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

Abstract

The present 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 generating circuit, a frequency multiplication circuit and an acousto-optic modulation driving circuit. The clock signal generating circuit is used to generate a standard clock signal. The frequency multiplication circuit is used to process the standard clock signal upon receiving a trigger signal to obtain a first frequency multiplication signal and a second frequency multiplication signal. The acousto-optic modulation circuit is used to generate a driving signal according to the first frequency multiplication signal. The data acquisition circuit is used to receive the second frequency multiplication signal, and to sample the electrical signal output by the balanced photodetector according to the second frequency multiplication signal to generate a sampling signal. The present application provides a standard clock signal through a clock signal generating circuit, and simultaneously outputs the first frequency multiplication signal and the second frequency multiplication signal through a frequency multiplication circuit, so that the starting phase of the detection light signal is synchronized with the phase of the sampling signal of the data acquisition circuit, thereby reducing the phase error and improving the phase recognition accuracy.

Description

Technical Field

[0001] The present application relates to the field of optical fibers, and in particular to a phase synchronization circuit, an optical fiber vibration monitoring device, and a phase synchronization method. Background Art

[0002] Distributed fiber optic vibration monitoring equipment based on φOTDR (optical time domain reflectometry) technology has become a conventional vibration monitoring equipment, and the technology is currently being expanded to the application of sound restoration. Sound restoration not only shows that the equipment has high-precision phase accuracy control, but also has high-reliability restoration of vibration events.

[0003] For the φOTDR system, the phase measurement accuracy will significantly affect the vibration measurement accuracy of the system. At present, due to the overall development of the industry, the supplier of the φOTDR device acousto-optic modulator and the supplier of the data acquisition card are different suppliers, resulting in the two being physically from different sources, and the phase oscillation will be out of sync, such as Figure 1 Each time the AOM modulates the optical signal, the phase of the starting point is random. After interference, this part of the optical signal will also be added with a random phase term, resulting in the phase error cannot be eliminated. Summary of the invention

[0004] In order to solve the problems in the prior art, the present application provides a phase synchronization circuit, an optical fiber vibration monitoring device and a phase synchronization method, so as to reduce phase error and improve phase recognition accuracy.

[0005] The present application provides a phase synchronization circuit, which is applied to an optical fiber vibration monitoring device, wherein the optical fiber vibration monitoring device includes a balanced photoelectric detector, and the phase synchronization circuit includes:

[0006] A clock signal generating circuit, wherein the clock signal generating circuit is used to generate a standard clock signal;

[0007] A frequency multiplication circuit, the input end of which is electrically connected to the clock signal generating circuit; the frequency multiplication circuit is used to perform a first frequency multiplication process on the standard clock signal to obtain a first frequency multiplication signal, and to perform a second frequency multiplication process on the standard clock signal to obtain a second frequency multiplication signal when receiving a trigger signal;

[0008] an acousto-optic modulation driving circuit, wherein the input end of the acousto-optic modulation driving circuit is electrically connected to the first output end of the frequency multiplication circuit; the acousto-optic modulation circuit is used to receive the first frequency multiplication signal and generate a driving signal according to the first frequency multiplication signal;

[0009] A data acquisition circuit, wherein the input end of the data acquisition circuit is electrically connected to the second output end of the frequency doubling circuit, and the acquisition end of the data acquisition circuit is used to be electrically connected to the balanced photodetector; the data acquisition circuit is used to receive the second frequency doubling signal, and to sample the electrical signal output by the balanced photodetector according to the second frequency doubling signal to generate a sampling signal.

[0010] In one embodiment, the frequency multiplication circuit comprises:

[0011] A phase-locked circuit, the input end of the phase-locked circuit being the input end of the frequency multiplication circuit; the phase-locked circuit is used to phase-lock the standard clock signal;

[0012] A first frequency multiplier, wherein the input end of the first frequency multiplier is electrically connected to the output end of the phase-locked circuit, and the output end of the first frequency multiplier is the first output end of the frequency multiplier circuit; the first frequency multiplier is used to perform a first frequency multiplication process on the standard clock signal;

[0013] A second frequency multiplier, wherein the input end of the second frequency multiplier is electrically connected to the output end of the phase-locked circuit, and the output end of the first frequency multiplier is the second output end of the frequency multiplier circuit; the second frequency multiplier is used to perform a second frequency multiplication process on the standard clock signal.

[0014] In one embodiment, the acousto-optic modulation driving circuit includes:

[0015] a first delay circuit, wherein the input end of the first delay circuit is electrically connected to the first output end of the frequency multiplication circuit; the first delay circuit is further used to detect the phase of the first frequency multiplication signal, and delay the first frequency multiplication signal when it is detected that the phase of the first frequency multiplication signal is not a preset phase; and output the first frequency multiplication signal when it is detected that the phase of the first frequency multiplication signal is a preset phase;

[0016] A first amplifier circuit, wherein the input end of the first amplifier circuit is electrically connected to the output end of the first delay circuit; the first amplifier circuit is used to amplify the received first frequency-doubled signal according to a preset amplification factor to generate a driving signal.

[0017] In one embodiment, the acousto-optic modulation driving circuit further includes:

[0018] a second amplifier circuit, wherein the input end of the second amplifier circuit is electrically connected to the first output end of the frequency multiplication circuit, and the output end of the second amplifier circuit is electrically connected to the input end of the first delay circuit; the second amplifier circuit is used to amplify the driving signal output by the phase-locked circuit and then output it;

[0019] A shaping circuit, wherein the input end of the shaping circuit is electrically connected to the output end of the first amplifying circuit; the shaping circuit is used to shape and output the driving signal output by the first amplifying circuit.

[0020] In one embodiment, the data acquisition circuit includes:

[0021] a second delay circuit, wherein 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 to the output end of the first delay circuit; the second delay circuit is used to delay the second frequency-doubled signal;

[0022] The first delay circuit is further used to output a phase signal when it is detected that the phase of the driving signal is a preset phase, and the second delay circuit is further used to delay the second frequency-doubled signal when the phase signal is not received; and output the second frequency-doubled signal when the phase signal is received;

[0023] A data acquisition card, wherein the input end of the data acquisition card is electrically connected to 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 to sample the electrical signal output by the balanced photodetector according to the second frequency-doubled signal to generate the sampling signal.

[0024] The present application also proposes an optical fiber vibration monitoring device, the optical fiber vibration monitoring device comprising:

[0025] The phase synchronization circuit mentioned above;

[0026] an acousto-optic modulation circuit, electrically connected to the phase synchronization circuit; the acousto-optic modulation circuit is used to receive a driving signal output by the phase synchronization circuit and output a detection light signal under the control of the driving signal;

[0027] A balanced photodetector, electrically connected to the phase synchronization circuit; the balanced photodetector is used to receive the feedback optical signal, and convert the feedback optical signal into a corresponding electrical signal and output it to the phase synchronization circuit;

[0028] The phase synchronization circuit is also used to sample the electrical signal output by the balanced photodetector to generate a sampling signal.

[0029] In one embodiment, the optical fiber vibration monitoring device further includes:

[0030] A control circuit, the control circuit being electrically connected to the phase synchronization circuit; the control circuit being used to output a trigger signal to the phase synchronization circuit; the phase synchronization circuit being also used to generate the drive signal according to the trigger signal;

[0031] The control circuit is also used to receive the sampling signal output by the phase synchronization circuit and perform phase demodulation on the sampling signal to obtain phase information.

[0032] The present application also proposes a phase synchronization method, which is applied to an optical fiber vibration monitoring device, wherein the optical fiber vibration monitoring device includes a balanced photoelectric detector and an acousto-optic modulation circuit, and the phase synchronization method includes:

[0033] Generate standard clock signal;

[0034] When a trigger signal is received, performing a first frequency multiplication process on the standard clock signal and outputting a first frequency multiplication signal, and performing a second frequency multiplication process on the standard clock signal and outputting a second frequency multiplication signal;

[0035] generating a driving signal according to the first frequency-doubled signal to drive the acousto-optic modulation circuit to output a detection light signal;

[0036] The electrical signal output by the balanced photodetector is sampled according to the second frequency-doubled signal to generate a sampling signal.

[0037] In one embodiment, generating a driving signal according to the first frequency-doubled signal comprises:

[0038] The phase of the first frequency-doubled signal is detected, and when it is detected that the phase of the first frequency-doubled signal is not a preset phase, the first frequency-doubled signal is delayed; and when it is detected that the phase of the driving signal is a preset phase, the first frequency-doubled signal is amplified to generate a driving signal.

[0039] In one embodiment, the phase synchronization method further includes:

[0040] detecting a phase of the first frequency-multiplied signal, and outputting a phase signal when detecting that the phase of the driving signal is a preset phase;

[0041] When the phase signal is not received, the second frequency-doubled signal is delayed; and when the phase signal is received, the second frequency-doubled signal is output.

[0042] The present application realizes clock synchronization of the first frequency multiplication signal and the second frequency multiplication signal through a standard clock signal, and realizes trigger time synchronization of the first frequency multiplication signal and the second frequency multiplication signal through a trigger signal, so that when the acousto-optic modulation circuit modulates the detection light signal, the starting phase of the detection light signal is synchronized with the phase of the sampling signal of the phase synchronization circuit, thereby reducing the phase error and improving the phase recognition accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the phase synchronization circuit of the present application.

[0044] Figure 2 It is a structural schematic diagram of an embodiment of a frequency multiplication circuit of the present application.

[0045] Figure 3 Schematic diagram of the structure of an embodiment of the acousto-optic modulation driving circuit of the present application.

[0046] Figure 4a This is a schematic diagram of the signal waveform before synchronization delay.

[0047] Figure 4b This is a schematic diagram of the signal waveform after synchronization delay.

[0048] Figure 5 This is a schematic diagram of the structure of an embodiment of a data acquisition circuit of the present application.

[0049] Figure 6 It is a structural schematic diagram of an embodiment of the optical fiber vibration monitoring device of the present application.

[0050] Figure 7 It is a flowchart diagram of an embodiment of a phase synchronization method of the present application.

[0051] Main component symbols

[0052] Phase synchronization circuit 100 Balanced photodetector 200

[0053] Clock signal generation circuit 110 Frequency multiplication circuit 120

[0054] Acousto-optic modulation drive circuit 130 Data acquisition circuit 140

[0055] Acousto-optic modulation circuit 300 Phase-locked circuit 121

[0056] First frequency multiplier 122 Second frequency multiplier 133

[0057] The first delay circuit 131 The first amplifier circuit 132

[0058] Filter circuit 133 Second amplifier circuit 134

[0059] Shaping circuit 135 Third amplifier circuit 136

[0060] Single-ended transformer 137 Second delay circuit 141

[0061] Data acquisition card 142 Control circuit 400

[0062] Mixing circuit 500 Fiber under test 600

[0063] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0064] The following description will refer to the accompanying drawings to more fully describe the content of the present application. Shown in the accompanying drawings are exemplary embodiments of the present application. However, the present application can be implemented in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided to make the present application thorough and complete, and to fully convey the scope of the present application to those skilled in the art. Similar reference numerals represent identical or similar components.

[0065] The terms used herein are only used for the purpose of describing specific exemplary embodiments and are not intended to limit the present application. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to also include the plural forms. In addition, when used herein, "including" and / or "comprising" and / or "having", integers, steps, operations, components and / or components, but do not exclude the existence or addition of one or more other features, regions, integers, steps, operations, components and / or groups thereof.

[0066] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. In addition, unless explicitly defined herein, terms such as those defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant technology and the content of this application, and will not be interpreted as an idealized or overly formal meaning.

[0067] The following will describe exemplary embodiments in conjunction with the accompanying drawings. It should be noted that the components depicted in the reference drawings 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.

[0068] Reference Figures 1 to 5The present application proposes a phase synchronization circuit 100, which is applied to an optical fiber vibration monitoring device, and the optical fiber vibration monitoring device includes a balanced photodetector 200. The phase synchronization circuit 100 includes a clock signal generating circuit 110, a frequency multiplication circuit 120, an acousto-optic modulation driving circuit 130 and a data acquisition circuit 140. The clock signal generating circuit 110 is used to generate a standard clock signal. The input end of the frequency multiplication circuit 120 is electrically connected to the clock signal generating circuit 110; the frequency multiplication circuit 120 is used to perform a first frequency multiplication processing on the standard clock signal to obtain a first frequency multiplication signal when receiving a trigger signal, and to perform a second frequency multiplication processing on the standard clock signal to obtain a second frequency multiplication signal. The input end of the acousto-optic modulation driving circuit 120 is electrically connected to the first output end of the frequency multiplication circuit 120; the acousto-optic modulation circuit 300 is used to receive the first frequency multiplication signal, and to generate a driving signal according to the first frequency multiplication signal. The input end of the data acquisition circuit 140 is electrically connected to the second output end of the frequency doubling circuit 120, and the acquisition end of the data acquisition circuit 140 is used to be electrically connected to the balanced photodetector 200; the data acquisition circuit 140 is used to receive the second frequency doubling signal, and to sample the electrical signal output by the balanced photodetector 200 according to the second frequency doubling signal to generate a sampling signal.

[0069] In this embodiment, the optical fiber vibration monitoring device may further include an acousto-optic modulation circuit 300. The driving signal output by the acousto-optic modulation driving circuit 120 may be used to drive the acousto-optic modulation circuit 300 to output a detection optical signal to the optical fiber 600 to be tested. The balanced photodetector 200 is used to receive the 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, the dynamic vibration information along the optical fiber 600 to be tested can be obtained.

[0070] The clock signal generating circuit 110 is used to provide a standard clock signal of a preset frequency. The preset frequency can be set according to the operating frequency of the acousto-optic modulation circuit 300 and the data acquisition circuit 140, such as 5MHz, 10MHz, 20MHz, etc., which is not limited here. When receiving the trigger signal, the frequency multiplication circuit 120 divides the input standard clock signal into two paths for processing. One path generates a first frequency multiplication signal after the first frequency multiplication process and outputs it to the acousto-optic modulation driving circuit 120, and the other path generates a second frequency multiplication signal after the second frequency multiplication process and outputs it to the data acquisition circuit 140. Among them, the trigger signal can be issued by the control circuit 400 in the host computer or the optical fiber vibration monitoring device when it is necessary to detect the optical fiber 600 to be tested. 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 to achieve clock synchronization. When the optical fiber 600 to be tested needs to be tested, the frequency doubling circuit 120 is controlled by a trigger signal to simultaneously output the first frequency doubling signal and the second frequency doubling signal, so that the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140 can start working at the same time according to the same standard clock signal. When the acousto-optic modulation circuit 300 modulates the detection light signal, the starting phase of the detection light signal is synchronized with the phase of the sampling signal of the data acquisition circuit 140, thereby reducing the phase error and improving the phase recognition accuracy.

[0071] For example, the clock signal generating circuit 110 generates a standard clock signal of 10 MHz. When the frequency multiplication circuit 120 receives the trigger signal, the input standard clock signal of 10 MHz is processed by 8 times and 25 times respectively, and a first frequency multiplication signal of 80 MHz is generated and output to the acousto-optic modulation driving circuit 120, and a second frequency multiplication signal of 250 MHz is output to the data acquisition circuit 140, so as to control the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140 to start working at the same time. After the acousto-optic modulation driving circuit 120 performs multi-stage amplification, delay, shaping and other processing on the first frequency multiplication signal of 80 MHz, it 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 80 MHz driving signal. At the same time, the data acquisition circuit 140 samples the electrical signal output by the balanced photodetector 200 according to the second frequency multiplication signal of 250 MHz. In this way, by synchronizing the clock and the start time of the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140, the start point of the acousto-optic modulation circuit 300 modulating the detection light signal is synchronized with the sampling point of the data acquisition circuit 140, thereby reducing the sampling phase error and improving the phase recognition accuracy. Among them, the frequency parameters of the standard clock signal and the frequency multiplication parameters of the first and second frequency multiplication circuits 120 can be set according to actual needs and sampling principles, and are not limited here.

[0072] The present application provides a standard clock signal through a clock signal generating circuit 110, and processes the standard clock signal through a frequency multiplication circuit 120 to simultaneously output a first frequency multiplication signal and a second frequency multiplication signal, so that the acousto-optic modulation driving circuit 120 and the data acquisition circuit 140 can start working at the same time according to the same standard clock signal, and further, when the acousto-optic modulation circuit 300 modulates the detection light signal, the starting phase of the detection light signal is synchronized with the phase of the sampling signal of the data acquisition circuit 140, thereby reducing the phase error and improving the phase recognition accuracy.

[0073] Reference Figure 2 In one embodiment, the frequency multiplier circuit 120 includes a phase-locked 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 multiplier circuit 120; the phase-locked circuit 121 is used to phase-lock 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 to perform a first frequency multiplication process 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 to perform a second frequency multiplication process on the standard clock signal.

[0074] In this embodiment, the input standard clock signal is phase-locked by the phase-locked circuit 121, so that the output signal thereof is the same as the input standard clock signal. The signal output by the phase-locked circuit 121 is subjected to a first frequency multiplication process by the first frequency multiplier 122, so as to output the first frequency multiplication signal to the acousto-optic modulation driving circuit 120. The signal output by the phase-locked circuit 121 is subjected to a second frequency multiplication process by the second frequency multiplier 133, so as to output the second frequency multiplication signal to the data acquisition circuit 140. The phase-locked circuit 121 can be implemented by using a DDS (Direct Digital Frequency Synthesis) or a PLL (Phase Locked Loop).

[0075] Reference Figure 3 In one embodiment, the acousto-optic modulation driving circuit 120 includes a first delay circuit 131 and a first amplifier circuit 132 .

[0076] The input end of the first delay circuit 131 is electrically connected to the first output end of the frequency multiplication circuit 120; the first delay circuit 131 is also used to detect the phase of the first frequency multiplication signal, and delay the first frequency multiplication signal when it is detected that the phase of the first frequency multiplication signal is not the preset phase; and output the first frequency multiplication signal when it is detected that the phase of the first frequency multiplication signal is the preset phase. The delay circuit 131 can be implemented by components such as resistors and capacitors, and the delay of the first frequency multiplication signal is achieved through the delay characteristics of the capacitor.

[0077] The input end of the first amplifier circuit 132 is electrically connected to the output end of the first delay circuit 131; the first amplifier circuit 132 is used to amplify the received first frequency-multiplied signal according to a preset amplification factor to generate a driving signal. The first amplifier circuit 132 may include an amplifier, and the amplifier is used to amplify the received first frequency-multiplied signal according to a preset amplification factor.

[0078] The acousto-optic modulation driving circuit 120 can only drive the acousto-optic modulation circuit 300 to work after the driving voltage outputted by the acousto-optic modulation driving circuit 120 exceeds the preset voltage threshold. The existing acousto-optic modulation driving circuit 120 usually adopts a linear amplification method, that is, the amplification factor increases from 0 to the maximum value over time, such as Figure 4a The left side shows the signal before amplification, and the right side shows the signal after amplification. In this way, in the early stage of the amplification process, there is a rising edge, and the pulse signal outputted by the rising edge is incomplete. It is possible that the signal at a certain point is not amplified to the maximum value, but its voltage value has exceeded the preset voltage threshold, causing the acousto-optic modulation circuit 300 to start working and output a weak optical signal, which interferes with the recognition of the optical signal.

[0079] In this embodiment, the first delay circuit 131 detects the phase of the first frequency-doubled signal, and when the phase of the first frequency-doubled signal does not reach the preset phase, delays the first frequency-doubled signal; when the first frequency-doubled signal reaches the preset phase, the first frequency-doubled signal is output to the first amplification circuit 132. Figure 4b As shown, the first amplifier circuit 132 directly amplifies the first frequency doubling circuit 120 to the maximum value according to the preset amplification factor, generates a driving signal and outputs it to the acousto-optic modulation circuit 300. In this way, the interference of the rising edge to the acousto-optic modulation circuit 300 during the linear amplification process is avoided, and the consistency of the driving signal is ensured. The driving signal can excite the crystal of the acousto-optic modulation circuit 300 with a complete modulation cycle, so that it outputs a stable detection light signal. Among them, the preset phase can be set to 0. When the phase of the first frequency doubling signal is 0, the first delay circuit 131 outputs it to the first amplifier circuit 132. In this way, the signal starts from 0, which is convenient for subsequent calculation and analysis. In addition, the preset phase can also be set to π / 3, π / 2, π, etc., which is not limited here.

[0080] In one embodiment, the acousto-optic modulation driving circuit 120 further includes a filter circuit 133. The input end of the filter circuit 133 is electrically connected to the first output end of the frequency multiplication circuit 120, and the output end of the filter circuit 133 is electrically connected to the input end of the first delay circuit 131. The filter circuit 133 is used to filter the first frequency multiplication signal output by the frequency multiplication circuit 120 to improve the quality of the first frequency multiplication signal. The filter circuit 133 may include a capacitor.

[0081] In one embodiment, the AOM driving circuit 120 further includes a second amplifier circuit 134 and a shaping circuit 135 .

[0082] The input end of the second amplifier circuit 134 is electrically connected to the first output end of the frequency multiplication circuit 120, and the output end of the second amplifier circuit 134 is electrically connected to the input end of the first delay circuit 131; the second amplifier circuit 134 is used to amplify and output the driving signal output by the phase-locked circuit 121. The input end of the shaping circuit 135 is electrically connected to the output end of the first amplifier circuit 132; the shaping circuit 135 is used to shape and output the driving signal output by the first amplifier circuit 132.

[0083] In this embodiment, the first frequency-doubled signal is amplified in one stage by the second amplifier circuit 134, and then output to the first amplifier circuit 132 for two-stage amplification through the first delay circuit 131. The multi-stage amplification can increase the amplification factor of the acousto-optic modulation driving circuit 120 and the stability of the amplified signal. Furthermore, the acousto-optic modulation driving circuit 120 can also include a third amplifier circuit 136, which is connected in series between the first amplifier circuit 132 and the first delay circuit 131.

[0084] The shaping circuit 135 performs shaping and correction processing on the driving signal output by the first amplifying circuit 132 to ensure the integrity of the signal. The shaping circuit may include components such as resistors, capacitors, and diodes.

[0085] In one embodiment, the acousto-optic modulation driving circuit 120 may further include a single-ended transformer 137, which is connected in series between the second amplifier circuit 134 and the third amplifier circuit 136. After the first frequency-doubled signal is amplified by the second amplifier circuit 134, signal instability may occur, for example, the amplitudes of the various peaks of the signal waveform are different, some are large and some are small. The amplitude of the first frequency-doubled signal output by the second amplifier circuit 134 can be compensated by the single-ended transformer 137 so that the amplitudes of the various peaks are the same. In this way, the third amplifier circuit 136 and the first amplifier circuit 132 at the rear can amplify the complete first frequency-doubled signal with stable power, thereby improving the stability of the signal.

[0086] Reference Figure 5In one embodiment, the data acquisition circuit 140 includes a second delay circuit 141 and a data acquisition card 142 .

[0087] 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 to the output end of the first delay circuit 131 ; the second delay circuit 141 is used to delay the second frequency-doubled signal.

[0088] The first delay circuit 131 is further configured to output a phase signal when it is detected 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-doubled signal when it receives the phase signal.

[0089] The input end of the data acquisition card 142 is electrically connected to 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 used to sample the electrical signal output by the balanced photodetector 200 according to the second frequency-doubled signal to generate a sampling signal.

[0090] The transmission paths of the first frequency multiplication signal and the second frequency multiplication signal are different, and the transmission time in the circuit is also different. If the first frequency multiplication signal and the second frequency multiplication signal are not synchronized in time, random jitter may occur in the sampling signal of the data acquisition card 142. In other words, the electrical signal that the data acquisition card 142 should have collected corresponds to the detection light signal output by the acousto-optic modulation circuit 300 at the time T1, but due to the difference in the transmission time of the first frequency multiplication signal in the circuit, the electrical signal actually collected by the data acquisition card 142 corresponds to the detection light signal output by the acousto-optic modulation circuit 300 at the time T2. In this case, it is equivalent to aliasing the electrical signal between the sampling intervals during the long-term test process, which reduces the resolution and sensitivity of the system. After the delay synchronization of the second delay circuit 141 and the first delay circuit 131, during the long-term test process, the sampling signals of the data acquisition card 142 at the same sampling point are concentrated at one point, and the data of this point are also analyzed when the sampling signal is analyzed. Without synchronization, it is equivalent to superimposing and analyzing the signal of a certain length.

[0091] In this embodiment, the second delay circuit 141 delays the second frequency-multiplied signal until the phase signal output by the first delay circuit 131 is received, 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, while the first delay circuit 131 outputs the first frequency-multiplied signal to the second amplifying circuit 134 at a preset phase, the second delay circuit 141 also outputs the second frequency-multiplied signal to the data acquisition card 142 at a preset phase. The signal received by the data acquisition card 142 is delayed synchronously with the signal received by the first amplifying circuit 132, reducing the phase difference of the sampling signal of the data acquisition card 142, avoiding the jitter of the sampling point of the data acquisition card 142, and improving the sampling accuracy.

[0092] Reference Figure 6 The present application also proposes an optical fiber vibration monitoring device, which includes the above-mentioned phase synchronization circuit 100, acousto-optic modulation circuit 300 and a balanced photodetector 200.

[0093] The acousto-optic modulation circuit 300 is electrically connected to the phase synchronization circuit 100; the acousto-optic modulation circuit 300 is used to receive the driving signal output by the phase synchronization circuit 100, and output the detection light signal under the control of the driving signal.

[0094] The balanced photodetector 200 is electrically connected to the phase synchronization circuit 100; the balanced photodetector 200 is used to receive the feedback optical signal and convert the feedback optical signal into a corresponding electrical signal and output it to the phase synchronization circuit 100;

[0095] The phase synchronization circuit 100 is further used to sample the electrical signal output by the balanced photodetector 200 to generate a sampling signal.

[0096] The detailed structure of the phase synchronization circuit 100 can refer to the above-mentioned embodiment, which will not be repeated here; it can be understood that since the above-mentioned phase synchronization circuit 100 is used in the optical fiber vibration monitoring device of the present application, the embodiment of the optical fiber vibration monitoring device of the present application includes all technical solutions of all embodiments of the above-mentioned phase synchronization circuit 100, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0097] In one embodiment, the optical fiber vibration monitoring device further includes a control circuit 400 .

[0098] The control circuit 400 is electrically connected to the phase synchronization circuit 100; the control circuit 400 is used to output a trigger signal to the phase synchronization circuit 100; the phase synchronization circuit 100 is also used to generate a drive signal according to the trigger signal. The control circuit 400 can be implemented by a microprocessor, FPGA (Field Programmable Gate Array) or other chips with control functions.

[0099] 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.

[0100] In this embodiment, when it is necessary to detect the optical fiber 600 to be tested, 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 light signal to the optical fiber 600 to be tested according to the driving signal output by the phase synchronization circuit 100. After being fed back by the optical fiber 600 to be tested, the balanced photodetector receives the feedback light signal of the optical fiber 600 to be tested, and converts the feedback light signal into a corresponding electrical signal and outputs it to the phase synchronization circuit 100. The phase synchronization circuit 100 samples the electrical signal, generates a sampling signal and outputs it to the control circuit 400. The control circuit 400 performs phase demodulation on the sampling signal to obtain phase information. According to the phase information, the vibration information in the optical fiber 600 to be tested can be restored.

[0101] Any external vibration waves (including sound waves) will affect the glass lattice in the optical fiber, causing the lattice to vibrate at the same frequency. After a certain intensity of detection light signal is injected into the optical fiber 600 to be tested, a corresponding feedback light signal will be received, which will bring back the vibration information of the lattice. By converting the feedback light signal into a corresponding electrical signal and sampling the electrical signal, and then demodulating and analyzing this information by the control circuit 400, the vibration information of the vibration area can be restored and the position of the vibration area can be determined.

[0102] In one embodiment, the optical fiber vibration monitoring device further includes a frequency mixing circuit 500 .

[0103] The input end of the frequency mixing circuit 500 is electrically connected to the first output end of the frequency multiplication circuit 120 of the phase synchronization circuit 100, and the output end of the frequency mixing circuit 500 is electrically connected to the control circuit 400; the frequency mixing circuit 500 is used to mix the first frequency multiplication signal to generate a demodulation reference frequency signal and output it to the control circuit 400. The frequency mixing circuit 500 may include a mixer.

[0104] In this embodiment, the frequency of the driving signal (ie, the frequency of the first frequency-multiplied signal) is mixed with the frequency of the sampling signal by the frequency mixing circuit 500 to provide a reference frequency signal for subsequent signal demodulation.

[0105] Reference Figure 7 The present application also proposes a phase synchronization method, which is applied to an optical fiber vibration monitoring device. The optical fiber vibration monitoring device includes a balanced photodetector 200 and an acousto-optic modulation circuit 300. The phase synchronization method includes:

[0106] S100: Generate a standard clock signal;

[0107] S200: When a trigger signal is received, performing a first frequency multiplication process on the standard clock signal and outputting a first frequency multiplication signal, and performing a second frequency multiplication process on the standard clock signal and outputting a second frequency multiplication signal;

[0108] S300: generating a driving signal according to the first frequency-doubled signal to drive the acousto-optic modulation circuit 300 to output a detection light signal;

[0109] S400: Sampling the electrical signal output by the balanced photodetector 200 according to the second frequency-doubled signal to generate a sampling signal.

[0110] In this embodiment, the standard clock signal is used to synchronize the clock. When the trigger signal is received, the input standard clock signal is divided into two paths for processing. One path generates a first frequency-doubled signal after the first frequency-doubled signal, and generates a drive signal after a series of processing on the first frequency-doubled signal and outputs it to the acousto-optic modulation drive circuit 120. The other path generates a second frequency-doubled signal after the second frequency-doubled signal, and samples according to the frequency provided by the second frequency-doubled signal to generate a sampling signal. Among them, the trigger signal can be issued by the control circuit 400 in the host computer or the optical fiber vibration monitoring device when it is necessary to detect the optical fiber 600 to be tested. In this way, the clocks of the first frequency-doubled signal and the second frequency-doubled signal are synchronized, and the trigger time is also synchronized. The phase synchronization circuit 100 samples the electrical signal output by the balanced photodetector 200 while outputting the drive signal, reduces the phase error between the start-up phase of the acousto-optic modulation circuit 300 driven by the drive signal and the sampling of the phase synchronization circuit 100, and improves the phase recognition accuracy.

[0111] For example, the standard clock signal is 10MHz. When the trigger signal is received, the standard clock signal of 10MHz is multiplied by 8 and 25 times respectively to generate a first frequency-multiplied signal of 80MHz and a second frequency-multiplied signal of 250MHz. After multi-stage amplification, delay, shaping and other processing are performed on the first frequency-multiplied signal of 80MHz, an 80MHz driving signal is generated and output to the acousto-optic modulation circuit 300 to drive the acousto-optic modulation circuit 300 to output the detection light signal to the optical fiber 600 to be tested according to the 80MHz driving signal. At the same time, the phase synchronization circuit 100 samples the electrical signal output by the balanced photodetector 200 according to the second frequency-multiplied signal of 250MHz. In this way, the clock synchronization and trigger time synchronization of the first frequency-multiplied signal and the second frequency-multiplied signal are achieved, so that the starting point of the acousto-optic modulation circuit 300 modulating the detection light signal is synchronized with the sampling point of the data acquisition circuit 140, thereby reducing the sampling phase error and improving the phase recognition accuracy. The frequency parameters of the standard clock signal and the frequency multiplication parameters of the first and second frequency multiplication circuits 120 can be set according to actual needs and sampling principles, and are not limited here.

[0112] The present application realizes clock synchronization of the first frequency-multiplied signal and the second frequency-multiplied signal through a standard clock signal, and realizes trigger time synchronization of the first frequency-multiplied signal and the second frequency-multiplied signal through a trigger signal, so that when the acousto-optic modulation circuit 300 modulates the detection light signal, the starting phase of the detection light signal is synchronized with the phase of the sampling signal of the phase synchronization circuit 100, thereby reducing the phase error and improving the phase recognition accuracy.

[0113] In one embodiment, generating a driving signal according to the first frequency-doubled signal includes:

[0114] The phase of the first frequency-doubled signal is detected, and when it is detected that the phase of the first frequency-doubled signal is not a preset phase, the first frequency-doubled signal is delayed; and when it is detected that the phase of the driving signal is a preset phase, the first frequency-doubled signal is amplified to generate a driving signal.

[0115] The acousto-optic modulation driving circuit 120 can only drive the acousto-optic modulation circuit 300 to work after the driving voltage outputted by the acousto-optic modulation driving circuit 120 exceeds the preset voltage threshold. The existing acousto-optic modulation driving circuit 120 usually adopts a linear amplification method, that is, the amplification factor increases from 0 to the maximum value over time, such as Figure 4a The left side shows the signal before amplification, and the right side shows the signal after amplification. In this way, in the early stage of the amplification process, there is a rising edge, and the pulse signal outputted by the rising edge is incomplete. It is possible that the signal at a certain point is not amplified to the maximum value, but its voltage value has exceeded the preset voltage threshold, causing the acousto-optic modulation circuit 300 to start working and output a weak optical signal, which interferes with the recognition of the optical signal.

[0116] In this embodiment, by detecting the phase of the first frequency multiplication signal, when the phase of the first frequency multiplication signal does not reach the preset phase, the first frequency multiplication signal is delayed; when the first frequency multiplication signal reaches the preset phase, the first frequency multiplication signal is output to the first amplifier circuit 132. The first amplifier circuit 132 directly amplifies the first frequency multiplication circuit 120 to the maximum value according to the preset amplification factor. Figure 4b As shown, a driving signal is generated and output to the acousto-optic modulation circuit 300. In this way, the interference of the rising edge on the acousto-optic modulation circuit 300 during the linear amplification process is avoided, and the consistency of the driving signal is ensured. The driving signal can excite the crystal of the acousto-optic modulation circuit 300 with a complete modulation cycle, so that it outputs a stable detection light signal. Among them, the preset phase can be set to 0. When the phase of the first frequency-doubled signal is 0, the first delay circuit 131 outputs it to the first amplification circuit 132. In this way, the signal starts from 0, which is convenient for subsequent calculation and analysis. In addition, the preset phase can also be set to π / 3, π / 2, π, etc., which is not limited here.

[0117] In one embodiment, the phase synchronization method further includes:

[0118] Detecting the phase of the first frequency-multiplied signal, and outputting a phase signal when detecting that the phase of the driving signal is a preset phase;

[0119] When the phase signal is not received, the second frequency-doubled signal is delayed; and when the phase signal is received, the second frequency-doubled signal is output.

[0120] The transmission paths of the first frequency multiplication signal and the second frequency multiplication signal are different, and the transmission time in the circuit is also different. If the first frequency multiplication signal and the second frequency multiplication signal are not synchronized in time, random jitter may occur in the sampling signal of the data acquisition card 142. In other words, the electrical signal to be collected corresponds to the detection light signal output by the acousto-optic modulation circuit 300 at time T1, but due to the difference in the transmission time of the first frequency multiplication signal in the circuit, the electrical signal actually collected corresponds to the detection light signal output by the acousto-optic modulation circuit 300 at time T2. In this case, it is equivalent to aliasing the electrical signals between the sampling intervals during the long-term test process, which reduces the resolution and sensitivity of the system. After the delay synchronization of the second delay circuit 141 and the first delay circuit 131, during the long-term test process, the sampling signals at the same sampling point are concentrated at one point, and the data at this point are also analyzed when the sampling signal is analyzed. Without synchronization, it is equivalent to superimposing and analyzing the signal of a certain length.

[0121] In this embodiment, the second delay circuit 141 outputs the second frequency-doubled signal by delaying the second frequency-doubled signal until the phase signal output by the first delay circuit 131 is received, so as to sample the electrical signal output by the balanced photodetector 200 according to the second frequency-doubled signal. In this way, while the first delay circuit 131 outputs the first frequency-doubled signal to the second amplifying circuit 134 at a preset phase, the second delay circuit 141 also outputs the second frequency-doubled signal to the data acquisition card 142 at a preset phase. The signal received by the data acquisition card 142 is delayed synchronously with the signal received by the first amplifying circuit 132, the phase difference of the sampling 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 accuracy is improved.

[0122] In the above, the specific implementation of the present application is described with reference to the accompanying drawings. However, those skilled in the art will appreciate that various changes and substitutions may be made to the specific implementation of the present application without departing from the spirit and scope of the present application. These changes and substitutions are all within the scope defined by the present application.

Claims

1. A phase synchronization circuit, applied to an optical fiber vibration monitoring device, wherein the optical fiber vibration monitoring device comprises a balanced photoelectric detector, characterized in that: The phase synchronization circuit comprises: A clock signal generating circuit, wherein the clock signal generating circuit is used to generate a standard clock signal; A frequency multiplication circuit, the input end of which is electrically connected to the clock signal generating circuit; the frequency multiplication circuit is used to perform a first frequency multiplication process on the standard clock signal to obtain a first frequency multiplication signal, and to perform a second frequency multiplication process on the standard clock signal to obtain a second frequency multiplication signal when receiving a trigger signal; an acousto-optic modulation driving circuit, wherein the input end of the acousto-optic modulation driving circuit is electrically connected to the first output end of the frequency multiplication circuit; the acousto-optic modulation driving circuit is used to receive the first frequency multiplication signal and generate a driving signal according to the first frequency multiplication signal; a data acquisition circuit, wherein the input end of the data acquisition circuit is electrically connected to the second output end of the frequency multiplication circuit, and the acquisition end of the data acquisition circuit is used to be electrically connected to the balanced photodetector; the data acquisition circuit is used to receive the second frequency multiplication signal, and to sample the electrical signal output by the balanced photodetector according to the second frequency multiplication signal to generate a sampling signal; Wherein, the acousto-optic modulation driving circuit comprises: a first delay circuit, wherein the input end of the first delay circuit is electrically connected to the first output end of the frequency multiplication circuit; the first delay circuit is further used to detect the phase of the first frequency multiplication signal, and delay the first frequency multiplication signal when it is detected that the phase of the first frequency multiplication signal is not a preset phase; and output the first frequency multiplication signal when it is detected that the phase of the first frequency multiplication signal is a preset phase; a first amplifier circuit, wherein an input end of the first amplifier circuit is electrically connected to an output end of the first delay circuit; the first amplifier circuit is used to amplify the received first frequency-doubled signal according to a preset amplification factor to generate the driving signal; The data acquisition circuit comprises: a second delay circuit, wherein 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 to the output end of the first delay circuit; the second delay circuit is used to delay the second frequency-doubled signal; The first delay circuit is further used to output a phase signal when it is detected that the phase of the driving signal is a preset phase, and the second delay circuit is further used to delay the second frequency-doubled signal when the phase signal is not received; and output the second frequency-doubled signal when the phase signal is received; A data acquisition card, wherein the input end of the data acquisition card is electrically connected to 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 to sample the electrical signal output by the balanced photodetector according to the second frequency-doubled signal to generate the sampling signal.

2. The phase synchronization circuit according to claim 1, characterized in that: The frequency multiplication circuit comprises: A phase-locked circuit, the input end of the phase-locked circuit being the input end of the frequency multiplication circuit; the phase-locked circuit is used to phase-lock the standard clock signal; A first frequency multiplier, wherein the input end of the first frequency multiplier is electrically connected to the output end of the phase-locked circuit, and the output end of the first frequency multiplier is the first output end of the frequency multiplier circuit; the first frequency multiplier is used to perform a first frequency multiplication process on the standard clock signal; A second frequency multiplier, wherein the input end of the second frequency multiplier is electrically connected to the output end of the phase-locked circuit, and the output end of the first frequency multiplier is the second output end of the frequency multiplier circuit; the second frequency multiplier is used to perform a second frequency multiplication process on the standard clock signal.

3. The phase synchronization circuit according to claim 2, characterized in that: The acousto-optic modulation driving circuit further comprises: a second amplifier circuit, wherein the input end of the second amplifier circuit is electrically connected to the first output end of the frequency multiplication circuit, and the output end of the second amplifier circuit is electrically connected to the input end of the first delay circuit; the second amplifier circuit is used to amplify the driving signal output by the phase-locked circuit and then output it; A shaping circuit, wherein the input end of the shaping circuit is electrically connected to the output end of the first amplifying circuit; the shaping circuit is used to shape and output the driving signal output by the first amplifying circuit.

4. 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 3; an acousto-optic modulation circuit, electrically connected to the phase synchronization circuit; the acousto-optic modulation circuit is used to receive a driving signal output by the phase synchronization circuit and output a detection light signal under the control of the driving signal; A balanced photodetector, electrically connected to the phase synchronization circuit; the balanced photodetector is used to receive the feedback optical signal, and convert the feedback optical signal into a corresponding electrical signal and output it to the phase synchronization circuit; The phase synchronization circuit is also used to sample the electrical signal output by the balanced photodetector to generate a sampling signal.

5. The optical fiber vibration monitoring device according to claim 4, characterized in that: The optical fiber vibration monitoring device also includes: A control circuit, the control circuit being electrically connected to the phase synchronization circuit; the control circuit being used to output a trigger signal to the phase synchronization circuit; the phase synchronization circuit being also used to generate the drive signal according to the trigger signal; The control circuit is also used to receive the sampling signal output by the phase synchronization circuit and perform phase demodulation on the sampling signal to obtain phase information.

6. A phase synchronization method, applied to an optical fiber vibration monitoring device, wherein the optical fiber vibration monitoring device comprises a balanced photodetector and an acousto-optic modulation circuit, characterized in that: The phase synchronization method comprises: Generate standard clock signal; When a trigger signal is received, performing a first frequency multiplication process on the standard clock signal and outputting a first frequency multiplication signal, and performing a second frequency multiplication process on the standard clock signal and outputting a second frequency multiplication signal; generating a driving signal according to the first frequency-doubled signal to drive the acousto-optic modulation circuit to output a detection light signal; Sampling the electrical signal output by the balanced photodetector according to the second frequency-doubled signal to generate a sampling signal; Generating a driving signal according to the first frequency-doubled signal comprises: detecting a phase of the first frequency-doubled signal, and delaying the first frequency-doubled signal when it is detected that the phase of the first frequency-doubled signal is not a preset phase; and amplifying the first frequency-doubled signal to generate the drive signal when it is detected that the phase of the drive signal is a preset phase; The outputting of the second frequency-doubled signal comprises: detecting a phase of the first frequency-doubled signal, and outputting a phase signal when detecting that the phase of the first frequency-doubled signal is a preset phase; When the phase signal is not received, the second frequency-doubled signal is delayed; and when the phase signal is received, the second frequency-doubled signal is output.

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