CN108225540A - A kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range - Google Patents
A kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range Download PDFInfo
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Abstract
A kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range, including narrow linewidth laser, the first coupler, first sound-optic modulator, second sound-optic modulator, the first fiber delay time ring, acousto-optic modulator driving, the second coupler, first annular device, the second circulator, the first photodetector, the second photodetector, reference probe, sensing probe and signal demodulation module；The optical signal of the narrow linewidth laser output two pulses light that by first sound-optic modulator and second sound-optic modulator to become frequency different, pulsed light interferes after fiber optic hydrophone unit, beat frequency obtains the heterodyne signal of certain frequency, the system is by improving the frequency of beat frequency heterodyne signal, the dynamic range of heterodyne interference type fibre optic hydrophone is considerably increased, so as to meet the needs of measuring significantly signal.
Description
Technical field
The invention belongs to sensor fields, are related to a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range.
Background technology
At present, fall into marine measuring method for aerial target and mainly there is water column radar, aerial survey, aeroacoustics to measure,
Compared with other measurement methods, environmental suitability is strong for underwater acoustic measurement etc., wherein underwater acoustic measurement mode, can be in night, severe day
Measurement task is performed under gas (dense fog, precipitation etc.), severe sea condition and various marine sites.Marine survey is fallen into for aerial target
Amount demand, using the sonobuoy underwater acoustic measurement scheme based on fiber-optic hydrophone system, at sea in the range of target area, with mesh
Mark is set to the center of circle, and more unjacketed optical fiber hydrophone sonobuoys are uniformly laid on a certain circumference of specified radius, forms Long baselines
Array.Compared with conventional piezoelectric formula hydrophone array, Scale Fiber-Optic Hydrophone Array has that high sensitivity, frequency response be wide, anti-electromagnetism
Interference, light structure, is easy to the features such as telemetering and composition large scale array at adverse environment resistant.
When the energy of striking waters that aerial target falls into sea is larger, general hydrophone is susceptible to amplitude limit phenomenon, leads to nothing
Method is positioned.Being accordingly used in measuring the fiber-optic hydrophone system of impact point positioning needs have higher dynamic range headroom.
Invention content
The technical problem to be solved by the present invention is to：A kind of the outer of Larger Dynamic range is overcome the deficiencies of the prior art and provide
Poor interference formula fiber-optic hydrophone system increases the dynamic range headroom of fiber-optic hydrophone system by improving heterodyne frequency, full
The measurement demand of sufficient Larger Dynamic range.
The object of the invention is achieved by the following technical programs：
A kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range, including narrow linewidth laser, the first coupler,
First sound-optic modulator, second sound-optic modulator, the first fiber delay time ring, acousto-optic modulator driving, the second coupler, the first ring
Shape device, the second circulator, the first photodetector, the second photodetector, reference probe, sensing probe and signal solution mode transfer
Block；
The continuous light of narrow linewidth laser output is divided into two-beam by the first coupler, and two-beam respectively enters the first sound
Optical modulator and second sound-optic modulator, it is different that two-beam by first sound-optic modulator is modulated into frequency from second sound-optic modulator
Two pulses light；The pulsed light of first sound-optic modulator output is by the first fiber delay time ring into being input to second after line delay
Coupler, the pulsed light of second sound-optic modulator output are directly inputted to the second coupler；Two beams are inputted arteries and veins by the second coupler
It washes off and two beams is further divided into after being coupled, the second coupler exports wherein a branch of pulsed light and enters reference after first annular device
Probe, reference probe are exported after pulse light reflection as with reference to optical signal, and reference optical signal enters after first annular device
First photodetector, the first photodetector carry out reference optical signal opto-electronic conversion, the first photodetector output telecommunications
Number give signal demodulation module；Another beam pulse light of second coupler output enters sensing probe after the second circulator,
Sensing probe enters the second light as sensing optical signal output, sensing optical signal using after pulse light reflection after the second circulator
Electric explorer, the second photodetector carry out sensing optical signal opto-electronic conversion, and the second photodetector exports electric signal to letter
Number demodulation module, signal demodulation module demodulate underwater sound signal according to the two path signal received.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, pulsed light pass through the first fiber delay time ring
Delay time be more than or equal to pulsed light pulsewidth.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, reference probe include third coupler, first
Faraday rotation mirror, the second faraday rotation mirror and the second fiber delay time ring；
Pulsed light into reference probe is divided into two-way after third coupler, and pulsed light passes through the first faraday all the way
Third coupler is output to after revolving mirror reflection；Another way pulsed light by the second fiber delay time ring into line delay, after delay
Pulsed light is reflected by the second faraday rotation mirror, and the pulsed light after reflection exports after the delay of the second fiber delay time ring
To third coupler；Third coupler couples the two-way received reflection signal, and output reference optical signal is to first annular
Device.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, the two-way reflection letter coupled at third coupler
Number optical path difference and pulsed light it is identical by the light path of the first fiber delay time ring.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, sensing probe include the 4th coupler, third
Faraday rotation mirror, the 4th faraday rotation mirror and third fiber delay time ring；
Pulsed light into sensing probe is divided into two-way after the 4th coupler, and pulsed light passes through third faraday all the way
Returned in the 4th coupler after revolving mirror reflection, another way pulsed light by third fiber delay time ring into line delay, after delay
Pulsed light is reflected by the 4th faraday rotation mirror, and the pulsed light after reflection exports after the delay of third fiber delay time ring
Into the 4th coupler, the 4th coupler couples the two-way received reflection signal, output sensing optical signal to the second ring
Shape device.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, the two-way reflection letter coupled at the 4th coupler
Number optical path difference and pulsed light it is identical by the light path of the first fiber delay time ring.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, the outside of the reference probe be equipped with sound insulation,
The encapsulation of vibration isolation.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, the outside of the sensing probe are equipped with enhanced sensitivity
Encapsulation, for picking up underwater sound signal.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, the heterodyne interference type light of the Larger Dynamic range
The dynamic range of fine hydrophone system is D, and D takes the first dynamic range headroom D1maxWith the second dynamic range headroom D2maxMinimum
Value；
Wherein
In formula, beat frequencies of the Δ f for heterodyne signal pulse train, fsFor the frequency of acoustical signal, fsamFor heterodyne interference type optical fiber
The efficiently sampling rate of hydrophone system.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, the beat frequency Δ of the heterodyne signal pulse train
F is：
Δ f=f1-f2
Wherein, f1For the continuous light of first sound-optic modulator input terminal, with the pulsed light of first sound-optic modulator output terminal
Between difference on the frequency；f2For the continuous light of second sound-optic modulator input terminal, with the pulsed light of second sound-optic modulator output terminal
Between difference on the frequency.
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, the first sound-optic modulator and the second acousto-optic
The pulse width of the pulsed light of modulator output is τ, and the value range of τ is：
Wherein, Δ f is the beat frequency of heterodyne signal pulse train,；
The period of the first sound-optic modulator and the pulsed light of second sound-optic modulator output is t, the value of t
Ranging from：
t≥3T
In formula
Wherein, fsamFor the efficiently sampling rate of heterodyne interference type fiber-optic hydrophone system, T is the pulse spacing of pulse train,
2L is the fiber lengths of the first fiber delay time ring, and n is optical fibre refractivity, and c is the light velocity；The value range of the T is：
T≥τ
The heterodyne interference type fiber-optic hydrophone system of above-mentioned Larger Dynamic range, the heterodyne interference type light of the Larger Dynamic range
Fine hydrophone system further includes isolator, and the continuous light of narrow linewidth laser output is input to the first coupling after isolator
Device.
The present invention has the advantages that compared with prior art：
(1) present invention is by controlling the shift frequency frequency of first sound-optic modulator and second sound-optic modulator that can improve heterodyne
Carrier frequency so as to improve the dynamic range headroom of fiber-optic hydrophone system, ensures saturation do not occur when demodulating significantly signal
The phenomenon that, so as to preferably apply in target positioning measurment system；
(2) present invention obtains high-frequency carrier wave letter by the shift frequency of first sound-optic modulator and second sound-optic modulator
Number, the interference far from low frequency region improves the signal-to-noise ratio of fiber-optic hydrophone system；
(3) length of the invention by controlling the first fiber delay time ring, the second fiber delay time ring, third fiber delay time ring,
So that the light path that is passed through of pulsed light for generating two different frequencies of carrier signal is identical, two-beam is equiarm interference, can be with
Reduce the influence of laser phase noise；
(4) present invention sets rational pulse width, can be obtained in a beat pulse when heterodyne frequency is higher
Carrier signal more than a cycle, therefore carrier signal can be picked up directly, not need to carry out bandpass filtering, carrier signal again
For exponent number with the low-pass filtering after reference signal multiplication cross than relatively low, these two aspects all greatly reduces the money of digital display circuit
Source improves the efficiency of demodulation.
Description of the drawings
Fig. 1 is the light channel structure figure of the present invention；
Fig. 2 is the sensing probe pulse sequence diagram of the present invention；
Fig. 3 is the demodulation flow diagram of the present invention.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with implementation of the attached drawing to the present invention
Mode is described in further detail.
Fig. 1 is the light channel structure figure of the present invention, and the heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range includes：Narrow line
Wide laser 1, isolator 2, the first coupler 3, first sound-optic modulator 4, second sound-optic modulator 5, the first fiber delay time ring
6th, acousto-optic modulator drives the 7, second coupler 8, first annular device 9, the second circulator 10, the first photodetector 11, second
Photodetector 12, reference probe 13, sensing probe 14 and signal demodulation module 15；
The continuous light that narrow linewidth laser 1 exports divides using the first coupler 3 for two-beam after isolator 2, and two
Shu Guang respectively enters first sound-optic modulator 4 and second sound-optic modulator 5, and two-beam is by first sound-optic modulator 4 and the rising tone
Optical modulator 5 is modulated into the different two pulses light of frequency；The pulsed light that first sound-optic modulator 4 exports prolongs by the first optical fiber
When ring 6 into line delay, pulsed light is more than or equal to the pulsewidth of pulsed light by the delay time of the first fiber delay time ring 6, prolongs
When after pulsed light enter the second coupler 8, the pulsed light that second sound-optic modulator 5 exports is directly inputted to the second coupler
8；Second coupler 8 is further divided into two beams after two beam input pulse light are coupled, the second coupler 8 exports a wherein beam pulse
Light enters reference probe 13 after first annular device 9, and reference probe 13 is exported after pulse light reflection as with reference to optical signal,
Reference optical signal enters the first photodetector 11 after first annular device 9, and the first photodetector 11 is to reference optical signal
Opto-electronic conversion is carried out, the first photodetector 11 exports electric signal to signal demodulation module 15；Second coupler 8 exports another
Beam pulse light enters sensing probe 14 after the second circulator 10, sensing probe 14 using after pulse light reflection as sense light
Signal exports, and sensing optical signal enters the second photodetector 12 after the second circulator 10, and the second photodetector 12 is right
It senses optical signal and carries out opto-electronic conversion, the second photodetector 12 exports electric signal to signal demodulation module 15, signal solution mode transfer
Block 15 demodulates underwater sound signal according to the two path signal received.
Reference probe 13 include third coupler 131, the first faraday rotation mirror 132, the second faraday rotation mirror 133 with
Second fiber delay time ring 134；Pulsed light into reference probe 13 is divided into two-way after third coupler 131, pulse all the way
Light is output to third coupler 131 after the reflection of the first faraday rotation mirror 132；Another way pulsed light prolongs by the second optical fiber
When ring 134 into line delay, the pulsed light after delay is reflected by the second faraday rotation mirror 133, the pulsed light after reflection
Third coupler 131 is output to after the delay of the second fiber delay time ring 134；Third coupler 131 reflects the two-way received
Signal is coupled, and the optical path difference of two-way reflection signal coupled at third coupler 131 is prolonged with pulsed light by the first optical fiber
When ring 6 light path it is identical, output reference optical signal is to first annular device 9.Pressed down in reference probe 13 using faraday rotation mirror
Polarization decay phenomenon processed eliminates polarization state variation influence caused by 13 performance of reference probe.The outside of reference probe 13 is equipped with
Sound insulation, the encapsulation of vibration isolation.
Sensing probe 14 include the 4th coupler 141, third faraday rotation mirror 142, the 4th faraday rotation mirror 143 with
Third fiber delay time ring 144；Pulsed light into sensing probe 14 is divided into two-way after the 4th coupler 141, pulse all the way
Light is returned to after the reflection of third faraday rotation mirror 142 in the 4th coupler 141, and another way pulsed light prolongs by third optical fiber
When ring 144 into line delay, the pulsed light after delay is reflected by the 4th faraday rotation mirror 143, the pulsed light after reflection
It is output in the 4th coupler 141 after the delay of third fiber delay time ring 144, the 4th coupler 141 is anti-by the two-way received
It penetrates signal to be coupled, the optical path difference of two-way reflection signal coupled at the 4th coupler 141 passes through the first optical fiber with pulsed light
The light path of time delay ring 6 is identical, output sensing optical signal to the second circulator 10.Faraday rotation mirror is used in sensing probe 14
Inhibit polarization decay phenomenon, eliminate polarization state variation influence caused by 14 performance of sensing probe.The outside of sensing probe 14 is set
There is the encapsulation of enhanced sensitivity, for picking up underwater sound signal.
The realization of heterodyne interference type fiber-optic hydrophone system Larger Dynamic range, is as follows：
Step 1: 1 output frequency of narrow linewidth laser is f0Continuous light after isolator 2 using the first coupler
3 points of two-beams, two-beam respectively enter first sound-optic modulator 4 and second sound-optic modulator 5；First sound-optic modulator 4 will be even
Continuous light modulation into the period be t, pulse width τ, frequency f0+f1Pulsed light, frequency f0+f1Pulsed light pass through optical fiber
Enter the second coupler 8 after the first fiber delay time ring 6 that length is 2L；Second sound-optic modulator 5 is by continuous light modulation into the period
For t, pulse width τ, frequency f0+f2Pulsed light, frequency f0+f2Pulsed light be directly entered the second coupler 8；Frequently
Rate is f0+f1Pulsed light and frequency be f0+f2Pulsed light time interval be T=2L*n/c；N is optical fibre refractivity, and c is
The light velocity.
Step 2: the second coupler 8 is f to frequency in step 10+f1It is f with frequency0+f2Two pulses light is coupled
After be further divided into two beams, wherein a branch of enter after the second circulator 10 in sensing probe 14, the optics knot of sensing probe 14
Structure is non-equiarm Michelson's interferometer, and arm length difference L, speculum is faraday rotator mirror；Another beam passes through the second ring
It is entered after shape device 9 in reference probe 13, examines the optical texture of probe 13 as non-equiarm Michelson's interferometer, arm length difference L,
Speculum is faraday rotator mirror.
Step 3: the pulsed light into reference probe 13 is divided into two-way after third coupler 131, pulsed light passes through all the way
It is returned in third coupler 131 after crossing the reflection of the first faraday rotation mirror 132, another way pulsed light is L the by fiber lengths
Two fiber delay time rings 134 are into line delay, and the pulsed light after delay is reflected by the second faraday rotation mirror 133, after reflection
Pulsed light by the second fiber delay time ring 134 delay after be output in third coupler 131, the first faraday rotator mirror
Frequency is f in 132 reflected impulse light0+f1Part, the frequency with the reflection of, the second faraday rotator mirror 133 is f0+f2's
After part interferes in third coupler 131, form one group and contain beat frequency for Δ f=f1-f2Heterodyne signal pulse sequence
Row, the period of pulse train is t, and the pulse spacing of pulse train is T；Above-mentioned pulse train enters after first annular device 9
First photodetector 11, the first photodetector 11 carry out opto-electronic conversion to pulse train, the electric signal after opto-electronic conversion into
Enter signal demodulation module 15.
Step 4: the pulsed light into sensing probe 14 is divided into two-way after the 4th coupler 141, pulsed light passes through all the way
It crosses after third faraday rotation mirror 142 reflects and returns in the 4th coupler 141, another way pulsed light is L the by fiber lengths
Three fiber delay time rings 144 are into line delay, and the pulsed light after delay is reflected by the 4th faraday rotation mirror 143, after reflection
Pulsed light by third fiber delay time ring 144 delay after be output in the 4th coupler 141, third faraday rotator mirror
Frequency is f in 142 reflected impulse light0+f1Part, the frequency with the reflection of, the 4th faraday rotator mirror 143 is f0+f2's
After part interferes in the 4th coupler 141, form one group and contain beat frequency for Δ f=f1-f2Heterodyne signal pulse sequence
Row, the period of pulse train is t, and the pulse spacing of pulse train is T；Above-mentioned pulse train enters after the second circulator 10
Second photodetector 12, the second photodetector 12 carry out opto-electronic conversion to pulse train, the electric signal after opto-electronic conversion into
Enter signal demodulation module 15.
Step 5: sensing probe 14 returns in reference probe 13 returns in step 3 periodic pulse train and step 4
Periodic pulse train, as shown in Fig. 2, being made of in each period three pulses, intermediate pulse is beat pulse, wherein
The beat pulse that sensing probe 14 returns is loaded with extraneous signal.After heterodyne frequency is improved, pulse width τ, Ke Yi are set
Carrier signal more than a cycle is obtained in one beat pulse.This carrier signal is directly carried out using the algorithm of arc tangent
Demodulation, obtains outer signals.In periodic pulse train, the period of pulse train is t, and the pulse spacing of pulse train is T
It needs to meet following relationship with pulse width τ：
The fiber lengths of second fiber delay time ring 134 and third fiber delay time ring 144 are L, and as can be seen from the above equation
The length of 144 optical fiber of two fiber delay time rings 134 and third fiber delay time ring determines heterodyne interference type fiber-optic hydrophone system
Maximum efficiently sampling rate fsam。
Step 6: determine the value range of each parameter in step 5.It is outer in order to demodulate in the case where improving heterodyne frequency
Sector signal, heterodyne frequency Δ f, the efficiently sampling rate f of heterodyne interference type fiber-optic hydrophone systemsamWith capture card sample rate facqIt will
Meet following relationship：
Δ f=Nfsam, N=2,3 ...
When N is integer, the form that can cause carrier signal in each beat pulse is identical, ensures to each pulse
Identical data processing method may be used, improve treatment effeciency.
In addition at least there are 1.25 carrier signals more than period in each beat pulse width, as a result of optics
Reference probe 13, the signal of reference probe 13 is identical with the signal of sensing probe 14, does not contain extraneous letter in carrier signal only
Number.Reference probe 13 provides the reference signal in arc tangent algorithm, needs to carry out orthogonal processing by shifting point method to reference signal,
As orthogonal reference signal, if as shown in figure 3, the carrier signal in pulse will lead to sampled point not less than 1.25 periods
Phase shift can not be carried out enough.Therefore pulse width τ and heterodyne frequency Δ f will meet following relationship：
According to nyquist sampling law, processing be digitized to the carrier signal in beat pulse, need number
The sample rate of change is at least 4 times of heterodyne frequency, and guarantee has enough sampling numbers.Therefore heterodyne frequency Δ f and signal demodulation
Digitized sampling rate f in module 15acqMeet following relationship：
Step 7: determine the dynamic range D of heterodyne interference type fiber-optic hydrophone system.Heterodyne interference type fibre optic hydrophone system
The signal psi (t) of system can be expressed as:
Amplitudes of the wherein A for interference signal, frequencies of the Δ f for heterodyne, φs(t) be extraneous acoustical signal form, D ' expressions
The amplitude of signal, fsFor the frequency of acoustical signal, φ0For the initial phase of acoustical signal, t is the time.
The upper limit for the dynamic range that heterodyne frequency Δ f is determined can be derived according to Carson's criterion, effective harmonic wave bandwidth E and letter
The peak value df of number instantaneous frequencypAnd the frequency f of acoustical signalsIt is related, it can be expressed as：
E=2 (dfp+fs)
So
E=2 (D ' fs+fs)
The width E maximums of effective harmonic wave are no more than frequency, that is, E of heterodyne<Thus 2 Δ f are determined knowable to formula by heterodyne frequency
The first fixed dynamic range headroom D1maxIt can be expressed as：
The upper limit of the dynamic range of heterodyne interference type fiber-optic hydrophone system is listened by heterodyne frequency, heterodyne interference type optical fiber water
The sample rate and demodulating algorithm of device system determine.Common demodulating algorithm has differential multiplication cross and arc tangent, wherein arc tangent
The upper limit of the dynamic range of algorithm is higher than differential multiplication cross.Second dynamic range headroom D of arc tangent algorithm2maxIt can be with table
It is shown as：
The dynamic range D, D of heterodyne interference type fiber-optic hydrophone system take the first dynamic range headroom D1maxWith the second dynamic
Range limit D2maxMinimum value.
Traditional heterodyne interference type fiber-optic hydrophone system, in the case where light channel structure is certain, heterodyne interference type optical fiber
The efficiently sampling rate f of hydrophone systemsamIt is one and determines value, fsamThe frequency Δ f of heterodyne is also determined, relationship between the two will
Meet Nyquist's theorem, i.e. fsam>4Δf.Based on Nyquist's theorem, in the situation that system efficiently sampling frequency is definite value
Under, using the method for improving the fibre optic hydrophone heterodyne frequency upper limit, the effect that can improve fibre optic hydrophone dynamic range is limited,
Cannot meet the needs of measuring significantly signal.Marine measurement demand is fallen into order to meet aerial target, in systematic sampling frequency
In the case that rate is certain value, the method for the Dynamic Range upper limit is improved using fibre optic hydrophone heterodyne frequency is improved, is made
It is more than the efficiently sampling frequency of system with heterodyne frequency, the two no longer meets Nyquist's theorem, and the system upper limit is had by system
It imitates sample frequency to determine, the dynamic range D of heterodyne interference type fiber-optic hydrophone system still takes the first dynamic range headroom D1maxWith
Second dynamic range headroom D2maxMinimum value.And in traditional heterodyne interference type fiber-optic hydrophone system, D1maxIt is less than
D2max, therefore the value of the dynamic range of traditional heterodyne interference type fiber-optic hydrophone system is D1max, and the present invention no longer meets
Dynamic range D values after Nyquist's theorem are D2max, so dynamic range is far above traditional heterodyne interference type optical fiber water
Listen device system.
In the present embodiment, the length of the first fiber delay time ring 6 is 30m, sensing probe 14 and the mikey in reference probe 13
The two-arm arm length difference of your inferior interferometer is 15m, and design in this way can ensure the different frequency pulse institute of two acousto-optic modulators modulation
The light path of process is identical, is interfered respectively at third coupler 131 and the 4th coupler 141, respectively as reference signal
With transducing signal.The shift frequency frequency of first sound-optic modulator 4 is 95MHz, and the shift frequency frequency of second sound-optic modulator 5 is 85MHz,
The frequency interval of pulsed light is 1.25MHz, pulse width 136ns, is formed at third coupler 131 and the 4th coupler 141
Sensing optical signal and reference optical signal frequency be 10MHz.As shown in figure 3, sensing optical signal passes through A/D with reference optical signal
Digital demodulation is carried out after conversion, carries out the pretreatment of transducing signal and reference signal using FPGA, i.e., the extraction of carrier wave, with reference to letter
Number 90 ° of phase shifts, reference signal are multiplied with transducing signal, low-pass filtering, and the solution of underwater sound signal is then carried out using arc tangent algorithm
It adjusts, last underwater sound signal is obtained using high-pass filtering.
The heterodyne interference type fiber-optic hydrophone system formed with above-mentioned parameter and device, can the dynamic of system be transferred to of solution
Range limit is 625rad, be carrier frequency is 3.1 times of the 200KHz Dynamic Range upper limits, dynamic range headroom have compared with
Big raising meets the needs of impact point positioning measurement.
The content not being described in detail in description of the invention belongs to the known technology of those skilled in the art.
Claims (12)
1. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range, it is characterised in that：Including narrow linewidth laser
(1), the first coupler (3), first sound-optic modulator (4), second sound-optic modulator (5), the first fiber delay time ring (6), acousto-optic
Modulator driving (7), the second coupler (8), first annular device (9), the second circulator (10), the first photodetector (11),
Second photodetector (12), reference probe (13), sensing probe (14) and signal demodulation module (15)；
The continuous light of narrow linewidth laser (1) output is divided into two-beam by the first coupler (3), and two-beam respectively enters first
Acousto-optic modulator (4) and second sound-optic modulator (5), two-beam is by first sound-optic modulator (4) and second sound-optic modulator (5)
It is modulated into the different two pulses light of frequency；The pulsed light of first sound-optic modulator (4) output passes through the first fiber delay time ring (6)
The second coupler (8) is input to after into line delay, the pulsed light of second sound-optic modulator (5) output is directly inputted to the second coupling
Device (8)；Second coupler (8) is further divided into two beams after two beam input pulse light are coupled, the second coupler (8) exports wherein
A branch of pulsed light after first annular device (9) enter reference probe (13), reference probe (13) using after pulse light reflection as
Reference optical signal exports, and reference optical signal enters the first photodetector (11) after first annular device (9), and the first photoelectricity is visited
It surveys device (11) and opto-electronic conversion is carried out to reference optical signal, the first photodetector (11) exports electric signal to signal demodulation module
(15)；Another beam pulse light of second coupler (8) output enters sensing probe (14) after the second circulator (10), passes
Sense probe (14) enters after pulse light reflection as sensing optical signal output, sensing optical signal after the second circulator (10)
Second photodetector (12), the second photodetector (12) carry out opto-electronic conversion, the second photodetector to sensing optical signal
(12) it exports electric signal and gives signal demodulation module (15), signal demodulation module (15) is demodulated according to the two path signal received
Underwater sound signal.
2. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to claim 1, it is characterised in that：
Pulsed light is more than or equal to the pulsewidth of pulsed light by the delay time of the first fiber delay time ring (6).
3. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to claim 1, it is characterised in that：
Reference probe (13) including third coupler (131), the first faraday rotation mirror (132), the second faraday rotation mirror (133) with
Second fiber delay time ring (134)；
Pulsed light into reference probe (13) is divided into two-way after third coupler (131), and pulsed light passes through first all the way
Third coupler (131) is output to after faraday rotation mirror (132) reflection；Another way pulsed light passes through the second fiber delay time ring
(134) into line delay, the pulsed light after delay is reflected by the second faraday rotation mirror (133), the pulsed light after reflection
Third coupler (131) is output to after the delay of the second fiber delay time ring (134)；Third coupler (131) will receive two
Road reflection signal is coupled, output reference optical signal to first annular device (9).
4. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to claim 3, it is characterised in that：
The optical path difference of two-way reflection signal coupled at third coupler (131) passes through the light of the first fiber delay time ring (6) with pulsed light
Cheng Xiangtong.
5. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to claim 1, it is characterised in that：
Sensing probe (14) including the 4th coupler (141), third faraday rotation mirror (142), the 4th faraday rotation mirror (143) with
Third fiber delay time ring (144)；
Pulsed light into sensing probe (14) is divided into two-way after the 4th coupler (141), and pulsed light passes through third all the way
It is returned in the 4th coupler (141) after faraday rotation mirror (142) reflection, another way pulsed light passes through third fiber delay time ring
(144) into line delay, the pulsed light after delay is reflected by the 4th faraday rotation mirror (143), the pulsed light after reflection
It is output in the 4th coupler (141) after third fiber delay time ring (144) delay, the 4th coupler (141) is by what is received
Two-way reflection signal is coupled, output sensing optical signal to the second circulator (10).
6. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to claim 5, it is characterised in that：
The optical path difference of two-way reflection signal coupled at 4th coupler (141) passes through the light of the first fiber delay time ring (6) with pulsed light
Cheng Xiangtong.
7. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to one of claim 1~6, special
Sign is：The outside of the reference probe (13) is equipped with the encapsulation of sound insulation, vibration isolation.
8. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to one of claim 1~6, special
Sign is：The outside of the sensing probe (14) is equipped with the encapsulation of enhanced sensitivity, for picking up underwater sound signal.
9. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to claim 1, it is characterised in that：
The dynamic range of the heterodyne interference type fiber-optic hydrophone system of the Larger Dynamic range is D, and D takes the first dynamic range headroom D1max
With the second dynamic range headroom D2maxMinimum value；
Wherein
In formula, beat frequencies of the Δ f for heterodyne signal pulse train, fsFor the frequency of acoustical signal, fsamIt is listened for heterodyne interference type optical fiber water
The efficiently sampling rate of device system.
10. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to claim 9, feature exist
In：The beat frequency Δ f of the heterodyne signal pulse train is：
Δ f=f1-f2
Wherein, f1For the continuous light of first sound-optic modulator (4) input terminal, with the pulse of first sound-optic modulator (4) output terminal
Difference on the frequency between light；f2For the continuous light of second sound-optic modulator (5) input terminal, with second sound-optic modulator (5) output terminal
Pulsed light between difference on the frequency.
11. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to claim 9, feature exist
In：The pulse width of the pulsed light of the first sound-optic modulator (4) and second sound-optic modulator (5) output is τ, and τ's takes
Value is ranging from：
Wherein, Δ f is the beat frequency of heterodyne signal pulse train；
The period of the pulsed light of the first sound-optic modulator (4) and second sound-optic modulator (5) output is t, and t's takes
Value is ranging from：
t≥3T
In formula
Wherein, fsamFor the efficiently sampling rate of heterodyne interference type fiber-optic hydrophone system, T is the pulse spacing of pulse train, and 2L is
The fiber lengths of first fiber delay time ring (6), n are optical fibre refractivities, and c is the light velocity；The value range of the T is：
T≥τ。
12. a kind of heterodyne interference type fiber-optic hydrophone system of Larger Dynamic range according to one of claim 1~6,
It is characterized in that：The heterodyne interference type fiber-optic hydrophone system of the Larger Dynamic range further includes isolator (2), narrow linewidth laser
(1) the continuous light of output is input to the first coupler (3) after isolator (2).
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