CN111337061A - Phase generation carrier demodulation method for eliminating disturbance - Google Patents
Phase generation carrier demodulation method for eliminating disturbance Download PDFInfo
- Publication number
- CN111337061A CN111337061A CN202010203943.XA CN202010203943A CN111337061A CN 111337061 A CN111337061 A CN 111337061A CN 202010203943 A CN202010203943 A CN 202010203943A CN 111337061 A CN111337061 A CN 111337061A
- Authority
- CN
- China
- Prior art keywords
- module
- signal
- phase
- output
- demodulation
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000001914 filtration Methods 0.000 claims abstract description 15
- 230000008030 elimination Effects 0.000 claims abstract description 10
- 238000003379 elimination reaction Methods 0.000 claims abstract description 10
- 230000010354 integration Effects 0.000 claims abstract description 9
- 238000011084 recovery Methods 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 239000000835 fiber Substances 0.000 abstract description 10
- 230000007774 longterm Effects 0.000 abstract description 3
- 238000001514 detection method Methods 0.000 description 11
- 239000013307 optical fiber Substances 0.000 description 11
- 230000003287 optical effect Effects 0.000 description 9
- 230000008569 process Effects 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 7
- 230000009467 reduction Effects 0.000 description 7
- 239000000919 ceramic Substances 0.000 description 5
- 238000001228 spectrum Methods 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 230000001629 suppression Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005562 fading Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
- G01D5/35325—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using interferometer with two arms in reflection, e.g. Mickelson interferometer
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
- G01D5/35329—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using interferometer with two arms in transmission, e.g. Mach-Zender interferometer
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
Abstract
The invention belongs to the field of phase demodulation algorithms of fiber optic interferometers, and particularly relates to a phase generation carrier demodulation method for eliminating disturbance. According to the method, interference signals acquired by a signal modulation module pass through a frequency mixing filtering module, an interference elimination module, a differential resolving module and an integration module in sequence to finally output phase demodulation signals. The invention eliminates the signals containing the alternating current intensity B and the modulation depth C by adding the interference elimination module, so that the output item only contains the differential value of the phase signal, the influence of light intensity disturbance on the output signal is eliminated, the uncertainty of the demodulation result caused by factors such as unstable light source and the like is avoided, and the long-term stability of the demodulation system is effectively improved.
Description
Technical Field
The invention belongs to the field of phase demodulation algorithms of fiber optic interferometers, and particularly relates to a Phase Generated Carrier (PGC) demodulation method for eliminating disturbance.
Background
The optical fiber sensor has the characteristics of high sensitivity, high linearity, small size, electromagnetic interference resistance, large dynamic range and the like, and is widely applied to the fields of optical fiber underwater sound detection, seismic wave detection and the like. The interferometric fiber sensor measures physical quantities including vibration, stress, displacement, velocity and the like by using phase change in an optical path, and is typically applied to fiber optic hydrophones, fiber optic seismometers, fiber optic strain gauges and the like. Random phase fading of an interferometer can cause random fluctuation of the signal-to-noise ratio of an output signal, phase change in an optical path needs to be solved through a specific algorithm, and the phase demodulation algorithm mainly comprises the following steps: active detection, passive detection, heterodyne detection, homodyne detection. Wherein the phase generation carrier algorithm is a relatively classical demodulation method.
The conventional PGC-DCM demodulation technology adopts difference and cross multiplication, is related to light intensity, has poor Stability when the light intensity changes rapidly, the PGC-Arctan demodulation technology demodulates two paths of signals by dividing and arctangent, has serious dependence on modulation depth, has serious Harmonic Distortion when the modulation depth deviates from 2.63rad, and the university Howland Zhang-sensitive technology deeply researches on noise suppression of an independent fiber hydrophone (CN201110191719.4) and a multiplexed hydrophone array (CN 201210143601.9) based on the PGC principle, the university Howland Zhang-sensitive technology discloses a method for performing large-scale hydrophone array demodulation (CN200910100600.4), the university Howland Grumman company David has related patent publication (US 7038784B2) on array demodulation by Hal, the university Howland Scholk laboratory and Schwary and the like also discloses a method for performing direct current system suppression analysis (US 677B) on water demodulation system (CN 5631 and Schwary), and the university Howland Scholk-Scholk algorithm shows that the influence of the direct current system demodulation system is reduced by the Harmonic Distortion of the Harmonic demodulation method on the Harmonic Distortion of the water demodulation system demodulation, the Harmonic Distortion is reduced by the Harmonic Distortion, and the Harmonic Distortion of the Harmonic filtering process of the Harmonic Distortion, the Harmonic Distortion of the Harmonic filtering process of the Harmonic Distortion generated by the Harmonic Distortion of the Harmonic demodulation technology and the Harmonic Distortion of the Harmonic filtering process of the Harmonic Distortion of the Harmonic demodulation technology in the Harmonic filtering system is reduced in the Harmonic demodulation technology, and the Harmonic filtering process of the Harmonic system, and the Harmonic filtering process of the Harmonic system, the Harmonic filtering process of the Harmonic Distortion of the Harmonic system, the Harmonic filtering process of the Harmonic system, the Harmonic Distortion of the Harmonic system.
For a demodulation system, on the basis of not increasing overhead as much as possible, the method eliminates the influence of modulation depth and light intensity disturbance and simultaneously inhibits harmonic distortion, and has very important significance and practical value. The invention provides a PGC demodulation method for eliminating disturbance, which is characterized in that an interference elimination module is introduced on the basis of the traditional PGC demodulation scheme, two paths of signals after frequency mixing and filtering are subjected to differential cross division operation and multiplication operation, the purpose of eliminating light intensity disturbance and modulation depth influence is achieved, signals only containing a phase signal differential value square term are obtained, and then a phase to be resolved is obtained. The invention can not only reduce the dependence of the demodulation signal on the modulation depth of an additional carrier, but also eliminate the influence of light intensity disturbance on output, improves the accuracy of signal amplitude detection and the stability of a demodulation system, and can be widely applied to high-precision optical fiber measurement and sensing systems.
Disclosure of Invention
It is an object of the present invention to overcome the disadvantages and drawbacks of the prior art and to provide a Phase Generated Carrier (PGC) demodulation method that eliminates disturbances.
The purpose of the invention is realized as follows:
a Phase Generated Carrier (PGC) demodulation method for eliminating disturbance is characterized in that interference signals collected by a signal modulation module 10 sequentially pass through a mixing filter module 11, an interference elimination module 12, a differential resolving module 13 and an integration module 14 to finally output phase demodulation signals.
The signal modulation module 10 comprises a data acquisition module 102 and a modulation output module 103, wherein the modulation output module 103 outputs sine waves to a light source modulator 211 for modulating a light source 221, and modulated light is injected into an interferometer 23, wherein the modulation frequency is 2 kHz-50 MHz, and the modulation amplitude is set within the range of 1-6 rad to ensure the stability of interference fringes; the data acquisition module 102 is configured to acquire a result of the interferometer 23 after completing the photoelectric conversion, so as to obtain an interference signal.
The frequency mixing filtering module 11 sends the acquired interference signals, the fundamental frequency signal 111 and the frequency multiplication signal 114 to the first multiplier 112 and the second multiplier 113 simultaneously, sends the output results of the first multiplier 112 and the second multiplier 113 to the first low-pass filter 115 and the second low-pass filter 116, and the cutoff frequency is selected to be between 1kHz and 25MHz according to the frequency of the carrier signal.
The interference cancellation module 12 includes a differential cross division module 121 and a multiplication module 122, where the differential cross division module 121 sends output results of the first low-pass filter 115 and the second low-pass filter 116 to a first differentiator 1211 and a second differentiator 1212, respectively, and sends output results of the first differentiator 1211 and the second differentiator 1212 and outputs of the second low-pass filter 116 and the first low-pass filter 115 to a first divider 1213 and a second divider 1214 at the same time, so as to achieve the purpose of removing light intensity disturbance; the multiplication module 122 multiplies the output results of the first divider 1213 and the second divider 1214 by the third multiplier 1221 to obtain a signal containing only the square term of the differential value of the phase signal, and the influence of the modulation depth drift is eliminated.
The differential resolving module 13 comprises a power reduction module 131 and a symbol recovery module 132, wherein the power reduction module 131 performs sign negation and power reduction operation 131 on a signal only containing a phase signal differential value squared term to obtain a phase signal differential value with a positive sign; the sign recovery module 132 determines the sign of the differential value of the phase signal by using the sign output from the first divider 1213 as a condition, and obtains the true differential value of the phase signal.
The integration module 14 sends the real differential value of the phase signal output by the differential resolving module 13 to the integration module 141, and resolves the phase signal to be detected to obtain a phase demodulation result 142.
The invention relates to an algorithm improvement of a PGC demodulation algorithm. The improved algorithm principle is shown in figure 1:
the signal modulation module 10 comprises a data acquisition module 102 and a modulation output module 103, wherein the modulation output module 103 outputs a sine wave to a light source modulator 211 for modulating a light source 221 to generate a phase carrier wave to add a change to the light phase
The modulated light is injected into the interferometer 21; the data acquisition module 102 is configured to acquire a result of the interferometer after completing photoelectric conversion, and obtain an interference signal in the form of formula (1):
the input signal is expanded by a Bessel function to obtain the frequency spectrum components of the input signal:
where A is the DC intensity of the output signal, B is the AC intensity, C is the modulation depth, and ω is0Is the carrier frequency and is,
for the signal to be measured, Jk(C) K is the high order component of the signal, and the amplitude of each secondary side frequency component around the zero frequency is proportional to Jk(C) In that respect The larger the C value, Jk(C) The slower the speed towards zeroAnd a smaller value of C is advantageous for reducing system phase noise.
Obtaining a pair of orthogonal components containing phase-shifted signals by a mixing filter module 11
In an actual system G, H, the amplitude of the detection wave signal is generally set to G ═ H, and the parameters B and C drift due to changes in the external environment or instability of the internal period of the system.
In order to recover the precise phase shift of the interferometric fiber sensor from the quadrature component, the signal is passed through a differential cross-division 121 operation in the interference cancellation module 12 to cancel the effect of the optical intensity disturbance, resulting in a signal of the following form:
the two paths of signals pass through a multiplication operation 122 and a power reduction module 131 in the differential resolving module 13, so that the influence of modulation depth drift is further removed, and a differential value of a phase signal with a positive sign is obtained, and the form is as follows:
selecting appropriate C value to make J1(C) And J2(C) The sign is consistent, the sign recovery module 124 uses the output K of the first divider 12131Is used as a condition to judge the sign of the differential value of the phase signal if K1If the signal sign is more than 0, the signal sign of the formula (7) is positive, otherwise, the signal sign is negative, and then the real differential value of the phase signal is obtained;
the real differential value of the phase signal output by the differential resolving module 13 is sent to the integrating module 141, and the signal to be detected is resolved to obtain a phase demodulation result 142. The result does not contain an alternating current intensity B value and a modulation depth C value, and is not influenced by light intensity disturbance and modulation depth drift.
The invention has the beneficial effects that:
(1) the interference elimination module is added to eliminate the signals containing the alternating current intensity B and the modulation depth C, so that the output item only contains the differential value of the phase signal, the influence of light intensity disturbance on the output signal is eliminated, the uncertainty of a demodulation result caused by factors such as unstable light source and the like is avoided, and the long-term stability of the demodulation system is effectively improved;
(2) the demodulation result does not contain nonlinear components, new harmonic components are not introduced, and when the modulation depth generates micro offset, no distortion item is formed, so that the dependence of the demodulation result on the modulation depth introduced by an external loading wave is reduced, the harmonic is effectively inhibited, the nonlinear influence is reduced, the signal amplitude is stable, and the error of signal amplitude detection is reduced;
(3) any optical interferometer can be demodulated by using the algorithm, such as a Mach-Zehnder interferometer or a Michelson interferometer, and the like, software programs are changed on the basis of the original hardware overhead, extra cost is not increased, the compatibility with the existing system is good, and the method can be widely applied to the fields of high-precision optical fiber measurement, optical fiber sensing and the like.
Drawings
FIG. 1 is a flow chart of a PGC demodulation algorithm for canceling disturbances;
FIG. 2 is a diagram of an interferometer modulation-demodulation detection optical path device;
FIG. 3 is a demodulation signal waveform of a PGC demodulation algorithm for eliminating disturbance;
FIG. 4 is a demodulation spectrum of a PGC algorithm with disturbance removal for a signal with a frequency of 144 Hz;
fig. 5 shows the harmonic distortion of the demodulated signal after the algorithm is improved.
Detailed Description
For clarity of explanation, the present invention will be further explained with reference to the drawings and the embodiments, but the scope of the present invention should not be limited thereby.
Embodiment-a mach zehnder interferometer based phase generation carrier demodulation method.
Modem device As shown in FIG. 2, the device selection and parameters of the interferometer measuring device are as follows:
(1) the center wavelength of the light source 221 is 1550nm, the half-spectrum width is larger than 45nm, and the fiber output power is 1-10 mW;
(2) the working wavelength of the optical fiber isolator 222 is 1550nm +/-5 nm, the insertion loss is less than or equal to 1.0dB (at the working temperature of 23 ℃), and the return loss is more than or equal to 55 dB;
(3) the first 1 × 2 coupler 231 and the second 1 × 2 coupler 234 have working wavelengths of 1550nm and 1310nm, a splitting ratio of 50.5%/49.5%, and insertion losses of the two paths are 3.03dB and 3.12dB respectively;
(4) the size of the piezoelectric ceramic 233 used for loading the calibration signal is 24mm, the capacitance is 22nF, and the withstand voltage amplitude is 0-120V;
(5) the photodetector 20 is an InGaAs photodetector, the connection mode belongs to a pigtail FC/PC, the operating wavelength is 1100nm to 1650nm, the light intensity responsivity R is 0.85A/W, and the capacitance is 0.35 pF;
(6) the data acquisition module 214 is an NI-6366 acquisition card, the sampling rate is 2Mbps, the input voltage amplitude is +/-10V, the sampling clock is an internal clock of the acquisition card, and the input resistor is 20 k;
(7) the light source modulator 211 and the piezoelectric ceramic driver 212 are power amplifiers, and an AD8040 rail-to-rail power amplifier of AD company is used, wherein the working voltage is 2.7-12V, the working bandwidth is 125MHz, the maximum output current is 200mA, and the load capacitance is 15 pF;
the specific flow of the algorithm is as follows:
(1) the system operation signal modulation module 10 firstly uses the computer 213 to modulate the frequency of the light source 221 through the light source modulator 211, sets the amplitude of the carrier signal to be 2.6rad, the signal frequency to be 6kHz, the signal is not changed with the factors such as environmental transformation, and simultaneously uses the piezoelectric ceramic driver 212 to generate the calibration signal with the amplitude of 1.2rad and the frequency of 144Hz to the piezoelectric ceramic ring 233, the frequency-modulated optical signal is injected into the Mach Zehnder interferometer 23 through the optical fiber isolator 222, the light is divided into two beams through the 1 × 2 coupler 231, one path of optical signal passes through the optical fiber ring 232, the other path of optical signal passes through the optical fiber wound on the piezoelectric ceramic ring 233, the two paths of optical signals are interfered in the second 1 × 2 coupler 234, the interference signal is output through the photoelectric detector module 20, the data is sent into the computer 213 through the data acquisition module 214 to be demodulated through the algorithm, and the whole process is synchronously carried out.
(2) The data acquisition module 102 obtains an interference signal containing direct current bias, wherein the peak value of the signal is 4V, and the direct current bias is about 2V;
(3) performing frequency mixing filtering operation on interference signals, setting the first and second filters 115 and 116 as FIR Blackman windows, setting parameters of passband cut-off frequency of 2kHz, stopband cut-off frequency of 3kHz, attenuation of-80 dB, passband ripple of 0.01dB and order of 265, and obtaining two paths of signals after data passes through the filters;
(4) the two paths of signals are subjected to corresponding operation through a differential cross division module 121 and a multiplication module 122 in the interference elimination module 12 to obtain a square term of a differential value of the phase signal, at the moment, the influence of the PGC algorithm caused by the drift of a B value and a C value due to the change of an external environment or the instability of the internal period of the system is eliminated, the square term is sent to a power reduction module 131 in the differential calculation module 13 to perform sign negation and power reduction operation 131, and a sign recovery module 132 performs sign recovery on the differential value by taking a sign output by a first divider 1213 as a judgment condition to obtain a real differential value of the phase signal;
(5) the differential value of the signal is integrated 141 by the integration module 14 to obtain the final result, and the demodulation result 142 is obtained.
Fig. 3 shows the demodulated output waveform of the signal with the frequency of 144Hz, fig. 4 shows the demodulated signal spectrum comparison, the algorithm has lower harmonic distortion degree and clear spectrum after the improvement, and the demodulated signal has the harmonic distortion degree of-82.83 dB and better harmonic suppression effect as shown in fig. 5 after the algorithm is improved.
The invention belongs to the field of phase demodulation algorithms of fiber optic interferometers, and particularly relates to a Phase Generated Carrier (PGC) demodulation method for eliminating disturbance. The invention comprises a signal modulation module, a frequency mixing filtering module, an interference elimination module, a differential resolving module and an integration module. The method is characterized in that an interference elimination module is added, sine components and cosine components after frequency mixing filtering are respectively subjected to differential cross division to achieve the purpose of removing light intensity disturbance, the influence of modulation depth drift is eliminated through a multiplication module, and after power reduction operation and symbol recovery in a differential resolving module, a phase to be resolved is obtained through integral accurate calculation. The invention can eliminate the influence of light intensity on output signals, reduce the dependence on modulation depth, effectively inhibit harmonic distortion, reduce the detection error of signal amplitude, improve the long-term stability of a signal demodulation system, and can be widely applied to the fields of high-precision optical fiber measurement, optical fiber sensing and the like.
Claims (6)
1. A phase generation carrier demodulation method for eliminating disturbance is characterized in that: according to the method, interference signals acquired by a signal modulation module (10) sequentially pass through a mixing filtering module (11), an interference elimination module (12), a differential resolving module (13) and an integration module (14), and finally phase demodulation signals are output.
2. The phase-generated carrier demodulation method with disturbance cancellation according to claim 1, wherein: the signal modulation module (10) comprises a data acquisition module (102) and a modulation output module (103), the modulation output module (103) outputs sine waves to a light source modulator (211) for modulating a light source (221), and modulated light is injected into an interferometer (23), wherein the modulation frequency is 2 kHz-50 MHz, and the modulation amplitude is set within the range of 1-6 rad to ensure the stability of interference fringes; the data acquisition module (102) is used for acquiring the result of the interferometer (23) after the photoelectric conversion is completed, and obtaining an interference signal.
3. A phase-generated carrier demodulation method for canceling disturbance according to claim 1, wherein said mixing filter module (11) is characterized by: the acquired interference signals are respectively sent to a first multiplier (112) and a second multiplier (113) together with a fundamental frequency signal (111) and a frequency multiplication signal (114), output results of the first multiplier (112) and the second multiplier (113) are sent to a first low-pass filter (115) and a second low-pass filter (116), and the cutoff frequency is selected to be between 1kHz and 25MHz according to the frequency of a carrier signal.
4. The phase-generated carrier demodulation method for canceling disturbance according to claim 1, characterized in that: the interference elimination module (12) comprises a differential cross division module (121) and a multiplication module (122), wherein the differential cross division module (121) respectively sends output results of a first low-pass filter (115) and a second low-pass filter (116) to a first differentiator (1211) and a second differentiator (1212), and simultaneously sends output results of the first differentiator (1211) and the second differentiator (1212) and outputs of the second low-pass filter (116) and the first low-pass filter (115) to a first divider (1213) and a second divider (1214), so that the purpose of removing light intensity disturbance is achieved; the multiplication module (122) multiplies the output results of the first divider (1213) and the second divider (1214) by a third multiplier (1221) to obtain a signal only containing a differential value squared term of the phase signal, and the influence of modulation depth drift is eliminated.
5. The phase-generated carrier demodulation method for canceling disturbance according to claim 1, characterized in that: the differential resolving module (13) comprises a power reducing module (131) and a symbol recovery module (132), wherein the power reducing module (131) performs sign negation and power reducing operation (131) on a signal only containing a phase signal differential value squared term to obtain a phase signal differential value with a positive sign; the sign recovery module (132) judges the sign of the differential value of the phase signal by taking the sign output by the first divider (1213) as a condition, and obtains the real differential value of the phase signal.
6. The phase-generated carrier demodulation method with disturbance cancellation according to claim, characterized in that: and the integration module (14) sends the real differential value of the phase signal output by the differential resolving module (13) to the integration module (141) to solve the phase signal to be detected to obtain a phase demodulation result (142).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010203943.XA CN111337061A (en) | 2020-03-21 | 2020-03-21 | Phase generation carrier demodulation method for eliminating disturbance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010203943.XA CN111337061A (en) | 2020-03-21 | 2020-03-21 | Phase generation carrier demodulation method for eliminating disturbance |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111337061A true CN111337061A (en) | 2020-06-26 |
Family
ID=71182526
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010203943.XA Pending CN111337061A (en) | 2020-03-21 | 2020-03-21 | Phase generation carrier demodulation method for eliminating disturbance |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111337061A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113375785A (en) * | 2021-06-08 | 2021-09-10 | 中国人民解放军国防科技大学 | Method for detecting full-sea-depth high-stability photoelectric signal of optical fiber hydrophone |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105486225A (en) * | 2015-12-01 | 2016-04-13 | 哈尔滨工程大学 | Phase demodulation device and demodulation method capable of suppressing light-intensity fluctuation noise |
| CN109459070A (en) * | 2018-11-15 | 2019-03-12 | 浙江理工大学 | Phase delay is extracted and compensation method in a kind of PGC phase demodulating method |
| CN110411486A (en) * | 2019-07-26 | 2019-11-05 | 浙江理工大学 | The PGC-DCDM demodulation method insensitive to phase delay and modulation depth |
| CN110429987A (en) * | 2019-07-31 | 2019-11-08 | 中船海洋探测技术研究院有限公司 | A kind of phase generated carrier demodulation system based on FPGA |
-
2020
- 2020-03-21 CN CN202010203943.XA patent/CN111337061A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105486225A (en) * | 2015-12-01 | 2016-04-13 | 哈尔滨工程大学 | Phase demodulation device and demodulation method capable of suppressing light-intensity fluctuation noise |
| CN109459070A (en) * | 2018-11-15 | 2019-03-12 | 浙江理工大学 | Phase delay is extracted and compensation method in a kind of PGC phase demodulating method |
| CN110411486A (en) * | 2019-07-26 | 2019-11-05 | 浙江理工大学 | The PGC-DCDM demodulation method insensitive to phase delay and modulation depth |
| CN110429987A (en) * | 2019-07-31 | 2019-11-08 | 中船海洋探测技术研究院有限公司 | A kind of phase generated carrier demodulation system based on FPGA |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113375785A (en) * | 2021-06-08 | 2021-09-10 | 中国人民解放军国防科技大学 | Method for detecting full-sea-depth high-stability photoelectric signal of optical fiber hydrophone |
| CN113375785B (en) * | 2021-06-08 | 2022-04-15 | 中国人民解放军国防科技大学 | Method for detecting full-sea-depth high-stability photoelectric signal of optical fiber hydrophone |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112097813B (en) | 3X 3 coupler photoelectric detection method and device based on optical frequency modulation | |
| CN108007550B (en) | Improved PGC modulation-demodulation detection method | |
| CN110864714B (en) | Distributed sensing system based on Michelson-Sagnac fiber optic interferometer | |
| CN105067017B (en) | A kind of improved generation carrier phase PGC demodulation methods | |
| EP1985967B1 (en) | Fiber interferometric sensor and phase compensation method of PGC demodulator | |
| CN105486225B (en) | A kind of phase demodulating device and demodulation method for inhibiting light-intensity variation noise | |
| CN108981767A (en) | Optical fiber distributed type monitors system and method | |
| CN112197849A (en) | Sound wave measuring system and method | |
| CN109141490B (en) | Optical fiber sensing device and demodulation method for simultaneously measuring disturbance waveform and position | |
| CN105157733B (en) | A kind of improved generation carrier phase PGC demodulation methods | |
| CN101231367A (en) | High resolution wavelength demodulation system and demodulation method thereof | |
| CN104330104A (en) | Measuring device for interferential sensor arm length difference | |
| CN111289089A (en) | Distributed optical fiber sensing system based on heterodyne detection technology | |
| CN101686087B (en) | Wavelength demodulation system and method based on two outputs of a 3 x 3 coupler | |
| CN109724685A (en) | Fiber grating underwater sound sensing array demodulation method and system based on Fizeau interference | |
| CN110411334B (en) | Improved phase carrier PGC demodulation method and system | |
| CN101799610A (en) | Orthogonal demodulation device for heterodyne phase interference fiber sensor | |
| CN111366179A (en) | Self-differential phase division phase generation carrier demodulation method | |
| CN111337061A (en) | Phase generation carrier demodulation method for eliminating disturbance | |
| CN106247930A (en) | The residual compensation method of phase carrier formula laser interferometer closed loop demodulating algorithm | |
| CN106323346B (en) | A kind of phase carrier formula laser interference signal dual-frequency point closed loop demodulation method | |
| CN112880711A (en) | Distributed optical fiber sensing method and system based on double-pulse modulation | |
| CN103759924A (en) | System for comprehensively measuring multiple parameters of fiber optic interferometer | |
| Xiao et al. | An improved high stability and low distortion phase generated carrier demodulation algorithm for phase-sensitive optical time-domain reflectometers | |
| Wu et al. | Improved differential phase detecting optical fiber interferometer with a low-frequency compensation scheme |
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 | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200626 |