Satellite navigation BOC signal multipath suppression method

Abstract

The invention relates to the technical field of satellite navigation signal processing, in particular to a satellite navigation BOC signal multipath suppression method, which specifically adopts a sub-orthogonal synthesis correlation processing algorithm, and performs collaborative optimization on the sub-orthogonal synthesis correlation processing algorithm and a traditional narrow correlation and HRC scheme to form two novel multipath suppression combined technical schemes, namely an SQC-narrow correlation scheme and an SQC-HRC scheme. Simulation results show that the technical method shows significant technical advantages in processing sine and cosine BOC (1, 1) signals, not only successfully eliminates the problem of fuzzy measurement in the traditional BOC signal code tracking process, but also significantly improves the anti-interference capability of the system in a multipath environment, so that the tracking error of the BOC signal under the multipath signal condition is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite navigation signal processing, and in particular to a method for suppressing multipath of satellite navigation BOC signals. Background Art

[0002] With the rapid development of global satellite navigation systems, the coexistence of multiple systems will pose new technical challenges. Although the expansion of constellation size has improved positioning performance, the increasingly scarce spectrum resources have led to prominent compatibility issues between systems. To meet the needs of spectrum sharing, Betz proposed a binary offset carrier (BOC) modulation method. This modulation signal has significant advantages over traditional BPSK signals. The BOC signal has a narrower autocorrelation main peak, which can improve code tracking accuracy, and has stronger multipath suppression potential, which can improve positioning performance. However, existing multipath suppression technology is mainly designed for the single-peak correlation characteristics of BPSK signals. Direct application to BOC signals with multi-peak characteristics has obvious limitations. For example, traditional phase-locked detection parameters do not match BOC signals, and code tracking is ambiguous. Therefore, the performance of directly applying traditional multipath suppression methods to BOC signals is generally poor. There is an urgent need to develop new and adaptive multipath suppression methods to fully unleash the potential advantages of BOC modulation in multipath resistance and precise tracking. Summary of the Invention

[0003] The present invention aims to provide a satellite navigation BOC signal multipath suppression method, aiming to solve the problems of fuzzy code tracking and poor multipath suppression capability when traditional multipath suppression technology is used for BOC signals.

[0004] To achieve the above object, the present invention provides a method for suppressing multipath of a satellite navigation BOC signal, comprising:

[0005] Generate autocorrelation functions of Sine-BOC(n,n) and Cosine-BOC(n,n) signals;

[0006] Generate the positive cross-correlation function R of Sine-BOC(n,n) and Cosine-BOC(n,n) s / c The positive cross-correlation function R of Cosine-BOC(n,n) and Sine-BOC(n,n) c / s , where R s / c and R c / s Inverse relationship

[0007] R s / c and R c / s Decompose to obtain the corresponding sub-orthogonal correlation function;

[0008] Shift the sub-orthogonal correlation functions corresponding to Sine-BOC(n,n) and Cosine-BOC(n,n) by 0.25Tc;

[0009] The synthetic correlation function is reconstructed by using the corresponding relationship and sharp characteristics of the main and secondary peaks of the shifted sub-orthogonal correlation function and the peak of the BOC autocorrelation function;

[0010] The synthetic correlation function replaces the autocorrelation function in the traditional phase detection function and is combined with narrow correlation and HRC technology to form an improved BOC multipath suppression technology.

[0011] Among them, the BOC signal is used to generate the autocorrelation function of the Sine-BOC(n,n) and Cosine-BOC(n,n) signals, where the mathematical models of the autocorrelation functions of the Sine-BOC(n,n) and Cosine-BOC(n,n) signals are respectively:

[0012]

[0013] Among them, Λ Tc It represents a trigonometric function with a bandwidth of Tc, an amplitude of 1, and a center at zero. i, j, i1, and j1 are all variables, indicating the number of accumulations.

[0014] Among them, the positive cross-correlation function R s / c and R c / s The expression is decomposed into sub-orthogonal correlation functions R s / c1 and R s / c2 , sub-orthogonal correlation function R s / c1 and R s / c2 The sum is the positive cross-correlation function R s / c ;

[0015]

[0016] in, It represents a trigonometric function with a bandwidth of Tc / 2, an amplitude of 1, and a center at zero. i, j, i1, and j1 are all variables, indicating the number of accumulations.

[0017] Among them, the positive cross-correlation function R s / c and R c / s The expression is decomposed into sub-orthogonal correlation functions R c / s1 and R c / s2 , sub-orthogonal correlation function R c / s1 and R c / s2 The sum is the positive cross-correlation function R c / s ;

[0018]

[0019]

[0020] in, It represents a trigonometric function with a bandwidth of Tc / 2, an amplitude of 1, and a center at zero. i, j, i1, and j1 are all variables, indicating the number of accumulations.

[0021] Among them, R sc1 Shift 0.25Tc to the left to get the correlation function Shift_R sc1 (τ), since the positions of the main and secondary peaks correspond to those of the original autocorrelation function of the BOC signal and are sharper than the main peak, the new synthetic correlation function is obtained by the reconstruction synthesis method of the following formula:

[0022] R proposed (τ)=Shift_R s / c1 (τ)*R BOCs (τ)+|Shift_R s / c1 (τ)|*R BOCs (τ);

[0023] Among them, R BOCs (τ) is the mathematical model of the autocorrelation function of Sine-BOC(n,n).

[0024] Among them, the new synthetic correlation function replaces the autocorrelation function of the received signal in the original phase detection function, and the EML lead-minus-lag phase detection method is adopted. By analyzing the model of multipath signals and the tracking error problem caused by multipath effects, the phase detection output in the presence of multipath signals is analyzed, and the phase detection output functions of the narrow correlation and HRC multipath suppression methods are given. Then, the improved outputs of the two combined with the SQC peak elimination method are given. The mathematical model of the phase detection output function of the narrow correlation multipath suppression method combined with the peak elimination algorithm is obtained:

[0025] S SQC-NC (τ e )=R proposed_E1 (τ e )-R proposed_L1 (τ e );

[0026] Among them, R proposed_E1 (τ e ) and R proposed_L1 (τ e ) are the correlation functions of the unambiguous leading signal and the lagging signal in the receiver code tracking loop, respectively.

[0027] The phase detection function of HRC technology is obtained as follows:

[0028]

[0029] Among them, τ e is the code phase delay error caused by multipath; Narrow(d) is the SQC-narrow correlation phase detection output function S with a correlator interval of d SQC-NC (τ e ), Narrow(2d) is the phase detector output with the phase detector spacing expanded to 2d.

[0030] The present invention proposes a method for suppressing multipath in satellite navigation BOC signals. This method generates an orthogonal correlation function by cross-correlating the Sine-BOC(n,n) and Cosine-BOC(n,n) signals, decomposing and shifting them to reconstruct a sub-orthogonal correlation function that eliminates the secondary peaks. The reconstructed correlation function retains only the sharpened main peak, significantly improving the code tracking accuracy. On this basis, the present invention innovatively replaces the autocorrelation function in the phase detection function of the traditional narrow correlation method and the HRC method with an optimized sub-orthogonal synthetic correlation function. This not only completely solves the code tracking loop ambiguity problem caused by the multimodality of the BOC signal, but also optimizes the phase detection curve, essentially eliminating false lock points and significantly reducing the multipath error envelope area. By combining the narrow correlation technology of the SQC algorithm and the HRC method, this scheme realizes a BOC signal processing scheme with excellent performance. While maintaining the original signal acquisition sensitivity, it improves the code tracking accuracy and multipath suppression capability, significantly enhancing the positioning stability and reliability of the navigation receiver in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 The present invention provides a flowchart of an improved method for BOC signal multipath suppression technology based on autocorrelation peak elimination.

[0033] Figure 2 This is a block diagram of the sub-orthogonal synthesis correlation function algorithm provided by the present invention.

[0034] Figure 3 It is a diagram of the sub-orthogonal synthesis correlation function process of the Sine-BOC(n,n) signal.

[0035] Figure 4 It is a diagram of the sub-orthogonal synthesis correlation function process of the Cosine-BOC(n,n) signal.

[0036] Figure 5The figure is a comparison diagram of the normalized autocorrelation functions obtained by applying various traditional peak elimination algorithms and the algorithm provided by the present invention to the Sine-BOC (1,1) signal.

[0037] Figure 6 The figure is a comparison diagram of the normalized autocorrelation functions obtained by applying various traditional peak elimination algorithms and the algorithm provided by the present invention to the Cosine-BOC (n, n) signal.

[0038] Figure 7 These are the lead-minus-lag EML phase detection curves for the narrow correlation method and the SQC-narrow correlation method for the Sine-BOC(1,1) signal.

[0039] Figure 8 These are the lead-minus-lag EML phase detection curves for the narrow correlation method and the SQC-narrow correlation method for the Cosine-BOC(1,1) signal.

[0040] Figure 9 These are the lead-minus-lag EML phase detection curves for the HRC method and the SQC-HRC method for the Sine-BOC(1,1) signal.

[0041] Figure 10 These are the lead-minus-lag EML phase-locking curves of the HRC method and the SQC-HRC method for the Cosine-BOC(1,1) signal.

[0042] Figure 11 These are the multipath envelope error curves of the narrow correlation method and the SQC-narrow correlation method for the Sine-BOC(1,1) signal.

[0043] Figure 12 These are the multipath envelope error curves of the narrow correlation method and the SQC-narrow correlation method for the Cosine-BOC(1,1) signal.

[0044] Figure 13 These are the multipath envelope error curves of the HRC method and the SQC-HRC correlation method for the Sine-BOC(1,1) signal.

[0045] Figure 14 These are the multipath envelope error curves of the HRC method and the SQC-HRC correlation method for the Cosine-BOC(1,1) signal. DETAILED DESCRIPTION

[0046] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0047] See also Figure 1 , Figure 1 1 is a flow chart of an improved method for BOC signal multipath suppression technology based on autocorrelation peak elimination provided by an embodiment of the present invention. Specifically, the improved method for BOC signal multipath suppression technology based on autocorrelation peak elimination may include the following steps:

[0048] S101. Generate autocorrelation functions of Sine-BOC(n,n) and Cosine-BOC(n,n) signals using the BOC signal.

[0049] In the embodiment of the present invention, the BOC signal is a binary offset carrier signal, BOC(n,n) is a modulation signal, the Sine-BOC(n,n) signal is a sine modulation signal, and the Cosine-BOC(n,n) signal is a cosine modulation signal.

[0050] The mathematical models of the autocorrelation functions of Sine-BOC(n,n) and Cosine-BOC(n,n) are as follows:

[0051]

[0052] Among them, Λ Tc Represents a trigonometric function with bandwidth Tc, amplitude 1, and center at zero.

[0053] S102. Using the autocorrelation expressions of the Sine-BOC(1,1) and Cosine-BOC(1,1) signals, generate the positive cross-correlation function R of Sine-BOC(n,n) and Cosine-BOC(n,n) s / c The positive cross-correlation function R of Cosine-BOC(n,n) and Sine-BOC(n,n) c / s ;

[0054] In the embodiment of the present invention, the above R BOCs and R BOCc The orthogonal correlation function between Sine-BOC(n,n) and Cosine-BOC(n,n) and the orthogonal correlation function between Cosine-BOC(n,n) and Sine-BOC(n,n) are inversely related, as shown in the following equations:

[0055]

[0056] in, It represents a trigonometric function with a bandwidth of Tc / 2, an amplitude of 1, and a center at the origin. i, j, i1, and j1 are all variables, indicating the number of accumulations.

[0057] S103, the positive cross-correlation function Rs / c and R c / s Decompose the expression of to obtain the corresponding sub-orthogonal correlation function;

[0058] In the embodiment of the present invention, the two sub-orthogonal cross-correlation functions R s / c1 The sum of the functions is equal to the positive cross-correlation before decomposition, that is, R s / c1 and R s / c2 The sum is still the orthogonal function R s / c The decomposition of the sub-orthogonal interaction correlation mathematical model can be expressed as:

[0059]

[0060] Cosine-BOC(n,n) positive cross-correlation function R c / s The decomposition of Cosine-BOC(n,n) can be done in the same way. The orthogonal function of Cosine-BOC(n,n) can be decomposed, which has an inverse relationship with the sub-orthogonal correlation function of Sine-BOC(n,n).

[0061] S104. Shift the sub-orthogonal correlation functions corresponding to Sine-BOC(n,n) and Cosine-BOC(n,n) by 0.25Tc;

[0062] In the embodiment of the present invention, there is only a translation and inversion relationship between the sub-orthogonal cross-correlation functions of BOC(n,n). The following analysis is conducted by taking Sine-BOC(n,n) as an example. sc1 Shifting 0.25Tc to the left, we can get the correlation function Shift_R sc1 (τ), which can be expressed as:

[0063]

[0064] S105, obtaining a new synthetic correlation function based on the reconstruction rule;

[0065] In the embodiment of the present invention, the related function Shift_R is used sc1 (τ) The main and secondary peak positions correspond to the main and secondary peaks of the BOC autocorrelation function and Shift_R sc1 The main peak of (τ) is sharper. Based on the reconstruction rule, a new synthetic correlation function is obtained as follows:

[0066] R proposed (τ)=Shift_R s / c1 (τ)*R BOCs (τ)+|Shift_R s / c1 (τ)|*R BOCs (τ);

[0067] Similarly, for Cosine-BOC(n,n), we only need to invert it and then use the same synthesis method to obtain a new synthetic correlation function R proposed .

[0068] S106: Replace the autocorrelation function of the received signal in the original phase detection function with the new synthetic correlation function, and use it for narrow correlation and HRC anti-multipath technology, that is, generate a BOC multipath suppression technology combined with a peak elimination technology.

[0069] In the embodiment of the present invention, starting from the phase detection function of the traditional narrow correlator and HRC multipath suppression method, the autocorrelation function of the received signal in the original phase detection function is replaced by the correlation function based on sub-orthogonal synthesis to generate SQC-narrow correlation technology and SQC-HRC technology.

[0070] Narrow correlation technology is a multipath mitigation method based on the receiver hardware structure. Assuming there is only one multipath signal and the correlator interval is d, the lead and lag signals in the receiver code tracking loop can be expressed as:

[0071]

[0072] The narrow correlation method uses the lead-minus-lag EML phase detector, so the phase detection output of the narrow correlation method can be obtained by subtracting the above two equations. The sub-orthogonal synthetic correlation function R provided by the present invention is proposed (τ e ) replaces the correlation function R(τ e ), so the mathematical model of the phase detection output function of the narrow correlation multipath suppression method combined with the edge peak elimination algorithm is:

[0073] S SQC-NC (τ e )=R proposed_E1 (τ e )-R proposed_L1 (τ e );

[0074] Wherein, the SQC-narrow correlation advance minus lag correlator interval d<1Tc, Tc is one code chip.

[0075] HRC technology improves on the lead-minus-lag EML phase detector. By adding a pair of early and late correlators, it utilizes the slope information on both sides of the correlation peak for phase detection. This achieves better multipath mitigation than narrow correlation, but also reduces the range of phase detection. The two sets of correlators in the HRC method are lead-minus-lag and far-lead-minus-lag. Generally, the correlator spacing of the latter is set to twice that of the former. Combining these four correlators as shown below yields the phase detection output function of the HRC method:

[0076]

[0077] Among them, R E1 and R L1 The branch correlation function of the lead-minus-lag correlator E1 and L1 with an interval of d, R E2 and R L2 The branch correlation function of the far-advanced minus-lag correlator E2 and L2 with an interval of 2d. Combined with the phase-locked output model of the narrow correlation method above, it can be seen that the phase-locked output (R E1 -R L1 ) is equivalent to the phase detection output S of the narrow correlation method NC (τ e )=Narrow(d), and combined with the sub-orthogonal correlation function proposed in the present invention, the phase detection function of the HRC technology can be re-expressed as:

[0078]

[0079] Assuming the correlator spacing of the HRC method is consistent with narrow correlation, the phase-detection output function of the SQC-HRC method can be expressed as the phase-detection output function of the SQC-narrow correlation method. Thus, the present invention improves multipath mitigation technology, achieving significant multipath mitigation effectiveness for BOC signals and eliminating code tracking ambiguity.

[0080] The present invention proposes a sub-quadrature complex correlation function-based peak elimination algorithm (abbreviated as SQC algorithm), which is combined with the traditional narrow correlator method and HRC (High-Resolution Correlator) method to generate a new SQC-narrow correlation and SQC-HRC multipath suppression technology. The following is an explanation with the accompanying drawings, please refer to Figure 2 , Figure 2 This is a block diagram of the sub-orthogonal synthesis correlation function algorithm provided by the present invention; please refer to Figure 3 and Figure 4 , Figure 3 and Figure 4 It is a diagram of the sub-orthogonal synthesis correlation function process between the Sine-BOC(n,n) signal and the Cosine-BOC(n,n) signal; please refer to Figure 5 and Figure 6 , Figure 5 and Figure 6 This is a comparison of the normalized autocorrelation functions obtained by applying various traditional peak removal algorithms and the algorithm provided by the present invention to Sine-BOC (1,1) and Cosine-BOC (n,n) signals; please refer to Figure 7 and Figure 8 , Figure 7 and Figure 8 The lead-minus-lag EML phase detection curves of the narrow correlation method and the SQC-narrow correlation method for Sine-BOC (1,1) and Cosine-BOC (1,1) signals are shown in Figure 2. Figure 9 and Figure 10 , Figure 9 and Figure 10 The lead-minus-lag EML phase detection curves of the HRC method and the SQC-HRC method for Sine-BOC(1,1) and Cosine-BOC(1,1) signals are shown in Figure 2. Figure 11 and Figure 12 , Figure 11 and Figure 12 are the multipath envelope error curves of the narrow correlation method and the SQC-narrow correlation method for Sine-BOC(1,1) and Cosine-BOC(1,1) signals; see Figure 13 and Figure 14 , Figure 13 and Figure 14 The following are the multipath envelope error curves for the HRC method and the SQC-HRC correlation method for Sine-BOC(1,1) and Cosine-BOC(1,1) signals. Simulation results show that for Sine-BOC(1,1) and Cosine-BOC(1,1) signals, the improved multipath mitigation technique combined with the SQC algorithm not only effectively resolves the code tracking ambiguity problem but also significantly reduces the impact of multipath on the BOC signal, significantly improving the multipath mitigation capability. This provides an improved multipath mitigation technique for BOC signals, improving the accuracy of the code tracking loop while resolving the issues of false lock and poor multipath mitigation performance that exist with traditional multipath mitigation techniques when applied to BOC signals.

[0081] Furthermore, the present invention proposes an improved method for multipath suppression applicable to BOC(n,n) signals. The central idea of the present invention is to first generate an orthogonal correlation function R by cross-correlating the Sine-BOC(n,n) and Cosine-BOC(n,n) signals. s / c and R c / s , then decompose and translate the orthogonal correlation to obtain the sub-orthogonal correlation function Shift_R required to reconstruct the correlation function sc1 (τ), using the reconstruction method proposed by the present invention based on the characteristics of the correlation signal, a new correlation function R proposedThe reconstructed new correlation function completely eliminates the secondary peaks, and through the sharpening of the main peak, the receiver code tracking loop can achieve more precise synchronization control. Based on the phase detection principle of the traditional narrow correlation and HRC methods, the present invention innovatively replaces the autocorrelation function in the original phase detector with an optimized sub-orthogonal synthetic correlation function. This technological breakthrough has achieved two significant effects: on the one hand, it effectively eliminates the pseudo-code phase ambiguity problem caused by the multi-peak nature of the traditional BOC signal; on the other hand, after the organic integration of the SQC narrow correlation technology and the HRC method, the false locking points in the phase detection characteristic curve can be almost completely eliminated, and the multipath error envelope area is greatly reduced, which makes the signal tracking performance of the system in a multipath environment achieve a breakthrough improvement.

[0082] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of the rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for multipath suppression of satellite navigation BOC signals, characterized in that: include: Generate autocorrelation functions of Sine-BOC(n,n) and Cosine-BOC(n,n) signals; Generate the positive cross-correlation function R of Sine-BOC(n,n) and Cosine-BOC(n,n) s / c The positive cross-correlation function R of Cosine-BOC(n,n) and Sine-BOC(n,n) c / s , where R s / c and R c / s Inverse relationship R s / c and R c / s Decompose to obtain the corresponding sub-orthogonal correlation function; Shift the sub-orthogonal correlation functions corresponding to Sine-BOC(n,n) and Cosine-BOC(n,n) by 0.25Tc; The synthetic correlation function is reconstructed by using the corresponding relationship and sharp characteristics of the main and secondary peaks of the sub-orthogonal correlation function after translation and the peak of the BOC autocorrelation function; The synthetic correlation function replaces the autocorrelation function in the traditional phase detection function and is combined with narrow correlation and HRC technology to form an improved BOC multipath suppression technology.

2. The satellite navigation BOC signal multipath suppression method according to claim 1, wherein: The positive cross-correlation function R s / c and R c / s The expression is decomposed into sub-orthogonal correlation functions R s / c1 and R s / c2 , sub-orthogonal correlation function R s / c1 and R s / c2 The sum is the positive cross-correlation function R s / c ; in, It represents a trigonometric function with a bandwidth of Tc / 2, an amplitude of 1, and a center at zero. i, j, i1, and j1 are all variables, indicating the number of accumulations.

3. The satellite navigation BOC signal multipath suppression method according to claim 2, wherein: The positive cross-correlation function R c / s Decomposed into sub-orthogonal correlation functions R c / s1 and R c / s2 , sub-orthogonal correlation function R c / s1 and R c / s2 The sum is the positive cross-correlation function R c / s ; in, It represents a trigonometric function with a bandwidth of Tc / 2, an amplitude of 1, and a center at zero. i, j, i1, and j1 are all variables, indicating the number of accumulations.

4. The satellite navigation BOC signal multipath suppression technology method according to claim 3, characterized in that: R sc1 Shift 0.25Tc to the left to get the correlation function Shift_R sc1 (τ), since the positions of the main and secondary peaks correspond to those of the original autocorrelation function of the BOC signal and are sharper than the main peak, the new synthetic correlation function is obtained by the reconstruction synthesis method of the following formula: R proposed (t)=Shift_R s / c1 (t)*R BOCs (t)+|Shift_R s / c1 (t)|*R BOCs (t); Among them, R BOCs (τ) is the mathematical model of the autocorrelation function of Sine-BOC(n,n); A satellite navigation BOC signal multipath suppression method can be generated by replacing the autocorrelation function of the received signal in the original phase detection function with a new synthetic correlation function and combining it with narrow correlation and HRC anti-multipath technology. The navigation receiver obtains the phase detection output in the presence of multipath signals by analyzing the phase detection output, and gives the phase detection output functions of the narrow correlation and HRC multipath suppression methods. Then, the improved outputs of the two methods combined with the SQC peak elimination method are given, and the mathematical model of the SQC-narrow correlation phase detection output function is obtained as follows: S SQC-NC (t e )=R proposed_E1 (t e )-R proposed_L1 (t e ); Among them, R proposed_E1 (τ e ) and R proposed_L1 (τ e ) are the correlation functions of the unambiguous leading signal and the lagging signal in the receiver code tracking loop, respectively; The phase detection function of SQC-HRC is obtained as: Among them, τ e is the code phase delay error caused by multipath; Narrow(d) is the SQC-narrow correlation phase detection output function S with a correlator interval of d SQC-NC (τ e ), Narrow(2d) is the phase detector output with the phase detector spacing expanded to 2d.

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