Modulation and demodulation system for maintaining precision of fiber-optic gyroscope

Abstract

The invention relates to a modulation-demodulation system for maintaining the precision of a fiber-optic gyroscope, belongs to the technical field of fiber-optic gyroscopes, and solves the problem that the precision of the gyroscope is reduced due to optical power attenuation of the fiber-optic gyroscope in the prior art. The system comprises a fiber-optic gyroscope optical path subsystem used for outputting an optical interference signal to a signal processing and conversion subsystem in real time; the phase modulation subsystem is also used for receiving the analog modulation signal output by the modulation-demodulation subsystem in real time and carrying out real-time phase modulation on the fiber-optic gyroscope; the signal processing and conversion subsystem is used for processing the interference signal, generating a digital interference signal and inputting the digital interference signal into the modulation-demodulation subsystem; the modulation and demodulation subsystem is used for carrying out rate demodulation and additional interference demodulation according to the digital interference signal, and superposing a step wave signal obtained by the rate demodulation, a normal modulation signal obtained by the additional interference demodulation and an additional modulation signal to obtain a digital modulation signal; and performing signal processing on the digital modulation signal to generate the analog modulation signal.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope technology, and more particularly to a modulation and demodulation system for maintaining the accuracy of fiber optic gyroscopes. Background Technology

[0002] Fiber optic gyroscopes can be categorized into guidance-grade, navigation-grade, precision-grade, and reference-grade based on their accuracy levels. For guidance-grade fiber optic gyroscopes, dynamic correlation is of greater concern in engineering applications; while for high-precision gyroscopes such as navigation-grade, precision-grade, and reference-grade gyroscopes, accuracy performance is paramount. Currently, numerous techniques exist to improve the accuracy of fiber optic gyroscopes, such as using fiber optic rings with larger enclosing areas and matching optical path designs to suppress noise. However, the photoelectric parameters determined by these techniques are not adjustable after the gyroscope is manufactured. Therefore, once the fiber optic gyroscope is delivered to the system, the slow changes in its photoelectric parameters, especially the attenuation of optical power, lead to a decrease in gyroscope accuracy, thus affecting system usability. Currently, there is a lack of methods for real-time online adjustment of gyroscope photoelectric parameters to maintain the accuracy of fiber optic gyroscopes.

[0003] The random walk coefficient (RWC) is an important indicator of the accuracy and performance of a fiber optic gyroscope. A higher RWC corresponds to greater white noise and lower gyroscope accuracy. The most significant noise in a fiber optic gyroscope includes shot noise σ. SI Relative intensity noise σ RINI Thermal noise σ hI and preamp noise σ eI The expression for the RWC of a fiber optic gyroscope can be derived from various noise calculation formulas:

[0004]

[0005] In the above formula, λ is the wavelength of light, c is the speed of light, L is the length of the sensitive fiber in the fiber ring, D is the average diameter of the fiber ring, q is the electron charge, and η is the coupling efficiency of the fiber ring. Let K be the average wavelength of light, Δλ be the bandwidth of the light source, and K be the bandwidth of the light source. b R is Boltzmann's constant, T is the thermodynamic temperature, and R is the temperature. f For the detector's transimpedance, σ V0 Let P0 be the preamplifier voltage noise, P0 be the optical power, and Φ0 be the modulation depth. Simulation calculations using the above formulas show that, given a fixed set of parameters, there exists an optimal modulation depth Φ0 that minimizes the gyroscope's RWC, thus achieving optimal accuracy. During long-term storage or use of fiber optic gyroscopes, the optical power is the most significant variable, slowly decreasing due to factors such as light source aging and creep of the adhesive used in the light source. Therefore, by monitoring changes in the gyroscope's optical power and adjusting the modulation depth in real time based on these changes, the fiber optic gyroscope's accuracy can be maintained at its optimal value for the current optical power, thus preserving its accuracy.

[0006] In summary, researching methods that allow for real-time adjustment of the gyroscope modulation depth based on changes in optical power without adding optical or electronic components is crucial for maintaining the accuracy of fiber optic gyroscopes and also contributes to the long-term reliability of high-precision fiber optic gyroscopes in system applications. Summary of the Invention

[0007] Based on the above analysis, the embodiments of the present invention aim to provide a modulation and demodulation system for maintaining the accuracy of fiber optic gyroscopes, thereby solving the problem of decreased gyroscope accuracy caused by optical power attenuation in existing technologies.

[0008] This invention discloses a modulation and demodulation system for maintaining the accuracy of fiber optic gyroscopes, the system comprising:

[0009] The fiber optic gyroscope optical path subsystem is used to output optical interference signals to the signal processing and conversion subsystem in real time; it is also used to receive analog modulation signals output by the modulation and demodulation subsystem in real time and perform real-time phase modulation on the fiber optic gyroscope.

[0010] The signal processing and conversion subsystem is used to process the interference signal, generate a digital interference signal, and input it into the modulation and demodulation subsystem.

[0011] The modulation and demodulation subsystem is used to perform rate demodulation and additional interference demodulation based on the digital interference signal, and to superimpose the step wave signal obtained by rate demodulation, the normal modulation signal obtained by additional interference demodulation, and the additional modulation signal to obtain a digital modulation signal; and to perform signal processing on the digital modulation signal to generate the analog modulation signal.

[0012] Based on the above solution, the present invention also makes the following improvements:

[0013] Furthermore, the modulation and demodulation subsystem includes:

[0014] The demodulation information classification module is used to decompose the digital interference signal into the demodulation rate signal and the demodulation optical power signal;

[0015] The optical power information demodulation module is used to perform additional interference demodulation on the optical power signal to be demodulated to obtain the demodulated amount of optical power.

[0016] The modulation depth adjustment module is used to determine the optimal modulation depth corresponding to the current optical power based on the demodulation amount of the optical power.

[0017] The normal modulation signal generation module is used to generate the corresponding normal modulation signal according to the optimal modulation depth.

[0018] Furthermore, the modulation and demodulation subsystem also includes:

[0019] An additional modulation signal generation module is used to periodically output additional modulation signals.

[0020] Furthermore, the period of the additional modulation signal is 2Nτ, where τ is the transit time of the fiber optic gyroscope and N is a positive integer; within one period of the additional modulation signal, the duration of the additional interference signal is 2τ.

[0021] Furthermore, in the optical power information demodulation module, the following is performed:

[0022] Demodulate the digital signal amplitude C1 with additional interference signal and the digital signal amplitude C2 without additional interference signal from the optical power signal to be demodulated;

[0023] The step height ΔC is calculated using the formula C1 - C2, and is used as the demodulation amount of the optical power.

[0024] Furthermore, the modulation and demodulation subsystem also includes:

[0025] The modulation signal combination module is used to superimpose the stepped wave signal, the normal modulation signal, and the additional modulation signal to generate a digital modulation signal.

[0026] Furthermore, the modulation and demodulation subsystem also includes:

[0027] The rate information demodulation module is used to demodulate the rate signal to be demodulated and generate a closed-loop feedback step signal corresponding to the rate information of the rate signal to be demodulated.

[0028] A stepped wave signal generator is used to integrate the closed-loop feedback stepped signal to generate a stepped wave signal.

[0029] Furthermore, the modulation and demodulation subsystem also includes:

[0030] The digital-to-analog converter and subsequent amplifier circuit is used to convert digital modulation signals into digital-to-analog signals and amplify the signals to generate corresponding analog modulation signals.

[0031] Furthermore, the signal processing and conversion subsystem is implemented using a pre-amplifier and analog-to-digital converter circuit;

[0032] The preamplifier and analog-to-digital converter circuit is used to amplify and convert the interference signal into a digital interference signal.

[0033] Furthermore, in the fiber optic gyroscope optical path subsystem, a photodetector outputs an optical interference signal, which is then used to apply an analog modulation signal to the integrated optical modulator.

[0034] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0035] The modulation and demodulation system for maintaining the accuracy of fiber optic gyroscopes provided by this invention has the following beneficial effects:

[0036] I. Significantly improves the accuracy and stability of fiber optic gyroscopes

[0037] This system, through the optical power information demodulation module in the modulation and demodulation subsystem, can accurately separate the optical power-related signal from the digital interference signal and calculate the demodulated amount of optical power according to a specific formula. Based on this demodulated amount, the modulation depth adjustment module can determine the optimal modulation depth corresponding to the current optical power. Subsequently, the normal modulation signal generation module generates the corresponding normal modulation signal according to the optimal modulation depth. This series of operations enables the fiber optic gyroscope to adjust the modulation depth in a timely manner when the optical power changes, effectively avoiding the problem of gyroscope accuracy degradation caused by optical power attenuation. This achieves online maintenance of gyroscope accuracy, ensuring that the accuracy of the fiber optic gyroscope remains at a high level during long-term operation, which is crucial for the long-term stability of navigation-grade, precision-grade, and reference-grade high-precision fiber optic gyroscopes.

[0038] II. Enhancing the long-term reliability of fiber optic gyroscopes

[0039] Without altering the original hardware configuration of the fiber optic gyroscope, including its optical path structure and circuitry, this system achieves real-time monitoring of optical power changes and online adjustment of modulation depth solely through software algorithm optimization. This software algorithm-driven optimization approach reduces the risk of malfunctions introduced by hardware modifications and lowers system complexity. Simultaneously, it dynamically adjusts the modulation depth based on the actual operating state of the fiber optic gyroscope, ensuring it remains in optimal working condition. This reduces the negative impact of uncertainties such as optical power fluctuations on gyroscope performance, thereby extending the gyroscope's lifespan and improving its long-term reliability. This is of significant value in ensuring the reliable operation of high-precision fiber optic gyroscopes in complex environments and during long-term missions.

[0040] III. Improve the adaptability and flexibility of fiber optic gyroscopes

[0041] The additional modulation signal generation module in this system periodically outputs an additional modulation signal, and the period of the additional modulation signal and the duration of the additional interference signal can be flexibly set according to the transit time of the fiber optic gyroscope. This adjustable additional modulation signal design allows the fiber optic gyroscope to better adapt to different working environments and task requirements, enhancing its adaptability in various application scenarios. Furthermore, the entire modulation and demodulation process is implemented based on software algorithms, facilitating parameter adjustment and optimization according to actual needs, further improving the flexibility of the fiber optic gyroscope and enabling it to quickly respond to different accuracy requirements and changes in working conditions.

[0042] IV. Simplifying the process of maintaining accuracy in fiber optic gyroscopes

[0043] Compared to traditional methods that require large-scale modifications to the optical path and circuitry of fiber optic gyroscopes to maintain accuracy, this system relies solely on software algorithm optimization, without altering the gyroscope's optical path and circuitry. This significantly simplifies the accuracy maintenance process and reduces implementation costs and complexity. Furthermore, the use of pre-amplifier and analog-to-digital converter circuits for the signal processing and conversion subsystem, and digital-to-analog converter and post-amplifier circuits for the modulation and demodulation subsystem to convert digital modulation signals to analog modulation signals, further ensures the system's stability and reliability. This makes the invention easily applicable to existing fiber optic gyroscope systems, providing strong support for the widespread adoption of fiber optic gyroscope accuracy maintenance technology.

[0044] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0045] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0046] Figure 1 This is a schematic diagram of a modulation and demodulation system for maintaining the accuracy of a fiber optic gyroscope, provided in an embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram of a stepped-wave modulation signal, a normal modulation signal, and an additional modulation signal provided in an embodiment of the present invention;

[0048] Figure 3 This is a schematic diagram of the demodulated power signal provided in an embodiment of the present invention;

[0049] Figure reference numerals: 1-Fiber optic gyroscope optical circuit subsystem, 2-Pre-amplifier and analog-to-digital converter circuit, 3-Demodulation information classification module, 4-Rate information demodulation module, 5-Step wave signal generator, 6-Optical power information demodulation module, 7-Modulation depth adjustment module, 8-Normal modulation signal generation module, 9-Additional modulation signal generation module, 10-Modulation signal combination module, and 11-Digital-to-analog converter and post-amplifier circuit. Detailed Implementation

[0050] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0051] A specific embodiment of the present invention discloses a modulation and demodulation system for maintaining the accuracy of a fiber optic gyroscope. A schematic diagram of the system is shown below. Figure 1 As shown, this modulation and demodulation system includes a fiber optic gyroscope optical path subsystem, a signal processing and conversion subsystem, and a modulation and demodulation subsystem. The following sections provide a detailed description of each subsystem.

[0052] (1) Fiber Optic Gyroscope Optical Circuit Subsystem

[0053] The fiber optic gyroscope optical path subsystem is used to output optical interference signals to the signal processing and conversion subsystem in real time; it is also used to receive analog modulation signals output by the modulation and demodulation subsystem in real time and to perform real-time phase modulation on the fiber optic gyroscope.

[0054] In this embodiment, the fiber optic gyroscope optical path subsystem consists of a light source, a coupler, a fiber optic ring, an integrated optical modulator, and a photodetector, and is capable of realizing the Sagnac effect of the fiber optic gyroscope.

[0055] In the specific operation, the light source generates a stable optical signal, which serves as the basis for subsequent interference and modulation. The coupler splits the optical signal into two beams, propagating clockwise and counterclockwise along the fiber optic loop, respectively. As the fiber loop rotates, the two beams experience an optical path difference due to the rotation, forming a Sagnac phase difference, which is the core manifestation of the Sagnac effect. The integrated optical modulator modulates the two beams in real time based on the received analog modulation signal. The modulated signal is superimposed on the Sagnac phase difference, facilitating subsequent signal processing. The two modulated optical signals interfere at the coupler, and the intensity change of the interference signal reflects the combined effect of the Sagnac phase difference and the modulation phase. The photodetector converts the interfering optical signal into an electrical signal, outputting an optical power signal (i.e., the interference signal) related to the interference intensity. This signal contains information about the Sagnac effect and is used for subsequent demodulation and calculation of the rotational angular velocity. Therefore, the optical interference signal is output by the photodetector, and the analog modulation signal is applied to the integrated optical modulator.

[0056] (2) Signal Processing and Conversion Subsystem

[0057] The signal processing and conversion subsystem is used to process the interference signal, generate a digital interference signal, and input it into the modulation and demodulation subsystem.

[0058] Specifically, in this embodiment, the signal processing and conversion subsystem can be implemented using a preamplifier and analog-to-digital converter circuit 2.

[0059] The preamplifier and analog-to-digital converter circuit 2 is used to amplify and convert the optical interference signal (i.e., the electrical signal converted by the photodetector) to generate a digital interference signal, which is then input into the demodulation information classification module in the modulation and demodulation subsystem.

[0060] (3) Modulation and demodulation subsystem

[0061] The modulation and demodulation subsystem is used to perform rate demodulation and additional interference demodulation based on the digital interference signal, and to superimpose the step wave signal obtained by rate demodulation, the normal modulation signal obtained by additional interference demodulation, and the additional modulation signal to obtain a digital modulation signal; and to perform signal processing on the digital modulation signal to generate the analog modulation signal.

[0062] The modulation and demodulation subsystem includes a demodulation information classification module 3, a rate information demodulation module 4, a stepped wave signal generator 5, an optical power information demodulation module 6, a modulation depth adjustment module 7, a normal modulation signal generation module 8, an additional modulation signal generation module 9, a modulation signal combination module 10, and a digital-to-analog converter and subsequent amplifier circuit 11. The functions of each component are described in detail below.

[0063] 1) Demodulation information classification module 3

[0064] The demodulation information classification module 3 is used to decompose the digital interference signal into the demodulation rate signal and the demodulation optical power signal, and input the demodulation rate signal and the demodulation optical power signal into the rate information demodulation module 4 and the optical power information demodulation module 6, respectively.

[0065] In the specific implementation process, the demodulation information classification module 3 can decompose the digital interference signal according to the preset control timing sequence.

[0066] 2) Rate information demodulation module 4

[0067] The rate information demodulation module 4 is used to demodulate the rate signal to be demodulated and generate a closed-loop feedback step signal corresponding to the rate information of the rate signal to be demodulated; the closed-loop feedback step signal is input into the step wave signal generation module 5.

[0068] In practice, the demodulation rate signal can be demodulated according to the demodulation timing sequence.

[0069] 3) Step wave signal generation module 5

[0070] Step wave signal generation module 5 is used to integrate the closed-loop feedback step signal to generate a step wave signal.

[0071] 4) Optical power information demodulation module 6

[0072] The optical power information demodulation module 6 is used to perform additional interference demodulation on the optical power signal to be demodulated to obtain the demodulated amount of optical power; and inputs the demodulated amount of optical power into the modulation depth adjustment module 7.

[0073] Specifically, the optical power information demodulation module 6 demodulates the optical power signal to be demodulated by: demodulating the digital signal amplitude C1 with and without additional interference signals from the optical power signal to be demodulated; calculating the step height ΔC = C1 - C2 according to the formula; and using the step height ΔC as the demodulated amount of optical power. Further details will follow. Figure 2 and Figure 3 The handling method here will be further explained.

[0074] In the specific implementation process, the demodulation information classification module 3 extracts the optical power signal to be demodulated according to the application timing of the additional modulation signal and sends it to the optical power information demodulation module 6.

[0075] 5) Modulation depth adjustment module 7

[0076] The modulation depth adjustment module 7 is used to determine the optimal modulation depth corresponding to the current optical power based on the demodulation amount of the optical power; and input the optimal modulation depth into the normal modulation signal generation module 8.

[0077] In the specific implementation process, this embodiment uses the pre-established relationship between the step height ΔC (i.e. the demodulation amount of the optical power signal to be demodulated) and the optimal modulation depth (digital quantity) to obtain the optimal modulation depth corresponding to the current optical power based on the demodulation amount of the optical power signal to be demodulated, i.e. the optimal modulation depth corresponding to the modulation signal to be applied, so as to optimize the accuracy of the fiber optic gyroscope.

[0078] 6) Normal modulation signal generation module 8

[0079] Normal modulation signal generation module 8 is used to generate the corresponding normal modulation signal according to the optimal modulation depth.

[0080] In some embodiments, the normal modulation mode generated by the normal modulation signal generation module 8 can be four-state modulation, square wave modulation, or a hybrid modulation mode. The optimal modulation depth is used as the modulation phase of the normal modulation signal, and a corresponding normal modulation signal is generated according to the normal modulation mode of the gyroscope.

[0081] The normal modulation signal generation module 8 receives the optimal modulation depth output by the modulation depth adjustment module 7 and changes the current gyroscope modulation depth to the optimal modulation depth, thereby achieving modulation phase adjustment of the fiber optic gyroscope and making the gyroscope's accuracy optimal.

[0082] 7) Additional modulation signal generation module 9

[0083] Additional modulation signal generation module 9 is used to periodically output additional modulation signals.

[0084] In this embodiment, the period of the additional modulation signal is 2Nτ, where τ is the transit time of the fiber optic gyroscope and N is a positive integer. Since the change in optical power is a very slow process, N can be very large.

[0085] Within one period of the additional modulation signal, the duration of the additional interference signal is 2τ. The amplitude of the additional interference signal in the first τ is π / M, and the amplitude of the additional interference signal in the second τ is -π / M, where M is a positive integer.

[0086] 8) Modulation signal combination module 10

[0087] The modulation signal combination module 10 is used to superimpose the stepped wave signal, the normal modulation signal and the additional modulation signal to generate a digital modulation signal.

[0088] In the specific implementation process, the stepped wave signal output by the stepped wave signal generation module 5, the normal modulation signal output by the normal modulation signal generation module 8, and the additional modulation signal generated by the additional modulation signal generation module 9 are synchronously superimposed in the modulation signal combination module 10 with a transit time τ as the period.

[0089] The advantage of this modulation method is that it combines the modulation signals required for the normal operation of the fiber optic gyroscope—namely, the normal modulation signal and the step-wave signal—while also accommodating the additional modulation signal used for accuracy maintenance. This modulation method can operate without affecting the normal operation of the fiber optic gyroscope, while simultaneously generating the optical power to be demodulated at the demodulation end due to the additional modulation signal, which is used to demodulate the optical power.

[0090] The periodic additional modulation signal enables the integrated optical modulator to generate periodic additional phase modulation, which acts on the optical interference signal of the fiber optic gyroscope optical circuit subsystem and generates a periodic additional step digital signal (i.e., the optical power signal to be demodulated) through the pre-amplifier and analog-to-digital converter circuit 2.

[0091] 9) Post-amplifier and digital-to-analog converter circuit 11

[0092] The post-amplifier and digital-to-analog converter circuit 11 is used to perform digital-to-analog conversion and signal amplification on the digital modulation signal to generate the corresponding analog modulation signal.

[0093] The analog modulation signal is input to the integrated optical modulator in the fiber optic gyroscope optical path subsystem to achieve phase modulation of the fiber optic gyroscope.

[0094] This embodiment, through the above modulation and demodulation method, ultimately achieves real-time monitoring of changes in gyroscope optical power and adjusts the modulation depth of the gyroscope online according to the changes in optical power, so that the accuracy of the fiber optic gyroscope is maintained at the optimal value under the current optical power, thus achieving the accuracy maintenance of the fiber optic gyroscope.

[0095] In this embodiment, the generated digital modulation signal can achieve rate information demodulation output and modulation phase feedback generation.

[0096] Figure 2 This is a schematic diagram of a stepped wave modulated signal, a normal modulated signal, and an additional modulated signal.

[0097] Figure 3 This is a schematic diagram of the optical power signal to be demodulated.

[0098] It should be noted that, in this embodiment, the demodulation amount of optical power is... Figure 3 The step height ΔC is given by the additional modulation signal, which carries a periodic additional interference signal (i.e., additional step digital information). The step height ΔC is proportional to the current optical power amplitude. Without the additional interference signal, the digital signal amplitude is C1; with the additional interference signal, the digital signal amplitude is C2. (Refer to...) Figure 3 Part B1 is due to the application of Figure 2 The response signal generated by the additional modulation signal shown is represented by the combination of B1 and A, which is the optical power signal to be demodulated, and the combination of B and A is the rate signal to be demodulated. When an additional modulation signal is applied... Figure 2 The additional modulation signal shown will inevitably produce Figure 3 The A1 and B1 signals in the optical power demodulation module 6 generate the optical power signal to be demodulated. During the demodulation process of the optical power information demodulation module 6, the corresponding signals in two adjacent demodulation cycles are subtracted. The amplitude of the digital signal without additional interference signal is C1, and the amplitude of the digital signal with additional interference signal is C2. The step height ΔC is obtained by subtracting the two signals.

[0099] Furthermore, in the modulation depth adjustment module 7, the optimal modulation depth corresponding to the current optical power can be determined based on the relationship between the optimal modulation depth and the step height, according to the demodulation amount of the optical power signal to be demodulated. In specific implementation, the relationship between the optimal modulation depth and the step height can be constructed in the following manner.

[0100] First, we construct a curve relating the optical power of the fiber optic gyroscope to the optimal modulation depth.

[0101] Multiple optical power points are set according to a fixed power interval; at each optical power point, multiple modulation depths are set with a fixed modulation depth interval. For example, for a certain optical power point, the modulation depths are set sequentially to π / 2, ..., π. In specific implementation, the modulation depth interval corresponds to the resolution of the digital-to-analog converter. For example, if the number of bits of the digital-to-analog converter is M, the minimum modulation depth interval ΔΦ0 is determined by formula (2):

[0102]

[0103] For each optical power point, calculate the RWC corresponding to each modulation depth at the current optical power point (using the fiber optic gyroscope RWC calculation formula in formula (1)), and take the modulation depth when the RWC takes the minimum value as the optimal modulation depth corresponding to the current optical power point.

[0104] Based on each optical power point and its corresponding optimal modulation depth, the relationship between optical power and optimal modulation depth is fitted to establish a curve relationship between optical power and optimal modulation depth.

[0105] For example, in this embodiment, a linear equation in two variables is used to fit the relationship between the two. During the fitting process, quadratic fitting parameters a0, a1, and a2 are determined, thereby establishing a quadratic fitting curve relationship between optical power and optimal modulation depth, expressed as:

[0106] Φ 0i =a0+a1P 0i +a2P 0i 2 (3)

[0107] Among them, P 0i Φ represents optical power. 0i This indicates the optimal modulation depth corresponding to the current optical power.

[0108] This embodiment establishes a quadratic fitting curve relationship between optical power and optimal modulation depth, enabling real-time adjustment of the optimal modulation depth and thus maintaining accuracy.

[0109] Then, based on the curve relationship between the optical power of the fiber optic gyroscope and the optimal modulation depth, the relationship between the optimal modulation depth and the step height can be constructed. It should be noted that since the step height is proportional to the amplitude of the optical power, the relationship between the optimal modulation depth and the step height is expressed as:

[0110] Φ 0i =b0+b1ΔC i +b2ΔC i 2 (4)

[0111] Where, ΔC i Indicates the step height; b0 = a0, b1 = a1 / K, b2 = a2 / K, K = P 0i / ΔC i .

[0112] It should be noted that the functional algorithm implementation shown in the above embodiments can be implemented in hardware, software, or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application-specific integrated circuit (ASIC), etc. When implemented in software, the elements of this invention are programs or code segments used to perform the required tasks.

[0113] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A modem system for implementing fiber optic gyroscope precision maintenance, characterized in that, The system comprises: an optical fiber gyroscope optical path subsystem, configured to output an optical interference signal to a signal processing and conversion subsystem in real time, and further configured to receive an analog modulation signal output by a modulation and demodulation subsystem in real time and perform real-time phase modulation on the optical fiber gyroscope; the signal processing and conversion subsystem, configured to perform signal processing on the interference signal, generate a digital interference signal, and input the digital interference signal to the modulation and demodulation subsystem; the modulation and demodulation subsystem, configured to perform rate demodulation and additional interference demodulation on the digital interference signal, superimpose a step wave signal obtained by rate demodulation, a normal modulation signal obtained by additional interference demodulation, and an additional modulation signal to obtain a digital modulation signal, and perform signal processing on the digital modulation signal to generate the analog modulation signal.

2. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to claim 1, wherein, The modulation and demodulation subsystem comprises: a demodulation information classification module, configured to decompose the digital interference signal into a to-be-demodulated rate signal and a to-be-demodulated optical power signal; an optical power information demodulation module, configured to perform additional interference demodulation on the to-be-demodulated optical power signal to obtain a demodulation amount of optical power; a modulation depth adjustment module, configured to determine an optimal modulation depth corresponding to the current optical power according to the demodulation amount of optical power; a normal modulation signal generation module, configured to generate a corresponding normal modulation signal according to the optimal modulation depth.

3. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to claim 2, characterized in that, The modulation and demodulation subsystem further comprises: an additional modulation signal generation module, configured to periodically output an additional modulation signal.

4. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to claim 3, characterized in that, The period of the additional modulation signal is 2Nτ, where τ is the transit time of the optical fiber gyroscope, and N is a positive integer; and the duration of the additional interference signal in one period of the additional modulation signal is 2τ.

5. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to claim 4, characterized in that, In the optical power information demodulation module, the following is performed: demodulating a digital signal amplitude C1 when the additional interference signal is present and a digital signal amplitude C2 when the additional interference signal is absent from the to-be-demodulated optical power signal; calculating a step height ΔC=C1-C2 according to a formula, and taking the step height ΔC as the demodulation amount of optical power.

6. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to any one of claims 1-5, characterized in that, The modulation and demodulation subsystem further comprises: a modulation signal combination module, configured to superimpose the step wave signal, the normal modulation signal, and the additional modulation signal to generate a digital modulation signal.

7. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to claim 6, characterized in that, The modulation and demodulation subsystem further comprises: a rate information demodulation module, configured to perform rate demodulation on the to-be-demodulated rate signal to generate a closed-loop feedback step signal corresponding to the rate information of the to-be-demodulated rate signal; a step wave signal generator, configured to integrate the closed-loop feedback step signal to generate a step wave signal.

8. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to claim 7, characterized in that, The modulation and demodulation subsystem further comprises: a digital-to-analog conversion and post-amplification circuit, configured to perform digital-to-analog conversion and signal amplification on the digital modulation signal to generate a corresponding analog modulation signal.

9. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to claim 8, characterized in that, The signal processing and conversion subsystem is implemented by using a pre-amplification and analog-to-digital conversion circuit; the pre-amplification and analog-to-digital conversion circuit, configured to perform signal amplification and analog-to-digital conversion on the interference signal to generate a digital interference signal.

10. The modem system for realizing the precision maintenance of fiber-optic gyroscope according to claim 9, characterized in that, In the optical fiber gyroscope optical path subsystem, the optical interference signal is output by a photodetector, and the analog modulation signal is applied to an integrated optical modulator.

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