CN109855719A - High-stability interference type optical fiber hydrophone signal demodulation method - Google Patents
High-stability interference type optical fiber hydrophone signal demodulation method Download PDFInfo
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Abstract
The invention discloses a signal demodulation method for an interference type optical fiber hydrophone, which comprises the following steps: step S100: the laser applies sinusoidal frequency modulation, the laser inputs the output light wave into the unbalanced interference type optical fiber hydrophone, the optical fiber hydrophone applies a large-amplitude test acoustic signal, the optical fiber hydrophone inputs the output test interference signal into the signal demodulation system, and the test interference signal is processed to obtain a demodulation system parameter estimation value; step S200: the optical fiber hydrophone is placed in a measuring environment to measure the acoustic signal to be measured, outputs an actual interference signal to be input into a signal demodulation system, processes the actual interference signal and corrects the actual interference signal through the parameter estimation value of the demodulation system to obtain the acoustic signal to be measured. The high-stability signal detection of the interference type optical fiber hydrophone is realized.
Description
Technical field
The present invention relates to the signal demodulation techniques field of fibre optic hydrophone more particularly to a kind of interference type optical fiber hydrophones
Signal demodulating method.
Background technique
Fibre optic hydrophone is a kind of novel underwater sound sensor, has high sensitivity, structure dexterity, easily multiplexing composition extensive
The features such as array, the fields such as target acquisition, seismic wave detection have important application under water.It is listened in various types of optical fiber water
In device, interferometric optical fiber sensor is based on fibre optic interferometer structure, by highly sensitive coherent detection technology, by measured signal
With phase representation load in sensor output signal, there are many excellent characteristics such as high sensitivity, noise be low.But due to dry
Relating to type fibre optic hydrophone, there is random phase fade-outs, it is necessary to carry out modulating and demodulating signal to it, just be able to achieve stable
Signal detection, therefore signal demodulating method becomes the key technology in interference type optical fiber hydrophone application.
Phase modulated carrier signal (PGC) modulation-demodulation technique is interference-type optical fiber water as a kind of passive homodyne demodulation techniques
Listen one of most common demodulation techniques of device.Wherein for internal modulation PGC mode by applying sinusoidal frequency modulation to laser, use is non-
Frequency modulation(PFM) is converted phase-modulation by balance interference instrument, to realize phase modulated carrier signal.This mode may be implemented to sense
Primitive all-fiber is suitable for the application of large-scale optical fiber hydrophone array.
But in traditional fibre optic hydrophone PGC demodulation scheme, there are modulation depth stability and laser in real system
Non-ideal factors, these factors such as the modulation of device additional strength will lead to PGC demodulating error, make the reduction of demodulated signal stability, together
The biggish signal harmonic distortion of Shi Yinqi, seriously affects demodulating system performance.
Extensively and profoundly with interference type optical fiber hydrophone application, fibre optic hydrophone signal detection stability is proposed more
Carry out higher requirement.For example, can be realized in the application of vector fibre optic hydrophone by comparing orthogonal hydrophone channel signal amplitude
Estimation to target bearing, and the unstable of demodulated signal will result directly in target Bearing Estimation error；In large-scale optical fiber water
It listens in the application of device array, jitter will affect amplitude consistency between multichannel optical fiber hydrophone primitive, to directly lead
The decline of array gain level is caused, array application performance is seriously affected.
Summary of the invention
The technical problem to be solved by the present invention is to overcome drawbacks described above of the existing technology, provide a kind of interference-type light
Fine hydrophone signal demodulating method, to realize the high stable signal detection of interference type optical fiber hydrophone.
Interference type optical fiber hydrophone signal demodulating method provided by the invention, comprising the following steps:
Step S100: laser applies sinusoidal frequency modulation, and laser is by the light wave inputting earthquake waves interference-type light of output
Acoustical signal is significantly tested in fine hydrophone, fibre optic hydrophone application, and the test interference signal of output is inputted letter by fibre optic hydrophone
Number demodulating system, and to obtaining demodulating system parameter estimation value after test interference signal processing；
Step S200: fibre optic hydrophone being placed in measurement environment and measures tested acoustical signal, and fibre optic hydrophone output is practical
Interference signal input signal demodulating system, by practical interference signal handle and demodulated system parameter estimated value amendment after, obtain
Acoustical signal must be tested.
Preferably, the step S100 specifically:
Step S101: laser applies sinusoidal frequency modulation, and laser is by the light wave inputting earthquake waves interference-type light of output
Acoustical signal is significantly tested in fine hydrophone, fibre optic hydrophone application, and the test interference signal of output is inputted letter by fibre optic hydrophone
Number demodulating system；
Step S102: test interference signal is multiplied with carrier frequency two, frequency tripling reference signal and low-pass filtered respectively,
Obtain test interference signal two, frequency tripling rectified signal；
Step S103: elliptic curve is constructed using the two of test interference signal, frequency tripling rectified signal；
Step S104: building elliptic curve is subjected to elliptic parameter fitting, obtains the match value of each elliptic curve parameter；
Step S105: demodulating system parameter estimation value is obtained according to elliptic curve parameter fitting value.
Preferably, the step S200 specifically:
Step S201: fibre optic hydrophone being placed in measurement environment and measures tested acoustical signal, and fibre optic hydrophone output is practical
Interference signal input signal demodulating system；
Step S202: practical interference signal is multiplied with carrier frequency two, frequency tripling reference signal and low-pass filtered respectively,
Obtain practical interference signal two, frequency tripling rectified signal；
Step S203: the two of practical interference signal, frequency tripling rectified signal is carried out using demodulating system parameter estimation value
Amendment obtains quadrature demodulated signal；
Step S204: orthogonal signalling demodulation is carried out using quadrature demodulated signal and is calculated, tested acoustical signal is obtained.
Preferably, in the step S101 fibre optic hydrophone by the test interference signal I of outputc(t) are as follows:
Wherein, I0For light intensity DC quantity, m is the intensity modulated amplitude of laser, ωcFor phase carrier circular frequency,For
Intensity modulated initial phase, v are interference signal visibility, and C is phase carrier modulation amplitude,To test acoustical signal.
Preferably, in the step S102 test interference signal two, frequency tripling rectified signal Sc2(t) and Sc3(t) respectively
Are as follows:
Wherein, X2(t) two frequency multiplication reference signal of carrier frequency, X3(t) carrier frequency frequency tripling reference signal, hLPF(t) it is
Low pass filter response, a2And a3For error parameter.
Preferably, elliptic curve in the step S103 are as follows:
Wherein,
Sc2(t) and Sc3(t) it is denoted as Sc2And Sc3。
Preferably, in the step S105 specifically: demodulated according to elliptic curve parameter a, b, c, d, e, f match value
System parameter B2,B3, δ estimated value:
Preferably, in the step S203 specifically: utilize demodulating system parameter estimation value B2,B3, δ is to practical interference letter
Number two, frequency tripling rectified signal St2And St3It is modified, obtains quadrature demodulated signal SR and CR:
Wherein,
To be tested acoustical signal.
Preferably, in the step S204 specifically: carry out orthogonal signalling demodulation meter using quadrature demodulated signal SR and CR
It calculates, obtains tested acoustical signal
This method is divided into two big steps and carries out, and step S100 realizes that demodulating system parameter accurately obtains, and step S100 is completed
The demodulation of high stable signal calculates.Signal stabilization demodulation is realized under conditions of completing demodulating system parameter and accurately calculating, and is eliminated
The influence of phase carrier modulation amplitude error and additional strength mudulation effect.It does not need to increase extra hardware expense, can not increase
Demodulating system performance is effectively improved under the premise of adding demodulating system complexity and cost, realizes that the height of interference type optical fiber hydrophone is steady
Determine signal detection.
Detailed description of the invention
Fig. 1 is a kind of flow chart for interference type optical fiber hydrophone signal demodulating method that the first embodiment provides；
Fig. 2 is a kind of flow chart for interference type optical fiber hydrophone signal demodulating method that second of embodiment provides；
Fig. 3 is a kind of system construction drawing for realizing interference type optical fiber hydrophone signal demodulating method that invention provides；
Fig. 4 is a kind of interference type optical fiber hydrophone letter that conventional PGC demodulation method result and second of embodiment provide
The experimental result picture of number demodulation method.
Specific embodiment
In order that those skilled in the art will better understand the technical solution of the present invention, with reference to the accompanying drawing to the present invention
It is described in further detail.
Referring to Fig. 1, Fig. 1 is a kind of stream for interference type optical fiber hydrophone signal demodulating method that the first embodiment provides
Cheng Tu.
Interference type optical fiber hydrophone signal demodulating method provided by the invention, comprising the following steps:
Step S100: laser applies sinusoidal frequency modulation, and laser is by the light wave inputting earthquake waves interference-type light of output
Acoustical signal is significantly tested in fine hydrophone, fibre optic hydrophone application, and the test interference signal of output is inputted letter by fibre optic hydrophone
Number demodulating system, and demodulating system parameter estimation value is obtained after testing interference signal processing；
Step S200: fibre optic hydrophone being placed in measurement environment and measures tested acoustical signal, and fibre optic hydrophone output is practical
Interference signal input signal demodulating system, after practical interference signal is handled and after the amendment of demodulated system parameter estimated value,
Obtain tested acoustical signal.
Present embodiment proposes that a kind of interference type optical fiber hydrophone signal demodulating method is divided into two big steps and carries out, step
S100 realizes that demodulating system parameter accurately obtains, and step S200 completes the demodulation of high stable signal and calculates.Complete system parameter
Realization signal stabilization demodulation under conditions of accurate measuring and calculating, elimination phase carrier modulation amplitude error and additional strength mudulation effect
It influences.It does not need to increase extra hardware expense, solution can be effectively improved under the premise of not increasing demodulating system complexity and cost
Adjusting system performance realizes the high stable signal detection of interference type optical fiber hydrophone.
Referring to fig. 2, Fig. 2 is a kind of stream for interference type optical fiber hydrophone signal demodulating method that second of embodiment provides
Cheng Tu.
In PGC modulation-demo-demodulation method, ideally, fibre optic hydrophone output interference light intensity I (t) can be indicated are as follows:
Wherein, I0For light intensity DC quantity, v is interference signal visibility, and C is phase carrier modulation amplitude, ωcFor phase load
Wave circular frequency,Phase signal is sensed for fibre optic hydrophoneWith interferometer initial phaseThe sum of.
In view of the presence of additional strength effect in phase carrier modulation, at this moment fibre optic hydrophone output interference light intensity can be with
It indicates are as follows:
Wherein, m is the intensity modulated amplitude of laser,For intensity modulated initial phase.
Using trigonometric function Bezier expansion formula, formula (2) can be unfolded are as follows:
Wherein k is that order is unfolded in Bezier trigonometric function.
Carrier frequency one, two, frequency tripling reference signal it is as follows:
By interference signal I (t) shown in formula (3), respectively with carrier frequency one, two, frequency tripling reference signal X1(t)、 X2
(t) and X3(t) it is multiplied, and low-pass filtered, one, two, frequency tripling rectified signal S can be obtained1(t)、S2(t) and S3(t) such as
Under:
Wherein, hLPFIt (t) is low pass filter response.
For the expression of simplified style (5), (6) and (7), error parameter is defined:
Then one, two, frequency tripling rectified signal S1(t)、S2(t) and S3(t) it is represented by S1、S2And S3:
In formula (9), (10), (11), first item is ideally each harmonic amplitude on the right of equation, on the right of equation
Second and third is the error term introduced by additional strength modulation, and error term size and carrier modulation amplitude, additional strength are modulated
Parameter and interferometer initial phase are related.
In conventional PGC demodulation method, orthogonal signalling are constructed using one, two frequency multiplication rectified signals, and use arc tangent
Method or differential multiplication cross method carry out quadrature phase resolving.
By taking blanking method anyway as an example, in the ideal case, additional strength modulation error, error parameter b is not present1,a1,a2,
a3It is zero, by formula (9) and (10) it is found that at this moment orthogonal detection signal are as follows:
Make following formula such as to calculate:
Arctangent computation is done to formula (14), can must be tested phase information are as follows:
But in actual modulated system, there are factors that can cause phase demodulating error, lead to the unstable of signal detection,
It is wherein major to have following two aspect:
(1) additional strength mudulation effect
By formula (9) (10) it is found that due to additional strength mudulation effect during phase carrier presence, quadrature phase detector
There is error term in signal, if at this moment being calculated still according to formula (15) formula, calculated result are as follows:
As it can be seen that due to the presence of error term, calculated resultThe actual phase of ratioRelatively large deviation to occur, and this
Deviation is related with interferometer initial phase.In the application of actual fiber hydrophone system, hydrophone initial phase can change with environment
And slow drift is generated, and it is unstable so as to cause signal detection, seriously affect demodulating system performance.
(2) phase carrier modulation amplitude error
When being calculated using formula (15), need to introduce J according to system phase carrier amplitude C value1(C) and J2(C), usually
C value is set as 2.63rad, at this moment J1(C)=J2(C), the influence of C value can be eliminated.But system is listened in actual fiber water, it is special
It is not in the application of multichannel optical fiber hydrophone array, due to long inconsistent of the non-equilibrium interferometer arm difference of each hydrophone primitive
Property, the phase carrier amplitude of different fibre optic hydrophones can generate difference, deviate 2.63rad, at this moment need to each hydrophone base
The modulation amplitude of member is calculated, then by J2(C)/J1(C) formula (15) are substituted into be calculated.
Common modulation amplitude measuring method is to calculate J using each frequency multiplication rectified signal1(C)/J3(C) or J2(C)/J4
(C), then by the methods of look-up table C value size is estimated.But when there are additional strength mudulation effect, each frequency multiplication detection
Signal will appear error, so that the error of measuring and calculating C value is also led to, and C value measuring and calculating error also will result directly in signal detection
The fluctuation of amplitude.
The interference type optical fiber hydrophone signal demodulating method that second of embodiment of the invention provides, comprising the following steps:
Step S101: laser applies sinusoidal frequency modulation, and laser is by the light wave inputting earthquake waves interference-type light of output
Acoustical signal is significantly tested in fine hydrophone, fibre optic hydrophone application, and fibre optic hydrophone is by the test interference signal I of outputc(t) defeated
Enter signal demodulating system.
It is ω that laser, which applies frequency,cAfter sinusoidal frequency modulation, output light wave inputting earthquake waves interference-type optical fiber water is listened
After device, frequency of light wave modulation is converted into interferometer phase modulation, to realize phase modulated carrier signal.When laser frequency modulation
Inevitably there are additional strength mudulation effect, the at this moment output interference signal I of fibre optic hydrophonec(t) it can indicate are as follows:
Acoustical signal is significantly tested in fibre optic hydrophone application, uses sinusoidal test signal in this example, at this momentIt can be with table
It is shown as:
Wherein, ωsFor the test acoustical signal circular frequency of application, D is test acoustical signal amplitude,For interferometer initial phase.
To realize system parameter measuring and calculating, acoustical signal is testedAmplitude should be greater than π, and in order not to cause distorted signals, test acoustical signal
Amplitude D should be in Dynamic Range.
Step S102: test interference signal Ic(t) respectively with carrier frequency two, frequency tripling reference signal X2(t) and X3(t)
It is multiplied and low-pass filtered, obtains testing the two of interference signal, frequency tripling rectified signal Sc2(t) and Sc3(t)。
By X2(t) and X3(t) respectively at test interference signal Ic(t) it is multiplied, filters out carrier wave letter using low-pass filter
Breath obtains testing the two of interference signal, frequency tripling rectified signal Sc2(t) and Sc3(t) as follows:
Step S103: the two of test interference signal, frequency tripling rectified signal S are utilizedc2(t) and Sc3(t) building is oval bent
Line；
According to formula (19) and (20), Sc2(t) and Sc3(t) S can be expressed asc2And Sc3:
Wherein, parameter B2,B3,θ2,θ3,δ is shown below:
Therefore, S is utilizedc2And Sc3Value can construct following elliptic curve as (x, y) coordinate:
Compared with conventional PGC demodulation method is using one, two frequency multiplication rectified signals, this method uses two, frequency tripling detection
Signal constructs elliptic curve and quadrature phase demodulation.By formula (9), (10) and (11) it is found that compared with a frequency multiplication rectified signal,
Two, frequency tripling rectified signal will be free of DC error item relevant to additional strength modulation, and building elliptic curve parameter is reduced, energy
The influence for reducing system parameter measuring and calculating error to a certain degree, improves signal demodulation performance.
Step S104: building elliptic curve is subjected to elliptic parameter fitting, obtains elliptic equation ax2+bxy+cy2+dx+
A in ey+f=0, b, c, d, each fit parameter values of e, f；
By formula (24) it is found that due to x, the phase difference of y two paths of signals is close to 90 degree, if in mutually perpendicular two coordinates
X, y are drawn simultaneously on axis, track can form a stable ellipse, and elliptic equation can be indicated with implicit equation:
L (au)=ax2+bxy+cy2+ dx+ey+f=0 (25)
Wherein a=[a b c d e f] is oval coefficient vector, u=[x2 xy y2x y 1].Realize that elliptic curve is quasi-
There are many conjunction methods, and ballot clustering method and optimal method etc. can be used, to obtain a, b, c, d, e, each elliptic parameter of f is quasi-
Conjunction value.
Step S105: demodulating system parameter B is obtained according to elliptic curve parameter a, b, c, d, e, f match value2,B3, δ estimation
Value.
Formula (24) and (25) are the expressions of elliptic curve, the member arrangement that disappears are unfolded in formula (24), and compare with formula (25)
Compared with demodulation parameter B in formula (24) can be obtained2,B3, the relationship in δ and formula (25) between elliptic curve parameter a, b, c, d, e, f is as follows:
According to above formula, demodulation system can be calculated using elliptic curve parameter a, b, c, d, e, f value is obtained in step S104
Unite parameter B2,B3, δ estimated value.
Step S201: fibre optic hydrophone is placed in measurement environment and measures tested acoustical signalFibre optic hydrophone output is real
Border interference signal input signal demodulating system；
Step S202: practical interference signal is multiplied with carrier frequency two, frequency tripling reference signal and low-pass filtered respectively,
Obtain practical interference signal two, frequency tripling rectified signal St2And St3；
Step S203: demodulating system parameter estimation value B is utilized2,B3, δ believes the two of practical interference signal, frequency tripling detection
Number St2And St3It is modified, obtains quadrature demodulated signal SR and CR；
According to formula (24), St2And St3It can be expressed as follows:
Wherein,
To St2And St3It is modified as follows:
It is as follows then to can get quadrature demodulation item:
Step S204: orthogonal signalling demodulation is carried out using quadrature demodulated signal SR and CR and is calculated, tested acoustical signal is obtained
Arc tangent quadrature demodulation calculating is carried out using SR and CR, calculating formula is as follows:
Above formula calculation result isAccording to formula (23), with practical tested phaseCompared to only differing θ2, and θ2Value and C, m
WithIt is related, it is unrelated with interferometer initial phase, it is one metastable a small amount of, shadow will not be generated to signal amplitude stability
It rings.
It will no longer include light intensity I in the result using this method resolving compared with conventional PGC demodulation method0, interference degree v,
Phase-modulation amplitude C, additional strength modulation amplitude m and phaseEtc. parameters, and it is unrelated with interferometer initial phase, in this way, can
The influence of intensity modulated effect and various parameters error is effectively eliminated, signal is improved and demodulates stability, obtain high stable signal solution
Adjust output.
Referring to Fig. 3 and Fig. 4, Fig. 3 be invention provide it is a kind of realize interference type optical fiber hydrophone signal demodulating method be
System structure chart, Fig. 4 are a kind of interference type optical fiber hydrophone letters that conventional PGC demodulation method result and second of embodiment provide
The experimental result picture of number demodulation method.
In order to verify the feasibility of this method, a practicable experimental system is as shown in figure 3, by laser 1, non-flat
Weigh Optical Fiber Michelson Interferometer 2, photoelectric converter 3, AD capture card 4 and the composition of signal generator 5.Laser 1 is through sinusoidal frequency
After rate modulation, light wave inputting earthquake waves fibre optic interferometer 2 is issued, non-equilibrium fibre optic interferometer 2 converts 1 frequency modulation(PFM) of laser
Phase carrier is realized for phase-modulation, is returned to interference signal by photoelectric converter 3 and is converted to electric signal, and by AD capture card 4
After completing digitized sampling, carries out signal demodulation and calculate.
Fibre optic interferometer uses non-equilibrium Michelson fiber-optic interferometer structure in experimental system, and analog optical fiber hydrophone is to tested
The response of acoustical signal.Interferometer two-arm is respectively equipped with two PZT phase-modulators, signal generator issue respectively 200Hz and
10mHz sinusoidal signal drives phase-modulator PZT1 and PZT2, and 200Hz signal imitation fibre optic hydrophone senses the underwater sound of 200Hz
Signal, the initial phase difference of 10mHz signal imitation fibre optic interferometer with environmental change slow drift.Control 200Hz sine first drives
Dynamic signal amplitude makes to generate the phase-modulation for (being greater than π) by a relatively large margin, complete elliptic curve at this moment can be obtained, by ellipse
Circle Parameters fitting obtains demodulating system parameter.Then reduce 200Hz sinusoidal drive signals amplitude, generate phase-modulator PZT1
1rad sinusoidal phase modulation, analog optical fiber hydrophone sense acoustical signal, and conventional PGC demodulation method and of the invention is respectively adopted
High stable demodulation method carries out signal demodulation and calculates, and compares the signal stabilization of two methods.
Experimental result is as shown in Figure 4.Fig. 4 (a) be using routine PGC demodulation method acquisition 200Hz signal amplitude at any time
Between variation, upper figure signal amplitude unit be rad, following figure signal amplitude unit be dB (ref:1rad), it is seen that since PZT2 is applied
Add low frequency phase modulation simulation, fibre optic interferometer initial phase generates periodic slow drift, the signal amplitude resolved
Also cyclic fluctuation is generated therewith, and for 1rad signal, signal amplitude fluctuations (difference of signal amplitude maxima and minima) reach
20.3% and 1.76dB.Fig. 4 (b) is the high stable demodulation method calculation result using the application, it is seen that is believed compared with Fig. 4 (a)
Number amplitude fluctuations are obviously reduced, and are 1.89% and 0.16dB for 1rad signal amplitude fluctuations, demonstrate the validity of the application.
A kind of interference type optical fiber hydrophone signal demodulating method provided by the present invention is described in detail above.This
Apply that a specific example illustrates the principle and implementation of the invention in text, the explanation of above example is only intended to
Help understands core of the invention thought.It should be pointed out that for those skilled in the art, not departing from this
, can be with several improvements and modifications are made to the present invention under the premise of inventive principle, these improvement and modification also fall into the present invention
In scope of protection of the claims.
Claims (9)
1. a kind of interference type optical fiber hydrophone signal demodulating method, which comprises the following steps:
Step S100: laser applies sinusoidal frequency modulation, and laser is by the light wave inputting earthquake waves interference-type optical fiber water of output
Listen device, acoustical signal is significantly tested in fibre optic hydrophone application, and fibre optic hydrophone is by the test interference signal input signal solution of output
Adjusting system, and demodulating system parameter estimation value is obtained after testing interference signal processing；
Step S200: fibre optic hydrophone being placed in measurement environment and measures tested acoustical signal, the practical interference of fibre optic hydrophone output
Signal input signal demodulating system is obtained after the processing of practical interference signal and after the amendment of demodulated system parameter estimated value
Tested acoustical signal.
2. interference type optical fiber hydrophone signal demodulating method according to claim 1, which is characterized in that the step S100
Specifically:
Step S101: laser applies sinusoidal frequency modulation, and laser is by the light wave inputting earthquake waves interference-type optical fiber water of output
Listen device, acoustical signal is significantly tested in fibre optic hydrophone application, and fibre optic hydrophone is by the test interference signal input signal solution of output
Adjusting system；
Step S102: test interference signal is multiplied with carrier frequency two, frequency tripling reference signal and low-pass filtered respectively, obtains
Test interference signal two, frequency tripling rectified signal；
Step S103: elliptic curve is constructed using the two of test interference signal, frequency tripling rectified signal；
Step S104: building elliptic curve is subjected to elliptic parameter fitting, obtains the match value of each elliptic curve parameter；
Step S105: demodulating system parameter estimation value is obtained according to elliptic curve parameter fitting value.
3. interference type optical fiber hydrophone signal demodulating method according to claim 2, which is characterized in that the step S200
Specifically:
Step S201: fibre optic hydrophone being placed in measurement environment and measures tested acoustical signal, the practical interference of fibre optic hydrophone output
Signal input signal demodulating system；
Step S202: practical interference signal is multiplied with carrier frequency two, frequency tripling reference signal and low-pass filtered respectively, obtains
Practical interference signal two, frequency tripling rectified signal；
Step S203: being modified the two of practical interference signal, frequency tripling rectified signal using demodulating system parameter estimation value,
Obtain quadrature demodulated signal；
Step S204: orthogonal signalling demodulation is carried out using quadrature demodulated signal and is calculated, tested acoustical signal is obtained.
4. interference type optical fiber hydrophone signal demodulating method according to claim 3, which is characterized in that the step S101
Middle fibre optic hydrophone is by the test interference signal I of outputc(t) are as follows:
Wherein, I0For light intensity DC quantity, m is the intensity modulated amplitude of laser, ωcFor phase carrier circular frequency,For intensity tune
Initial phase processed, v are interference signal visibility, and C is phase carrier modulation amplitude,To test acoustical signal.
5. interference type optical fiber hydrophone signal demodulating method according to claim 4, which is characterized in that the step S102
It is middle test interference signal two, frequency tripling rectified signal Sc2(t) and Sc3(t) it is respectively as follows:
Wherein, X2(t) two frequency multiplication reference signal of carrier frequency, X3(t) carrier frequency frequency tripling reference signal, hLPFIt (t) is low pass
Filter response, a2And a3For error parameter.
6. interference type optical fiber hydrophone signal demodulating method according to claim 5, which is characterized in that the step S103
Middle elliptic curve are as follows:
Wherein,
Sc2(t) and Sc3(t) it is denoted as Sc2And Sc3。
7. interference type optical fiber hydrophone signal demodulating method according to claim 6, which is characterized in that the step S105
In specifically: demodulating system parameter B is obtained according to elliptic curve parameter a, b, c, d, e, f match value2,B3, δ estimated value:
8. interference type optical fiber hydrophone signal demodulating method according to claim 7, which is characterized in that the step S203
In specifically: utilize demodulating system parameter estimation value B2,B3, δ is to the two of practical interference signal, frequency tripling rectified signal St2And St3
It is modified, obtains quadrature demodulated signal SR and CR:
Wherein,
To be tested acoustical signal.
9. interference type optical fiber hydrophone signal demodulating method according to claim 8, which is characterized in that the step S204
In specifically: orthogonal signalling demodulation is carried out using quadrature demodulated signal SR and CR and is calculated, and tested acoustical signal is obtained
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| CN110617872A (en) * | 2019-09-20 | 2019-12-27 | 中国人民解放军国防科技大学 | Optical fiber hydrophone remote transmission array system and method based on compensation interference |
| CN111579047A (en) * | 2020-05-09 | 2020-08-25 | 中国电子科技集团公司第七研究所 | Signal demodulation method of optical fiber vector hydrophone |
| CN111693133A (en) * | 2020-06-24 | 2020-09-22 | 中国电子产品可靠性与环境试验研究所（（工业和信息化部电子第五研究所）（中国赛宝实验室）） | Optical path difference testing device and method for optical fiber hydrophone and computer equipment |
| 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 |
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| CN114383635B (en) * | 2022-01-17 | 2022-11-04 | 中国人民解放军国防科技大学 | PGC signal detection additional phase noise suppression method based on initial phase zero setting |
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