circuit and carrying out phase demodulation on the sampling signal so as to acquire phase information.

The application also provides a phase synchronization method which is applied to optical fiber vibration monitoring equipment, wherein the optical fiber vibration monitoring equipment comprises a balanced photoelectric detector and an acousto-optic modulation circuit, and the phase synchronization method comprises the following steps:

generating a standard clock signal;

when a trigger signal is received, performing first frequency multiplication on the standard clock signal, outputting a first frequency multiplication signal, performing second frequency multiplication on the standard clock signal, and outputting a second frequency multiplication signal;

generating a driving signal according to the first frequency multiplication signal so as to drive the acousto-optic modulation circuit to output a detection light signal;

And sampling the electric signal output by the balanced photoelectric detector according to the second frequency multiplication signal to generate a sampling signal.

In an embodiment, the generating the driving signal from the first frequency multiplied signal comprises:

detecting the phase of the first frequency multiplication signal, and delaying the first frequency multiplication signal when detecting that the phase of the first frequency multiplication signal is not a preset phase; and amplifying the first frequency multiplication signal when the phase of the driving signal is detected to be a preset phase, so as to generate the driving signal.

In an embodiment, the phase synchronization method further comprises:

detecting the phase of the first frequency multiplication signal, and outputting a phase signal when the phase of the driving signal is detected to be a preset phase;

delaying the second frequency multiplication signal when the phase signal is not received; and outputting the second frequency multiplied signal upon receiving the phase signal.

According to the method, clock synchronization of the first frequency multiplication signal and the second frequency multiplication signal is realized through the standard clock signal, trigger time synchronization of the first frequency multiplication signal and the second frequency multiplication signal is realized through the trigger signal, when the acousto-optic modulation circuit modulates the detection optical signal, the oscillation starting phase of the detection optical signal is synchronous with the phase of the sampling signal of the phase synchronization circuit, phase errors are reduced, and phase identification accuracy is improved.

Drawings

Fig. 1 is a schematic diagram of a phase synchronization circuit of the present application.

Fig. 2 is a schematic diagram of a frequency multiplier circuit according to an embodiment of the present application.

Fig. 3 is a schematic structural diagram of an embodiment of an acousto-optic modulation driving circuit of the present application.

Fig. 4a is a schematic diagram of signal waveforms before synchronous delay.

Fig. 4b is a schematic diagram of signal waveforms after synchronous delay.

Fig. 5 is a schematic structural diagram of an embodiment of a data acquisition circuit of the present application.

Fig. 6 is a schematic structural diagram of an embodiment of the optical fiber vibration monitoring device of the present application.

Fig. 7 is a flowchart of an embodiment of a phase synchronization method of the present application.

Description of the main reference signs

Phase synchronization circuit 100 balances photo detector 200

Frequency multiplier circuit 120 of clock signal generating circuit 110

Data acquisition circuit 140 of acousto-optic modulation driving circuit 130

Phase lock circuit 121 of acousto-optic modulation circuit 300

First frequency multiplier 122 and second frequency multiplier 133

First delay circuit 131 first amplifying circuit 132

The filter circuit 133 and the second amplifying circuit 134

Shaping circuit 135 third amplifying circuit 136

Second delay circuit 141 of single-ended transformer 137

Data acquisition card 142 control circuit 400

Optical fiber 600 to be tested of mixer circuit 500

The following detailed description will further illustrate the application in conjunction with the above-described figures.

Detailed Description

The following description will refer to the accompanying drawings in order to more fully describe the present application. Exemplary embodiments of the present application are illustrated in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. Like reference numerals designate identical or similar components.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, as used herein, "comprises" and/or "comprising" and/or "having," integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Furthermore, unless the context clearly defines otherwise, terms such as those defined in a general dictionary should be construed to have meanings consistent with their meanings in the relevant art and the present application, and should not be construed as idealized or overly formal meanings.

The following description of exemplary embodiments will be provided with reference to the accompanying drawings. It is noted that the components depicted in the referenced figures are not necessarily shown to scale; and the same or similar components will be given the same or similar reference numerals or similar technical terms.

Referring to fig. 1-5, the present application proposes a phase synchronization circuit 100 for use in an optical fiber vibration monitoring device that includes a balanced photodetector 200. The phase synchronization circuit 100 includes a clock signal generation circuit 110, a frequency multiplication circuit 120, an acousto-optic modulation driving circuit 130, and a data acquisition circuit 140. The clock signal generation circuit 110 is used to generate a standard clock signal. The input end of the frequency doubling circuit 120 is electrically connected with the clock signal generating circuit 110; the frequency doubling circuit 120 is configured to perform a first frequency doubling process on the standard clock signal to obtain a first frequency doubling signal when the trigger signal is received, and perform a second frequency doubling process on the standard clock signal to obtain a second frequency doubling signal. The input end of the acousto-optic modulation driving circuit 120 is electrically connected with the first output end of the frequency doubling circuit 120; the acousto-optic modulation circuit 300 is configured to receive the first frequency multiplication signal and generate a driving signal according to the first frequency multiplication signal. The input end of the data acquisition circuit 140 is electrically connected with the second output end of the frequency doubling circuit 120, and the acquisition end of the data acquisition circuit 140 is electrically connected with the balance photoelectric detector 200; the data acquisition circuit 140 is configured to receive the second frequency-multiplied signal, and sample the electrical signal output by the balanced photodetector 200 according to the second frequency-multiplied signal, so as to generate a sampled signal.

In this embodiment, the optical fiber vibration monitoring apparatus may further include an acousto-optic modulation circuit 300. The driving signal output by the acousto-optic modulation driving circuit 120 can be used to drive the acousto-optic modulation circuit 300 to output the probe optical signal to the optical fiber 600 to be tested. The balanced photodetector 200 is configured to receive an optical signal fed back by the optical fiber 600 to be tested, and convert the fed-back optical signal into a corresponding electrical signal. The data acquisition circuit 140 samples the electrical signal output by the balanced photodetector 200 and generates a sampled signal output. By analyzing the sampled signal, dynamic vibration information along the line of the optical fiber 600 to be measured can be obtained.

The clock signal generating circuit 110 is configured to provide a standard clock signal with a preset frequency. The preset frequency may be set according to the operating frequency of the acousto-optic modulation circuit 300 and the data acquisition circuit 140, for example, 5MHz, 10MHz, 20MHz, etc., which is not limited herein. The frequency doubling circuit 120 divides the input standard clock signal into two paths for processing when receiving the trigger signal. One path generates a first frequency multiplication signal after first frequency multiplication processing and outputs the first frequency multiplication signal to the acousto-optic modulation driving circuit 120, and the other path generates a second frequency multiplication signal after second frequency multiplication processing and outputs the second frequency multiplication signal to the data acquisition circuit 140. The trigger signal may be sent by the control circuit 400 in the host computer or the optical fiber vibration monitoring device when the optical fiber 600 to be detected needs to be detected. In this way, the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140 can work according to the same standard clock signal provided by the clock signal generating circuit 110, so as to realize clock synchronization. When the optical fiber 600 to be detected needs to be detected, the trigger signal controls the frequency doubling circuit 120 to output the first frequency doubling signal and the second frequency doubling signal simultaneously, so that the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140 can start working simultaneously according to the same standard clock signal. When the acousto-optic modulation circuit 300 modulates the detection light signal, the oscillation starting phase of the detection light signal is synchronous with the phase of the sampling signal of the data acquisition circuit 140, so that phase errors are reduced, and the phase identification precision is improved.

For example, the clock signal generation circuit 110 generates a 10MHz standard clock signal. When the frequency doubling circuit 120 receives the trigger signal, 8 frequency doubling and 25 frequency doubling processing are respectively performed on the input 10MHz standard clock signal, a first frequency doubling signal of 80MHz is generated and output to the acousto-optic modulation driving circuit 120, and a second frequency doubling signal of 250MHz is output to the data acquisition circuit 140, so that the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140 are controlled to start working simultaneously. The acousto-optic modulation driving circuit 120 performs multistage amplification, delay, shaping and other processes on the first frequency multiplication signal of 80MHz, and outputs a driving signal to the acousto-optic modulation circuit 300, so as to drive the acousto-optic modulation circuit 300 to output a detection light signal to the optical fiber 600 to be tested according to the driving signal of 80 MHz. Meanwhile, the data acquisition circuit 140 samples the electric signal output from the balanced photodetector 200 according to the second frequency-multiplied signal of 250 MHz. In this way, by clock synchronization and start working time synchronization of the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140, synchronization of the oscillation starting point of the acousto-optic modulation circuit 300 for modulating the detection light signal and the sampling point of the data acquisition circuit 140 is realized, so that sampling phase errors are reduced, and phase identification precision is improved. The frequency parameters of the standard clock signal and the frequency multiplication parameters of the first frequency multiplication and the second frequency multiplication of the frequency multiplication circuit 120 can be set according to the actual requirements and the sampling principle, which is not limited herein.

The standard clock signal is provided by the clock signal generating circuit 110, and is processed by the frequency doubling circuit 120, so that the first frequency doubling signal and the second frequency doubling signal are output simultaneously, the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140 can start to work simultaneously according to the same standard clock signal, and when the acousto-optic modulation circuit 300 modulates the detection light signal, the oscillation starting phase of the detection light signal is synchronous with the phase of the sampling signal of the data acquisition circuit 140, the phase error is reduced, and the phase identification precision is improved.

Referring to fig. 2, in one embodiment, the frequency multiplier circuit 120 includes a phase lock circuit 121, a first frequency multiplier 122, and a second frequency multiplier 133. The input end of the phase-locked circuit 121 is the input end of the frequency doubling circuit 120; the phase lock circuit 121 is used for phase locking the standard clock signal. The input end of the first frequency multiplier 122 is electrically connected to the output end of the phase-locked circuit 121, the output end of the first frequency multiplier 122 is the first output end of the frequency multiplier circuit 120, and the first frequency multiplier 122 is used for performing a first frequency multiplication on the standard clock signal. The input end of the second frequency multiplier 133 is electrically connected to the output end of the phase-locked circuit 121, the output end of the first frequency multiplier 122 is the second output end of the frequency multiplier circuit 120, and the second frequency multiplier 133 is used for performing the second frequency multiplication processing on the standard clock signal.

In this embodiment, the phase lock circuit 121 performs phase lock on the input standard clock signal so that the output signal is the same as the input standard clock signal. The signal output from the phase lock circuit 121 is subjected to a first frequency multiplication process by the first frequency multiplier 122 to output a first frequency multiplied signal to the acousto-optic modulation driving circuit 120. The second frequency multiplier 133 performs a second frequency multiplication on the signal output by the phase lock circuit 121 to output a second frequency multiplied signal to the data acquisition circuit 140. The phase-locked circuit 121 may be implemented by a DDS (Direct Digital Frequency Synthesis, direct digital frequency synthesizer) or a PLL (Phase Locked Loop, phase-locked loop or phase-locked loop).

Referring to fig. 3, in an embodiment, the acousto-optic modulation driving circuit 120 includes a first delay circuit 131 and a first amplifying circuit 132.

The input end of the first delay circuit 131 is electrically connected with the first output end of the frequency doubling circuit 120; the first delay circuit 131 is further configured to detect a phase of the first frequency-multiplied signal, and delay the first frequency-multiplied signal when detecting that the phase of the first frequency-multiplied signal is not a preset phase; and outputting the first frequency multiplied signal when detecting that the phase of the first frequency multiplied signal is a preset phase. The delay circuit 131 may be implemented by a resistor, a capacitor, or the like, and delay the first frequency-multiplied signal by a delay characteristic of the capacitor.

The input end of the first amplifying circuit 132 is electrically connected with the output end of the first delay circuit 131; the first amplifying circuit 132 is configured to amplify the received first frequency-multiplied signal according to a preset amplification factor, and generate a driving signal. The first amplifying circuit 132 may include an amplifier through which amplification of the received first frequency multiplied signal according to a preset amplification factor is achieved.

The acousto-optic modulation circuit 300 can be driven to work only after the driving voltage output by the acousto-optic modulation driving circuit 120 exceeds the preset voltage threshold. The conventional acousto-optic modulation driving circuit 120 generally adopts a linear amplification manner, that is, the amplification factor increases from 0 to a maximum value with time, and the left side represents a signal before amplification and the right side represents a signal after amplification as shown in fig. 4 a. In this way, in the early stage of the amplifying process, there is a section of rising edge, the pulse signal output by the rising edge is incomplete, and a signal at a certain point may not be amplified to the maximum value, but the voltage value of the pulse signal is already above the preset voltage threshold value, so that the acousto-optic modulation circuit 300 starts to work, outputs a weak optical signal, and causes interference to the identification of the optical signal.

In this embodiment, the first delay circuit 131 delays the first frequency-multiplied signal by detecting the phase of the first frequency-multiplied signal, when the phase of the first frequency-multiplied signal does not reach the preset phase; when the first frequency-multiplied signal reaches the preset phase, the first frequency-multiplied signal is output to the first amplifying circuit 132. As shown in fig. 4b, the first amplifying circuit 132 directly amplifies the first frequency multiplier 120 to a maximum value according to a preset amplification factor, and generates a driving signal to output to the acousto-optic modulation circuit 300. Thus, the interference of the rising edge to the acousto-optic modulation circuit 300 in the linear amplification process is avoided, and the consistency of the driving signals is ensured. The driving signal can excite the crystal of the acousto-optic modulation circuit 300 in a complete modulation period, so that the crystal outputs a stable detection light signal. Wherein the preset phase may be set to 0. When the phase of the first frequency multiplied signal is 0, the first delay circuit 131 outputs it to the first amplifying circuit 132. Thus, the signal starts from 0, facilitating subsequent computational analysis. In addition, the preset phase may be set to pi/3, pi/2, pi, etc., without limitation.

In one embodiment, the acousto-optic modulation driving circuit 120 further includes a filtering circuit 133. An input terminal of the filter circuit 133 is electrically connected to the first output terminal of the frequency multiplier circuit 120, and an output terminal of the filter circuit 133 is electrically connected to an input terminal of the first delay circuit 131. The filter circuit 133 is configured to filter the first frequency-multiplied signal output by the frequency-multiplying circuit 120 to improve the quality of the first frequency-multiplied signal. The filter circuit 133 may include a capacitor.

In an embodiment, the acousto-optic modulation driving circuit 120 further includes a second amplifying circuit 134 and a shaping circuit 135.

An input end of the second amplifying circuit 134 is electrically connected with a first output end of the frequency doubling circuit 120, and an output end of the second amplifying circuit 134 is electrically connected with an input end of the first delay circuit 131; the second amplifying circuit 134 is configured to amplify and output the driving signal output from the phase lock circuit 121. An input end of the shaping circuit 135 is electrically connected to an output end of the first amplifying circuit 132; the shaping circuit 135 is configured to shape and output the driving signal output from the first amplifying circuit 132.

In this embodiment, the second amplifying circuit 134 amplifies the first frequency-multiplied signal at one stage, and outputs the first frequency-multiplied signal to the first amplifying circuit 132 via the first delay circuit 131 for performing second-stage amplification, and the multi-stage amplification is provided to increase the amplification factor of the acousto-optic modulation driving circuit 120 and the stability of the amplified signal. Further, the acousto-optic modulation driving circuit 120 may further include a third amplifying circuit 136, where the third amplifying circuit 136 is connected in series between the first amplifying circuit 132 and the first delay circuit 131.

The shaping circuit 135 performs shaping, trimming, etc. on the driving signal output by the first amplifying circuit 132 to ensure the integrity of the signal. The shaping circuit may include devices such as resistors, capacitors, diodes, etc.

In an embodiment, the acousto-optic modulation driving circuit 120 may further include a single-ended transformer 137, and the single-ended transformer 137 is connected in series between the second amplifying circuit 134 and the third amplifying circuit 136. After the first frequency-multiplied signal is amplified by the second amplifying circuit 134, a signal instability may occur, for example, the amplitude of each peak of the signal waveform is different, and the amplitude is larger or smaller. The single-ended transformer 137 can compensate the amplitude of the first frequency-multiplied signal output by the second amplifying circuit 134, so that the amplitudes of the peaks are the same. In this way, the third amplifying circuit 136 and the first amplifying circuit 132 at the rear can amplify the complete first frequency-multiplied signal with stable power, so as to improve the stability of the signal.

Referring to fig. 5, in one embodiment, the data acquisition circuit 140 includes a second delay circuit 141 and a data acquisition card 142.

The input end of the second delay circuit 141 is the input end of the data acquisition circuit 140, and the controlled end of the second delay circuit 141 is electrically connected with the output end of the first delay circuit 131; the second delay circuit 141 is configured to delay the second frequency multiplied signal.

The first delay circuit 131 is further configured to output a phase signal when detecting that the phase of the driving signal is a preset phase, and the second delay circuit 141 is further configured to output a second frequency multiplied signal when receiving the phase signal.

The input end of the data acquisition card 142 is electrically connected with the input end of the second delay circuit 141, and the acquisition end of the data acquisition card 142 is the acquisition end of the data acquisition circuit 140; the data acquisition card 142 is configured to sample the electrical signal output by the balanced photodetector 200 according to the second frequency multiplication signal, and generate a sampling signal.

The transmission paths of the first frequency multiplied signal and the second frequency multiplied signal are different, and the transmission time in the circuit is also different. If the first frequency multiplied signal and the second frequency multiplied signal are not synchronized in time, random jitter may occur in the sampling signal of the data acquisition card 142. That is, the electrical signal actually collected by the data collection card 142 corresponds to the detection optical signal output by the acousto-optic modulation circuit 300 at the time T1, but the electrical signal actually collected by the data collection card 142 corresponds to the detection optical signal output by the acousto-optic modulation circuit 300 at the time T2 due to the difference of the transmission time lengths of the first frequency multiplication signals in the circuits. In this case, the aliasing of the electrical signals between sampling intervals during the long-term test is equivalent to a reduction in resolution and sensitivity of the system. After the delay of the second delay circuit 141 and the delay of the first delay circuit 131 are synchronized, in the long-term test process, the sampling signals of the same sampling point are collected on one point by the data acquisition card 142, and the data of the sampling point are also analyzed when the sampling signals are analyzed. Whereas without synchronization a superposition analysis is quite performed on a length of the signal.

In this embodiment, the second delay circuit 141 delays the second frequency-multiplied signal until the second frequency-multiplied signal is received from the first delay circuit 131, and the second delay circuit 141 outputs the second frequency-multiplied signal to the data acquisition card 142, so that the data acquisition card 142 can sample according to the second frequency-multiplied signal. In this way, the first delay circuit 131 outputs the first frequency-multiplied signal to the second amplifying circuit 134 at the preset phase, and the second delay circuit 141 outputs the second frequency-multiplied signal to the data acquisition card 142 at the preset phase. The signal received by the data acquisition card 142 and the signal received by the first amplifying circuit 132 are synchronous and delayed, so that the phase difference of the sampled signal of the data acquisition card 142 is reduced, the jitter of the sampling point of the data acquisition card 142 is avoided, and the sampling precision is improved.

Referring to fig. 6, the present application also proposes an optical fiber vibration monitoring apparatus including the above-described phase synchronization circuit 100, acousto-optic modulation circuit 300, and balanced photodetector 200.

The acousto-optic modulation circuit 300 is electrically connected with the phase synchronization circuit 100; the acousto-optic modulation circuit 300 is configured to receive the driving signal output by the phase synchronization circuit 100, and output a detection light signal under the control of the driving signal.

The balanced photodetector 200 is electrically connected with the phase synchronization circuit 100; the balanced photodetector 200 is configured to receive the feedback optical signal, convert the feedback optical signal into a corresponding electrical signal, and output the electrical signal to the phase synchronization circuit 100;

the phase synchronization circuit 100 is further configured to sample the electrical signal output by the balanced photodetector 200 to generate a sampled signal.

The detailed structure of the phase synchronization circuit 100 can refer to the above embodiments, and will not be described herein again; it can be understood that, because the above-mentioned phase synchronization circuit 100 is used in the optical fiber vibration monitoring device of the present application, the embodiments of the optical fiber vibration monitoring device of the present application include all the technical solutions of all the embodiments of the above-mentioned phase synchronization circuit 100, and the achieved technical effects are also identical, and are not described herein again.

In one embodiment, the fiber vibration monitoring device further includes a control circuit 400.

The control circuit 400 is electrically connected to the phase synchronization circuit 100; the control circuit 400 is configured to output a trigger signal to the phase synchronization circuit 100; the phase synchronization circuit 100 is also configured to generate a driving signal according to the trigger signal. The control circuit 400 may be implemented using a microprocessor, FPGA (Field Programmable Gate Array ) or other chip with control functions.

The control circuit 400 is further configured to receive the sampling signal output by the phase synchronization circuit 100, and perform phase demodulation on the sampling signal to obtain phase information.

In this embodiment, when the optical fiber 600 to be detected is required to be detected, the control circuit 400 outputs a trigger signal to the phase synchronization circuit 100 to control the phase synchronization circuit 100 to output a driving signal to the acousto-optic modulation circuit 300 and collect the electrical signal output by the balanced photodetector 200. The acousto-optic modulation circuit 300 generates a detection optical signal to the optical fiber 600 to be detected according to the driving signal output by the phase synchronization circuit 100, receives the feedback optical signal of the optical fiber 600 to be detected by the balance photodetector after feeding back the feedback optical signal by the optical fiber 600 to be detected, and converts the feedback optical signal into a corresponding electrical signal to be output to the phase synchronization circuit 100. The phase synchronization circuit 100 samples the electric signal, generates a sampling signal, and outputs the sampling signal to the control circuit 400. The control circuit 400 performs phase demodulation on the sampling signal to obtain phase information, and according to the phase information, vibration information in the optical fiber 600 to be measured can be restored.

Any external vibration wave (including sound wave) can affect the glass lattice in the optical fiber, so as to cause the same-frequency vibration of the lattice. After the detection light signal with a certain intensity is input into the optical fiber 600 to be tested, corresponding feedback light signals are received, and the feedback light signals can bring back vibration information of the crystal lattice. The feedback optical signals are converted into corresponding electric signals, the electric signals are sampled, and the control circuit 400 demodulates and analyzes the information, so that the vibration information of the vibration area can be restored, and the position of the vibration area can be determined.

In one embodiment, the fiber vibration monitoring device further includes a mixer circuit 500.

The input end of the mixing circuit 500 is electrically connected with the first output end of the frequency doubling circuit 120 of the phase synchronization circuit 100, and the output end of the mixing circuit 500 is electrically connected with the control circuit 400; the mixer circuit 500 is configured to mix the first multiplied signal to generate a demodulation reference frequency signal, and output the demodulation reference frequency signal to the control circuit 400. The mixer circuit 500 may include a mixer.

In this embodiment, the frequency of the driving signal (i.e. the frequency of the first frequency multiplication signal) is overlapped with the frequency of the sampling signal by the mixing circuit 500 to provide a reference frequency signal for subsequent signal demodulation.

Referring to fig. 7, the present application further provides a phase synchronization method applied to an optical fiber vibration monitoring device, where the optical fiber vibration monitoring device includes a balanced photoelectric detector 200 and an acousto-optic modulation circuit 300, and the phase synchronization method includes:

s100: generating a standard clock signal;

s200: when the trigger signal is received, performing first frequency multiplication on the standard clock signal, outputting a first frequency multiplication signal, performing second frequency multiplication on the standard clock signal, and outputting a second frequency multiplication signal;

s300: generating a driving signal according to the first frequency multiplication signal to drive the acousto-optic modulation circuit 300 to output a detection light signal;

S400: the electrical signal output by the balanced photodetector 200 is sampled according to the second frequency multiplied signal, generating a sampled signal.

In this embodiment, the standard clock signal is used to synchronize clocks. When receiving the trigger signal, the input standard clock signal is divided into two paths for processing. One path generates a first frequency multiplication signal after first frequency multiplication, and generates a driving signal after a series of processing on the first frequency multiplication signal, and outputs the driving signal to the acousto-optic modulation driving circuit 120. The other path generates a second frequency multiplication signal after second frequency multiplication so as to sample according to the frequency provided by the second frequency multiplication signal and generate a sampling signal. The trigger signal may be sent by the control circuit 400 in the host computer or the optical fiber vibration monitoring device when the optical fiber 600 to be detected needs to be detected. Thus, the clocks of the first frequency multiplication signal and the second frequency multiplication signal are synchronous, and the trigger time is also synchronous. The phase synchronization circuit 100 samples the electric signal output by the balanced photoelectric detector 200 while outputting the driving signal, so as to reduce the phase error between the oscillation starting phase of the driving signal driving the acousto-optic modulation circuit 300 and the sampling of the phase synchronization circuit 100, and improve the phase recognition precision.

For example, the standard clock signal is 10MHz. When the trigger signal is received, 8 times and 25 times are respectively carried out on the standard clock signal of 10MHz, and a first frequency multiplication signal of 80MHz and a second frequency multiplication signal of 250MHz are generated. After performing multistage amplification, delay, shaping and other processes on the first frequency multiplication signal of 80MHz, an 80MHz driving signal is generated and output to the acousto-optic modulation circuit 300, so as to drive the acousto-optic modulation circuit 300 to output a detection light signal to the optical fiber 600 to be tested according to the 80MHz driving signal. Meanwhile, the phase synchronization circuit 100 samples the electric signal output from the balanced photodetector 200 according to the second frequency multiplied signal of 250 MHz. In this way, the clock synchronization and the trigger time synchronization of the first frequency multiplication signal and the second frequency multiplication signal realize the synchronization of the oscillation starting point of the acousto-optic modulation circuit 300 for modulating the detection light signal and the sampling point of the data acquisition circuit 140, thereby reducing sampling phase error and improving phase identification precision. The frequency parameters of the standard clock signal and the frequency multiplication parameters of the first frequency multiplication and the second frequency multiplication of the frequency multiplication circuit 120 can be set according to the actual requirements and the sampling principle, which is not limited herein.

According to the method, clock synchronization of the first frequency multiplication signal and the second frequency multiplication signal is realized through the standard clock signal, trigger time synchronization of the first frequency multiplication signal and the second frequency multiplication signal is realized through the trigger signal, when the acousto-optic modulation circuit 300 modulates the detection optical signal, the oscillation starting phase of the detection optical signal is synchronous with the phase of the sampling signal of the phase synchronization circuit 100, phase errors are reduced, and phase identification precision is improved.

In one embodiment, generating the drive signal from the first multiplied signal comprises:

detecting the phase of the first frequency multiplication signal, and delaying the first frequency multiplication signal when the phase of the first frequency multiplication signal is detected to be not a preset phase; and amplifying the first frequency multiplication signal when the phase of the driving signal is detected to be a preset phase, and generating the driving signal.

The acousto-optic modulation circuit 300 can be driven to work only after the driving voltage output by the acousto-optic modulation driving circuit 120 exceeds the preset voltage threshold. The conventional acousto-optic modulation driving circuit 120 generally adopts a linear amplification manner, that is, the amplification factor increases from 0 to a maximum value with time, and the left side represents a signal before amplification and the right side represents a signal after amplification as shown in fig. 4 a. In this way, in the early stage of the amplifying process, there is a section of rising edge, the pulse signal output by the rising edge is incomplete, and a signal at a certain point may not be amplified to the maximum value, but the voltage value of the pulse signal is already above the preset voltage threshold value, so that the acousto-optic modulation circuit 300 starts to work, outputs a weak optical signal, and causes interference to the identification of the optical signal.

In this embodiment, by detecting the phase of the first frequency-multiplied signal, when the phase of the first frequency-multiplied signal does not reach the preset phase, the first frequency-multiplied signal is delayed; when the first frequency-multiplied signal reaches the preset phase, the first frequency-multiplied signal is output to the first amplifying circuit 132. The first amplifying circuit 132 directly amplifies the first frequency doubling circuit 120 to a maximum value according to a preset amplification factor, as shown in fig. 4b, to generate a driving signal and output the driving signal to the acousto-optic modulation circuit 300. Thus, the interference of the rising edge to the acousto-optic modulation circuit 300 in the linear amplification process is avoided, and the consistency of the driving signals is ensured. The driving signal can excite the crystal of the acousto-optic modulation circuit 300 in a complete modulation period, so that the crystal outputs a stable detection light signal. Wherein the preset phase may be set to 0. When the phase of the first frequency multiplied signal is 0, the first delay circuit 131 outputs it to the first amplifying circuit 132. Thus, the signal starts from 0, facilitating subsequent computational analysis. In addition, the preset phase may be set to pi/3, pi/2, pi, etc., without limitation.

In an embodiment, the phase synchronization method further comprises:

detecting the phase of the first frequency multiplication signal, and outputting a phase signal when the phase of the driving signal is detected to be a preset phase;

When the phase signal is not received, delaying the second frequency multiplication signal; and outputting a second multiplied signal upon receiving the phase signal.

The transmission paths of the first frequency multiplied signal and the second frequency multiplied signal are different, and the transmission time in the circuit is also different. If the first frequency multiplied signal and the second frequency multiplied signal are not synchronized in time, random jitter may occur in the sampling signal of the data acquisition card 142. That is, the collected electrical signal corresponds to the detection optical signal output by the acousto-optic modulation circuit 300 at time T1, but the actual collected electrical signal corresponds to the detection optical signal output by the acousto-optic modulation circuit 300 at time T2 due to the difference in transmission time length of the first frequency multiplication signal in the circuit. In this case, the aliasing of the electrical signals between sampling intervals during the long-term test is equivalent to a reduction in resolution and sensitivity of the system. After the delay of the second delay circuit 141 and the delay of the first delay circuit 131 are synchronized, in the long-term test process, the sampled signals at the same sampling point are concentrated at one point, and the data of the point is also analyzed when the sampled signals are analyzed. Whereas without synchronization a superposition analysis is quite performed on a length of the signal.

In this embodiment, the second delay circuit 141 outputs the second frequency-multiplied signal by delaying the second frequency-multiplied signal until receiving the phase signal output by the first delay circuit 131, so as to sample the electric signal output by the balanced photodetector 200 according to the second frequency-multiplied signal. In this way, the first delay circuit 131 outputs the first frequency-multiplied signal to the second amplifying circuit 134 at the preset phase, and the second delay circuit 141 outputs the second frequency-multiplied signal to the data acquisition card 142 at the preset phase. The signal received by the data acquisition card 142 and the signal received by the first amplifying circuit 132 are synchronous and delayed, so that the phase difference of the sampled signal of the data acquisition card 142 is reduced, the jitter of the sampling point of the data acquisition card 142 is avoided, and the sampling precision is improved.

Hereinabove, the specific embodiments of the present application are described with reference to the accompanying drawings. However, those of ordinary skill in the art will understand that various changes and substitutions can be made in the specific embodiments of the present application without departing from the spirit and scope of the present application. Such modifications and substitutions are intended to be within the scope of the present application.

Claims (10)

1. A phase synchronization circuit for use in a fiber vibration monitoring device comprising a balanced photodetector, the phase synchronization circuit comprising:

A clock signal generation circuit for generating a standard clock signal;

the input end of the frequency doubling circuit is electrically connected with the clock signal generating circuit; the frequency doubling circuit is used for carrying out first frequency doubling processing on the standard clock signal to obtain a first frequency doubling signal when receiving the trigger signal, and carrying out second frequency doubling processing on the standard clock signal to obtain a second frequency doubling signal;

the input end of the acousto-optic modulation driving circuit is electrically connected with the first output end of the frequency doubling circuit; the acousto-optic modulation circuit is used for receiving the first frequency multiplication signal and generating a driving signal according to the first frequency multiplication signal;

the input end of the data acquisition circuit is electrically connected with the second output end of the frequency doubling circuit, and the acquisition end of the data acquisition circuit is electrically connected with the balance photoelectric detector; the data acquisition circuit is used for receiving the second frequency multiplication signal and sampling the electric signal output by the balance photoelectric detector according to the second frequency multiplication signal to generate a sampling signal.

2. The phase synchronization circuit of claim 1, wherein the frequency doubling circuit comprises:

The input end of the phase-locked circuit is the input end of the frequency doubling circuit; the phase-locking circuit is used for phase-locking the standard clock signal;

the input end of the first frequency multiplier is electrically connected with the output end of the phase-locked circuit, and the output end of the first frequency multiplier is a first output end of the frequency multiplication circuit; the first frequency multiplier is used for performing first frequency multiplication processing on the standard clock signal;

the input end of the second frequency multiplier is electrically connected with the output end of the phase-locked circuit, and the output end of the first frequency multiplier is a second output end of the frequency multiplication circuit; the second frequency multiplier is used for performing second frequency multiplication processing on the standard clock signal.

3. The phase synchronization circuit of claim 2, wherein the acousto-optic modulation drive circuit comprises:

the input end of the first delay circuit is electrically connected with the first output end of the frequency doubling circuit; the first delay circuit is further used for detecting the phase of the first frequency multiplication signal and delaying the first frequency multiplication signal when detecting that the phase of the first frequency multiplication signal is not a preset phase; and outputting the first frequency multiplied signal when detecting that the phase of the first frequency multiplied signal is a preset phase;

The input end of the first amplifying circuit is electrically connected with the output end of the first delay circuit; the first amplifying circuit is used for amplifying the received first frequency multiplication signal according to preset amplification factors to generate the driving signal.

4. The phase synchronization circuit of claim 3, wherein the acousto-optic modulation drive circuit further comprises:

the input end of the second amplifying circuit is electrically connected with the first output end of the frequency doubling circuit, and the output end of the second amplifying circuit is electrically connected with the input end of the first delay circuit; the second amplifying circuit is used for amplifying the driving signal output by the phase-locked circuit and outputting the driving signal;

the input end of the shaping circuit is electrically connected with the output end of the first amplifying circuit; the shaping circuit is used for shaping and outputting the driving signal output by the first amplifying circuit.

5. The phase synchronization circuit of claim 3, wherein the data acquisition circuit comprises:

the input end of the second delay circuit is the input end of the data acquisition circuit, and the controlled end of the second delay circuit is electrically connected with the output end of the first delay circuit; the second delay circuit is used for delaying the second frequency multiplication signal;

The first delay circuit is further used for outputting a phase signal when the phase of the driving signal is detected to be a preset phase, and the second delay circuit is further used for delaying the second frequency multiplication signal when the phase signal is not received; and outputting the second multiplied signal upon receiving the phase signal;

the input end of the data acquisition card is electrically connected with the input end of the second delay circuit, and the acquisition end of the data acquisition card is the acquisition end of the data acquisition circuit; the data acquisition card is used for sampling the electric signals output by the balance photoelectric detector according to the second frequency multiplication signal to generate the sampling signals.

6. An optical fiber vibration monitoring device, characterized in that the optical fiber vibration monitoring device comprises:

the phase synchronization circuit according to any one of claims 1 to 5;

the acousto-optic modulation circuit is electrically connected with the phase synchronization circuit; the acousto-optic modulation circuit is used for receiving the driving signal output by the phase synchronization circuit and outputting a detection light signal under the control of the driving signal;

the balance photoelectric detector is electrically connected with the phase synchronization circuit; the balanced photoelectric detector is used for receiving the feedback optical signal, converting the feedback optical signal into a corresponding electric signal and outputting the corresponding electric signal to the phase synchronization circuit;

The phase synchronization circuit is also used for sampling the electric signals output by the balance photoelectric detector to generate sampling signals.

7. The fiber optic vibration monitoring device according to claim 6, further comprising:

the control circuit is electrically connected with the phase synchronization circuit; the control circuit is used for outputting a trigger signal to the phase synchronization circuit; the phase synchronization circuit is also used for generating the driving signal according to the trigger signal;

the control circuit is also used for receiving the sampling signal output by the phase synchronization circuit and carrying out phase demodulation on the sampling signal so as to acquire phase information.

8. The phase synchronization method is applied to optical fiber vibration monitoring equipment, and the optical fiber vibration monitoring equipment comprises a balanced photoelectric detector and an acousto-optic modulation circuit, and is characterized by comprising the following steps of:

generating a standard clock signal;

when a trigger signal is received, performing first frequency multiplication on the standard clock signal, outputting a first frequency multiplication signal, performing second frequency multiplication on the standard clock signal, and outputting a second frequency multiplication signal;

Generating a driving signal according to the first frequency multiplication signal so as to drive the acousto-optic modulation circuit to output a detection light signal;

and sampling the electric signal output by the balanced photoelectric detector according to the second frequency multiplication signal to generate a sampling signal.

9. The phase synchronization method of claim 8, wherein the generating a drive signal from the first multiplied signal comprises:

detecting the phase of the first frequency multiplication signal, and delaying the first frequency multiplication signal when detecting that the phase of the first frequency multiplication signal is not a preset phase; and amplifying the first frequency multiplication signal when the phase of the driving signal is detected to be a preset phase, so as to generate the driving signal.

10. The phase synchronization method of claim 8, wherein the phase synchronization method further comprises:

detecting the phase of the first frequency multiplication signal, and outputting a phase signal when the phase of the driving signal is detected to be a preset phase;

delaying the second frequency multiplication signal when the phase signal is not received; and outputting the second frequency multiplied signal upon receiving the phase signal.

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