QPSK (Quadrature Phase Shift Keying) non-cooperative navigation signal analysis method and system for multi-domain feature joint estimation

Abstract

The invention relates to the technical field of navigation signal analysis, in particular to a QPSK (Quadrature Phase Shift Keying) non-cooperative navigation signal analysis method and a QPSK non-cooperative navigation signal analysis system for multi-domain feature joint estimation. Traversing phases in the phase sequence in sequence, and obtaining an energy threshold value in combination with the center frequency estimation value of the current section; performing iterative analysis on the frequency and the phase to obtain estimated values of the frequency and the phase; obtaining a complex baseband signal through the estimated values of the frequency and the phase; judging whether IQ code crossing occurs or not according to a cross-correlation relationship between the complex baseband signal and a local code stream sequence, and if the code crossing occurs, performing adjustment to obtain a corrected I-path baseband signal and a corrected Q-path baseband signal; adjusting the length of a chip through a code rate so as to reconstruct a code element sequence and obtain I-path and Q-path pure code element sequences; and taking the I-path and Q-path pure code element sequences as analysis results of the non-cooperative navigation signals. According to the invention, the accuracy of analyzing the non-cooperative navigation signal is improved.

Description

Technical Field

[0001] This invention relates to the field of navigation signal analysis technology, and in particular to a QPSK non-cooperative navigation signal analysis method and system based on multi-domain feature joint estimation. Background Technology

[0002] With the development of navigation technology, the need for processing non-cooperative navigation signals is becoming increasingly prominent, especially in the military field. Traditional symbol analysis methods rely on preset civilian reference signals and fixed phase coupling relationships, making it difficult to cope with problems such as high overlap of I / Q (In-phase / Quadrature-phase) branch parameters, dynamic changes in carrier frequency offset, and IQ code mixing in QPSK (Quadrature Phase Shift Keying) modulated signals at the same frequency. Furthermore, the high-speed motion of low-Earth orbit satellites causes time-varying signal code rates, resulting in insufficient symbol reconstruction accuracy. This invention addresses these challenges by proposing robust analysis of non-cooperative signals through multi-domain feature joint estimation, solving the semi-blind demodulation problem under conditions of no prior information. Summary of the Invention

[0003] This invention provides a method and system for parsing QPSK non-cooperative navigation signals based on joint estimation of multi-domain features, which addresses the problem of insufficient parsing accuracy of traditional symbol parsing methods for non-cooperative signals when no prior information is available.

[0004] The objective of this invention can be achieved through the following technical solutions: The first aspect of this invention is to provide a method for parsing QPSK non-cooperative navigation signals based on joint estimation of multi-domain features, comprising: Based on the B3 frequency transmission frequency, satellite velocity, the angle between the satellite velocity direction and the receiver direction, and the speed of light, a Doppler frequency shift sequence is constructed; the center frequency estimate of the current segment is predicted and obtained through the Doppler frequency shift sequence; a set of phase sequences is obtained; the phases in the phase sequence are traversed sequentially, and combined with the center frequency estimate of the current segment, the energy value corresponding to each phase is obtained; then, the energy threshold is selected from the energy values ​​corresponding to all phases. A short data segment is defined, and the frequency adjustment range and phase adjustment range are obtained. The frequency and phase within the frequency adjustment range and phase adjustment range are iteratively analyzed. By comparing the energy value corresponding to each combination of frequency and phase with the energy threshold, the optimal values ​​of frequency and phase are determined as the estimated values ​​of frequency and phase. The I-channel regulated baseband signal and the Q-channel regulated baseband signal are obtained from the estimated values ​​of frequency and phase. The complex baseband signal is obtained by adjusting the I-channel and Q-channel baseband signals; the receiver internally generates a local code stream sequence; the cross-correlation relationship between the complex baseband signal and the local code stream sequence is used to determine whether IQ code crosstalk occurs. If crosstalk occurs, adjustments are made to obtain the corrected I-channel and Q-channel baseband signals. By identifying the sign of the data in the corrected I-channel and Q-channel baseband signals, the symbol sequences of the I-channel and Q-channel are obtained. The chip length is adjusted by the code rate to obtain several chips. Based on the symbol sequences, the symbol sequence is reconstructed by counting the number of all +1s and all -1s in each chip to obtain the pure symbol sequences of the I-channel and Q-channel. The pure symbol sequences of the I-channel and Q-channel are used as the analysis results of the non-cooperative navigation signal.

[0005] Furthermore, the construction of the Doppler frequency shift sequence based on the B3 frequency transmission frequency, satellite velocity, the angle between the satellite velocity direction and the receiver direction, and the speed of light includes: The Doppler frequency shift at each moment is obtained based on the B3 frequency transmission frequency, satellite velocity, the angle between the satellite velocity direction and the receiver direction, and the speed of light; the Doppler frequency shift at each moment is specifically expressed by the formula:

[0006] In the formula, This indicates the transmission frequency of the B3 frequency point. Indicates the first The satellite's velocity at that moment. Indicates the first The angle between the direction of the satellite's velocity and the direction of the receiver at any given moment. Represents the speed of light. Indicates the first Doppler frequency shift at each moment; The Doppler frequency shifts at all times are obtained by a preset time interval; the Doppler frequency shifts at all times are arranged into a sequence in chronological order, which is denoted as the Doppler frequency shift sequence.

[0007] Further, the process of predicting and obtaining the estimated center frequency of the current segment using a Doppler frequency shift sequence; obtaining a set of phase sequences; sequentially traversing the phases in the phase sequences; combining the estimated center frequency of the current segment to obtain the energy value corresponding to each phase; and then filtering out energy thresholds from all the energy values ​​corresponding to all phases includes: Based on the Doppler frequency shift sequence, a curve fitting using a quadratic polynomial with the least squares method is performed to obtain the Doppler frequency shift fitting curve; the Doppler frequency shift at subsequent times is estimated using the Doppler frequency shift fitting curve; The estimated center frequency of the current segment is obtained by predicting the Doppler frequency shift fitting curve. Divide the interval from 0 to π / 2 into a phase sequence using a preset phase interval; The phases in the phase sequence are traversed sequentially. Combined with the estimated center frequency of the current segment, several local carrier stripping functions corresponding to several phases are obtained through the conventional baseband signal acquisition process. By combining each local carrier stripping function obtained through traversal with the input signal and low-pass filter, the I-path baseband signal and Q-path baseband signal corresponding to each phase are obtained. Obtain the amplitudes of the I-channel and Q-channel baseband signals corresponding to each phase; based on the amplitudes of the I-channel and Q-channel baseband signals corresponding to each phase, obtain the energy value corresponding to each phase; the specific formula for obtaining the energy value corresponding to each phase is as follows:

[0008] In the formula, This represents the amplitude of the I-channel baseband signal corresponding to each phase. This represents the amplitude of the Q-path baseband signal corresponding to each phase. This represents the energy value corresponding to each phase; The maximum energy value corresponding to all phases in the phase sequence is selected as the energy threshold.

[0009] Further, the process of obtaining the frequency adjustment range and phase adjustment range involves iteratively analyzing the frequencies and phases within these ranges. By comparing the energy value corresponding to each frequency and phase combination with an energy threshold, the optimal values ​​of the frequency and phase are determined as estimated values. Using these estimated values, the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal are obtained, including: The reference frequency is determined, and the frequency adjustment range is determined as the reference frequency. The frequency and phase are adjusted in Hz, with a phase adjustment range of 0 to π / 2. Iterative analysis is performed on the frequency and phase within both the frequency and phase adjustment ranges to determine the optimal values ​​of frequency and phase, which are then used as estimates. The specific process for iteratively obtaining these estimates is as follows: An initial frequency and initial phase are determined based on the frequency adjustment range and phase adjustment range. The initial local carrier stripping function is obtained by substituting the initial frequency and initial phase into the local carrier stripping function. The initial energy value is obtained by acquiring the energy value corresponding to each phase in the phase sequence based on the initial local carrier stripping function. The difference between the initial energy value and the energy threshold is compared and recorded as the initial difference for the short-time data segment. When the initial difference is less than or equal to the energy threshold... If the initial frequency and initial phase are obtained, then the initial frequency and initial phase are used as estimated values ​​of frequency and phase; otherwise, continue to the next judgment. The frequency and phase fine-tuning directions are determined using gradient descent or hill-climbing algorithms. New frequencies and phases are obtained from the frequency and phase adjustment ranges, respectively denoted as the second frequency and second phase of the short-time data segment. The second frequency and second phase are substituted into the local carrier stripping function to obtain the second local carrier stripping function for the short-time data segment. Based on the second local carrier stripping function, the second energy value is obtained by acquiring the energy value corresponding to each phase in the phase sequence. The difference between the second energy value and the energy threshold is compared and denoted as the second difference of the short-time data segment. When the second difference is less than or equal to the energy threshold... If the second frequency and second phase are used as estimated values ​​for the frequency and phase, then proceed to the next judgment. This process continues until estimates of the frequency and phase are obtained, at which point the process stops. in, The preset ratio threshold; An adjusted local carrier stripping function is constructed using frequency and phase estimates. The adjusted local carrier stripping function, combined with the input signal and a low-pass filter, yields the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal.

[0010] Further, the step of determining whether IQ code crosstalk occurs by the cross-correlation relationship between the complex baseband signal and the local code stream sequence, and if crosstalk occurs, making adjustments to obtain the corrected I-path baseband signal and Q-path baseband signal, includes: By using a preset time interval segment, the complex baseband signal and the local code stream sequence are synchronously divided into several data segments; based on the corresponding data segments in the complex baseband signal and the local code stream sequence, the complex correlation vector is obtained through a cross-correlation function; The vector angle of each data segment is obtained based on the complex correlation vector corresponding to each data segment; the vector angle of each data segment is specifically expressed by the formula:

[0011] In the formula, Represents the complex correlation vector. This represents the real part of the complex correlation vector. This represents the imaginary part of the complex correlation vector. Represents the arctangent function. The vector angle representing each data segment; Based on the relationship between the vector angles of two adjacent data segments, determine whether IQ code has occurred; the specific process for determining whether IQ code has occurred is as follows: When the difference in the vector angle between two adjacent data segments is less than or equal to a preset angle threshold, no IQ code has occurred, and the data is output directly without processing. When the difference in the vector angle between two adjacent data segments is greater than the preset angle threshold, it is determined that IQ code has occurred. Once code has occurred, the I and Q code streams of the current data segment of the complex baseband signal are swapped. Based on the adjustment results of the I-channel and Q-channel code stream data, the corrected I-channel baseband signal and Q-channel baseband signal are obtained.

[0012] Further, obtaining the symbol sequence of the I-channel and the symbol sequence of the Q-channel by determining the sign of the data in the corrected I-channel and Q-channel baseband signals includes: The corrected I-channel baseband signal and Q-channel baseband signal are respectively subjected to symbol determination; the symbol determination is specifically as follows: the corrected I-channel baseband signal and Q-channel baseband signal are divided into several sample data at a preset time interval; for each sample data, when each sample data is greater than or equal to 0, it is determined as 1, and when each sample data is less than 0, it is determined as -1. Obtain the symbol sequence of the I-path and the symbol sequence of the Q-path through symbol decision.

[0013] Further, the step of adjusting the chip length by the code rate to obtain several chips; and reconstructing the symbol sequence based on the symbol sequence by the number of all +1s and all -1s in each chip to obtain pure symbol sequences for both I and Q paths, includes: Starting from the first sampled data, the chip length is corrected; starting from the first sampled data, the number of sampling points of the first chip is obtained according to the sampling rate and the code rate corresponding to the first chip, and the length of the first chip is obtained through the number of sampling points of the first chip; it is determined whether the number of remaining sampled data is less than the number of sampling points of the first chip. If it is, the iterative block division stops; if it is not, the division of the second chip length continues. Based on the sampling rate and the code rate corresponding to the second chip, the number of sampling points of the second chip is obtained, and the length of the second chip is obtained through the number of sampling points of the second chip; it is determined whether the number of remaining sampled data is less than the number of sampling points of the second chip. If it is, the iterative block division is stopped; if it is not, the division of the third chip length is continued. This process continues until there are not enough remaining sampled data points to stop iterative partitioning. The number of sampling points for each chip is expressed by the formula:

[0014] In the formula, Indicates the sampling rate. This indicates the code rate corresponding to each chip. Indicates to Round to the nearest integer. This indicates the number of sampling points per chip; The number of all +1s and all -1s in each chip is determined by the symbol sequences of the I-path and Q-path. Based on the number of all +1s and all -1s in each chip, the corresponding common value within each chip is determined. The pure symbol sequences of the I-path and Q-path are then reconstructed using the corresponding common values ​​within all chips. Specifically, the process for determining the corresponding common value within each chip is as follows: If the number of +1s in each chip is greater than or equal to the number of -1s, then the value in each chip is uniformly set to +1; if the number of +1s in each chip is less than the number of -1s, then the value in each chip is uniformly set to -1. At this point, the pure symbol sequences for the I and Q paths have been determined.

[0015] A second aspect of the present invention is to provide a QPSK non-cooperative navigation signal parsing system for joint estimation of multi-domain features, comprising: The code stream information estimation module is used to construct a Doppler frequency shift sequence based on the B3 frequency transmission frequency, satellite motion speed, the angle between the satellite motion speed direction and the receiver direction, and the speed of light; predict and obtain the estimated center frequency of the current segment using the Doppler frequency shift sequence; acquire a set of phase sequences; sequentially traverse the phases in the phase sequences, combine them with the estimated center frequency of the current segment to obtain the energy value corresponding to each phase, and then filter out the energy threshold from all the energy values ​​corresponding to the phases; determine a short-time data segment, acquire the frequency adjustment range and phase adjustment range, and perform iterative analysis on the frequencies and phases within the frequency adjustment range and phase adjustment range. By comparing the energy value corresponding to each pair of frequency and phase combinations with the energy threshold, the optimal values ​​of frequency and phase are determined as the estimated values ​​of frequency and phase; and obtain the I-channel adjusted baseband signal and Q-channel adjusted baseband signal using the estimated values ​​of frequency and phase. The IQ dynamic code splitting module is used to obtain a complex baseband signal by adjusting the I-channel and Q-channel baseband signals. The receiver internally generates a local code stream sequence. By using the cross-correlation relationship between the complex baseband signal and the local code stream sequence, it determines whether IQ code splitting has occurred. If code splitting has occurred, it makes adjustments to obtain the corrected I-channel and Q-channel baseband signals. The sampling information reconstruction module is used to obtain the symbol sequences of the I-channel and Q-channel baseband signals by identifying the sign of the data in the corrected I-channel and Q-channel baseband signals; adjust the chip length by adjusting the code rate to obtain several chips; reconstruct the symbol sequence based on the symbol sequences by counting all +1s and all -1s in each chip to obtain the pure symbol sequences of the I-channel and Q-channel; and use the pure symbol sequences of the I-channel and Q-channel as the parsing result of the non-cooperative navigation signal.

[0016] A third aspect of the present invention is to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the QPSK non-cooperative navigation signal parsing method for joint estimation of multi-domain features.

[0017] A fourth aspect of the present invention is to provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the QPSK non-cooperative navigation signal parsing method for joint estimation of multi-domain features.

[0018] Compared with existing technologies, the beneficial effects of this invention are: constructing a Doppler frequency shift sequence; sequentially traversing the phases in the phase sequence, combining the current segment center frequency estimate to obtain the energy value corresponding to each phase, and then filtering out the energy threshold from all phase-corresponding energy values; improving the accuracy of energy threshold analysis; performing iterative analysis on frequencies and phases within the frequency adjustment range and phase adjustment range, obtaining frequency and phase estimates by comparing the energy value corresponding to each pair of frequency and phase combinations with the energy threshold; obtaining I-channel and Q-channel adjusted baseband signals through the frequency and phase estimates; improving the accuracy of code stream information estimation; obtaining complex baseband signals through I-channel and Q-channel adjusted baseband signals; the receiver internally generates its own local code stream sequence; and the complex baseband signal... The cross-correlation relationship between the local code stream sequence and the signal is used to determine whether IQ code jamming occurs. If jamming occurs, adjustments are made to obtain corrected I-channel and Q-channel baseband signals, reducing the impact of IQ dynamic code jamming. The symbol sequences of the I-channel and Q-channel are obtained by identifying the sign of the data in the corrected I-channel and Q-channel baseband signals. The chip length is adjusted by the code rate to obtain several chips. Based on the symbol sequences, the symbol sequence is reconstructed by counting all +1s and all -1s in each chip, resulting in pure symbol sequences for the I-channel and Q-channel. The pure symbol sequences of the I-channel and Q-channel are used as the analysis results for non-cooperative navigation signals, improving the accuracy of sampled information reconstruction. This solves the problem of insufficient accuracy in analyzing non-cooperative signals under conditions without prior information, which is a problem of traditional symbol analysis methods. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart illustrating the steps of the QPSK non-cooperative navigation signal parsing method for joint estimation of multi-domain features provided in this invention; Figure 2 A schematic diagram of the module flow of the QPSK non-cooperative navigation signal parsing system for multi-domain feature joint estimation provided by the present invention; Figure 3 This is a constellation diagram for the B3 frequency point of the low-orbit enhancement signal. Figure 4 The spectrum diagram of the B3 frequency point of the low-orbit enhancement signal; Figure 5 A schematic diagram illustrating the analysis results of the baseband information of the QPSK modulated signal from a low-Earth orbit navigation enhancement satellite. Figure 6 A schematic diagram illustrating the constellation analysis results of QPSK baseband signals for low-Earth orbit navigation enhancement satellites; Figure 7 This is a schematic diagram of the reconstruction results of the symbol sampling information. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] To address the problems existing in the background technology, this paper studies and designs a QPSK non-cooperative navigation signal analysis method and system based on multi-domain feature joint estimation, which has important practical significance.

[0024] like Figure 1 As shown, the first aspect of the present invention is to provide a QPSK non-cooperative navigation signal parsing method based on joint estimation of multi-domain features, comprising the following steps: Step S001: Construct a Doppler frequency shift sequence; sequentially traverse the phases in the phase sequence, and obtain the energy threshold by combining the current segment center frequency estimate; perform iterative analysis on the frequency and phase to obtain the frequency and phase estimates; obtain the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal through the frequency and phase estimates.

[0025] It should be noted that, in order to accurately describe the mathematical composition of the received QPSK modulated intermediate frequency signal and provide a theoretical basis and algorithm design basis for subsequent carrier stripping, parameter estimation, and signal processing, the analysis is performed using the input signal. To facilitate subsequent digital signal processing, since the baseband signal has a low frequency, it is easier to perform sampling, filtering, symbol decision, and decoding operations to extract the original symbol sequence. Therefore, by combining the stripping function with the input signal, the signal's spectrum is shifted to the baseband (zero frequency) and high-frequency (double harmonic) ranges for easier subsequent analysis.

[0026] It should be further noted that since a low-frequency baseband signal is used in the subsequent analysis, a low-pass filter is introduced to eliminate the high-frequency signal portion in order to obtain the final signal data used for analysis.

[0027] Specifically, the conventional baseband signal acquisition process is as follows: acquire the existing input signal and the local carrier stripping function, send the input signal and the local carrier stripping function into a mixer for multiplication to obtain the mixed signal; add a low-pass filter after the mixer, and adjust the mixed signal through the low-pass filter to obtain the I-channel baseband signal and the Q-channel baseband signal.

[0028] The mixer's function is to perform spectrum shifting through multiplication, converting high-frequency signals to the vicinity of the baseband, in preparation for subsequent filtering and extraction of the baseband signal.

[0029] It should be noted that because low-Earth orbit (LEO) satellites move at relatively high speeds, their frequency and phase information are constantly changing. Therefore, it is necessary to perform segmented calculations of the baseband code stream information. The constellation diagram of the LEO augmentation signal at frequency point B3 is shown below. Figure 3 As shown; the specific spectrum diagram of the low-orbit enhanced signal at frequency point B3 is as follows. Figure 4As shown. Among them, the B3 frequency is a specific radio channel used by China's BeiDou Navigation Satellite System, with a center frequency of 1268.52MHz (Megahertz).

[0030] Specifically, the continuous demodulation steps for baseband bitstream information are as follows: 1) Doppler Information Estimation: Based on the B3 frequency transmission frequency, satellite velocity, the angle between the satellite velocity direction and the receiver direction, and the speed of light, the Doppler frequency shift at each moment is obtained; the Doppler frequency shift at each moment is specifically expressed by the formula:

[0031] In the formula, This indicates the transmission frequency of the B3 frequency point. Indicates the first The satellite's velocity at that moment. Indicates the first The angle between the direction of the satellite's velocity and the direction of the receiver at any given moment. Represents the speed of light. Indicates the first The Doppler frequency shift at each moment. The Doppler frequency shift is the change in frequency.

[0032] Doppler shift is the offset of the frequency in the signal received by the receiver relative to the satellite's transmission frequency. The receiver is a dynamic / static user terminal located on the Earth's surface or in near-Earth space (such as vehicle-mounted, shipborne, airborne, or fixed station), and its specific location is unknown and may move; it is precisely the target that needs to be determined using navigation signals. B3 refers to the third civilian signal frequency band of the BeiDou system (BeiDou-3 Navigation Signal B3).

[0033] The Doppler frequency shift at all times is obtained at a preset time interval of 1 millisecond; the Doppler frequency shifts at all times are arranged into a sequence in chronological order, which is denoted as the Doppler frequency shift sequence.

[0034] 2) Doppler information fitting: Based on the Doppler frequency shift sequence, curve fitting is performed using a quadratic polynomial with the least squares method to obtain the Doppler frequency shift fitting curve; the Doppler frequency shift at subsequent times is estimated by using the Doppler frequency shift fitting curve.

[0035] The least squares method is a well-known technique and will not be elaborated on here.

[0036] 3) Divide the interval from 0 to π / 2 into a phase sequence using a preset phase interval; wherein, in this embodiment, the preset phase interval is... In this embodiment, the preset phase interval is not specifically limited, and the implementer can determine it according to the specific situation.

[0037] The estimated center frequency of the current segment is obtained by predicting the Doppler frequency shift fitting curve. By iterating through the phases in the phase sequence and combining them with the estimated center frequency of the current segment, several local carrier stripping functions corresponding to several phases are obtained through the conventional baseband signal acquisition process. By combining each local carrier stripping function obtained through the iteration with the input signal and the low-pass filter, the I-path baseband signal and Q-path baseband signal corresponding to each phase are obtained.

[0038] Obtain the amplitudes of the I-path and Q-path baseband signals corresponding to each phase, and denot them as follows: and Based on the amplitudes of the I-channel and Q-channel baseband signals corresponding to each phase, the energy value corresponding to each phase is obtained; the energy value corresponding to each phase is specifically expressed by the formula:

[0039] In the formula, This represents the amplitude of the I-channel baseband signal corresponding to each phase. This represents the amplitude of the Q-path baseband signal corresponding to each phase. This represents the energy value corresponding to each phase.

[0040] The maximum energy value corresponding to all phases in the phase sequence is selected and denoted as the energy threshold.

[0041] It's important to note that a highly efficient engineering optimization strategy is employed based on the unique four-fold rotational symmetry of QPSK modulation signals. Since the QPSK constellation diagram completely overlaps with itself after rotations of 90°, 180°, and 270°, the demodulated energy values ​​of the carrier phase are identical at the four points of optimal phase φ, φ+π / 2, φ+π, and φ+3π / 2. Therefore, searching within the complete range of 0 to 2π would yield four equivalent peaks, resulting in three-quarters computational redundancy. Compressing the search range to 0~π / 2 uniquely includes one optimal solution, thereby reducing the computational complexity to one-quarter while maintaining algorithm correctness, significantly improving real-time processing efficiency. The subsequent fixed-phase ambiguity (k*π / 2) problem is handled by frame synchronization, differential decoding, or a dedicated IQ dynamic serialization separation module, achieving decoupling between algorithm modules and maximizing efficiency.

[0042] 4) Determine a short data segment, establish a reference frequency, and define the frequency adjustment range as the reference frequency. The frequency and phase are adjusted in Hz, with a phase adjustment range of 0 to π / 2. Iterative analysis is performed on the frequency and phase within both the frequency and phase adjustment ranges to determine the optimal values ​​of frequency and phase, which are then used as estimates. The specific process for iteratively obtaining these estimates is as follows: An initial frequency and initial phase are determined based on the frequency adjustment range and phase adjustment range. The initial local carrier stripping function is obtained by substituting the initial frequency and initial phase into the local carrier stripping function. The initial energy value is obtained by acquiring the energy value corresponding to each phase in the phase sequence based on the initial local carrier stripping function. The difference between the initial energy value and the energy threshold is compared and recorded as the initial difference for the short-time data segment. When the initial difference is less than or equal to the energy threshold... If the initial frequency and initial phase are obtained, then the initial frequency and initial phase are used as estimated values ​​of frequency and phase; otherwise, continue to the next judgment. The frequency and phase fine-tuning directions are determined using gradient descent or hill-climbing algorithms. New frequencies and phases are obtained from the frequency and phase adjustment ranges, respectively denoted as the second frequency and second phase of the short-time data segment. The second frequency and second phase are substituted into the local carrier stripping function to obtain the second local carrier stripping function for the short-time data segment. Based on the second local carrier stripping function, the second energy value is obtained by acquiring the energy value corresponding to each phase in the phase sequence. The difference between the second energy value and the energy threshold is compared and denoted as the second difference of the short-time data segment. When the second difference is less than or equal to the energy threshold... If the second frequency and second phase are used as estimated values ​​for the frequency and phase, then proceed to the next judgment. This process continues until estimates of the frequency and phase are obtained, at which point the process stops.

[0043] in, The preset ratio threshold is used; in this embodiment... In this embodiment, for No specific restrictions are imposed; implementers can decide based on the circumstances.

[0044] Thus, the estimated values ​​of frequency and phase are obtained through the above method.

[0045] 5) Code stream information calculation: Construct an adjusted local carrier stripping function using the estimated values ​​of frequency and phase. Then, obtain the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal by combining the adjusted local carrier stripping function with the input signal and a low-pass filter.

[0046] The analytical results for the final I-channel and Q-channel adjusted baseband signals are as follows: Figure 5 The schematic diagram shows the analysis results of the baseband information of the QPSK modulated signal of the low-orbit navigation augmentation satellite.

[0047] At this point, the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal are obtained.

[0048] Step S002: Obtain a complex baseband signal by adjusting the I-channel baseband signal and the Q-channel baseband signal; determine whether IQ code crosstalk occurs by the cross-correlation relationship between the complex baseband signal and the local code stream sequence. If crosstalk occurs, adjust the signal to obtain the corrected I-channel baseband signal and Q-channel baseband signal.

[0049] It should be noted that the bitstream information obtained from the QPSK signal is determined based on the amplitude summation characteristic. When the phase reverses by 90 degrees, the amplitude sum remains unchanged, while the I / Q bitstream information is reversed. During segmented bitstream information decoding, the co-directional and quadrature branches of the QPSK signal may interchange, a phenomenon known as IQ dynamic crosstalk. Therefore, it is necessary to determine whether the bitstream parsed at each epoch belongs to the I or Q path. Utilizing the orthogonality of the epoch-time characteristics of the I / Q dual-path signals, a dynamic sliding window matching degree decision module is designed to suppress inter-symbol interference caused by time-varying characteristics.

[0050] Specifically, a complex baseband signal is obtained by adjusting the baseband signal through the I-channel and the Q-channel; wherein the I-channel adjusted baseband signal is the real part of the complex baseband signal, and the Q-channel adjusted baseband signal is the imaginary part of the complex baseband signal.

[0051] The receiver internally generates its own local code stream sequence (which is a known, ideal reference signal). The complex baseband signal and the local bitstream sequence are synchronously divided into several data segments by a preset time interval. Based on the corresponding data segments in the complex baseband signal and the local bitstream sequence, a complex correlation vector (a complex correlation vector is a complex number, and a complex number can be represented as a vector in the complex plane) is obtained through a cross-correlation function. The cross-correlation function is a well-known technique and will not be described in detail here. In this embodiment, the length of the preset time interval is 1 millisecond. However, the length of the preset time interval is not specifically limited in this embodiment and can be determined by the implementer according to specific circumstances.

[0052] Based on the complex correlation vector corresponding to each data segment, the vector angle of each data segment is obtained; specifically, the vector angle of each data segment is expressed by the formula:

[0053] In the formula, Represents the complex correlation vector. This represents the real part of the complex correlation vector. This represents the imaginary part of the complex correlation vector. Represents the arctangent function. This represents the vector angle of each data segment.

[0054] Based on the relationship between the vector angles of two adjacent data segments, determine whether IQ code has occurred; the specific process for determining whether IQ code has occurred is as follows: When the difference in the vector angle between two adjacent data segments is less than or equal to a preset angle threshold, no IQ code jamming occurs, and the data is directly output without further processing. When the difference in the vector angle between two adjacent data segments is greater than the preset angle threshold, IQ code jamming is determined to have occurred. Once jamming is determined to have occurred, the I and Q code streams within the current data segment of the complex baseband signal are swapped. In this embodiment, the preset angle threshold is... In this embodiment, the preset angle threshold is not specifically limited, and the implementer can determine it according to the specific situation.

[0055] It should be noted that if cross-referencing occurs within the current data segment, the I and Q paths within that segment need to be passed to subsequent segments for cross-referencing analysis. The specific effect of IQ cross-referencing separation is as follows: Figure 6 The diagram shows the analysis results of the constellation diagram of the QPSK baseband signal of the low-orbit navigation augmentation satellite.

[0056] Based on the adjustment results of the I-channel and Q-channel code stream data, the corrected I-channel baseband signal and Q-channel baseband signal are obtained.

[0057] Step S003: Obtain the symbol sequence of the I-channel and the symbol sequence of the Q-channel by identifying the sign of the data in the corrected I-channel and Q-channel baseband signals; adjust the chip length by adjusting the code rate to obtain several chips; reconstruct the symbol sequence based on the symbol sequence by counting all +1s and all -1s in each chip to obtain the pure symbol sequences of the I-channel and Q-channel; use the pure symbol sequences of the I-channel and Q-channel as the analysis result of the non-cooperative navigation signal.

[0058] It should be noted that, in order to obtain real-time and accurate information on carrier and pseudocode feature changes, a majority decision method using Doppler information compensation is employed to reconstruct the code stream information in blocks according to the symbol width. Since the code rate of the real satellite signal is constantly changing, the number of sampling points per chip width also changes over time. Based on the real-time carrier frequency information, the code Doppler frequency is corrected, and the symbol width is adjusted to achieve dynamic block division. Because the acquisition time of the acquisition device is random, in order to recover the binary data of the chip width, a majority decision method is used for block detection to reduce the misjudgment rate caused by non-integer symbol / fractional symbol information points.

[0059] Specifically, sign determination is performed on the corrected I-channel baseband signal and Q-channel baseband signal respectively. The sign determination is as follows: the corrected I-channel baseband signal and Q-channel baseband signal are divided into several sample data at a preset time interval. For each sample data, if each sample data is greater than or equal to 0, it is determined as 1, and if each sample data is less than 0, it is determined as -1.

[0060] Obtain the symbol sequence of the I-path and the symbol sequence of the Q-path through symbol decision.

[0061] It should be noted that, since the code rate changes over time, the number of sampling points for each chip (i.e., a segment of identical data consisting of consecutive 1s or -1s) also changes over time.

[0062] Specifically, starting from the first sampled data, the chip length is corrected; starting from the first sampled data, the number of sampling points of the first chip is obtained according to the sampling rate and the code rate corresponding to the first chip, and the length of the first chip is obtained through the number of sampling points of the first chip; it is determined whether the number of remaining sampled data is less than the number of sampling points of the first chip. If it is, the iterative block division stops; if it is not, the division of the second chip length continues. Based on the sampling rate and the code rate corresponding to the second chip, the number of sampling points of the second chip is obtained, and the length of the second chip is obtained through the number of sampling points of the second chip; it is determined whether the number of remaining sampled data is less than the number of sampling points of the second chip. If it is, the iterative block division is stopped; if it is not, the division of the third chip length is continued. This process continues until there are not enough remaining sampled data points to stop iterative partitioning.

[0063] The number of sampling points for each chip is expressed by the formula:

[0064] In the formula, Indicates the sampling rate. This indicates the code rate corresponding to each chip. Indicates to Round to the nearest integer. This indicates the number of sampling points per chip.

[0065] The sampling rate is determined by the receiver hardware design (such as ADC device parameters) and is a fixed value; the code rate is an inherent parameter defined in the signal system standard (such as 1.023 Mcps for GPS C / A code) and varies in real time. ADC stands for Analog-to-Digital Converter; GPS C / A code stands for Global Positioning System Coarse / Acquisition Code; Mcps stands for Million Chips per Second.

[0066] The number of all +1s and all -1s in each chip is determined by the symbol sequences of the I-path and Q-path. Based on the number of all +1s and all -1s in each chip, the corresponding common value within each chip is determined. The pure symbol sequences of the I-path and Q-path are then reconstructed using the corresponding common values ​​within all chips. Specifically, the process for determining the corresponding common value within each chip is as follows: If the number of +1s in each chip is greater than or equal to the number of -1s, then the value in each chip is set to +1; if the number of +1s in each chip is less than the number of -1s, then the value in each chip is set to -1.

[0067] Thus, the pure symbol sequences for the I and Q paths are obtained using the above method.

[0068] The pure symbol sequences from the I and Q paths are used as the analytical results of the non-cooperative navigation signal. This analytical result is the reconstructed result of the symbol sampling information; a schematic diagram of the reconstructed result of the symbol sampling information is shown below. Figure 7 As shown.

[0069] This completes the analysis of non-cooperative navigation signals.

[0070] like Figure 2 As shown, a second aspect of the present invention is to provide a QPSK non-cooperative navigation signal parsing system for joint estimation of multi-domain features, comprising: The code stream information estimation module 101 is used to construct a Doppler frequency shift sequence based on the B3 frequency transmission frequency, satellite motion speed, the angle between the satellite motion speed direction and the receiver direction, and the speed of light; predict and obtain the estimated center frequency of the current segment through the Doppler frequency shift sequence; obtain a set of phase sequences; sequentially traverse the phases in the phase sequences, combine them with the estimated center frequency of the current segment, obtain the energy value corresponding to each phase, and then filter out the energy threshold from all the energy values ​​corresponding to the phases; determine a short-time data segment, obtain the frequency adjustment range and phase adjustment range, perform iterative analysis on the frequencies and phases within the frequency adjustment range and phase adjustment range, and determine the optimal values ​​of the frequency and phase by the difference between the energy value corresponding to each pair of frequency and phase combinations and the energy threshold, which are used as the estimated values ​​of the frequency and phase; obtain the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal through the estimated values ​​of the frequency and phase; IQ dynamic code separation module 102: used to obtain complex baseband signal by adjusting the I-channel baseband signal and the Q-channel baseband signal; the receiver internally generates local code stream sequence; by the cross-correlation relationship between the complex baseband signal and the local code stream sequence, it determines whether IQ code crosstalk occurs. If crosstalk occurs, it makes adjustments to obtain the corrected I-channel baseband signal and Q-channel baseband signal. The sampling information reconstruction module 103 is used to obtain the symbol sequence of the I-channel and the symbol sequence of the Q-channel by the sign of the data in the corrected I-channel baseband signal and the Q-channel baseband signal; adjust the chip length by the code rate to obtain a number of chips; reconstruct the symbol sequence according to the symbol sequence by the number of all +1 and all -1 in each chip to obtain the pure symbol sequence of the I-channel and the Q-channel; and use the pure symbol sequence of the I-channel and the Q-channel as the parsing result of the non-cooperative navigation signal.

[0071] A third aspect of the present invention is to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a QPSK non-cooperative navigation signal parsing method for joint estimation of multi-domain features.

[0072] A fourth aspect of the present invention is to provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements a QPSK non-cooperative navigation signal parsing method for joint estimation of multi-domain features.

[0073] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, etc.) containing computer-usable program code.

[0074] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0075] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0076] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A QPSK non-cooperative navigation signal analysis method based on multi-domain feature joint estimation, characterized in that, include: Based on the B3 frequency transmission frequency, satellite velocity, the angle between the satellite velocity direction and the receiver direction, and the speed of light, a Doppler frequency shift sequence is constructed. The center frequency of the current segment is estimated by predicting the Doppler frequency shift sequence; a set of phase sequences is obtained; the phases in the phase sequence are traversed in turn, and the energy value corresponding to each phase is obtained by combining the center frequency estimate of the current segment; then the energy threshold is selected from the energy values ​​corresponding to all phases. A short data segment is defined, and the frequency adjustment range and phase adjustment range are obtained. The frequencies and phases within the frequency adjustment range and phase adjustment range are analyzed iteratively. By comparing the energy value corresponding to each pair of frequency and phase combinations with the energy threshold, the optimal values ​​of frequency and phase are determined as estimated values ​​of frequency and phase. The I-channel and Q-channel adjusted baseband signals are obtained by estimating the frequency and phase. A complex baseband signal is obtained by adjusting the I-channel baseband signal and the Q-channel baseband signal; The receiver internally generates its own local bitstream sequence; By analyzing the cross-correlation between the complex baseband signal and the local code stream sequence, it is determined whether IQ code jamming occurs. If jamming occurs, adjustments are made to obtain the corrected I-path baseband signal and Q-path baseband signal. By identifying the sign of the data in the corrected I-channel and Q-channel baseband signals, the symbol sequences of the I-channel and Q-channel are obtained. The chip length is adjusted by the code rate to obtain several chips. Based on the symbol sequences, the symbol sequence is reconstructed by counting the number of all +1s and all -1s in each chip to obtain the pure symbol sequences of the I-channel and Q-channel. The pure symbol sequences of the I-channel and Q-channel are used as the analysis results of the non-cooperative navigation signal.

2. The QPSK non-cooperative navigation signal parsing method based on multi-domain feature joint estimation according to claim 1, characterized in that, The process of constructing a Doppler frequency shift sequence based on the B3 frequency transmission frequency, satellite velocity, the angle between the satellite velocity direction and the receiver direction, and the speed of light includes: The Doppler frequency shift at each moment is obtained based on the B3 frequency transmission frequency, satellite velocity, the angle between the satellite velocity direction and the receiver direction, and the speed of light; the Doppler frequency shift at each moment is specifically expressed by the formula: In the formula, This indicates the transmission frequency of the B3 frequency point. Indicates the first The satellite's velocity at that moment. Indicates the first The angle between the direction of the satellite's velocity and the direction of the receiver at any given moment. Represents the speed of light. Indicates the first Doppler frequency shift at each moment; The Doppler frequency shifts at all times are obtained by a preset time interval; the Doppler frequency shifts at all times are arranged into a sequence in chronological order, which is denoted as the Doppler frequency shift sequence.

3. The QPSK non-cooperative navigation signal parsing method based on multi-domain feature joint estimation according to claim 1, characterized in that, The process involves predicting and obtaining the estimated center frequency of the current segment using a Doppler frequency shift sequence; acquiring a set of phase sequences; sequentially traversing the phases in the phase sequences; combining the estimated center frequency of the current segment with the phases to obtain the energy value corresponding to each phase; and then filtering out energy thresholds from all the energy values ​​corresponding to the phases, including: Based on the Doppler frequency shift sequence, a curve fitting using a quadratic polynomial with the least squares method is performed to obtain the Doppler frequency shift fitting curve; the Doppler frequency shift at subsequent times is estimated using the Doppler frequency shift fitting curve; The estimated center frequency of the current segment is obtained by predicting the Doppler frequency shift fitting curve. Divide the interval from 0 to π / 2 into a phase sequence using a preset phase interval; The phases in the phase sequence are traversed sequentially. Combined with the estimated center frequency of the current segment, several local carrier stripping functions corresponding to several phases are obtained through the conventional baseband signal acquisition process. By combining each local carrier stripping function obtained through traversal with the input signal and low-pass filter, the I-path baseband signal and Q-path baseband signal corresponding to each phase are obtained. Obtain the amplitudes of the I-channel and Q-channel baseband signals corresponding to each phase; based on the amplitudes of the I-channel and Q-channel baseband signals corresponding to each phase, obtain the energy value corresponding to each phase; the specific formula for obtaining the energy value corresponding to each phase is as follows: In the formula, This represents the amplitude of the I-channel baseband signal corresponding to each phase. This represents the amplitude of the Q-path baseband signal corresponding to each phase. This represents the energy value corresponding to each phase; The maximum energy value corresponding to all phases in the phase sequence is selected as the energy threshold.

4. The QPSK non-cooperative navigation signal parsing method based on multi-domain feature joint estimation according to claim 3, characterized in that, The process involves obtaining the frequency adjustment range and phase adjustment range, performing iterative analysis on the frequencies and phases within the frequency adjustment range and phase adjustment range, and determining the optimal values ​​of the frequency and phase by comparing the energy value corresponding to each pair of frequency and phase combinations with the energy threshold, which are then used as estimated values ​​of the frequency and phase. By estimating the frequency and phase, the I-channel regulated baseband signal and the Q-channel regulated baseband signal are obtained, including: The reference frequency is determined, and the frequency adjustment range is determined as the reference frequency. The frequency and phase are adjusted in Hz, with a phase adjustment range of 0 to π / 2. Iterative analysis is performed on the frequency and phase within both the frequency and phase adjustment ranges to determine the optimal values ​​of frequency and phase, which are then used as estimates. The specific process for iteratively obtaining these estimates is as follows: An initial frequency and initial phase are determined based on the frequency adjustment range and phase adjustment range. The initial local carrier stripping function is obtained by substituting the initial frequency and initial phase into the local carrier stripping function. The initial energy value is obtained by acquiring the energy value corresponding to each phase in the phase sequence based on the initial local carrier stripping function. The difference between the initial energy value and the energy threshold is compared and recorded as the initial difference for the short-time data segment. When the initial difference is less than or equal to the energy threshold... If the initial frequency and initial phase are obtained, then the initial frequency and initial phase are used as estimated values ​​of frequency and phase; otherwise, continue to the next judgment. The frequency and phase fine-tuning directions are determined using gradient descent or hill-climbing algorithms. New frequencies and phases are obtained from the frequency and phase adjustment ranges, respectively denoted as the second frequency and second phase of the short-time data segment. The second frequency and second phase are substituted into the local carrier stripping function to obtain the second local carrier stripping function for the short-time data segment. Based on the second local carrier stripping function, the second energy value is obtained by acquiring the energy value corresponding to each phase in the phase sequence. The difference between the second energy value and the energy threshold is compared and denoted as the second difference of the short-time data segment. When the second difference is less than or equal to the energy threshold... If the second frequency and second phase are used as estimated values ​​for the frequency and phase, then proceed to the next judgment. This process continues until estimates of the frequency and phase are obtained, at which point the process stops. in, The preset ratio threshold; An adjusted local carrier stripping function is constructed using frequency and phase estimates. The adjusted local carrier stripping function, combined with the input signal and a low-pass filter, yields the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal.

5. The QPSK non-cooperative navigation signal parsing method based on multi-domain feature joint estimation according to claim 1, characterized in that, The process of determining whether IQ code crosstalk occurs by analyzing the cross-correlation between the complex baseband signal and the local code stream sequence, and adjusting the signal to obtain the corrected I-channel and Q-channel baseband signals if crosstalk occurs, includes: By using a preset time interval segment, the complex baseband signal and the local code stream sequence are synchronously divided into several data segments; based on the corresponding data segments in the complex baseband signal and the local code stream sequence, the complex correlation vector is obtained through a cross-correlation function; The vector angle of each data segment is obtained based on the complex correlation vector corresponding to each data segment; the vector angle of each data segment is specifically expressed by the formula: In the formula, Represents the complex correlation vector. This represents the real part of the complex correlation vector. This represents the imaginary part of the complex correlation vector. Represents the arctangent function. The vector angle representing each data segment; Based on the relationship between the vector angles of two adjacent data segments, determine whether IQ code has occurred; the specific process for determining whether IQ code has occurred is as follows: When the difference in the vector angle between two adjacent data segments is less than or equal to a preset angle threshold, no IQ code has occurred, and the data is output directly without processing. When the difference in the vector angle between two adjacent data segments is greater than the preset angle threshold, it is determined that IQ code has occurred. Once code has occurred, the I and Q code streams of the current data segment of the complex baseband signal are swapped. Based on the adjustment results of the I-channel and Q-channel code stream data, the corrected I-channel baseband signal and Q-channel baseband signal are obtained.

6. The QPSK non-cooperative navigation signal parsing method based on multi-domain feature joint estimation according to claim 1, characterized in that, The step of obtaining the symbol sequence of the I-channel and the symbol sequence of the Q-channel by determining the sign of the data in the corrected I-channel and Q-channel baseband signals includes: The corrected I-channel baseband signal and Q-channel baseband signal are respectively subjected to symbol determination; the symbol determination is specifically as follows: the corrected I-channel baseband signal and Q-channel baseband signal are divided into several sample data at a preset time interval; for each sample data, when each sample data is greater than or equal to 0, it is determined as 1, and when each sample data is less than 0, it is determined as -1. Obtain the symbol sequence of the I-path and the symbol sequence of the Q-path through symbol decision.

7. The QPSK non-cooperative navigation signal parsing method based on multi-domain feature joint estimation according to claim 1, characterized in that, The process involves adjusting the chip length using the code rate to obtain several chips; then, based on the symbol sequence, reconstructing the symbol sequence using the number of all +1s and all -1s within each chip to obtain pure I-path and Q-path symbol sequences, including: Starting from the first sampled data, the chip length is corrected; starting from the first sampled data, the number of sampling points of the first chip is obtained according to the sampling rate and the code rate corresponding to the first chip, and the length of the first chip is obtained through the number of sampling points of the first chip; it is determined whether the number of remaining sampled data is less than the number of sampling points of the first chip. If it is, the iterative block division stops; if it is not, the division of the second chip length continues. Based on the sampling rate and the code rate corresponding to the second chip, the number of sampling points of the second chip is obtained, and the length of the second chip is obtained through the number of sampling points of the second chip; it is determined whether the number of remaining sampled data is less than the number of sampling points of the second chip. If it is, the iterative block division is stopped; if it is not, the division of the third chip length is continued. This process continues until there are not enough remaining sampled data points to stop iterative partitioning. The number of sampling points for each chip is expressed by the formula: In the formula, Indicates the sampling rate. This indicates the code rate corresponding to each chip. Indicates to Round to the nearest integer. This indicates the number of sampling points per chip; The number of all +1s and all -1s in each chip is determined by the symbol sequences of the I-path and Q-path. Based on the number of all +1s and all -1s in each chip, the corresponding common value within each chip is determined. The pure symbol sequences of the I-path and Q-path are then reconstructed using the corresponding common values ​​within all chips. Specifically, the process for determining the corresponding common value within each chip is as follows: If the number of +1s in each chip is greater than or equal to the number of -1s, then the value in each chip is uniformly set to +1; if the number of +1s in each chip is less than the number of -1s, then the value in each chip is uniformly set to -1. At this point, the pure symbol sequences for the I and Q paths have been determined.

8. A QPSK non-cooperative navigation signal analysis system based on multi-domain feature joint estimation, characterized in that, include: Code stream information estimation module: used to construct a Doppler frequency shift sequence based on the B3 frequency transmission frequency, satellite motion speed, the angle between the satellite motion speed direction and the receiver direction, and the speed of light; The center frequency of the current segment is estimated by predicting the Doppler frequency shift sequence; a set of phase sequences is obtained; the phases in the phase sequence are traversed in turn, and the energy value corresponding to each phase is obtained by combining the center frequency estimate of the current segment; then the energy threshold is selected from the energy values ​​corresponding to all phases. A short data segment is defined, and the frequency adjustment range and phase adjustment range are obtained. The frequencies and phases within the frequency adjustment range and phase adjustment range are analyzed iteratively. By comparing the energy value corresponding to each pair of frequency and phase combinations with the energy threshold, the optimal values ​​of frequency and phase are determined as estimated values ​​of frequency and phase. The I-channel and Q-channel adjusted baseband signals are obtained by estimating the frequency and phase. IQ dynamic serial code separation module: used to obtain complex baseband signals by adjusting the I-channel baseband signal and the Q-channel baseband signal; The receiver internally generates its own local bitstream sequence; By analyzing the cross-correlation between the complex baseband signal and the local code stream sequence, it is determined whether IQ code jamming occurs. If jamming occurs, adjustments are made to obtain the corrected I-path baseband signal and Q-path baseband signal. The sampling information reconstruction module is used to obtain the symbol sequences of the I-channel and Q-channel baseband signals by identifying the sign of the data in the corrected I-channel and Q-channel baseband signals; adjust the chip length by adjusting the code rate to obtain several chips; reconstruct the symbol sequence based on the symbol sequences by counting all +1s and all -1s in each chip to obtain the pure symbol sequences of the I-channel and Q-channel; and use the pure symbol sequences of the I-channel and Q-channel as the parsing result of the non-cooperative navigation signal.

9. An electronic device, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the QPSK non-cooperative navigation signal parsing method for joint estimation of multi-domain features as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the QPSK non-cooperative navigation signal parsing method for joint estimation of multi-domain features as described in any one of claims 1-7.

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