CN110095177B - System and method for suppressing fiber grating hydrophone phase demodulation polarization fading - Google Patents
System and method for suppressing fiber grating hydrophone phase demodulation polarization fading Download PDFInfo
- Publication number
- CN110095177B CN110095177B CN201910332727.2A CN201910332727A CN110095177B CN 110095177 B CN110095177 B CN 110095177B CN 201910332727 A CN201910332727 A CN 201910332727A CN 110095177 B CN110095177 B CN 110095177B
- Authority
- CN
- China
- Prior art keywords
- pulse
- optical fiber
- signals
- port
- fiber grating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
Abstract
The invention relates to the technical field of optical fiber sensing, in particular to a system and a method for suppressing phase demodulation polarization fading of an optical fiber grating hydrophone. The device is characterized by comprising a pulse generating device, an optical fiber circulator, an optical fiber grating hydrophone array, a polarization beam splitter, an FPGA signal modulation and demodulation system and a display control system. The pulse generating device is connected to the optical fiber circulator, the circulator is connected with the optical fiber grating hydrophone array, the third interface of the circulator is connected with the input end of the polarization beam splitter, the two output ends of the polarization beam splitter are connected to the FPGA, and the FPGA is connected with the display control system. The polarization beam splitter separates pulse signals, the FPGA carries out digital processing on the pulse samples, and orthogonal components of the pulse signals are obtained through orthogonal term multiplication frequency mixing and a low-pass filter. And selecting a group of signals with high visibility in the two orthogonal components, performing an arc tangent algorithm on the signals, performing a digital high-pass filtering algorithm on the signals, and finally performing low-pass down-sampling and outputting. The system and the method have high reliability and low cost and can effectively inhibit polarization fading.
Description
Technical Field
The invention relates to the technical field of optical fiber sensing, in particular to a system and a method for inhibiting polarization fading during phase demodulation of an optical fiber grating hydrophone array.
Background
The interference type optical fiber sensor has been developed and widely applied in the detection fields of underwater sound, strain, pressure and the like due to the extremely high detection sensitivity. With the improvement of the fiber grating writing technology, the interference hydrophone based on the fiber grating draws wide attention due to the advantages of low optical path loss, small volume, natural wavelength division devices, easy scale array formation and the like. Because the fringe visibility of the interference fiber grating hydrophone is related to the polarization state of two paths of interference light, when the polarization states of the two paths of light are orthogonal, the visibility of the generated interference fringes is zero, and a detection signal cannot be demodulated at the time, and the phenomenon is called polarization fading. The traditional available methods for resisting polarization fading mainly include a full polarization maintaining fiber method, a polarization disturbing method, a polarization diversity receiving method, a polarization compensation method and the like, wherein the full polarization maintaining fiber method has high cost due to high requirements on components and processing technologies, and the polarization disturbing method and the polarization compensation method are not suitable for large-scale hydrophone arrays.
The interference type optical fiber sensor polarization fading resistant diversity reception is originally proposed by Frigo n.j. et al in 1984, and the polarization diversity reception method adopts analyzers with different included angles to analyze signals at a receiving end and adopts a certain algorithm to eliminate the polarization fading problem of the detected signals. Typically, three analyzers at 120 ° to each other are used to analyze the input light, and the 1 path with the best visibility is selected for demodulation, so that 1 non-zero visibility can be always picked up from the input light, and no complete fading will occur. Researchers such as Zhouyong of Zhejiang university propose a processing mode of squaring and adding signals, so that real-time depolarization fading signal detection of units and arrays can be realized. The university of national defense science and technology, caochun et al, proposes that in a polarization diversity system, the visibility of a single-path signal is related to the polarization state and the polarization detection angle of two beams of light which interfere, when linear polarization interferes, a three-path analyzer is needed to achieve the depolarization effect, when ellipsometric light interferes, the maximum visibility is increased along with the reduction of the polarization extinction ratio of the interference light, when the polarization extinction ratio is less than 10dB, the two-path polarization detection can achieve the effect of three-path polarization detection when the linear polarization interferes, and the interference caused by the ellipsometric light cannot influence the signal demodulation.
Although the three analyzers can suppress the polarization fading phenomenon of the interference fiber grating hydrophone and recover the detected signal by a square sum addition mode, the reliability is reduced due to high assembly precision and complexity of the analyzers in practical use, and particularly for a large-scale fiber grating hydrophone array, the cost is high, the optical path loss is large along with the rapid increase of the number of the analyzers, and the demodulation of the large-scale array signal is not facilitated.
The interferometric optical phase recovery method mainly comprises three methods, namely a phase carrier method (PGC), a 3 x 3 coupler method and a heterodyne method, wherein the heterodyne method can modulate a signal to be detected onto a sideband with higher heterodyne frequency, so that low-frequency noise interference is effectively inhibited, and a modulation frequency harmonic term similar to that in a PGC demodulation method is not generated, so that the interferometric optical phase recovery method has a large demodulation dynamic range, is not influenced by interference light visibility change, and is widely applied to the fields of underwater acoustic detection, perimeter security protection, resource exploration and the like. However, the polarizer is generally needed, three signals are needed for demodulation, and the method is not suitable for large-scale arrays. Therefore, the invention provides a demodulation system and a demodulation method which do not need a polarizer, can be used for demodulation only by two paths of signals and can be used for large-scale arrays.
Disclosure of Invention
The invention discloses a fiber grating hydrophone array phase heterodyne modulation-demodulation system, which comprises: the device comprises a pulse generating device, a fiber circulator 7, a fiber grating hydrophone array, a Polarization Beam Splitter (PBS)14, an FPGA signal modulation and demodulation system 15 and a display control system 16; the pulse generating device is connected to a first port of the optical fiber circulator 7, a second port of the optical fiber circulator 7 is connected with the fiber grating hydrophone array, a third port of the optical fiber circulator 7 is connected with an input end of the Polarization Beam Splitter (PBS)14, two output ends (P end and S end) of the Polarization Beam Splitter (PBS)14 enter the FPGA signal modulation and demodulation system 15, and the FPGA signal modulation and demodulation system 15 is connected with the display control system 16 through a network.
The pulse generating device comprises a multi-wavelength laser light source 1, a first modulator 3, a second modulator 4, a first 1 × 2 optical fiber coupler 2, a second 1 × 2 optical fiber coupler 6 and a delay coil 5, wherein an output end of the multi-wavelength laser light source 1 is connected to a first port of the first 1 × 2 optical fiber coupler 2, a second port of the first 1 × 2 optical fiber coupler 2 is connected with a third input port In of the first modulator, a third port of the first 1 × 2 optical fiber coupler 2 is connected with an input port In of the second modulator 4, an output port Out of the second modulator 4 is connected with a second port of the second 1 × 2 optical fiber coupler 6, an output port Out of the first modulator 3 is connected with a delay coil and then is connected to a third port of the second 1 × 2 optical fiber coupler 6, and a first port of the second 1 × 2 optical fiber coupler 6 is an output pulse port.
The output pulse port of the second 1 × 2 fiber coupler 6 is connected to the first port of the fiber circulator 7, the second port of the fiber circulator 7 is connected to a fiber grating hydrophone array, the fiber grating hydrophone array is formed by serially connecting a plurality of fiber grating hydrophone units with different wavelengths, each fiber grating hydrophone unit is formed by a pair of fiber gratings with the same central wavelength and different reflectivity, an optical fiber coil with the length of delta L is additionally arranged, and the coil with the length of delta L is wound on the elastic body. An optical pulse train output by the sensor is output from a third port of the optical fiber circulator 7, interference pulses of each hydrophone unit are sequentially carried in the pulse train, the pulse train is connected to an input port of a Polarization Beam Splitter (PBS), and input ports P and S are directly connected to the FPGA signal modulation and demodulation system 15. The demodulation system consists of a wave separator, an optical fiber amplifier, a photoelectric conversion module and an FPGA signal processing board card.
The method for suppressing the phase heterodyne modulation-demodulation polarization fading of the fiber grating hydrophone array comprises the steps that firstly, a pulse generating device generates a front pulse pair and a back pulse pair which are respectively loaded with frequencies f1 and f2, a delay coil delta L is added to enable a delay tau to be generated between the pulse pairs, and meanwhile, the duration time and the duty ratio of f1 and f2 are controlled to generate the pulse pairs with specific repetition frequency. The generated periodic pulse pair enters the fiber grating hydrophone array through the fiber circulator, the returned light pulse signal enters the polarization beam splitter 14 and then is divided into two paths of light signals, and the two paths of light signals enter the FPGA signal modulation and demodulation system 14 for phase demodulation.
The FPGA signal modem system 15 samples the input continuous pulse train, and digitally collects the interference pulse signal reflected by the fiber grating hydrophone, so as to obtain two paths of digitized signals, which are multiplied by the digitized carrier and its orthogonal term for frequency mixing. And the two groups of signals after frequency mixing respectively pass through a low-pass filter to respectively obtain orthogonal components of the two groups of signals. Selecting a group of signals with high visibility in the two orthogonal components through a real-time switching algorithm, performing an arc tangent algorithm on the selected signals, and performing a phase expansion algorithm after the arc tangent algorithm; then, a digital high-pass filtering algorithm is carried out, and finally, low-pass down-sampling is carried out for output.
The invention provides a fiber grating hydrophone array signal demodulation method based on a Polarization Beam Splitter (PBS) and digital outer difference carrier modulation aiming at the signal demodulation requirements of a multi-channel large-scale fiber grating hydrophone array.
Drawings
FIG. 1 is a schematic diagram of a pulse generator;
FIG. 2 is a schematic diagram of a light path of a heterodyne modulation-demodulation system for a fiber grating hydrophone array phase;
FIG. 3 is a schematic diagram of an optical path of a fiber grating hydrophone unit;
FIG. 4 is a heterodyne modulation demodulation flowchart;
FIG. 5 shows the real-time P/S switching and corresponding time demodulation results at a sampling point of 1000;
fig. 6 shows the real-time switching and corresponding time demodulation results of the P terminal/S terminal at sampling point 3000;
FIG. 7 shows the P-side pulse signal acquisition results of fiber grating hydrophone production;
FIG. 8 shows the result of S-side pulse signal acquisition in fiber grating hydrophone production;
FIG. 9 is a time domain waveform at the P-terminal after the interference signal is mixed;
FIG. 10 is a time domain waveform at the S-terminal after the interference signal is mixed;
FIG. 11 is a cross-section of a circle formed by the interference pulse signals at the P-terminal;
FIG. 12 is a cross-section of a circle formed by the S-terminal interference pulse signal;
FIG. 13 is a cross-section of a circle formed by interference pulse signals at the P-terminal of the first set of signals;
FIG. 14 is a diagram of quadrature circles formed by interference pulse signals at the S-terminal of the first set of signals;
FIG. 15 is a cross-section of a circle formed by interference pulse signals at the P-terminal of the second set of signals;
FIG. 16 is a cross-section of a circle formed by interference pulse signals at the S-terminal of the second set of signals;
FIG. 17 is a cross-section of a third set of signals, the P-terminal interference pulse signals forming a quadrature circle;
FIG. 18 is a cross-section of a third set of S-terminal interference pulse signals;
fig. 19 is a diagram of heterodyne demodulation results for selecting a path with greater visibility through real-time switching according to the present invention.
In the figure:
1: multi-wavelength laser light source 2: first 1 × 2 fiber coupler 3: the first modulator 4: the second modulator 5: delay coil 6: second 1 × 2 fiber coupler 7: fiber circulator 8: first fiber grating 9: hydrophone coil 10: second fiber grating 11: third fiber grating 12: second hydrophone coil 13: fourth fiber grating 14: polarizing Beam Splitter (PBS) 15: FPGA signal modem system 16: a display control system I: 1 st injection pulse II: injection pulse No. 2 11': reflected pulse 12' of the first grating to the first injected pulse: reflected pulse 21' of the first grating to the second injected pulse: reflected pulse 22' of the second grating to the first injected pulse: the second grating reflects a second incident pulse.
Detailed Description
The invention relates to a heterodyne modulation-demodulation system (as shown in figure 2) for a fiber grating hydrophone array phase, which comprises: the device comprises a pulse generating device (shown in figure 1), a fiber circulator 7, a fiber grating hydrophone array (shown in figure 3), a Polarization Beam Splitter (PBS)14, an FPGA signal modulation and demodulation system 15 and a display control system 16.
The pulse generating device is connected to a first port of the optical fiber circulator 7, a second port of the optical fiber circulator 7 is connected with the fiber grating hydrophone array, a third port of the optical fiber circulator 7 is connected with an input end of the Polarization Beam Splitter (PBS)14, two output ends (P end and S end) of the Polarization Beam Splitter (PBS)14 enter the FPGA signal modulation and demodulation system 14, and the FPGA signal modulation and demodulation system 15 is connected with the display control system 16 through a network.
As shown in fig. 1, the pulse generating apparatus includes a multi-wavelength laser light source 1, a first modulator 3, a second modulator 4, a first 1 × 2 fiber coupler 2, a second 1 × 2 fiber coupler 6, and a delay coil 5; the multi-wavelength laser light source 1 is formed by combining a plurality of lasers with different wavelengths (lambda 1-lambda n) through a wave combiner, output lasers are connected to a 1 st port of a first 1x2 optical fiber coupler 2, a second port of the first 1x2 optical fiber coupler 2 is connected with an input port In of a first modulator 3, a third port of the first 1x2 optical fiber coupler 2 is connected with an input port In of a second modulator 4, an output port Out of the second modulator 4 is connected with a second port of a second 1x2 optical fiber coupler 6, an output port Out of the first modulator 3 is connected with a delay coil 5 and then connected to a third port of the second 1x2 optical fiber coupler 6, and an output pulse port of the second 1x2 optical fiber coupler 6.
Light emitted by the laser is divided into two beams by a first 1x2 optical fiber coupler 2, one beam is subjected to frequency shift of f1 after passing through a first modulator 3(AOM1), and is modulated into pulse light, pulse width w and pulse repetition frequency frep; the other beam is frequency-shifted by f2 after passing through a second modulator 4(AOM2), and is also modulated into pulsed light, pulse width w, pulse repetition frequency frep; since the first modulator 3 is followed by a pulse delay coil 5, the output from the pulse generating means is a tandem pulse pair comprising two pulses, each having a width w, a pulse repetition period frep and a mutual spacing τ, the spacing being determined by the length of the pulse delay coil 5 and carrying the frequencies f1 and f2, respectively.
The output pulse port of the second 1 × 2 fiber coupler 6 is connected to the first port of the fiber circulator 7, the second port of the fiber circulator 7 is connected to the fiber grating hydrophone array, as shown in fig. 3, the fiber grating hydrophone array is composed of a plurality of different wavelengths (λ:)1Lambdan) are connected in series to form a fiber grating hydrophone unit as shown in fig. 3, each fiber grating hydrophone unit is composed of a pair of fiber gratings with the same central wavelength and different reflectivity, and a section of fiber coil (namely a hydrophone delay coil) with the length of delta L, the coil with the length of delta L is wound on an elastic body and positioned between the two fiber gratings, the front fiber grating and the rear fiber grating which are contained in each fiber grating hydrophone unit reflect two light pulses with the same central wavelength as the light pulses before and after the light pulses enter the fiber grating unit, and the first fiber grating8, reflecting the first incident pulse I and the second incident pulse II to generate pulses 11 'and 12', reflecting the first incident pulse I and the second incident pulse II by the second fiber grating 10 to generate pulses 21 'and 22', and superposing the pulses 12 'and 21' on the light path to generate interference, so that each fiber grating hydrophone unit can generate interference pulses, and introducing a section of hydrophone coil 9 between the hydrophone units, wherein the length of the section of hydrophone coil is DeltaL, so that the pulses 12 'and 21' on the light path are superposed to generate interference. An optical pulse train output by the sensor is output from the 3 rd port of the optical fiber circulator 7, interference pulses of each hydrophone unit are carried in the pulse train in sequence, the pulse train is connected to an input port of a Polarization Beam Splitter (PBS), and input ports P and S are directly connected to the FPGA signal modulation and demodulation system 15.
The FPGA signal modulation and demodulation system 15 is composed of a wave splitter, an optical fiber amplifier, a photoelectric conversion module, and an FPGA signal processing board, interference pulses with different wavelengths are separately transmitted into different photoelectric conversion modules by the wave splitter, the photoelectric conversion modules convert input optical pulses into electric signals for the ADC (analog-to-digital conversion) carried by the FPGA board to acquire, and the acquired digital signals are demodulated by the FPGA board. The demodulation system passes the data directly to the display control system 16 for display via the gigabit ethernet.
The invention provides a method for inhibiting the heterodyne modulation-demodulation polarization fading of the phase of a fiber grating hydrophone array on the basis of a heterodyne modulation-demodulation system of the phase of the fiber grating hydrophone array, which comprises the following steps:
step 1:
the pulse generating device generates a front pulse pair and a rear pulse pair which respectively carry frequencies f1 and f2, a time delay tau is generated between the pulse pairs by adding a time delay coil delta L, and the duration and the duty ratio of f1 and f2 are controlled to generate the pulse pairs with specific repetition frequency;
generation methods of frequencies f1 and f 2: the FPGA board card generates digital frequency points f1 and f2 by calling DDS (IP core), outputs corresponding analog sine waveforms by using DAC (digital-to-analog conversion), amplifies the waveforms to +/-30V by using a power amplifier, and drives an acousto-optic modulation crystal, so that frequency shift of f1 and f2 is realized on the entering laser.
Step 2:
generated periodic pulse pairs (each group of pulse pairs comprises lambda)1N wavelengths of lambda n correspond to n fiber grating sensor arrays connected in series) enters the fiber grating hydrophone array through the fiber circulator 7, the returned optical pulse signals enter the Polarization Beam Splitter (PBS) and then are originally subjected to polarization fading signals, the signals are changed into two non-zero optical signals and are output from the P end and the S end, and the two optical signals at the P end and the S end enter the FPGA demodulation system for phase demodulation.
And step 3:
the FPGA demodulation system samples the input (P end, S end) continuous pulse train (the pulse signal is shown in fig. 7 and 8), and the embodiment intends to analyze and process the interference pulse signal reflected by the first fiber grating hydrophone, and the signal expression is as follows.
I＝A+Bcos[2πΔft+Φ(t)]
Wherein, I is the intensity of the optical signal collected after photoelectric conversion, a is a direct current term in the optical signal, B is the visibility of the interference signal, Δ f is the difference between frequencies f1 and f2, and Φ (t) is the external signal.
The demodulation process mainly includes the following steps, and the flow thereof is shown in fig. 4:
step1：
two paths of signals (P end and S end) of a first hydrophone are digitally collected to obtain Sp (P end signal) and Ss (S end signal), and the signal expression is as follows;
Sp＝Ap+Bp*cos[2πΔft+Φ(t)]
Ss＝As+Bs*cos[2πΔft+Φ(t)]
step 2：
two paths of signals Sp and Ss are respectively connected with a digital carrier cos (omega)ct) and its orthogonal term-sin (ω)ct) multiplication mixing, ω c2 pi f1 f2, Sp mixing to obtain Sp-i (t) (Sp and cos (omega)ct) results after mixing), Sp-q (t) (Sp and-sin (ω)ct) after mixing), and the Ss are mixed to obtain Ss-i (t) (Ss and cos (omega))ct) results of mixing), Ss-q (t) (Ss and-sin (ω)ct) the result of mixing) (as shown in fig. 9 and 10), the signal expression is as follows;
Sp-i(t)＝Sp*cos(ωct)
Sp-q(t)＝Sp*(-sin(ωct))
Ss-i(t)＝Ss*cos(ωct)
Ss-q(t)＝Ss*(-sin(ωct))
step 3：
the two groups of signals (Sp-i (t), Sp-q (t), (Ss-i (t), Ss-q (t)) after mixing pass through low-pass filters respectively, Sp-i (t), Sp-q (t) pass through the low-pass filters to obtain orthogonal components ip (t), Qp (t); the Ss-i (t) and the Ss-q (t) are subjected to a low-pass filter to obtain orthogonal components is (t) and qs (t);
step 4：
1 group of signals with high visibility (large area of circle formed, as shown in fig. 13 to 18) in two orthogonal components is selected by a real-time switching algorithm as follows;
p-terminal orthogonal circle radius R (t)2＝Ip(t)2+Qp(t)2 (8)
S-end orthogonal circle radius S (t)2＝Is(t)2+Qs(t)2 (9)
By detecting the size of the formed orthogonal circle radius of the P end and the S end in real time, if R (t)2>S(t)2The P-end signals ip (t), Qp (t) are selected to enter the subsequent algorithm, otherwise is (t), qs (t) are selected to enter the subsequent algorithm.
step 5：
Performing an arc tangent arctan algorithm on the selected signal;
step 6：
performing a phase expansion algorithm after the arc tangent algorithm;
step 7：
after the phase expansion algorithm, a digital high-pass filtering algorithm is carried out;
step 8：
the high-pass data is output by low-pass down-sampling (which may or may not be used as desired).
In this embodiment, the coil length is 2 Δ L, Δ L is 22.5m, f1 is 86.25MHz, f2 is 73.75MHz, the pulse width w is 220ns, the pulse repetition frequency frep is 250kHz, and the front-rear pulse interval is 220 ns.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein are intended to be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (3)
1. A system for suppressing the phase demodulation polarization fading of a fiber grating hydrophone is characterized in that: the device comprises a pulse generating device, an optical fiber circulator (7), an optical fiber grating hydrophone array, a polarization beam splitter (14), an FPGA signal modulation and demodulation system (15) and a display control system (16); the pulse generating device is connected to a first port of the optical fiber circulator (7), a second port of the optical fiber circulator (7) is connected with the fiber grating hydrophone array, a third port of the optical fiber circulator (7) is connected with an input end of the polarization beam splitter (14), two output ends of the polarization beam splitter (14) enter the FPGA signal modulation and demodulation system (15), and the FPGA signal modulation and demodulation system (15) is connected with the display control system (16);
the pulse generating device comprises a multi-wavelength laser light source (1), a first modulator (3), a second modulator (4), a first 1x2 optical fiber coupler (2), a second 1x2 optical fiber coupler (6) and a delay coil (5), wherein the output end of the multi-wavelength laser light source (1) is connected to the first port of the first 1x2 optical fiber coupler (2), the second port of the first 1x2 optical fiber coupler (2) is connected with the input port of the first modulator (3), the third port of the first 1x2 optical fiber coupler (2) is connected with the input port of the second modulator (4), the output port of the second modulator (4) is connected with the second port of the second 1x2 optical fiber coupler (6), the output port of the first modulator (3) is connected with the delay coil (5) and then connected with the third port of the second 1x2 optical fiber coupler (6), and the pulse of the second 1x2 optical fiber coupler (6) is connected with the first port (7) of the annular optical fiber coupler (7) The device can emit pulse laser with controllable pulse length and interval.
2. The fiber grating hydrophone phase demodulation polarization fading suppression system of claim 1, wherein: the fiber grating hydrophone array is formed by connecting a plurality of fiber grating hydrophone units with different wavelengths in series, and each fiber grating hydrophone unit is formed by a pair of fiber gratings with the same central wavelength and different reflectivity and an additional fiber coil with the length of delta L.
3. A fiber grating hydrophone phase demodulation polarization fading suppression method based on the fiber grating hydrophone phase demodulation polarization fading suppression system of claim 1, characterized in that: comprises the following steps of (a) carrying out,
step 1, generating pulse pairs
The pulse generating device generates a front pulse pair and a rear pulse pair which respectively carry frequencies f1 and f2, a time delay tau is generated between the pulse pairs by adding a time delay coil delta L, and the duration and the duty ratio of f1 and f2 are controlled to generate the pulse pairs with specific repetition frequency;
step 2: pulse pair interference
The generated periodic pulse pair enters the fiber grating hydrophone array through the fiber circulator (7), and the reflected light of the first grating to the second pulse and the reflected light of the second grating to the first pulse are overlapped on the light path to generate interference by controlling the length of a hydrophone coil in the grating hydrophone unit;
and step 3: demodulating pulse pair signals
The returned optical pulse signals enter a polarization beam splitter (14), are divided into two paths of optical signals and then enter an FPGA signal modulation and demodulation system (15), the FPGA signal modulation and demodulation system (15) samples input continuous pulse trains to obtain two paths of digital signals, and then the two paths of digital signals are multiplied by digital carriers and orthogonal terms thereof for frequency mixing; the two groups of signals after frequency mixing respectively pass through a low-pass filter to respectively obtain orthogonal components of the two groups of signals; selecting a group of signals with high visibility in the two orthogonal components through a real-time switching algorithm, performing an arc tangent algorithm on the selected signals, and performing a phase expansion algorithm after the arc tangent algorithm; then, a digital high-pass filtering algorithm is carried out, and finally, low-pass down-sampling is carried out for output.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910332727.2A CN110095177B (en) | 2019-04-24 | 2019-04-24 | System and method for suppressing fiber grating hydrophone phase demodulation polarization fading |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910332727.2A CN110095177B (en) | 2019-04-24 | 2019-04-24 | System and method for suppressing fiber grating hydrophone phase demodulation polarization fading |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110095177A CN110095177A (en) | 2019-08-06 |
| CN110095177B true CN110095177B (en) | 2021-08-03 |
Family
ID=67445678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910332727.2A Active CN110095177B (en) | 2019-04-24 | 2019-04-24 | System and method for suppressing fiber grating hydrophone phase demodulation polarization fading |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110095177B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111947782A (en) * | 2020-07-07 | 2020-11-17 | 中国南方电网有限责任公司超高压输电公司昆明局 | Extra-high voltage direct current control protection system OTDR device capable of self-adapting polarization fading suppression |
| CN114414032A (en) * | 2022-01-07 | 2022-04-29 | 上海传输线研究所（中国电子科技集团公司第二十三研究所） | Frequency shift quadrature demodulation system and method for optical fiber hydrophone |
| CN114485907B (en) * | 2022-03-21 | 2022-08-23 | 中国人民解放军国防科技大学 | Device and method for eliminating parasitic interference signals in fiber grating hydrophone array |
| CN116242278B (en) * | 2023-05-11 | 2023-07-11 | 山东高速工程检测有限公司 | Orthogonal optical fiber interference fringe projector for three-dimensional measurement of asphalt pavement texture |
| CN117030000B (en) * | 2023-10-10 | 2024-01-12 | 之江实验室 | Distributed acoustic wave sensing polarization control system and polarization fading inhibition method |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2121880A1 (en) * | 1993-04-27 | 1994-10-28 | Akbar Arab-Sadeghabadi | Optical Signal Detection Apparatus and Method for Preventing Polarization Signal Fading in Optical Fiber Interferometric Sensor Systems |
| CN2612938Y (en) * | 2003-05-14 | 2004-04-21 | 安徽大学 | Polarization resistant micro-vibration measurement and non-loss single mode optical fiber interferometer |
| CN101324446A (en) * | 2008-07-24 | 2008-12-17 | 北京航空航天大学 | Destabilization sensing localization method |
| CN101634571A (en) * | 2009-08-18 | 2010-01-27 | 重庆理工大学 | Optical pulse raster distributed fiber sensing device |
| CN102322880A (en) * | 2011-08-18 | 2012-01-18 | 天津大学 | Polarization sensitive distributive optical frequency domain reflection disturbance sensor and demodulation method |
| CN102538846A (en) * | 2011-12-14 | 2012-07-04 | 北京航空航天大学 | Phase-sensitive optical time domain reflectometer type optical fiber distributed disturbing sensor of double-arm pulse optical interference |
| CN103398771A (en) * | 2013-07-29 | 2013-11-20 | 中国电子科技集团公司第五十四研究所 | Distributed type optic fiber vibration-sensing polarization control system |
| CN104296783A (en) * | 2014-10-23 | 2015-01-21 | 武汉理工光科股份有限公司 | Sensor detecting method and device for enhanced coherent optical time domain reflection |
| US9009003B1 (en) * | 2012-05-03 | 2015-04-14 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Apparatus and method for elimination of polarization-induced fading in fiber-optic sensor system |
| CN107655561A (en) * | 2017-09-15 | 2018-02-02 | 浙江大学 | A kind of phase-modulation demodulating equipment based on optical fiber grating sonic device array |
| CN107990970A (en) * | 2017-11-03 | 2018-05-04 | 上海交通大学 | The method for eliminating the noise that declines in distribution type fiber-optic acoustic systems |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101403473B (en) * | 2006-06-30 | 2012-02-29 | 中国石油天然气集团公司 | Optical fiber security early-warning phase control system |
| CN103954310B (en) * | 2014-05-22 | 2016-05-25 | 中国人民解放军国防科学技术大学 | A kind of large Dynamic Signal demodulating equipment and demodulation method of interferometric optical fiber sensor |
| CA2965628A1 (en) * | 2014-12-23 | 2016-06-30 | Halliburton Energy Services, Inc. | Apparatus and method for characterization of fbg reflector array |
| GB2560522B (en) * | 2017-03-13 | 2022-03-16 | Aiq Dienstleistungen Ug Haftungsbeschraenkt | Dynamic sensitivity distributed acoustic sensing |
-
2019
- 2019-04-24 CN CN201910332727.2A patent/CN110095177B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2121880A1 (en) * | 1993-04-27 | 1994-10-28 | Akbar Arab-Sadeghabadi | Optical Signal Detection Apparatus and Method for Preventing Polarization Signal Fading in Optical Fiber Interferometric Sensor Systems |
| CN2612938Y (en) * | 2003-05-14 | 2004-04-21 | 安徽大学 | Polarization resistant micro-vibration measurement and non-loss single mode optical fiber interferometer |
| CN101324446A (en) * | 2008-07-24 | 2008-12-17 | 北京航空航天大学 | Destabilization sensing localization method |
| CN101634571A (en) * | 2009-08-18 | 2010-01-27 | 重庆理工大学 | Optical pulse raster distributed fiber sensing device |
| CN102322880A (en) * | 2011-08-18 | 2012-01-18 | 天津大学 | Polarization sensitive distributive optical frequency domain reflection disturbance sensor and demodulation method |
| CN102538846A (en) * | 2011-12-14 | 2012-07-04 | 北京航空航天大学 | Phase-sensitive optical time domain reflectometer type optical fiber distributed disturbing sensor of double-arm pulse optical interference |
| US9009003B1 (en) * | 2012-05-03 | 2015-04-14 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Apparatus and method for elimination of polarization-induced fading in fiber-optic sensor system |
| CN103398771A (en) * | 2013-07-29 | 2013-11-20 | 中国电子科技集团公司第五十四研究所 | Distributed type optic fiber vibration-sensing polarization control system |
| CN104296783A (en) * | 2014-10-23 | 2015-01-21 | 武汉理工光科股份有限公司 | Sensor detecting method and device for enhanced coherent optical time domain reflection |
| CN107655561A (en) * | 2017-09-15 | 2018-02-02 | 浙江大学 | A kind of phase-modulation demodulating equipment based on optical fiber grating sonic device array |
| CN107990970A (en) * | 2017-11-03 | 2018-05-04 | 上海交通大学 | The method for eliminating the noise that declines in distribution type fiber-optic acoustic systems |
Non-Patent Citations (1)
| Title |
|---|
| 齐龙舟 等.光纤激光水听器消偏振衰落技术研究.《传感器与微系统》.2008,第27卷(第7期), * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110095177A (en) | 2019-08-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110095177B (en) | System and method for suppressing fiber grating hydrophone phase demodulation polarization fading | |
| US20210033452A1 (en) | Frequency modulation demodulator based on fiber grating sensor array | |
| CN109282839B (en) | Distributed optical fiber sensing system and method based on multi-pulse and multi-wavelength | |
| JP5450408B2 (en) | Phase-based sensing | |
| CA2627099C (en) | A method and system of using odd harmonics for a phase generated carrier modulated optical signal | |
| US6466706B1 (en) | Pulsed system and method for fiber optic sensor | |
| CN107884060B (en) | Optical fiber distributed sensing detection method and device | |
| CN108759884B (en) | Distributed weak grating array sensing system and method for eliminating polarization fading influence | |
| CN113188647B (en) | Grating enhanced distributed vibration demodulation system and method for three-pulse dislocation interference | |
| GB2423149A (en) | Suppression of crosstalk and noise in time-division multiplexed interferometric sensor systems | |
| CN112697257B (en) | Non-fading multi-wavelength distributed acoustic wave sensing system and differential rotation vector superposition method | |
| CN116026447B (en) | Polarization fading inhibition device and method for distributed optical fiber acoustic wave sensing system | |
| CN102571200A (en) | Method and device of multi-frequency detecting-light coherent light time-domain reflectometer | |
| KR100850401B1 (en) | Two delay coils sagnac-based sensor array | |
| CN108225540A (en) | A kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range | |
| CN109974756B (en) | phi-OTDR technology based on differential phase pulse emission and time domain combination | |
| CN108592963B (en) | Method and system for inhibiting multiplicative noise of time division multiplexing optical fiber sensing system | |
| CN110617874A (en) | phi-OTDR system based on double-pulse phase-shifting interference and phase demodulation method | |
| CN115200691A (en) | Few-mode optical fiber distributed acoustic sensing system and signal processing method thereof | |
| CN114485907B (en) | Device and method for eliminating parasitic interference signals in fiber grating hydrophone array | |
| CN114608697A (en) | Low-noise broadband distributed acoustic wave detection device and method based on FBG | |
| KR20040043187A (en) | Amplified Tree Structure technology for Fiber Optic Sensor Arrays | |
| CN115112219A (en) | Long-distance optical fiber distributed vibration sensing device and working method | |
| Zhang et al. | Heterodyne demodulation scheme for fiber-optic hydrophone arrays | |
| CN113483795A (en) | Weak grating array distributed vibration sensing demodulation method and system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |