QPSK non-cooperative navigation signal analysis method and system based on multi-domain feature joint estimation

Abstract

The present application relates to navigation signal analysis technical field, specifically to QPSK non-cooperative navigation signal analysis method and system of multi-domain feature joint estimation, including: constructing Doppler frequency shift sequence;Phase in phase sequence is traversed in turn, combined with the current segment center frequency estimation value, obtain energy threshold;Frequency and phase are iteratively analyzed, and the estimation value of frequency and phase is obtained;Through the estimation value of frequency and phase, the complex baseband signal is obtained;Through the cross-correlation relationship between the complex baseband signal and the local code stream sequence, it is judged whether IQ string code occurs, if the string code occurs, adjustment is carried out, and the corrected I road baseband signal and Q road baseband signal are obtained;The chip length is adjusted by code rate, so as to reconstruct the code element sequence, and the I road and Q road pure code element sequence are obtained;The I road and Q road pure code element sequence are used as the analysis result of non-cooperative navigation signal.The present application improves the accuracy of non-cooperative navigation signal analysis.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of navigation signal analysis, and particularly relates to a QPSK non-cooperative navigation signal analysis method and system based on multi-domain feature joint estimation. BACKGROUND

[0002] With the development of navigation technology, the processing demand of non-cooperative navigation signals is increasingly prominent, especially in the military field. Traditional symbol analysis methods rely on preset civilian reference signals and fixed phase coupling relationships, and are difficult to cope with problems such as high overlap of I / Q (In-phase / Quadrature-phase) branch parameters, dynamic changes of carrier frequency offset, and IQ string code in the same frequency point QPSK (Quadrature Phase Shift Keying) modulated signals. In addition, the high-speed motion of low-orbit satellites leads to time-varying of code rate, which makes the symbol reconstruction accuracy insufficient. The present application aims at these challenges, and proposes to realize robust analysis of non-cooperative signals through multi-domain feature joint estimation, solving the problem of semi-blind demodulation under the condition of no prior information. SUMMARY

[0003] The present application provides a QPSK non-cooperative navigation signal analysis method and system based on multi-domain feature joint estimation, which is used to solve the problem of insufficient analysis accuracy of non-cooperative signals under the condition of no prior information in traditional symbol analysis methods.

[0004] The purpose of the present application can be achieved by the following technical solutions:

[0005] The first aspect of the present application provides a QPSK non-cooperative navigation signal analysis method based on multi-domain feature joint estimation, comprising:

[0006] A Doppler shift sequence is constructed according to the B3 frequency point transmission frequency, the satellite motion speed, the angle between the satellite motion speed direction and the receiver direction, and the speed of light; the current segment center frequency estimation value is predicted and obtained through the Doppler shift sequence; a group of phase sequences is obtained; the phases in the phase sequences are iterated in turn, and the energy value corresponding to each phase is obtained in combination with the current segment center frequency estimation value, and then the energy threshold is selected from the energy values corresponding to all phases;

[0007] A short-time data segment is determined, the frequency adjustment range and the phase adjustment range are obtained, the frequencies and phases in the frequency adjustment range and the phase adjustment range are iterated and analyzed in turn, the optimal values of the frequencies and phases are determined as the estimation values of the frequencies and phases by comparing the differences between the energy values corresponding to each combination of the frequencies and phases and the energy threshold; the I-path adjustment baseband signal and the Q-path adjustment baseband signal are obtained through the estimation values of the frequencies and phases;

[0008] The complex baseband signal is obtained by adjusting the I path baseband signal and the Q path baseband signal; the receiver internally generates a local code stream sequence; the IQ code string is judged by the cross-correlation relationship between the complex baseband signal and the local code stream sequence, and if the code string occurs, the I path baseband signal and the Q path baseband signal are adjusted to obtain the corrected I path baseband signal and the Q path baseband signal.

[0009] The sign sequence of the I path and the sign sequence of the Q path are obtained by the positive and negative of the data in the corrected I path baseband signal and the Q path baseband signal; the chip length is adjusted by the code rate to obtain a plurality of chips; the symbol sequence is reconstructed according to the sign sequence by the number of all +1 and all -1 in each chip to obtain the pure symbol sequence of the I path and the Q path; and the pure symbol sequence of the I path and the Q path is taken as the analysis result of the non-cooperative navigation signal.

[0010] Further, the Doppler shift sequence is constructed according to the B3 frequency point transmission frequency, the satellite movement speed, the angle between the satellite movement speed direction and the receiver direction, and the speed of light, and the Doppler shift sequence is constructed according to the B3 frequency point transmission frequency, the satellite movement speed, the angle between the satellite movement speed direction and the receiver direction, and the speed of light.

[0011] The Doppler shift at each time is obtained according to the B3 frequency point transmission frequency, the satellite movement speed, the angle between the satellite movement speed direction and the receiver direction, and the speed of light, and the Doppler shift at each time is obtained according to the B3 frequency point transmission frequency, the satellite movement speed, the angle between the satellite movement speed direction and the receiver direction, and the speed of light.

[0012]

[0013] In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time. In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time. In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time. In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time. In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time. In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time. In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time. In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time. In the formula, f B3 represents the B3 frequency point transmission frequency, v s represents the satellite movement speed, θ represents the angle between the satellite movement speed direction and the receiver direction, c represents the speed of light, and f D represents the Doppler shift at each time.

[0014] The Doppler shifts at all times are obtained by a preset time interval; the Doppler shifts at all times are arranged in time sequence to form a sequence, which is denoted as a Doppler shift sequence.

[0015] Further, the current segment center frequency estimation value is predicted and obtained by the Doppler shift sequence; a group of phase sequences are obtained; the energy value corresponding to each phase is obtained by traversing the phases in the phase sequence in sequence and combining the current segment center frequency estimation value, and then an energy threshold is screened out from the energy values corresponding to all phases, and the energy threshold is screened out from the energy values corresponding to all phases.

[0016] 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;

[0017] The estimated center frequency of the current segment is obtained by predicting the Doppler frequency shift fitting curve.

[0018] Divide the interval from 0 to π / 2 into a phase sequence with a preset phase interval;

[0019] 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.

[0020] 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:

[0021]

[0022] 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;

[0023] The maximum energy value corresponding to all phases in the phase sequence is selected as the energy threshold.

[0024] Further, the process of obtaining the frequency adjustment range and phase adjustment range involves iteratively analyzing the frequencies and phases within these ranges, comparing the energy values ​​corresponding to each frequency and phase combination with the energy threshold, and determining the optimal values ​​of the frequency and phase as estimated values. Using these estimated values, the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal are obtained, including:

[0025] 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:

[0026] 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.

[0027] 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.

[0028] This process continues until estimates of the frequency and phase are obtained, at which point the process stops.

[0029] in, The preset ratio threshold;

[0030] 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.

[0031] 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:

[0032] 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;

[0033] 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:

[0034]

[0035] In the formula, represents a complex correlation vector, represents a real part value of the complex correlation vector, represents an imaginary part value of the complex correlation vector, represents an arctangent function, represents a vector angle of each data segment;

[0036] According to the relationship between the vector angles of two adjacent data segments, it is determined whether IQ code string occurs; wherein the specific process of determining whether IQ code string occurs is:

[0037] When the difference between the vector angles of two adjacent data segments is less than or equal to a preset angle threshold, it is determined that IQ code string does not occur, and the output is directly processed; when the difference between the vector angles of two adjacent data segments is greater than the preset angle threshold, it is determined that IQ code string occurs, and once it is determined that code string occurs, the code stream data of the I path and the Q path in the current data segment of the complex baseband signal is exchanged;

[0038] According to the adjustment result of the code stream data of the I path and the Q path, the corrected I path baseband signal and the Q path baseband signal are obtained.

[0039] Further, the I path symbol sequence and the Q path symbol sequence are obtained by correcting the positive and negative of the data in the corrected I path baseband signal and the Q path baseband signal, comprising:

[0040] The corrected I path baseband signal and the Q path baseband signal are respectively subjected to symbol decision; the symbol decision is specifically: the corrected I path baseband signal and the Q path baseband signal are respectively divided into a plurality of sampling data at a preset time interval; for each sampling data, when each sampling data is greater than or equal to 0, it is determined to be 1, and when each sampling data is less than 0, it is determined to be -1;

[0041] The I path symbol sequence and the Q path symbol sequence are obtained by symbol decision.

[0042] Further, the code chip length is adjusted by the code rate to obtain a plurality of code chips; according to the symbol sequence, the number of all +1 and all -1 in each code chip is used to reconstruct the symbol sequence to obtain the pure symbol sequence of the I path and the Q path, comprising:

[0043] 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.

[0044] 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.

[0045] This process continues until there are not enough remaining sampled data points to stop iterative partitioning.

[0046] The number of sampling points for each chip is expressed by the formula:

[0047]

[0048] 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;

[0049] 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:

[0050] 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.

[0051] At this point, the pure symbol sequences for the I and Q paths have been determined.

[0052] 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:

[0053] The code stream information estimation module is used for constructing a Doppler frequency shift sequence according to a B3 frequency point transmitting frequency, a satellite movement speed, an included angle between a satellite movement speed direction and a receiver direction and a light speed, predicting and obtaining a current segment center frequency estimation value through the Doppler frequency shift sequence, obtaining a phase sequence, sequentially traversing phases in the phase sequence, combining the current segment center frequency estimation value, obtaining an energy value corresponding to each phase, then screening an energy threshold value from all energy values corresponding to the phases, determining a short time data segment, obtaining a frequency adjustment range and a phase adjustment range, sequentially iteratively analyzing frequencies and phases in the frequency adjustment range and the phase adjustment range, determining optimal values of the frequencies and the phases as estimation values of the frequencies and the phases by comparing differences between energy values corresponding to each combination of the frequencies and the phases and the energy threshold value, and obtaining I and Q adjustment baseband signals through the estimation values of the frequencies and the phases.

[0054] The IQ dynamic string code separation module is used for obtaining a complex baseband signal through the I and Q adjustment baseband signals, generating a local code stream sequence by the receiver itself, judging whether IQ string codes occur through a cross-correlation relationship between the complex baseband signal and the local code stream sequence, and adjusting to obtain corrected I and Q baseband signals if the string codes occur.

[0055] The sampling information reconstruction module is used for obtaining I and Q symbol sequences through positive and negative properties of data in the corrected I and Q baseband signals, adjusting a chip length through a code rate to obtain a plurality of chips, reconstructing a code element sequence through numbers of all +1 and all -1 in each chip according to the symbol sequences to obtain pure I and Q code element sequences, and taking the pure I and Q code element sequences as an analysis result of the non-cooperative navigation signal.

[0056] The third aspect of the present application provides an electronic device, including a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the multi-domain feature joint estimation QPSK non-cooperative navigation signal analysis method when executing the computer program.

[0057] The fourth aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program implements the multi-domain feature joint estimation QPSK non-cooperative navigation signal analysis method when executed by a processor.

[0058] Compared with the prior art, the beneficial effects of the present application are: constructing a Doppler frequency shift sequence; traversing the phases in the phase sequence in turn, combining the current segment center frequency estimation value, obtaining the energy value corresponding to each phase, and then screening out the energy threshold value from all the energy values corresponding to the phases; improving the accuracy of energy threshold analysis; iteratively analyzing the frequency and phase in the frequency adjustment range and the phase adjustment range in turn, and obtaining the estimation value of the frequency and phase through the difference between the energy value corresponding to each combination of frequency and phase and the energy threshold value; obtaining the I and Q adjustment baseband signals through the estimation value of the frequency and phase; improving the accuracy of code stream information estimation; obtaining the complex baseband signal through the I and Q adjustment baseband signals; the receiver generates a local code stream sequence by itself; judging whether IQ code string occurs through the cross-correlation relationship between the complex baseband signal and the local code stream sequence, and if code string occurs, adjusting to obtain the corrected I and Q baseband signals; reducing the influence degree of IQ dynamic code string; obtaining the symbol sequence of the I and Q channels through the positive and negative nature of the data in the corrected I and Q baseband signals; adjusting the chip length through the code rate to obtain a plurality of chips; reconstructing the symbol sequence according to the symbol sequence through the number of all +1 and all-1 in each chip to obtain the pure symbol sequence of the I and Q channels; taking the pure symbol sequence of the I and Q channels as the analysis result of the non-cooperative navigation signal, improving the accuracy of sampling information reconstruction; and solving the problem of insufficient non-cooperative signal analysis accuracy of the traditional symbol analysis method under the condition of no prior information. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0060] Figure 1 The step flowchart diagram of the QPSK non-cooperative navigation signal analysis method of the present application providing multi-domain feature joint estimation is shown in the figure.

[0061] Figure 2 The module flowchart diagram of the QPSK non-cooperative navigation signal analysis system of the present application providing multi-domain feature joint estimation is shown in the figure.

[0062] Figure 3 The low-orbit enhanced signal B3 frequency point signal constellation diagram is shown in the figure.

[0063] Figure 4 The low-orbit enhanced signal B3 frequency point signal spectrum diagram is shown in the figure.

[0064] Figure 5 A baseband information analysis result diagram of a QPSK modulation signal of a low-orbit navigation enhancement satellite is shown in Figure 1.

[0065] Figure 6 A QPSK baseband signal constellation diagram analysis result diagram of a low-orbit navigation enhancement satellite is shown in Figure 2.

[0066] Figure 7 A symbol sampling information reconstruction result diagram is shown in Figure 3. DETAILED DESCRIPTION

[0067] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without making creative efforts should belong to the scope of protection of the present application.

[0068] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0069] In view of the problems in the background art, a QPSK non-cooperative navigation signal analysis method and system with multi-domain feature joint estimation are designed and researched, which has important practical significance.

[0070] As shown in Figure 1, the first aspect of the present application provides a QPSK non-cooperative navigation signal analysis method with multi-domain feature joint estimation, including the following steps: Figure 1 Step S001: Construct a Doppler frequency shift sequence; traverse the phases in the phase sequence in turn, and obtain an energy threshold value in combination with the current segment center frequency estimation value; perform iterative analysis on the frequency and phase to obtain the estimation values of the frequency and phase; and obtain the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal through the estimation values of the frequency and phase.

[0071]

[0072] ​It should be noted that, in order to accurately describe the mathematical composition of the received QPSK modulated intermediate frequency signal, to provide theoretical basis and algorithm design basis for subsequent carrier stripping, parameter estimation and signal processing; therefore, the input signal is analyzed. In order to facilitate subsequent digital signal processing, because the baseband signal frequency is low, it is easier to sample, filter, symbol decision and decoding operation, so as to extract the original symbol sequence, therefore, the signal spectrum is moved to the baseband (zero frequency) and high frequency (twice frequency) by combining the stripping function with the input signal, which is convenient for subsequent analysis.

[0073] It should be further pointed out that, since the low-frequency baseband signal is used in subsequent analysis, a low-pass filter is introduced to eliminate the high-frequency signal part, so as to obtain the final signal data used for analysis.

[0074] Specifically, the conventional baseband signal acquisition process is to obtain the existing input signal and local carrier stripping function, input the input signal and local carrier stripping function into the mixer for multiplication to obtain the mixed signal; a low-pass filter is added behind the mixer, and the mixed signal is adjusted through the low-pass filter to obtain the I channel baseband signal and the Q channel baseband signal.

[0075] Among them, the function of the mixer is to realize the frequency spectrum shift by multiplication, and convert the high-frequency signal to the baseband, so as to prepare for the subsequent filtering of the baseband signal.

[0076] It should be noted that, since the low-orbit satellite moves relatively fast, the frequency and phase information are in a state of change, so the baseband code stream information needs to be calculated in segments. Among them, the low-orbit enhanced signal B3 frequency point signal constellation diagram is as shown in Figure 3 The low-orbit enhanced signal B3 frequency point signal spectrum diagram is as shown in Figure 4 Among them, B3 frequency point is a specific radio channel used by China Beidou satellite navigation system, and the center frequency is 1268.52 MHz (Megahertz).

[0077] Specifically, the continuous demodulation steps of the baseband code stream information are as follows:

[0078] 1) Doppler information estimation: according to the B3 frequency point transmission frequency, satellite movement speed, the angle between satellite movement speed direction and receiver direction and the speed of light, the Doppler shift at each time is obtained; wherein the Doppler shift at each time is specifically expressed by the formula:

[0079]

[0080] In the formula, B3 frequency point transmission frequency, the first a satellite movement speed at a moment, an angle between a satellite movement speed direction at a moment and a receiver direction, an angle between a satellite movement speed direction at a moment and a receiver direction, a light speed, a Doppler shift at a moment, a Doppler shift at a moment, wherein the Doppler shift is a frequency change amount.

[0081] wherein the Doppler shift is a frequency offset of a signal received by a receiver relative to a satellite transmission frequency; wherein the receiver is a dynamic / static user end (such as a vehicle-mounted, ship-mounted, airborne or fixed station) located on the earth's surface or near space, the specific position of which is unknown and can move, and is the target to be solved by a navigation signal. Wherein B3 is the third civilian signal frequency band of the Beidou system (BeiDou-3 Navigation Signal B3).

[0082] a preset time interval of 1 millisecond, all Doppler shifts at all moments are obtained through the preset time interval; all Doppler shifts at all moments are arranged in time sequence to form a sequence, which is recorded as a Doppler shift sequence.

[0083] 2) Doppler information fitting: a quadratic polynomial is used for curve fitting according to the Doppler shift sequence by the least square method to obtain a Doppler shift fitting curve; the Doppler shift fitting curve is used to estimate the Doppler shift at a subsequent moment.

[0084] wherein the least square method is a known technology, which will not be described in detail here.

[0085] 3) 0 to π / 2 is divided into a phase sequence with a preset phase interval; wherein the preset phase interval is π / 8 in this embodiment. wherein the preset phase interval is not specifically limited in this embodiment, and the implementer can determine it according to the specific situation.

[0086] a current segment center frequency estimation value is obtained through the Doppler shift fitting curve prediction;

[0087] phases in the phase sequence are traversed in turn, and a plurality of local carrier stripping functions corresponding to a plurality of phases are obtained through a conventional baseband signal acquisition process in combination with the current segment center frequency estimation value; I and Q baseband signals corresponding to each phase are obtained through each local carrier stripping function obtained by traversal in combination with an input signal and a low-pass filter.

[0088] amplitudes of the I and Q baseband signals corresponding to each phase are obtained, and are recorded as and ; obtaining an energy value corresponding to each phase according to the amplitude of the I baseband signal and the amplitude of the Q baseband signal corresponding to each phase; wherein the energy value corresponding to each phase is specifically expressed by a formula:

[0089]

[0090] In the formula, denotes the amplitude of the I baseband signal corresponding to each phase, denotes the amplitude of the Q baseband signal corresponding to each phase, denotes the energy value corresponding to each phase.

[0091] The maximum value of the energy values corresponding to all phases in the phase sequence is selected, and is denoted as an energy threshold.

[0092] It needs to be explained that it is an efficient engineering optimization strategy based on the unique 4-fold rotational symmetry of the QPSK modulation signal. Since the QPSK constellation diagram is completely coincident with itself after 90°, 180° and 270° rotation, the demodulation energy values of the carrier phase at the four points of the optimal phase φ, φ+π / 2, φ+π and φ+3π / 2 are completely the same. Therefore, searching in the complete range of 0 to 2π will obtain four equivalent peak values, resulting in three-quarters of the calculation redundancy. By compressing the search range to 0~π / 2, one of the optimal solutions can be uniquely included, thereby reducing the calculation complexity to one-fourth on the premise of ensuring the correctness of the algorithm, and greatly improving the real-time processing efficiency. The subsequent fixed phase ambiguity (k*π / 2) problem is then handled by the frame synchronization, differential decoding or dedicated IQ dynamic string code separation module, realizing the decoupling and efficiency maximization among the algorithm modules.

[0093] 4) Determine a short-time data segment, determine a reference frequency, and determine that the frequency adjustment range is the reference frequency Hz, and the phase adjustment range is 0~π / 2; the frequency and phase are iteratively analyzed in the frequency adjustment range and the phase adjustment range, and the optimal values of the frequency and the phase are determined as the estimated values of the frequency and the phase. The specific process of iteratively obtaining the estimated values of the frequency and the phase is as follows:

[0094] An initial frequency and an initial phase are determined according to the frequency adjustment range and the phase adjustment range; the initial local carrier stripping function of the short-time data segment is obtained by substituting the initial frequency and the initial phase into the local carrier stripping function; the initial energy value is obtained by the energy value obtaining process corresponding to each phase in the phase sequence according to the initial local carrier stripping function; the difference between the initial energy value and the energy threshold is compared, and is denoted as the initial difference of the short-time data segment, when the initial difference is less than or equal to the energy threshold If yes, the initial frequency and initial phase are taken as the estimated values of the frequency and phase; otherwise, the next judgment is continued.

[0095] The direction of frequency and phase fine adjustment is determined according to the gradient descent or hill climbing algorithm, and a new frequency and phase are obtained from the frequency adjustment range and the phase adjustment range, which are respectively recorded as the second frequency and the second phase of the short-time data segment; the second local carrier stripping function of the short-time data segment is obtained by substituting the second frequency and the second phase into the local carrier stripping function; the second energy value is obtained by the process of obtaining the energy value corresponding to each phase in the phase sequence according to the second local carrier stripping function; the difference between the second energy value and the energy threshold is recorded as the second difference of the short-time data segment, and if the second difference is less than or equal to the energy threshold , the second frequency and the second phase are taken as the estimated values of the frequency and phase; otherwise, the next judgment is continued.

[0096] In this way, until the estimated values of the frequency and the phase are obtained, the process is stopped.

[0097] wherein, the preset proportion threshold is 0.5; wherein in the embodiment , the preset proportion threshold is 0.5; wherein in the embodiment , the preset proportion threshold is 0.5; wherein in the embodiment is not specifically limited, and the implementer can determine it according to the situation.

[0098] At this point, the estimated values of the frequency and the phase are obtained by the above method.

[0099] 5) Code stream information calculation: the adjusted local carrier stripping function is constructed by the estimated values of the frequency and the phase, and the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal are obtained by the adjusted local carrier stripping function, in combination with the input signal and the low-pass filter.

[0100] wherein, the analytical results corresponding to the last I-channel adjusted baseband signal and the Q-channel adjusted baseband signal are as shown in the low-orbit navigation enhancement satellite QPSK modulation signal baseband information analytical result diagram. Figure 5

[0101] At this point, the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal are obtained.

[0102] Step S002: The complex baseband signal is obtained by the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal; and whether the IQ code string occurs is judged by the cross-correlation relationship between the complex baseband signal and the local code stream sequence, and if the code string occurs, the adjustment is performed to obtain the corrected I-channel baseband signal and the Q-channel baseband signal.

[0103] ​It should be noted that the code stream information obtained by the QPSK signal is determined according to the amplitude sum characteristic, when the phase is reversed by 90 degrees, the amplitude sum is unchanged, and the I / Q code stream information is reversed. When the code stream information is calculated in segments, the QPSK signal may be exchanged between the in-phase branch and the quadrature branch, which is called IQ dynamic code string, therefore, it is necessary to determine whether the code stream parsed in each epoch belongs to the I path or the Q path. By using the epoch timing characteristic orthogonality of the I / Q dual-path signal, a dynamic sliding window matching degree judgment module is designed to suppress the channel code inter-symbol interference caused by time variation.

[0104] Specifically, the complex baseband signal is obtained by adjusting the I-path baseband signal and the Q-path baseband signal; wherein the I-path adjusted baseband signal is the real part in the complex baseband signal, and the Q-path adjusted baseband signal is the imaginary part in the complex baseband signal.

[0105] The receiver internally generates a local code stream sequence (which is a known, ideal reference signal);

[0106] The complex baseband signal and the local code stream sequence are synchronously divided into a plurality of data segments by a preset time interval segment; according to the corresponding data segments in the complex baseband signal and the local code stream sequence, a complex correlation vector is obtained by using a cross-correlation function. The cross-correlation function is a known technology, and will not be described in detail here. In this embodiment, the time length of the preset time interval segment is 1 millisecond, and in this embodiment, the time length of the preset time interval segment is not specifically limited, and can be determined by the implementer according to the specific circumstances.

[0107] According to the complex correlation vector corresponding to each data segment, a vector angle of each data segment is obtained; wherein the vector angle of each data segment is specifically represented by the following formula:

[0108]

[0109] In the formula, represents the complex correlation vector, represents the real part value of the complex correlation vector, represents the imaginary part value of the complex correlation vector, represents the arctangent function, represents the vector angle of each data segment.

[0110] According to the relationship between the vector angles of adjacent two data segments, it is judged whether IQ code string occurs; wherein the specific process of judging whether IQ code string occurs is:

[0111] When the difference between the vector angles of the two adjacent data segments is less than or equal to the preset angle threshold, no IQ code string occurs, and the output is directly outputted without processing; when the difference between the vector angles of the two adjacent data segments is greater than the preset angle threshold, it is determined that the IQ code string occurs, and once it is determined that the code string occurs, the code stream data of the I path and the Q path in the current data segment of the complex baseband signal is exchanged. In the embodiment, the preset angle threshold is In the embodiment, the preset angle threshold is not specifically limited, and can be determined according to specific conditions.

[0112] It should be noted that if the code string occurs in the current data segment, the I path and the Q path in the current data segment need to be passed to the subsequent for use in subsequent code string determination. The effect after the IQ code string is separated is specifically shown in a low earth orbit navigation enhancement satellite QPSK baseband signal constellation diagram analysis result schematic diagram as shown in Figure 6

[0113] According to the adjustment result of the code stream data of the I path and the Q path, the corrected I path baseband signal and the corrected Q path baseband signal are obtained.

[0114] In step S003, the sign sequence of the I path and the sign sequence of the Q path are obtained by the positive and negative of the data in the corrected I path baseband signal and the corrected Q path baseband signal; the chip length is adjusted by the code rate to obtain a plurality of chips; the symbol sequence is reconstructed according to the sign sequence by the number of all +1 and all -1 in each chip to obtain the pure symbol sequence of the I path and the Q path; and the pure symbol sequence of the I path and the Q path is taken as the analysis result of the non-cooperative navigation signal.

[0115] It should be noted that in order to obtain real-time and accurate carrier and pseudo-code feature change information, the majority decision with Doppler information compensation is used to block reconstruction according to the symbol width. Since the code rate of the real satellite signal is constantly changing, the number of sampling points of each chip width also changes over time. Based on the real-time carrier frequency information, the code Doppler frequency is corrected, the symbol width is adjusted, and dynamic blocking is realized. Since the acquisition time of the acquisition device is random, in order to restore the binary data of the chip width, the majority decision is used for block detection to reduce the misjudgment rate caused by non-integer symbol / decimal part symbol information points.

[0116] Specifically, symbol decision is performed on the corrected I path baseband signal and the corrected Q path baseband signal respectively; the symbol decision is specifically: the corrected I path baseband signal and the corrected Q path baseband signal are respectively divided into a plurality of sampling data at a preset time interval; for each sampling data, when each sampling data is greater than or equal to 0, it is determined as 1, and when each sampling data is less than 0, it is determined as -1.

[0117] ​Obtain the symbol sequence of the I-path and the symbol sequence of the Q-path through symbol decision.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] This process continues until there are not enough remaining sampled data points to stop iterative partitioning.

[0122] The number of sampling points for each chip is expressed by the formula:

[0123]

[0124] 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.

[0125] 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.

[0126] The number of all +1 and all -1 in each chip is determined through the symbol sequence of the I path and the symbol sequence of the Q path, and a corresponding same value in each chip is determined according to the number of all +1 and all -1 in each chip, and the I path and the Q path pure symbol sequence is reconstructed through the corresponding same value in all chips; wherein the specific process of determining the corresponding same value in each chip is:

[0127] When the number of +1 in each chip is greater than or equal to the number of -1, the value in each chip is the same as +1; when the number of +1 in each chip is less than the number of -1, the value in each chip is the same as -1.

[0128] At this point, the I path and the Q path pure symbol sequence is obtained by the above method.

[0129] The I path and the Q path pure symbol sequence is taken as the analysis result of the non-cooperative navigation signal, and the analysis result is the symbol sampling information reconstruction result; wherein the symbol sampling information reconstruction result is specifically as shown in Figure 7 .

[0130] At this point, the non-cooperative navigation signal analysis is completed.

[0131] As shown in Figure 2 , the second aspect of the present application is to provide a QPSK non-cooperative navigation signal analysis system for multi-domain feature joint estimation, comprising:

[0132] The code stream information estimation module 101 is used for constructing a Doppler frequency shift sequence according to the B3 frequency point transmission frequency, the satellite motion speed, the included angle between the satellite motion speed direction and the receiver direction, and the speed of light; predicting and obtaining a current segment center frequency estimation value through the Doppler frequency shift sequence; obtaining a group of phase sequences; traversing the phases in the phase sequences in turn, combining the current segment center frequency estimation value, obtaining the energy value corresponding to each phase, and then screening out an energy threshold value from all the energy values corresponding to the phases; determining a short-time data segment, obtaining a frequency adjustment range and a phase adjustment range, and sequentially iteratively analyzing the frequencies and phases in the frequency adjustment range and the phase adjustment range; determining the optimal values of the frequencies and phases as the estimation values of the frequencies and phases by comparing the differences between the energy values corresponding to each combination of the frequencies and phases and the energy threshold value; and obtaining an I path adjusted baseband signal and a Q path adjusted baseband signal through the estimation values of the frequencies and phases.

[0133] The IQ dynamic string code separation module 102 is used for obtaining a complex baseband signal through the I path adjusted baseband signal and the Q path adjusted baseband signal; generating a local code stream sequence by itself inside the receiver; determining whether IQ string code occurs through the cross-correlation relationship between the complex baseband signal and the local code stream sequence, and if the string code occurs, adjusting to obtain a corrected I path baseband signal and a corrected Q path baseband signal.

[0134] The sampling information reconstruction module 103 is configured to obtain the symbol sequence of the I channel and the symbol sequence of the Q channel by correcting the positive and negative of the data in the corrected I channel baseband signal and the Q channel baseband signal; obtain a plurality of chips by adjusting the chip length according to the code rate; reconstruct the symbol sequence according to the number of all +1 and all -1 in each chip according to the symbol sequence to obtain the pure symbol sequence of the I channel and the Q channel; and take the pure symbol sequence of the I channel and the Q channel as the analysis result of the non-cooperative navigation signal.

[0135] The third aspect of the present application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the QPSK non-cooperative navigation signal analysis method of multi-domain feature joint estimation when executing the computer program.

[0136] The fourth aspect of the present application provides a computer readable storage medium, and the computer readable storage medium stores a computer program, and the computer program implements the QPSK non-cooperative navigation signal analysis method of multi-domain feature joint estimation when executed by a processor.

[0137] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer readable storage media containing computer usable program code (including but not limited to disk storage, optical storage, etc.).

[0138] The present application is described with reference to flowcharts and / or block diagrams of the method, system, and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The device that implements the functions specified in one or more flows and / or blocks. Figure 1 The device that implements the functions specified in one or more flows and / or blocks.

[0139] These computer program instructions can also be stored in a computer readable storage medium that can guide the computer or other programmable data processing devices to work in a specific way, so that the instructions stored in the computer readable storage medium produce a product including instruction devices that implement the functions specified in the flowcharts and / or block diagrams. Figure 1one or more processes and / or blocks Figure 1 the function specified in the one or more blocks.

[0140] These computer program instructions can also be loaded into computer or other programmable data processing devices, so that a series of operation steps are performed on the computer or other programmable data processing devices to generate computer-implemented processes, so that the instructions executed on the computer or other programmable data processing devices provide processes for implementing the flow Figure 1 one or more processes and / or blocks Figure 1 the function specified in the one or more blocks.

[0141] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it, although the above embodiments of the present application have been described in detail, those skilled in the art should understand: the specific embodiments of the present application can be modified or replaced by the same, without departing from the spirit and scope of the present application, any modification or equivalent replacement, which should be covered within the scope of protection of the present application.

Claims

1. A QPSK non-cooperative navigation signal analysis method based on multi-domain feature joint estimation, characterized in that, The method comprises the following steps: According to the B3 frequency point transmission frequency, the satellite movement speed, the angle between the satellite movement speed direction and the receiver direction, and the speed of light, a Doppler frequency shift sequence is constructed; The current segment center frequency estimate value is predicted and obtained through the Doppler frequency shift sequence; a group of phase sequences is obtained; the phases in the phase sequences are traversed in turn, and the current segment center frequency estimate value is combined to obtain the energy value corresponding to each phase, and then the energy threshold is screened out from all the energy values corresponding to the phases; A short data segment is determined, the frequency adjustment range and the phase adjustment range are obtained, and the frequency and the phase in the frequency adjustment range and the phase adjustment range are analyzed iteratively, the optimal value of the frequency and the phase is determined by comparing the difference between the energy value corresponding to each combination of the frequency and the phase and the energy threshold, and the optimal value is taken as the estimate value of the frequency and the phase; The I-channel adjusted baseband signal and the Q-channel adjusted baseband signal are obtained through the estimate value of the frequency and the phase; The complex baseband signal is obtained through the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal; The receiver generates a local code stream sequence by itself; Whether IQ code string occurs is judged through the cross-correlation relationship between the complex baseband signal and the local code stream sequence, and if the code string occurs, the I-channel baseband signal and the Q-channel baseband signal after correction are obtained through adjustment; The sign sequence of the I-channel and the sign sequence of the Q-channel are obtained through the positive and negative nature of the data in the I-channel baseband signal and the Q-channel baseband signal after correction; the chip length is adjusted through the code rate to obtain a plurality of chips; the symbol sequence is reconstructed through the number of all +1 and all -1 in each chip according to the sign sequence to obtain the pure symbol sequence of the I-channel and the Q-channel; and the pure symbol sequence of the I-channel and the Q-channel is taken as the analysis result of the non-cooperative navigation signal.

2. The multi-domain joint estimation of QPSK non-cooperative navigation signal analysis method according to claim 1, characterized in that, The Doppler frequency shift sequence is constructed according to the B3 frequency point transmission frequency, the satellite movement speed, the angle between the satellite movement speed direction and the receiver direction, and the speed of light, and comprises the following steps: The Doppler frequency shift at each moment is obtained according to the B3 frequency point transmission frequency, the satellite movement speed, the angle between the satellite movement speed direction and the receiver direction, and the speed of light; the Doppler frequency shift at each moment is specifically expressed by the following formula: wherein, denotes the B3 frequency transmission frequency, denotes the satellite movement speed at the time instant, denotes the angle between the satellite movement speed direction and the receiver direction at the time instant, denotes the light speed, denotes the Doppler shift at the time instant; All the Doppler frequency shifts at different moments are obtained through a preset time interval; all the Doppler frequency shifts at different moments are arranged in time sequence to form a sequence, which is recorded as the Doppler frequency shift sequence.

3. The multi-domain joint estimation of QPSK non-cooperative navigation signal analysis method according to claim 1, characterized in that, The current segment center frequency estimate value is predicted and obtained through the Doppler frequency shift sequence; a group of phase sequences is obtained; the phases in the phase sequences are traversed in turn, and the current segment center frequency estimate value is combined to obtain the energy value corresponding to each phase, and then the energy threshold is screened out from all the energy values corresponding to the phases, which comprises the following steps: The Doppler frequency shift fitting curve is obtained by using a quadratic polynomial to perform curve fitting on the Doppler frequency shift sequence through the least square method; the Doppler frequency shift at the subsequent moment is estimated through the Doppler frequency shift fitting curve; The current segment center frequency estimate value is predicted and obtained through the Doppler frequency shift fitting curve; 0 to π / 2 is divided into a group of phase sequences at a preset phase interval. The phases in the phase sequence are traversed in turn, and a plurality of local carrier stripping functions corresponding to a plurality of phases are obtained through a conventional baseband signal acquisition process in combination with the current segment center frequency estimation value; the I and Q baseband signals corresponding to each phase are obtained through each local carrier stripping function obtained by traversal in combination with the input signal and the low-pass filter; The amplitudes of the I and Q baseband signals corresponding to each phase are obtained; the energy value corresponding to each phase is obtained according to the amplitudes of the I and Q baseband signals corresponding to each phase; the energy value corresponding to each phase is specifically represented by a formula as follows: In the formula, denotes the amplitude of the I baseband signal corresponding to each phase, denotes the amplitude of the Q baseband signal corresponding to each phase, denotes the energy value corresponding to each phase; The maximum value of the energy values corresponding to all phases in the phase sequence is selected as the energy threshold.

4. The multi-domain joint estimation of QPSK non-cooperative navigation signal analysis method according to claim 3, characterized in that, The frequency adjustment range and the phase adjustment range are obtained, and the frequencies and phases in the frequency adjustment range and the phase adjustment range are iteratively analyzed in turn; the optimal values of the frequencies and phases are determined by comparing the differences between the energy values corresponding to each combination of the frequencies and phases and the energy threshold, and the optimal values of the frequencies and phases are taken as the estimation values of the frequencies and phases; The I and Q adjusted baseband signals are obtained through the estimation values of the frequencies and phases, including: The reference frequency is determined, and the frequency adjustment range is determined as the reference frequency Hz, and the phase adjustment range is 0~π / 2; the frequency and the phase in the frequency adjustment range and the phase adjustment range are analyzed iteratively, and the optimal value of the frequency and the phase is determined as the estimated value of the frequency and the phase; wherein the specific process of iteratively obtaining the estimated value of the frequency and the phase is: determining an initial frequency and an initial phase according to the frequency adjustment range and the phase adjustment range; substituting the initial frequency and the initial phase into the local carrier stripping function to obtain an initial local carrier stripping function of the short-time data segment; obtaining an initial energy value through an energy value obtaining process corresponding to each phase in the phase sequence according to the initial local carrier stripping function; comparing a difference between the initial energy value and an energy threshold value, denoted as an initial difference of the short-time data segment; when the initial difference is less than or equal to the energy threshold value, taking the initial frequency and the initial phase as the estimated values of the frequency and the phase; otherwise, continuing the next judgment; ​ According to the gradient descent or hill climbing algorithm, a frequency and phase fine-tuning direction is determined, a new frequency and phase are obtained from the frequency adjustment range and the phase adjustment range, and are recorded as a second frequency and a second phase of the short-time data segment; the second frequency and the second phase are substituted into the local carrier stripping function to obtain a second local carrier stripping function of the short-time data segment; a second energy value is obtained through the energy value obtaining process corresponding to each phase in the phase sequence according to the second local carrier stripping function; a second difference between the second energy value and the energy threshold value is compared, and is recorded as a second difference of the short-time data segment; when the second difference is less than or equal to the energy threshold value , the second frequency and the second phase are taken as the estimated values of the frequency and the phase; otherwise, the next judgment is continued. The above process is repeated until the estimation values of the frequencies and phases are obtained, and then the process is stopped; wherein, is a preset proportion threshold value; The adjusted local carrier stripping function is constructed through the estimation values of the frequencies and phases, and the I and Q adjusted baseband signals are obtained through the adjusted local carrier stripping function in combination with the input signal and the low-pass filter.

5. The multi-domain joint estimation of QPSK non-cooperative navigation signal analysis method according to claim 1, characterized in that, The correlation between the complex baseband signal and the local code stream sequence is used to determine whether IQ code stringing occurs, and if code stringing occurs, the I and Q baseband signals are adjusted to obtain corrected I and Q baseband signals, including: The complex baseband signal and the local code stream sequence are synchronously divided into a plurality of data segments through a preset time interval segment; the complex correlation vector is obtained through a correlation function according to the corresponding data segments in the complex baseband signal and the local code stream sequence; The vector angle of each data segment is obtained according to the complex correlation vector corresponding to each data segment; the vector angle of each data segment is specifically represented by a formula as follows: wherein denotes a complex correlation vector, denotes a real part value of the complex correlation vector, denotes an imaginary part value of the complex correlation vector, denotes an arctangent function, denotes a vector angle of each data segment; Whether IQ code stringing occurs is determined according to the relationship between the vector angles of adjacent two data segments; the specific process of determining whether IQ code stringing occurs is as follows: When the difference between the vector angles of adjacent two data segments is less than or equal to a preset angle threshold, it is determined that IQ code stringing does not occur, and the current data segment of the complex baseband signal is directly outputted without processing; when the difference between the vector angles of adjacent two data segments is greater than the preset angle threshold, it is determined that IQ code stringing occurs, and once it is determined that code stringing occurs, the code stream data of the I and Q channels in the current data segment of the complex baseband signal is exchanged; The sign sequence of the I channel and the sign sequence of the Q channel are obtained according to the adjustment results of the code stream data of the I and Q channels.

6. The multi-domain joint estimation of QPSK non-cooperative navigation signal analysis method according to claim 1, characterized in that, The sign sequence of the I channel and the sign sequence of the Q channel are obtained according to the adjustment results of the code stream data of the I and Q channels. respectively, the corrected I-path baseband signal and the corrected Q-path baseband signal are divided into a plurality of sampling data at a preset time interval; for each sampling data, when each sampling data is greater than or equal to 0, it is determined as 1, and when each sampling data is less than 0, it is determined as -1; The symbol sequence of the I-path and the symbol sequence of the Q-path are obtained through the symbol decision.

7. The multi-domain jointly estimated QPSK non-cooperative navigation signal analysis method of claim 1, wherein, The chip length is adjusted by the code rate to obtain a plurality of chips; and the symbol sequence is reconstructed by the number of all +1 and all -1 in each chip to obtain the pure symbol sequence of the I-path and the Q-path, including: The first chip length is obtained from the first sampling data according to the sampling rate and the code rate corresponding to the first chip; it is judged whether the number of the remaining sampling data is less than the sampling point number of the first chip; if yes, the iterative blocking is stopped; if no, the second chip length is divided; The second chip length is obtained from the first sampling data according to the sampling rate and the code rate corresponding to the second chip; it is judged whether the number of the remaining sampling data is less than the sampling point number of the second chip; if yes, the iterative blocking is stopped; if no, the third chip length is divided; The above process is repeated until the number of the remaining sampling data is insufficient for division. The sampling point number of each chip is expressed by the following formula: In the formula, denotes a sampling rate, denotes a code rate corresponding to each chip, denotes rounding off to an integer, denotes a number of sampling points per chip;​ The number of all +1 and all -1 in each chip is determined through the symbol sequence of the I-path and the symbol sequence of the Q-path; the corresponding same value in each chip is determined according to the number of all +1 and all -1 in each chip; the pure symbol sequence of the I-path and the Q-path is reconstructed through the corresponding same value in all chips; wherein, the specific process of determining the corresponding same value in each chip is as follows: When the number of +1 in each chip is greater than or equal to the number of -1, the value in each chip is unified as +1; when the number of +1 in each chip is less than the number of -1, the value in each chip is unified as -1. Thus, the pure symbol sequence of the I-path and the Q-path is determined.

8. A QPSK non-cooperative navigation signal analysis system with joint multi-domain feature estimation, characterized in that, The code stream information estimation module is configured to construct a Doppler shift sequence according to the B3 frequency point transmission frequency, the satellite movement speed, the included angle between the satellite movement speed direction and the receiver direction, and the speed of light; The current segment center frequency estimation value is predicted and obtained through the Doppler shift sequence; a group of phase sequences are obtained; the phases in the phase sequences are traversed in turn, and the energy value corresponding to each phase is obtained in combination with the current segment center frequency estimation value, and then the energy threshold is screened out from all the energy values corresponding to the phases; ​ Determine a short data segment, obtain a frequency adjustment range and a phase adjustment range, and iteratively analyze the frequency and phase in the frequency adjustment range and the phase adjustment range. By comparing the energy value corresponding to each combination of frequency and phase with the difference between the energy threshold value, the optimal value of the frequency and phase is determined as the estimated value of the frequency and phase. Obtain the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal through the estimated value of the frequency and phase. IQ dynamic code separation module: used to obtain the complex baseband signal through the I-channel adjusted baseband signal and the Q-channel adjusted baseband signal. The receiver generates a local code stream sequence by itself. Determine whether IQ code mixing occurs through the cross-correlation relationship between the complex baseband signal and the local code stream sequence. If code mixing occurs, adjust and obtain the corrected I-channel baseband signal and the Q-channel baseband signal. Sampling information reconstruction module: used to obtain the I-channel symbol sequence and the Q-channel symbol sequence through the positive and negative of the data in the corrected I-channel baseband signal and the Q-channel baseband signal; adjust the chip length through the code rate to obtain a plurality of chips; reconstruct the symbol sequence through the number of all +1 and all -1 in each chip according to the symbol sequence to obtain the pure I-channel symbol sequence and the pure Q-channel symbol sequence; and take the pure I-channel symbol sequence and the pure Q-channel symbol sequence as the analysis result of the non-cooperative navigation signal.

9. An electronic device, comprising: The computer readable storage medium stores a computer program, and the computer program is executed by the processor to realize the multi-domain feature joint estimation QPSK non-cooperative navigation signal analysis method of claim 1-7.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to realize the multi-domain feature joint estimation QPSK non-cooperative navigation signal analysis method of claim 1-7.

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