CN1858558A - Open-ring signal processing method and circuit of sagnac interference optical fiber sensor - Google Patents

Abstract

This invention relates to a process method to open-loop signals for a Sagnac interference fiber sensor, which utilizes an analog driving signal to drive a phase-modulator in the fiber sensor to further drive the sensor to output modulation signals, first of all, the output signals of the sensor DC blocked then filtered in low pass to get 2-2n adjacent negative peak values of the sensor output signals in 1 to n periods of the modulated driving signals by a negative peak value detecting circuit coupled to the low pass filter to get information of the tested phase difference from the 2-2n negative peak values.

Description

A kind of open-ring signal processing method and the circuit of Sagnac interferometric optical fiber sensor

Technical field

The present invention relates to the signal processing method and the circuit of Sagnac interferometric optical fiber sensor output, comprise that optical fibre gyro, optical fiber current mutual inductor etc. use Sagnac interferometric optical fiber sensors.Special the present invention is related to a kind of accurate open-ring signal processing method and the circuit of Sagnac interferometric optical fiber sensor.

Background technology

The Fibre Optical Sensor major part of at present researching and developing and commercially producing comprises optical fibre gyro, current sensor, flow sensor, sonic transducer, nautical receiving set etc. based on the fibre optic interferometer that adopts Sine Modulated.Here the magnetic field sensor output of United States Patent (USP) " the Fiber OpticInterferometer Circuit and Magnetic Field Sensor " optical fiber of being published in 1997 by J.Blake as a reference U.S.Pat.No.5664397) is exactly an example of interferometric optical fiber sensor.Another example is equally by open-ring signal processing method and the circuit U .S.Pat.No.5978084 of J.Blake at United States Patent (USP) " the Open Loop Signal ProcessingCircuit and Method For Λ Fiber Optic Interferometric Sensor " Fibre Optical Sensor of publication in 1999).As an example of Fibre Optical Sensor, optical fibre gyro can survey the Sagnac effect that causes of rotation and cause the phase differential of two-beam.The optical fibre gyro of low precision has begun to use on a large scale in the military and civilian goods at present, and high-precision optical fibre gyro is also in positive research and development.The Sagnac effect is meant in a closed-loop path, when ring interferometer rotates, along clockwise (CW, Clockwise) direction and counterclockwise (CCW Counterclockwise) produces a phase difference φ who is proportional to speed of rotation Ω between the two-beam that direction is propagated. the expression formula of phase difference φ is $\mathrm{\Δ\φ}=\frac{4\mathrm{\ωA}}{c^2}\mathrm{\Ω}---\left(1\right);$ In the formula, Λ is the area that light path is surrounded; ω is the angular frequency of light wave, and c is the light velocity, and Ω is a speed of rotation.Another purposes of Fibre Optical Sensor is electric current and magnetic field sensor, and the phase differential in this field between the two-beam is caused by Faraday magnetooptical effect.

Obtain useful information (generally being the phase differential of two-beam) from the output of Saganac Fibre Optical Sensor and adopt the open loop signal treatment technology usually.Though the closed signal treatment technology can obtain higher precision than open loop signal treatment technology, but the open loop signal treatment technology adopts the unifrequency modulation, rather than resemble and adopt wide-band modulation the closed signal treatment technology, this makes open loop signal treatment technology cost reduce greatly.Therefore, the open loop signal treatment technology is used widely under many circumstances.

Ideally the Sagnac fibre optic interferometer through Sine Modulated is output as:

$I_{\mathrm{out}}=\frac{I_0}{2}\{1+\cos [{\mathrm{\φ}}_s+{\mathrm{\φ}}_m\cos (\mathrm{\ωt}+\mathrm{\θ})\left]\right\}---\left(2\right)$

(2) in the formula, φ _sBe tested phase differential, φ _mBe depth of modulation, ω is a modulating frequency, and θ is the uncertain phase differential between the modulation signal of modulated drive signal and fibre optic interferometer output.The signal processing method of widespread use is to utilize combined synchronous demodulation technique the most, promptly uses and the modulated drive signal standard sine signal of frequency homophase together and the output I of fibre optic interferometer _OutCarry out mixing then filtering extract fibre optic interferometer output I _OutIn an order harmonic component: I _1st=I ₀J ₁(φ _m) cos θ sin φ _sBecause contain 4 unknown quantitys in the following formula, therefore, general open loop signal processing scheme comprises 4 basic circuits.Wherein three basic circuits are used for extracting I as synchronous demodulator (frequency mixer adds low-pass filter) _OutIn 3 harmonic components of same order not, the 4th circuit is used for determining θ.Synchronous demodulator needs the wave filter of stable high Q value to come more different order harmonic component with high-precision ratio circuit.Signal processing circuitry such in the practical application is very complicated, needs up to a hundred circuit components usually, has reduced the reliability of system, and has involved great expense.Therefore, thereby be necessary that the quantity that reduces circuit component reduces the complicacy of signal processing circuitry and realization easily, the reliability of raising signal processing circuit, and reduce cost.

In the middle of the actual conditions,, therefore must bring error because the element in the Fibre Optical Sensor is undesirable.The Fibre Optical Sensor output signal is expressed with following formula in this case:

$I_{\mathrm{out}}=\frac{I_0}{2}\{1+(1-\mathrm{\δ})\cos [{\mathrm{\φ}}_s+{\mathrm{\φ}}_m\cos (\mathrm{\ωt}+\mathrm{\θ})]-\mathrm{\δ}\cos [{\mathrm{\φ}}_m\cos (\mathrm{\ωt}+\mathrm{\θ})\left]\right\}---\left(3\right)$

If do not consider the error term δ in (3) formula then the performance index of the element in the Fibre Optical Sensor (for example polarization form converter in the fibre optic current sensor) are required very high, difficulty that realizes and the accuracy that reduces signal Processing certainly will have been increased.In addition, this error term generally varies with temperature, and this can cause scale factor to drift about with temperature.Therefore eliminate the signal processing method of this error term and circuit and can reduce the requirement of the performance index of the element in the Fibre Optical Sensor and the accuracy that can improve signal Processing, prior is that this has guaranteed that simultaneously scale factor is not with temperature drift.

Summary of the invention

The present invention seeks to: propose that a kind of with traditional closed loop and open-ring signal processing method compare with circuit that cost is cheaper, structure is simpler, easier realization, the signal processing method accurately and the circuit that are more suitable for manufacturing; The present invention also aims to: sort signal disposal route and circuit reduce the requirement of the performance index of the element in the Fibre Optical Sensor and the accuracy that can improve signal Processing.Compared with former invention, signal processing method of the present invention and circuit for eliminating reduced their deficiency in other words to a great extent.

The present invention seeks to realize like this: a kind of open-ring signal processing method of Sagnac interferometric optical fiber sensor, utilize the phase-modulator in the analog-modulated drive Fibre Optical Sensor and then make Fibre Optical Sensor output modulation signal, at first the modulation signal of Fibre Optical Sensor output is carried out every directly, then low-pass filtering; And the modulation signal that obtains Fibre Optical Sensor output of the negative peak detection circuit through being coupled to low-pass filter at 1 of modulated drive signal to n (n is a positive integer here) individual adjacent negative peak of the 2～2n individual cycle in, can obtain the information of tested phase differential by this 2～2n adjacent negative peak, n 〉=1, especially n=1.Below be that example describes with n=1.Notice that " negative peak " among the present invention is not numerically must be negative (just), but for just (bearing) peak value, its real physical meaning be two of modulation signal adjacent just (bear) minimum (greatly) value between the peak value, this depends on the interval of tested phase differential.When tested phase differential be in [90 °, 90 °] interval in the time is negative peak, its real physical meaning is the minimal value between two adjacent positive peaks of modulation signal; When tested phase differential be in [90 °, 270 °] interval in the time is positive peak, its real physical meaning is the maximum value between two adjacent negative peaks of modulation signal.Below be that example describes with the negative peak detection.Simultaneously the Fibre Optical Sensor output signal is carried out directly that peak value detects and and the output of negative peak detection circuit do division; The method that negative peak is surveyed is to utilize square-wave signal that the modulated drive signal zero passage produces that the modulation signal of the output of the Fibre Optical Sensor after straight low-pass filtering is carried out negative peak to detect; Division output is the output of signal processing system.

Regulate the amplitude of analog drive signal and can regulate depth of modulation, adjust depth of modulation by the feedback signal that feedback control circuit provides.

Signal processing method of the present invention utilizes the modulated drive signal zero passage that the Fibre Optical Sensor output signal is carried out negative peak peak detection directly to be carried out in the output of Fibre Optical Sensor when surveying, and makes the influence of the two error term of bringing divided by elimination light intensity and light path element (for example polarization form converter in the optical fiber current mutual inductor) to signal Processing.

To the negative peak after straight low-pass filtering survey and directly the output of peak detection do division and eliminate the error that light intensity and light path element (for example polarization form converter in the fibre optic current sensor) imperfection bring.

The signal that the negative peak detector provides has comprised the information of depth of modulation, the signal controlling that the feedback signal that feedback control circuit provides is provided by the negative peak detector.

During n=1, only 2 in 1 cycle of Fibre Optical Sensor output signal adjacent negative peaks are surveyed, eliminated the influence of the uncertain phase differential between modulated drive signal and the Fibre Optical Sensor output modulation signal, this phase differential generally changes with temperature and time.

Method provided by the invention makes that by the suitable choice of modulation degree of depth working point signal processing circuit of employing the method is insensitive to the variation of depth of modulation, thereby does not need to carry out the modulator FEEDBACK CONTROL under the room temperature situation.

Every the direct sum low-pass filtering flip-flop in the signal is removed, high frequency noise also removes, and has both avoided system signal to drift about with environmental factors such as temperature, has improved signal to noise ratio (S/N ratio) again.

Signal processing method provided by the invention makes the dynamic range of tested phase differential be not limited to [90 °, 270 °], dynamic range can be expanded to 1 cycle by counter is set, and promptly tested phase differential can also can be greater than 270 ° less than-90 °.The Sagnac interferometer situation that this design requires at great dynamic ranges such as optical fibre gyros especially.

Sagnac interferometric optical fiber sensor open loop signal treatment circuit: utilize the phase-modulator in the analog-modulated drive signal generator driving Fibre Optical Sensor and then make Fibre Optical Sensor output modulation signal, the output of Fibre Optical Sensor connects a capacitance that is coupled to the output of Fibre Optical Sensor and is used for eliminating the flip-flop of Fibre Optical Sensor output and one and is coupled to the low-pass filter that this capacitance is used for eliminating high frequency noise, be coupled to 2 adjacent negative peaks of negative peak detection circuit modulation signal of detection optical fiber sensor output in n the cycle of modulated drive signal of low-pass filter, the information of tested phase differential can be obtained by this 2n adjacent negative peak, and the FEEDBACK CONTROL phase-modulator can be used for to stablize the depth of modulation working point.Other one road signal that described analog drive signal generator is provided with output is similarly the standard sine signal, be coupled to comparer, whenever driving the upset of modulation signal zero-crossing comparator output square-wave signal electrical level polar, and this level remains to always and drives the modulation signal zero passage next time, and this logic level is used for control figure negative peak detector.The output of comparer connects digital negative peak detector, the output of numeral negative peak detector connects divider circuit, the simulated peak detection circuit that is directly coupled to Fibre Optical Sensor output is simultaneously imported divider through analog to digital conversion circuit, and carries out division arithmetic with the output of digital negative peak detector.The output of divider circuit is the output of signal processing system.

The simulated peak detector is directly coupled to the peak value that Fibre Optical Sensor is used for obtaining Fibre Optical Sensor output, and this peak value is used for and the output of digital negative peak detection circuit is done division to eliminate the error that light intensity and light path element imperfection bring.

The formation of comparator circuit: whenever the just upset of logic level of modulated drive signal zero-crossing comparator, and keep this level until modulated drive signal zero passage next time, the cycle of the square-wave signal of Chan Shenging is with regard to the corresponding cycle that drives modulation signal like this, preceding half period and back half period be the electrical level polar of respective opposite respectively, for example, preceding half period negative level, back half period positive level is perhaps opposite.The logical value that positive negative level is corresponding different respectively, this logical value is used for importing the negative peak detector, to obtain 2 adjacent negative peaks in the modulation signal that the one-period inner fiber sensor of modulated drive signal is exported.

The signal that 2 the adjacent negative peak additions of Fibre Optical Sensor output signal in each cycle of modulated drive signal obtain has comprised the information of depth of modulation, be coupled to feedback control circuit as an output of digital negative peak detector and be used for controlling depth of modulation, stablize the depth of modulation working point.The information that has comprised phase differential of subtracting each other 2 adjacent negative peaks of Fibre Optical Sensor output signal in 1 cycle of modulated drive signal is coupled to the input of divider as divider.

Thereby low-pass filter is used for the high frequency noise of filtering Fibre Optical Sensor output produces the modulation signal of exporting through filtered Fibre Optical Sensor.Through the modulation signal of the output of the Fibre Optical Sensor after the Filtering Processing owing to having eliminated its DC component thereby be not subjected to the variation of factors such as temperature to cause the drift of DC component every straight; Because low-pass filtering has been eliminated high frequency noise, has improved signal to noise ratio (S/N ratio).

Signal processing circuit provided by the invention makes the dynamic range of tested phase differential be not limited to [90 °, 270 °], dynamic range can be expanded to the individual cycle of m (m 〉=1 and be positive integer) by counter is set, promptly tested phase differential can also can be greater than 270 ° less than-90 °.The Sagnac interferometer situation that this design requires at great dynamic ranges such as optical fibre gyros especially.

Principle of the present invention below is described.The output of Fibre Optical Sensor obtains through every directly:

$I_{\mathrm{out}.\mathrm{dc}}=\frac{I_0}{2}(1-\mathrm{\δ})\cos [{\mathrm{\φ}}_s+{\mathrm{\φ}}_m\cos (\mathrm{\ωt}+\mathrm{\θ})]-\frac{I_0}{2}(1-\mathrm{\δ})\cos {\mathrm{\φ}}_s{J}_0\left({\mathrm{\φ}}_m\right)$ ?(4)

$-\frac{I_0}{2}\mathrm{\δ}\cos \left[{\mathrm{\φ}}_m\cos (\mathrm{\ωt}+\mathrm{\θ})\right]+\frac{I_0}{2}\mathrm{\δ}{J}_0\left({\mathrm{\φ}}_m\right)$

The negative peak detector detects Fibre Optical Sensor and is driving 2 the adjacent negative peaks of modulation signal in 1 cycle:

$\mathrm{\ωt}+\mathrm{\θ}=\mathrm{\π}\⇒I_{\mathrm{out}.\mathrm{dc}2}=\frac{I_0}{2}(1-\mathrm{\δ})\cos ({\mathrm{\φ}}_s-{\mathrm{\φ}}_m)-\frac{I_0}{2}(1-\mathrm{\δ})\cos {\mathrm{\φ}}_s{J}_0\left({\mathrm{\φ}}_m\right)-\frac{I_0}{2}\mathrm{\δ}\cos {\mathrm{\φ}}_m+\frac{I_0}{2}{\mathrm{\δJ}}_0\left({\mathrm{\φ}}_m\right)---\left(5\right)$

$\mathrm{\ωt}+\mathrm{\θ}=2\mathrm{\π}\⇒I_{\mathrm{out}.\mathrm{dc}4}=\frac{I_0}{2}(1-\mathrm{\δ})\cos ({\mathrm{\φ}}_s+{\mathrm{\φ}}_m)-\frac{I_0}{2}(1-\mathrm{\δ})\cos {\mathrm{\φ}}_s{J}_0\left({\mathrm{\φ}}_m\right)-\frac{I_0}{2}\mathrm{\δ}\cos {\mathrm{\φ}}_m+\frac{I_0}{2}{\mathrm{\δJ}}_0\left({\mathrm{\φ}}_m\right)---\left(6\right)$

The difference of these 2 adjacent negative peaks is:

$M=I_{\mathrm{out}.\mathrm{dc}2}-I_{\mathrm{out}.\mathrm{dc}4}=\frac{I_0}{2}(1-\mathrm{\δ})\cos ({\mathrm{\φ}}_s-{\mathrm{\φ}}_m)-\frac{I_0}{2}(1-\mathrm{\δ})\cos {\mathrm{\φ}}_s{J}_0\left({\mathrm{\φ}}_m\right)-\frac{I_0}{2}\mathrm{\δ}\cos {\mathrm{\φ}}_m+\frac{I_0}{2}{\mathrm{\δJ}}_0\left({\mathrm{\φ}}_m\right)$

$-\frac{I_0}{2}(1-\mathrm{\δ})\cos ({\mathrm{\φ}}_s+{\mathrm{\φ}}_m)+\frac{I_0}{2}(1-\mathrm{\δ})\cos {\mathrm{\φ}}_s{J}_0\left({\mathrm{\φ}}_m\right)+\frac{I_0}{2}\mathrm{\δ}\cos {\mathrm{\φ}}_m-\frac{I_0}{2}\mathrm{\δ}{J}_0\left({\mathrm{\φ}}_m\right)$

$=\frac{I_0}{2}(1-\mathrm{\δ})[\cos ({\mathrm{\φ}}_s-{\mathrm{\φ}}_m)-\cos ({\mathrm{\φ}}_s+{\mathrm{\φ}}_m)]=I_0(1-\mathrm{\δ})\sin {\mathrm{\φ}}_s\sin {\mathrm{\φ}}_m---\left(7\right)$

Under the less situation of signal, peak detector output:

I _out.peak＝I ₀(1-δ) (8)

Do division:

$\frac{M}{I_{\mathrm{out}.\mathrm{peak}}}=\frac{I_0(1-\mathrm{\δ})\sin {\mathrm{\φ}}_s\sin {\mathrm{\φ}}_m}{I_0(1-\mathrm{\δ})}=\sin {\mathrm{\φ}}_s\sin {\mathrm{\φ}}_m---\left(9\right)$

Depth of modulation is taken as ${\mathrm{\φ}}_m=\frac{\mathrm{\π}}{2}\⇒\sin {\mathrm{\φ}}_m=1---\left(10\right)$

This depth of modulation is operated in and changes insensitive interval, has guaranteed that the working point can not form bigger harm to the signal demodulation within the specific limits.For requiring than condition with higher, need feed back modulator, to stablize depth of modulation, in small-signal and the not serious situation of light path element (as the polarization form converter in the optical fiber current mutual inductor) imperfection, 2 adjacent negative peaks and be:

$N=I_{\mathrm{out}.\mathrm{dc}2}+I_{\mathrm{out}.\mathrm{dc}4}=\frac{I_0}{2}(1-\mathrm{\δ})\cos ({\mathrm{\φ}}_s-{\mathrm{\φ}}_m)-\frac{I_0}{2}(1-\mathrm{\δ})\cos {\mathrm{\φ}}_s{J}_0\left({\mathrm{\φ}}_m\right)-\frac{I_0}{2}\mathrm{\δ}\cos {\mathrm{\φ}}_m+\frac{I_0}{2}{\mathrm{\δJ}}_0\left({\mathrm{\φ}}_m\right)$

$+\frac{I_0}{2}(1-\mathrm{\δ})\cos ({\mathrm{\φ}}_s+{\mathrm{\φ}}_m)-\frac{I_0}{2}(1-\mathrm{\δ})\cos {\mathrm{\φ}}_s{J}_0\left({\mathrm{\φ}}_m\right)-\frac{I_0}{2}\mathrm{\δ}\cos {\mathrm{\φ}}_m+\frac{I_0}{2}{\mathrm{\δJ}}_0\left({\mathrm{\φ}}_m\right)$

$\≈-I_0(1-\mathrm{\δ})J_0\left({\mathrm{\φ}}_m\right)-I_0\mathrm{\δ}\cos {\mathrm{\φ}}_m+I_0\mathrm{\δ}{J}_0\left({\mathrm{\φ}}_m\right)\≈-J_0\left({\mathrm{\φ}}_m\right)I_0$

(11), this amount can be used for stablizing depth of modulation.

The present invention also can be used for the Sagnac effect and cause the signal of phase differential of two-beam, especially adopt unifrequency modulation available the present invention in back to handle to its signal processing technology.

Characteristics of the present invention are: on the one hand, the present invention is a kind of signal processing method and circuit engineering of handling the Fibre Optical Sensor output signal, proposes that a kind of with traditional closed loop and open-ring signal processing method compare with circuit that cost is cheaper, structure is simpler, easier realization, the signal processing method accurately and the circuit that are more suitable for manufacturing; Signal processing method of the present invention and circuit reduce the requirement of the performance index of the element in the Fibre Optical Sensor and the accuracy that can improve signal Processing, have guaranteed that simultaneously scale factor is not with temperature drift.Compared with former invention, signal processing method of the present invention and circuit for eliminating reduced their deficiency in other words to a great extent.

Description of drawings

Fig. 1 is the logic diagram of signal processing method of the present invention,

Fig. 2 is the block diagram of signal processing circuit of the present invention,

Fig. 3 a is that negative peak of the present invention is surveyed synoptic diagram,

Fig. 3 b is that positive peak of the present invention is surveyed synoptic diagram

Fig. 4 is the circuit diagram of signal processing circuit of the present invention.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment this programme is further described:

Referring to Fig. 2, the 10th, a kind of simple and clear description of signal processing method of the present invention and circuit.Be coupled to Sagnac interferometric optical fiber sensor 11 every straight wave filter 12, the flip-flop that is used for eliminating the modulation signal of Fibre Optical Sensor output is floated and drift and low-frequency noise to eliminate temperature.Can select active or passive filtering according to the modulating frequency and the actual demand of the Fibre Optical Sensor of reality every straight wave filter 12.Usually be chosen as an electric capacity here, the size of capacitance is according to the actual demand of circuit is decided.Low-pass filter 13 is coupled to every straight wave filter, is used for eliminating the high frequency noise of the modulation signal of Fibre Optical Sensor output, improves the signal to noise ratio (S/N ratio) of modulation signal.The cutoff frequency of bandpass filter or 3dB frequency are generally 2 times of modulated drive signal, and its scope is generally 1 to 5 times of modulated drive signal.

Be coupled to analog to digital converter 14 through the Fibre Optical Sensor output signal behind capacitance 12 and the low-pass filter 13, to realize analog to digital conversion, the circuit of supplying with the back carries out digital signal processing.The parameter that analog to digital converter is chosen chip according to the output of actual measured signal and Fibre Optical Sensor mainly is figure place and precision and the resolution of speed to satisfy signal Processing.

Signal generator 17 output two-way standard sine signals, one road signal is used for driving the phase-modulator in the Sagnac interferometric optical fiber sensor 11 and then makes Fibre Optical Sensor 11 output modulation signals.Depth of modulation be regulated and then be adjusted to the amplitude of the simulating signal that signal generator 17 provides should, and simultaneously, this can adjust depth of modulation to stablize the depth of modulation working point by the feedback signal that feedback control circuit 18 provides again.By aforementioned analysis as can be known, the signal that digital peak detector 15 provides has comprised the information of depth of modulation, therefore, and the signal controlling that the feedback signal that feedback control circuit 18 provides is provided by digital negative peak detector 15.

An other road sign quasi sine signal of signal generator 17 outputs is coupled to comparer 16.Through acquisition several different methods can be arranged, provide a kind of possible implementation method here every 2 adjacent negative peaks of the Fibre Optical Sensor output signal after the direct sum low-pass filtering in 1 cycle in modulated drive signal.As shown in Figure 3, just upset of logic level whenever the modulated drive signal zero-crossing comparator, and keep this level until modulated drive signal zero passage next time, the cycle of the square-wave signal of Chan Shenging is with regard to the corresponding cycle that drives modulation signal like this, preceding half period and back half period be the electrical level polar of respective opposite respectively, here, preceding half period negative level, back half period positive level.The negative level counterlogic value of preceding half period is taken as 1, and this logical value is used for importing the negative peak detector, in order to obtain first negative peak in the modulation signal that the preceding half period inner fiber sensor of modulated drive signal is exported; Can obtain second negative peak as a same reason.

The signal that 2 the adjacent negative peak additions of Fibre Optical Sensor output signal in 1 cycle of modulated drive signal obtain has comprised the information of depth of modulation, be input to feedback control circuit 18 as the output signal of digital negative peak detector 15 and be used for controlling depth of modulation, stablize the depth of modulation working point.Fibre Optical Sensor output signal 2 adjacent negative peaks in 1 cycle of modulated drive signal subtract each other the input as divider 21.

Simulated peak detector 19 is directly coupled to Fibre Optical Sensor 11 and surveys its peak value through analog to digital converter 20 input dividers 21, and carries out division arithmetic with the output of digital negative peak detector 15.Processor 22 is coupled in the output of divider 21, with the output of picked up signal disposal system.

Practical circuit as shown in Figure 4, the 11st, Fibre Optical Sensor, the 23rd, capacitance, the 24th, low-pass filter adopts AD8610; The 25th, analog to digital conversion adopts AD9260, according to actual conditions, also can adopt AD9240; The 27th, comparer adopts AD790; The 28th, signal generator adopts DAC8580; The 29th, peak detector adopts PKD01; The 30th, analog to digital conversion adopts AD7656; The 26th, digital signal processing chip adopts ADSP-bf534, mainly finishes the function of digital negative peak detection and computing, divider and processor.

Generally speaking, n gets 1 to 8, and special circumstances can get 16.

Claims (10)

1, the open-ring signal processing method of Sagnac interferometric optical fiber sensor, utilize the phase-modulator in the analog drive signal driving Fibre Optical Sensor and then make Fibre Optical Sensor output modulation signal, it is characterized in that at first the Fibre Optical Sensor output signal is carried out every directly, then low-pass filtering; And the negative peak detection circuit through being coupled to low-pass filter obtains Fibre Optical Sensor output signal individual adjacent negative peak of 2～2n in 1 to n the cycle in modulated drive signal, can obtain the information of tested phase differential by this 2～2n negative peak value, n 〉=1, simultaneously the Fibre Optical Sensor output signal is carried out directly that peak value detects and and the output of negative peak detection circuit do division; The method that negative peak is surveyed is to utilize the modulated drive signal zero passage that the Fibre Optical Sensor output signal is carried out negative peak to survey; Division output is the output of signal processing system, and n is the periodicity of modulated drive signal of 2 adjacent negative peaks of the modulation signal of detection optical fiber sensor output.

2, by the open-ring signal processing method of the described Sagnac interferometric optical fiber sensor of claim 1, it is characterized in that the amplitude of analog-modulated drive signal is regulated to regulate depth of modulation, the signal that is provided by the negative peak detection circuit has comprised the information of depth of modulation, the signal controlling that the feedback signal that feedback control circuit provides is provided by the negative peak detection circuit is adjusted depth of modulation by the feedback signal that feedback control circuit provides.

3,, when it is characterized in that utilizing the modulated drive signal zero passage to survey peak detection is directly carried out in the output of Fibre Optical Sensor to carry out negative peak every the Fibre Optical Sensor output signal after the straight low-pass filtering by the open-ring signal processing method of the described Sagnac interferometric optical fiber sensor of claim 1.

4, by the open-ring signal processing method of the described Sagnac interferometric optical fiber sensor of claim 1, it is characterized in that make adopting the signal processing circuit of the method insensitive, thereby do not need to carry out the modulated drive signal generator under the room temperature situation and carry out FEEDBACK CONTROL the variation of depth of modulation by choice of modulation degree of depth working point.

5,, it is characterized in that other one tunnel same standard sinusoidal signal that the negative peak detection circuit carries out utilizing the analog-modulated drive signal generator to be provided with output when negative peak detects is coupled to comparer by the open-ring signal processing method of the described Sagnac interferometric optical fiber sensor of claim 1; The output of comparer connects digital negative peak detector and carries out the negative peak detection.

6, by the described Sagnac interferometric optical fiber sensor of claim 1 open-ring signal processing method, the formation that it is characterized in that comparator circuit: whenever the just upset of logic level of modulated drive signal zero-crossing comparator, and keep this level until modulated drive signal zero passage next time, the cycle of the square-wave signal of Chan Shenging is with regard to the cycle of corresponding modulating drive signal like this, preceding half period and back half period be the electrical level polar of respective opposite respectively, for example, preceding half period negative level, back half period positive level is perhaps opposite.The negative level counterlogic value of preceding half period is taken as 1, and this logical value is used for importing the negative peak detector, in order to obtain first negative peak in the modulation signal that the preceding half period inner fiber sensor of modulated drive signal is exported; Can obtain second negative peak as a same reason.The simulated peak detector is directly coupled to that peak value that Fibre Optical Sensor is used for obtaining the modulation signal of Fibre Optical Sensor output is used for and division is done in the output of negative peak detection circuit.

7, by the open-ring signal processing method of the described Sagnac interferometric optical fiber sensor of claim 1, it is characterized in that " negative peak " is not numerically must be negative (just), but for just (bearing) peak value, its real physical meaning be two of modulation signal adjacent just (bear) minimum (greatly) value between the peak value, this depends on the interval of tested phase differential.When tested phase differential be in [90 °, 90 °] interval in the time is negative peak, its real physical meaning is the minimal value between two adjacent positive peaks of modulation signal; When tested phase differential be in [90 °, 270 °] interval in the time is positive peak, its real physical meaning is the maximum value between two adjacent negative peaks of modulation signal.

8, by the open-ring signal processing method of the described Sagnac interferometric optical fiber sensor of claim 1, it is characterized in that signal processing method makes the dynamic range of tested phase differential be not limited to [90 °, 270 °], by being set, dynamic range can be expanded to m cycle by counter, m 〉=1 and be positive integer, promptly tested phase differential less than-90 ° also greater than 270 °; Sagnac interferometer situation at the requirement of optical fibre gyro great dynamic range.

9, Sagnac interferometric optical fiber sensor open loop signal treatment circuit, utilize the phase-modulator in the analog drive signal driving Fibre Optical Sensor and then make Fibre Optical Sensor output modulation signal, it is characterized in that Fibre Optical Sensor output connects a capacitance that is coupled to the output of Fibre Optical Sensor and is used for removing flip-flop and low-pass filter that is used for eliminating high frequency noise that is coupled to this capacitance that Fibre Optical Sensor is exported, be coupled to adjacent 2n negative peak of negative peak detection circuit detection optical fiber sensor output signal in n the cycle of modulated drive signal of low-pass filter, obtain the information of tested phase differential by each cycle 2 adjacent negative peaks, and be used for the FEEDBACK CONTROL phase-modulator to stablize the depth of modulation working point; Other one road signal that described analog drive signal generator is provided with output is coupled to comparer for the same standard sinusoidal signal; The output of comparer connects digital negative peak detector, and digital negative peak detector output connects divider circuit, and the simulated peak detection circuit is imported divider through analog to digital conversion circuit simultaneously, and carries out division arithmetic with the output of digital negative peak detector; The output of divider circuit is the output of signal processing system.

10, by the described Sagnac interferometric optical fiber sensor of claim 9 open loop signal treatment circuit, it is characterized in that signal that 2 the adjacent negative peak additions of Fibre Optical Sensor in 1 cycle of modulated drive signal obtain has comprised the information of depth of modulation, 2 the adjacent negative peaks of Fibre Optical Sensor in 1 cycle of modulated drive signal subtract each other the input as divider; The simulated peak detector is directly coupled to that peak value that Fibre Optical Sensor is used for obtaining Fibre Optical Sensor output is used for and division is done in the output of digital negative peak detector.

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