A method and device for measuring the transit time of a fiber optic gyroscope fiber coil

Abstract

The application provides a kind of optical fiber gyro transit time measurement method, generates square wave bias modulation signal and triangular wave modulation signal, superimposes and generates special modulation signal;Special modulation signal is applied to Y waveguide phase modulator by D / A converter and amplification circuit, and the phase modulation of two beams of light in optical path is carried out, and the phase-modulated light propagates in optical fiber ring for a week and then interferes in Y waveguide phase modulator;Interference light returns coupler and converts light intensity signal into analog voltage signal by detector;By the detector signal demodulation of the rising half cycle and the falling half cycle of triangular wave signal, the optical fiber ring transit time error Δt is obtained;Adjust the square wave bias modulation signal period, when the error is zero, half of the square wave bias modulation signal period is the optical fiber ring transit time.The application can realize high-precision detection of optical fiber ring transit time by adjusting FPGA software only, realizes on-line closed-loop control of gyro control period while not affecting the angular rate measurement function of optical fiber gyro.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fiber-optic gyroscope application technology, and particularly relates to a fiber-optic gyroscope fiber-optic transit time measurement method. BACKGROUND

[0002] The fiber-optic ring is a sensitive element in the fiber-optic gyroscope, and based on the Sagnac effect, two light beams transmitted in opposite directions in the fiber-optic ring will produce a phase difference under angular rate input. The angular rate can be measured by detecting the Sagnac phase difference. The time for light to transmit one round in the fiber-optic ring is called the transit time τ. The transit time is an important parameter of the fiber-optic ring, and the control period of the gyroscope needs to be consistent with the transit time of the fiber-optic ring as much as possible. When the two are inconsistent, the performance of the fiber-optic gyroscope will be affected, and the fiber-optic gyroscope zero bias and threshold index will decrease.

[0003] The traditional method for measuring the transit time of the fiber-optic ring is to apply a square wave modulation and take the minimum value of the peak width of the interference comb wave signal. However, due to the non-ideal square wave of the modulation signal, there is a limited rise time and fall time in the signal. When the square wave modulation period is near the transit time, the peak width of the comb wave changes unobviously, and the accurate transit time cannot be measured. There are also other methods for measuring the transit time of the fiber-optic ring, such as using asymmetric square wave and sinusoidal wave modulation. These methods have a certain effect on improving the test precision of the transit time, but the modulation waveforms used are inconsistent with the conventional fiber-optic gyroscope closed-loop modulation waveform, which will affect the normal signal processing of the fiber-optic gyroscope, and the fiber-optic ring transit time cannot be measured at the same time without affecting the angular rate measurement. SUMMARY

[0004] To solve the above problems, the present application provides a fiber-optic gyroscope fiber-optic ring transit time measurement method, which effectively improves the detection precision of the fiber-optic ring transit time. The specific steps of the method are as follows:

[0005] S1, generate a square wave bias modulation signal and a triangular wave modulation signal, and superimpose the square wave bias modulation signal and the triangular wave modulation signal

[0006] The square wave bias modulation signal has a period T;

[0007] The high half cycle and the low half cycle of the square wave bias modulation signal are equal, and each has a time T hf , where T hf is close to the transit time τ of the fiber-optic ring to be measured, T hf is the difference between τ and T ;

[0008] The triangular wave modulation signal has a period T tri , T tri is less than T hf ;

[0009] The rising time of the triangular wave modulation signal is equal to the falling time, which is T tri / 2;

[0010] The rising edge or falling edge of the triangular wave modulation signal is delayed by the same time relative to the rising edge or falling edge of the square wave bias modulation signal;

[0011] A complete triangular wave signal is superimposed on each of the high half cycle and low half cycle of the square wave bias modulation signal;

[0012] The superimposed modulation signal is a special modulation signal;

[0013] The period of the special modulation signal is the same as the period of the square wave bias modulation signal, both of which are T.

[0014] S2, the special modulation signal is applied to the Y waveguide phase modulator after D / A conversion and amplification, for phase modulation of the two beams of light transmitted clockwise and counterclockwise along the fiber ring, and the phase-modulated light interferes in the Y waveguide phase modulator after propagating one round in the fiber ring.

[0015] S3, the light intensity information signal including the Sagnac phase difference information of the fiber optic gyroscope and the Δt in step S1 is converted into an analog voltage signal by the detector.

[0016] The error signal of the fiber ring transit time and half of the period of the special modulation signal is obtained by demodulating the detector signals of the rising half cycle and the falling half cycle of the triangular wave signal.

[0017] S4, the polarity and size of the error Δt are judged, and the period of the square wave bias modulation signal is adjusted

[0018] If the error Δt is 0, then half of the period of the square wave bias modulation signal is the transit time of the fiber ring at this time;

[0019] If the error Δt is not 0, adjust the period of the square wave bias modulation signal until the error Δt is 0.

[0020] S5, the above S1-S4 continuously work, and the period of the square wave bias modulation signal is kept equal to the transit time of the fiber ring.

[0021] The special modulation signal is generated by the internal logic of the FPGA processor, and the digital signal sequence is output in sequence according to the clock period, and the analog modulation signal is generated through the D / A converter and the amplification circuit;

[0022] The period adjustment of the special modulation signal can be realized by adjusting the length of the digital signal sequence in the FPGA;

[0023] The period adjustment of the special modulation signal is realized by adjusting the length of the digital signal sequence inside the FPGA processor;

[0024] The period of the special modulation signal is realized by adjusting the clock frequency through the phase-locked loop inside the FPGA processor or the digital frequency synthesizer outside the FPGA processor;

[0025] The special modulation signal is superimposed on the square wave bias modulation signal on the optical fiber, and a triangular wave signal is set for the half period T hf The half period T of the square wave bias modulation signal is set for the square wave bias modulation signal on the optical fiber ring hf The difference between τ and Δt is Δt; the modulation triangular wave signal is set as an isosceles triangle, that is, the rising time is equal to the falling time, and the period T of the triangular wave modulation signal tri is less than the half period T of the square wave bias modulation signal hf , and the delay time of the triangular wave relative to the rising edge or falling edge of the square wave bias modulation signal is the same;

[0026] The error Δt between the half period T / 2 of the special modulation signal and the transit time τ of the optical fiber ring affects the interference phase of the rising and falling sections of the triangular wave, causing the interference light intensity to change within the corresponding time;

[0027] The error of the transit time of the optical fiber ring is reflected in the interference light intensity signal, and the specific form is as follows:

[0028] The high level part of the square wave bias modulation signal in the special modulation signal is A, the low level part is B, the rising section time of the corresponding triangular wave is T Au , T Bu , the falling section time is T Ad , T Bd , and the output interference light intensity within the corresponding time is I Au , I Bu , I Ad , I Bd , then the error signal ΔI of the interference light intensity caused by the error Δt of the transit time of the optical fiber ring and the period of the modulation signal is ΔI = I Au – I Ad = I Bd – I Bu ; when Δt is small enough, ΔI is approximately proportional to Δt;

[0029] The method theoretically has no effect on the closed-loop detection signal of the fiber optic gyroscope, and can be used to design a fiber ring transit time measurement device alone, or can be added as an independent function to the closed-loop control loop of the fiber optic gyroscope to realize online detection and continuous closed-loop tracking of the control period of the fiber optic gyroscope;

[0030] A kind of optical fiber gyroscope optical fiber ring transit time measuring device, the device includes light source, coupler, Y waveguide modulator, the optical fiber ring to be measured, detector, preamplifier circuit, A / D converter, FPGA processor, D / A converter, amplification circuit;

[0031] The light emitted by the light source is divided into two beams of equal intensity in the Y waveguide modulator through the coupler;The two beams of equal intensity return to the Y waveguide modulator after one round of relative propagation in the optical fiber ring to be measured, and interference occurs;The interference light propagates to the detector through the coupler, converting the light intensity signal into an analog voltage signal;The analog voltage signal is amplified by the preamplifier circuit and converted into a digital quantity by the A / D converter before being input into the FPGA processor, where the fiber ring transit time error is calculated and the control cycle closed-loop control is completed;The digital modulation signal generated according to the control cycle is converted into an analog modulation signal by the D / A converter and the amplification circuit, and is applied to the Y waveguide modulator to complete phase modulation.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] (1) No need to change the existing digital closed-loop optical fiber gyroscope optical circuit and circuit, only need to adjust the FPGA software to realize the optical fiber ring transit time detection.

[0034] (2) By triangular wave modulation, the time error is converted into the difference of output voltage within the triangular wave modulation range, avoiding the influence of non-ideal rising and falling edges of square wave modulation;The detection resolution is independent of the sampling frequency, and no special high-speed or ultra-high-speed sampling device is needed.

[0035] (3) The special modulation signal of the present application makes the optical fiber ring transit time error and the Sagnac effect phase difference of the closed-loop optical fiber gyroscope independent of each other, and both work as independent control loops in the optical fiber gyroscope, realizing online closed-loop control of the optical fiber gyroscope control cycle.

[0036] (4) The optical fiber ring transit time detection method can be easily extended to four-state wave modulation optical fiber gyroscope. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The control loop diagram of the optical fiber gyroscope transit time measurement method of the present application.

[0038] Figure 2 The system schematic diagram of the optical fiber gyroscope transit time measurement method of the present application.

[0039] Figure 3 The modulation waveform applied to the Y waveguide modulator of the optical fiber gyroscope transit time measurement method of the present application.

[0040] Figure 4 The schematic diagram of the output voltage signal of the detector when the fiber ring transit time is greater than half of the modulation signal period for the method of measuring the fiber ring transit time of the fiber optic gyroscope without angular rate input.

[0041] Figure 5 The schematic diagram of the output voltage signal of the detector when the fiber ring transit time is less than half of the modulation signal period for the method of measuring the fiber ring transit time of the fiber optic gyroscope without angular rate input.

[0042] Figure 6 The schematic diagram of the output voltage signal of the detector when the fiber ring transit time is equal to half of the modulation signal period for the method of measuring the fiber ring transit time of the fiber optic gyroscope without angular rate input.

[0043] Figure 7 The schematic diagram of the output voltage signal of the detector when the fiber ring transit time is equal to half of the modulation signal period for the method of measuring the fiber ring transit time of the fiber optic gyroscope with angular rate input. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0045] A device for measuring the fiber ring transit time of a fiber optic gyroscope, the device comprising a light source, a coupler, a Y waveguide modulator, a fiber ring to be measured, a detector, a preamplifier circuit, an A / D converter, an FPGA processor, a D / A converter, an amplification circuit, as shown in Figure 2 ;

[0046] The light emitted by the light source is divided into two beams of equal intensity in the Y waveguide modulator through the coupler; the two beams of equal intensity return to the Y waveguide modulator after propagating one round in the fiber ring to be measured, and interference occurs; the interference light propagates to the detector through the coupler, and the light intensity signal is converted into an analog voltage signal; the analog voltage signal is amplified by the preamplifier circuit, converted into a digital quantity by the A / D converter, and input into the FPGA processor, where the fiber ring transit time error is calculated and the control cycle closed-loop control is completed; a digital modulation signal is generated according to the control cycle, converted into an analog modulation signal by the D / A converter and the amplification circuit, and applied to the Y waveguide modulator to complete phase modulation;

[0047] As Figure 1 shown, a method for measuring the fiber ring transit time of a fiber-optic gyroscope, effectively improving the detection accuracy of the fiber ring transit time, generates a special modulation signal according to a preset digital sequence in the FPGA processor, applies it to the Y waveguide modulator to complete phase modulation; the two beams of light after phase modulation propagate in the fiber ring to be measured for one round, return to the Y waveguide modulator to interfere, and input the light signal after interference into the detector; the detector outputs an error signal, which is demodulated in the FPGA processor, and the modulation signal period is corrected according to the demodulation result to gradually reduce the error signal; when the error signal is 0, the special modulation signal half period is equal to the fiber ring transit time, and the accurate fiber ring transit time can be obtained; the specific steps of the method are as follows:

[0048] S1, generate a square wave bias modulation signal and a triangular wave modulation signal, and superimpose the square wave bias modulation signal and the triangular wave modulation signal

[0049] The period of the square wave bias modulation signal is T;

[0050] The high half period and the low half period of the square wave bias modulation signal are equal, both being T hf , where T hf is close to the fiber ring transit time τ to be measured, T hf is the difference between T

[0051] The period of the triangular wave modulation signal is T tri , T tri is less than T hf ;

[0052] The rise time and the fall time of the triangular wave modulation signal are equal, being T tri / 2;

[0053] The rise edge or the fall edge of the triangular wave modulation signal is delayed by the same time relative to the square wave bias modulation signal;

[0054] Each of the high half period and the low half period of the square wave bias modulation signal superimposes a complete triangular wave signal;

[0055] The superimposed modulation signal is a special modulation signal;

[0056] The period of the special modulation signal is the same as that of the square wave bias modulation signal, both being T.

[0057] S2, the dedicated modulation signal is applied to the Y waveguide phase modulator after D / A converter and amplifier circuit, for phase modulation of two beams of light transmitted clockwise and counterclockwise along the fiber ring in the optical path, and the phase-modulated light interferes in the Y waveguide phase modulator after propagating one round in the fiber ring.

[0058] S3, the interference light returns to the coupler, and the light intensity information signal is converted into an analog voltage signal by the detector, wherein the light intensity information signal includes the Sagnac phase difference information of the fiber-optic gyroscope and the Δt in step S1;

[0059] By demodulating the detector signals of the rising half cycle and the falling half cycle of the triangular wave signal, an error signal of the fiber ring transit time and half of the period of the dedicated modulation signal is obtained.

[0060] S4, judging the polarity and size of the error Δt, and adjusting the period of the square wave bias modulation signal

[0061] If the error Δt is 0, then half of the period of the square wave bias modulation signal is the transit time of the fiber ring at this time;

[0062] If the error Δt is not 0, adjust the period of the square wave bias modulation signal until the error is 0.

[0063] S5, the above S1-S4 continuously work, and the period of the square wave bias modulation signal is kept equal to the transit time of the fiber ring.

[0064] The dedicated modulation signal is generated by the internal logic of the FPGA processor, and the digital signal sequence is output in sequence according to the clock period, and the analog modulation signal is generated through the D / A converter and the amplifier circuit;

[0065] The period adjustment of the dedicated modulation signal can be realized by adjusting the length of the digital signal sequence in the FPGA;

[0066] The period adjustment of the dedicated modulation signal is realized by adjusting the length of the digital signal sequence in the FPGA processor;

[0067] The period of the dedicated modulation signal is realized by adjusting the clock frequency through the phase-locked loop in the FPGA processor or the digital frequency synthesizer outside the FPGA processor;

[0068] The dedicated modulation signal is superimposed on the fiber square wave bias modulation signal with a triangular wave signal; the half period T of the square wave bias modulation signal is set hf The half period T of the square wave bias modulation signal is close to the transit time τ of the fiber ring to be measured hf The difference from τ is Δt; the modulation triangular wave signal is set as an isosceles triangle, that is, the rising section time is equal to the falling section time, and the period T of the triangular wave modulation signal triHalf cycle T of square wave bias modulation signal hf The delay time of the rising edge or the falling edge of the triangular wave relative to the square wave bias modulation signal is the same.

[0069] The error Δt between half cycle T / 2 of the special modulation signal and the fiber ring transit time τ affects the interference phase of the rising section and the falling section of the triangular wave, causing the interference light intensity to change in the corresponding time.

[0070] The fiber ring transit time error is reflected in the interference light intensity signal, and the specific form is as follows:

[0071] The high level part of the square wave bias modulation signal in the special modulation signal is A, and the low level part is B. The corresponding rising section time of the triangular wave is T Au , T Bu , the falling section time is T Ad , T Bd , and the output interference light intensity in the corresponding time is I Au , I Bu , I Ad , I Bd Therefore, the interference light intensity error signal ΔI caused by the fiber ring transit time and the modulation signal cycle error Δt is ΔI = I Au – I Ad = I Bd – I Bu When Δt is small enough, ΔI is approximately proportional to Δt.

[0072] The method theoretically has no effect on the closed-loop detection signal of the fiber optic gyroscope. It can be used alone to design a fiber ring transit time measurement device, or it can be added as an independent function to the closed-loop control loop of the fiber optic gyroscope to realize online detection and continuous closed-loop tracking of the control period of the fiber optic gyroscope.

[0073] The special modulation signal is composed of the square wave bias modulation signal and the triangular wave modulation signal, and is completed by digital superposition in the FPGA. The duty cycle of the square wave bias modulation signal is 50%, in which the half cycle output high voltage is A, the half cycle output low voltage is B, the modulation signal period is T, and the time of the two half cycles is T / 2. The triangular wave modulation signal is an isosceles triangle with a period of T tri The time positions of the triangular wave modulation signal in the two half cycles A and B are completely consistent, satisfying:

[0074] V AH = V BH , T A1 = T B1 , T Au = T Ad = T Bu = T Bd = T tri / 2, as Figure 3 shown;

[0075] The modulation signal of the present application applies modulation phase to two lights propagating oppositely in the fiber ring through the Y waveguide modulator, the modulation phase of two lights and the output signal of the detector in different cases are explained as follows;

[0076] Suppose the fiber ring transit time is τ, the special modulation signal period is T, define Δt = τ - T / 2;

[0077] As Figure 4 shown is the detector output voltage signal schematic diagram when Δt > 0 without angular rate input;

[0078] As Figure 5 shown is the detector output voltage signal schematic diagram when Δt < 0 without angular rate input;

[0079] As Figure 6 shown is the detector output voltage signal schematic diagram when Δt = 0 without angular rate input;

[0080] The special modulation signal is applied to the Y waveguide modulator, which applies phase modulation with period T to two lights propagating oppositely in the fiber ring, the two lights interfere after propagating one round in the fiber ring, and the modulation phase shift of the two lights has a delay of τ when the interference occurs;

[0081] When τ > T / 2 or τ < T / 2, i.e. Δt > 0 or Δt < 0, the phase difference of the two lights on the rising and falling sections of the triangular wave is not equal, the interference light intensity changes, and an error signal similar to square wave appears at the detector end; taking Δt as a variable, the error amount is an odd function of Δt, especially when Δt is small enough, the error amount can be approximately considered to be proportional to Δt; when Δt = 0, the error amount of the detector output is also 0, at this time the detector output is the traditional closed-loop fiber optic gyroscope comb wave;

[0082] The interference light intensity error signal is amplified by the preamplifier circuit and converted into digital quantity by the A / D converter, by increasing the sampling frequency, the signal-to-noise ratio can be improved in the form of multi-point sampling accumulation within a specified time period; the FPGA selects the data corresponding to the time to solve the error;

[0083] The FPGA internally smoothes the sampling data of different time periods by simple accumulation, and solves the digital time error by taking the relative difference value, which is proportional to Δt; according to the error amount, the modulation signal period is corrected until Δt = 0; that is, the closed-loop tracking of the fiber ring transit time is realized, at this time the modulation signal period is equal to twice the fiber ring transit time, i.e. T / 2 = τ;

[0084] The modulation signal period is corrected by various means; adjusting the length of the digital signal sequence, changing the internal phase-locked loop of the FPGA or the external digital frequency synthesizer of the FPGA, and adjusting the clock frequency can all achieve the correction of the modulation signal period T.

[0085] Figure 7 For the angular rate input, the schematic diagram of the detector output voltage signal when Δt=0 is shown in the figure;

[0086] The Sagnac phase difference caused by the angular rate input is shown in the figure, and the voltage difference in the A and B time periods is shown in the detector output; it is easy to see that the time error causes the detector output error in the A and B time periods, and the angular rate signal has no effect on it; after the closed-loop tracking of the modulation signal period is completed, the voltage error caused by the time error in the A and B time periods is 0, and will not affect the angular rate measurement; that is, the time error control loop and the angular rate measurement loop work independently at the same time, and do not affect each other.

[0087] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the above disclosed content without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. A method for measuring the transit time of an optical fiber ring of an optical fiber gyroscope, characterized in that: The specific steps of the method are as follows: S1. Generate a square wave bias modulation signal and a triangle wave modulation signal, and superimpose the square wave bias modulation signal and the triangle wave modulation signal. The period of the square wave bias modulation signal is T; The high half cycle and low half cycle time of the square wave bias modulation signal are equal, both are T hf , where T hf Close to the transit time of the fiber ring to be tested τ, T hf The difference from τ is the fiber loop transit time error Δt; The period of the triangular wave modulation signal is T tri , T tri Less than T hf ; The rise time and fall time of the triangle wave modulation signal are equal, which is T tri / 2; The rising edge or falling edge delay time of the triangular wave modulation signal is the same as that of the square wave bias modulation signal; A complete triangle wave signal is superimposed on each of the high half cycle and the low half cycle of the square wave bias modulation signal; The above-mentioned superimposed modulation signal is a dedicated modulation signal; The period of the dedicated modulation signal is the same as the period of the square wave bias modulation signal, both of which are T; S2. Applying the dedicated modulation signal to a Y-waveguide phase modulator after passing through a D / A converter and an amplifier circuit to phase modulate two light beams transmitted clockwise and counterclockwise along the optical fiber ring in the optical path. After the phase modulated light beams propagate one circle in the optical fiber ring, they interfere with each other in the Y-waveguide phase modulator. S3, the interference light returns to the coupler and converts the light intensity information signal into an analog voltage signal through the detector, wherein the light intensity information signal includes the Sagnac phase difference information of the fiber optic gyroscope and the Δt described in step S1; By demodulating the detector signals of the rising half cycle and the falling half cycle of the triangle wave signal, the error signal between the fiber loop transit time and half the period of the dedicated modulation signal is obtained; S4. Determine the polarity and magnitude of the error Δt and adjust the period of the square wave bias modulation signal. If the error Δt is 0, then half of the period of the square wave bias modulation signal is the transit time of the optical fiber ring; If the error Δt is not 0, adjusting the period of the square wave bias modulation signal until the error is 0; S5. The above steps S1 to S4 continue to operate, and the period of the square wave bias modulation signal is kept equal to the fiber loop transit time.

2. The method for measuring the transit time of an optical fiber gyroscope optical fiber ring according to claim 1, wherein: The dedicated modulation signal is generated by the internal logic of the FPGA processor, and its digital signal sequence is output in sequence according to the clock cycle, and an analog modulation signal is generated through a D / A converter and an amplifying circuit.

3. The method for measuring the transit time of an optical fiber gyroscope optical fiber loop according to claim 1, wherein: The period adjustment of the dedicated modulation signal can be achieved by adjusting the length of the digital signal sequence inside the FPGA.

4. The method for measuring the transit time of an optical fiber gyroscope optical fiber ring according to claim 1, wherein: The period adjustment of the dedicated modulation signal is achieved by adjusting the length of the digital signal sequence inside the FPGA processor.

5. The method for measuring the transit time of an optical fiber gyroscope optical fiber loop according to claim 1, wherein: The period of the dedicated modulation signal is achieved by adjusting the clock frequency through a phase-locked loop inside the FPGA processor or a digital frequency synthesizer outside the FPGA processor.

6. The method for measuring the transit time of an optical fiber ring of an optical fiber gyroscope according to claim 1, wherein: The special modulation signal is a triangular wave signal superimposed on the optical fiber square wave bias modulation signal; the half period T of the square wave bias modulation signal is set hf Close to the transit time τ of the fiber loop to be tested, half period T of the square wave bias modulation signal hf The difference from τ is Δt; the modulated triangular wave signal is set to an isosceles triangle shape, that is, the rising period is equal to the falling period, and the triangular wave modulation signal period T tri Less than half period T of square wave bias modulation signal hf At the same time, the delay time of the rising edge or falling edge of the triangle wave relative to the square wave bias modulation signal is the same.

7. The method for measuring the transit time of an optical fiber ring of an optical fiber gyroscope according to claim 1, wherein: The error Δt between half T / 2 of the special modulation signal period and the transit time τ of the optical fiber loop to be measured affects the interference phase of the rising and falling segments of the triangle wave, causing the interference light intensity to change within the corresponding time.

8. The method for measuring the transit time of an optical fiber gyroscope optical fiber loop according to claim 1, wherein: The fiber loop transit time error Δt is reflected in the interference light intensity signal, and the specific form is as follows: The high level part of the square wave bias modulation signal in the dedicated modulation signal is A, the low level part is B, and the corresponding triangle wave rising period is T Au 、T Bu , the descending time is T Ad 、T Bd The corresponding time output interference light intensity is I Au , I Bu , I Ad , I Bd , then the interference light intensity error signal ΔI=I caused by the error Δt between the transit time of the optical fiber ring and the modulation signal period Au -I Ad =I Bd -I Bu .

9. A device for measuring the transit time of an optical fiber ring of an optical fiber gyroscope, for implementing the method for measuring the transit time of an optical fiber ring of an optical fiber gyroscope according to any one of claims 1 to 8, characterized in that: The device includes a light source, a coupler, a Y-waveguide modulator, an optical fiber ring to be tested, a detector, a preamplifier circuit, an A / D converter, an FPGA processor, a D / A converter, and an amplifier circuit; The light emitted by the light source is divided into two beams of light with equal intensity in the Y-waveguide modulator by the coupler; the two beams of light with equal intensity propagate relatively for one cycle in the optical fiber ring to be tested, and then return to the Y-waveguide modulator to interfere; the interference light propagates to the detector through the coupler, and the light intensity signal is converted into an analog voltage signal; the analog voltage signal is amplified by the preamplifier circuit, converted into a digital quantity by the A / D converter, and then input into the FPGA processor, where the optical fiber ring transit time error is resolved within the FPGA processor, and the control cycle closed-loop control is completed; a digital modulation signal is generated according to the control cycle, converted into an analog modulation signal by the D / A converter and the amplifier circuit, and applied to the Y-waveguide modulator to complete phase modulation.

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