Loop adaptive GNSS anti-multipath method based on multi-correlator output
By constructing a multipath characteristic index M in the GNSS receiver and adaptively adjusting the code tracking loop parameters, the anti-multipath problem of the GNSS receiver under short-delay multipath conditions is solved, and the positioning accuracy and stability are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI ZHONGKE YUJIANG TECHNOLOGY CO LTD
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-12
AI Technical Summary
Existing GNSS receivers have limited multipath resistance capabilities in short-delay multipath scenarios, and their loop parameters cannot be adaptively adjusted and have high computational complexity, resulting in a decrease in positioning accuracy.
By setting multiple symmetric code delay positions on both sides of the Prompt point for correlation, a multipath feature index M is constructed, and the correlator interval and loop bandwidth of the code tracking loop are adaptively adjusted to improve the multipath resistance capability.
Without increasing computational complexity, the locking accuracy of the code tracking loop is improved, pseudorange measurement deviation is reduced, and the positioning accuracy and stability of the GNSS receiver in multipath environments are enhanced.
Smart Images
Figure CN122017891A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of satellite navigation signal processing, and in particular to a loop adaptive GNSS anti-multipath method based on the output of multiple correlators. Background Technology
[0002] Global Navigation Satellite Systems (GNSS), such as GPS, BeiDou, GLONASS, and Galileo, are widely used in surveying, transportation, unmanned systems, and precision time synchronization. GNSS receivers obtain the code delay and carrier phase of satellite signals through correlation processing, thereby generating pseudorange and carrier phase observations used to calculate the user's position, velocity, and time. In practical applications, especially in urban canyons, under bridges, and complex reflection scenarios, satellite signals are reflected or scattered by objects such as buildings, ground, and water surfaces during propagation, forming multipath signals that differ from the direct signal path. When multipath signals are superimposed on the direct signal at the receiver front end, the amplitude and shape of the correlation function are distorted, causing a shift in the lock point of the code tracking loop (such as the delay-locked loop DLL), resulting in pseudorange measurement errors and affecting navigation accuracy. GNSS systems employ direct sequence spread spectrum technology, which has excellent suppression capabilities against multipath signal interference with large multipath delays. However, when the multipath delay is small, such as less than one chip, traditional direct-sequence spread spectrum (DSS) anti-multipath techniques are difficult to achieve satisfactory performance when applied to GNSS systems. This is because traditional DSS anti-multipath techniques treat such small-delay signals as part of the useful signal without processing them, such as Rake receiver technology. Therefore, these multipath signals will still cause significant distortion in pseudorange and carrier phase measurements.
[0003] To improve the positioning accuracy of GNSS receivers and reduce the impact of multipath interference, researchers both domestically and internationally have conducted extensive work in four areas: satellite signal design, receiver antenna design and site selection, digital signal processing, and positioning and navigation calculation. This invention primarily focuses on anti-multipath methods at the receiver baseband processing level, which can be broadly categorized as follows: (1) Correlator structure improvement methods: such as narrow correlator technology to improve multipath resistance by compressing chip spacing, and double-Delta technology to construct a phase detection function by two pairs of correlators to improve the ability to distinguish local shape changes of the correlation function. These methods reduce code tracking errors caused by multipath to a certain extent, but they generally have problems such as being more sensitive to noise, having fixed parameters, and being difficult to adaptively optimize for environmental changes.
[0004] (2) Delay-locking methods based on multipath parameter estimation: These methods model the received correlation function as a superposition of the direct component and several multipath components, and extract the true delay of the direct component by estimating the amplitude and delay of each component using least squares or maximum likelihood estimation. Typical methods include multipath parameter estimation delay-locked loops. Theoretically, these methods can achieve good multipath suppression performance, but they often require a large number of correlator sampling points, resulting in high computational complexity and making them difficult to promote in resource-constrained or low-cost receivers.
[0005] (3) Signal Quality Monitoring (SQM) and Observation Weighting Methods: Signal quality indices are constructed by extracting several geometric or statistical features from the correlation function to detect multipath or distorted signals. These indices are then weighted down or removed during position calculation. However, this type of method generally operates at the observation and calculation level and cannot directly improve the locking performance of the code tracking loop itself under multipath conditions.
[0006] Therefore, it is necessary to propose a method and apparatus that can extract multipath features from the output of multiple correlators and adaptively adjust the code tracking loop parameters based on these features, thereby improving the multipath resistance capability of GNSS receivers in various environments, under the premise of controllable computational complexity. Summary of the Invention
[0007] The purpose of this invention is to address the limitations of existing GNSS multipath suppression methods in short-delay multipath scenarios, such as limited suppression effectiveness, lack of adaptive adjustment of loop parameters, and high implementation complexity. This invention proposes a multipath interference suppression method and apparatus for GNSS receivers. The method involves setting multiple symmetrical code delay positions on both sides of the Prompt point (the Prompt point being the punctual point of the code tracking loop, corresponding to the zero-delay position of the code delay axis) for correlation, constructing a multipath characteristic index M characterizing the asymmetry of the correlation function, and adaptively controlling the correlator interval and loop bandwidth of the code tracking loop based on this index to improve the code tracking accuracy of the receiver in multipath environments.
[0008] The technical solution of this invention is as follows: To achieve the above objectives, the present invention provides a multipath interference suppression method for a satellite navigation receiver, the method comprising the following steps.
[0009] Step 1 (Multi-channel correlation output calculation steps): The receiver calculates the local pseudo-code phase corresponding to the Prompt point on the code delay axis for the GNSS intermediate frequency or baseband signal obtained after down-conversion and sampling. Centered on the periphery, several symmetrical code delay positions are set on both sides. , Then, correlation is performed with the local pseudocode at each delay position to obtain the corresponding correlation output. , and Prompt-related outputs .
[0010] Specifically, it can be set , k=1,2,…,n in, For multiple pre-set chip intervals, One chip width, To separate digital segments, and preferably set as follows: The fractional interval is less than one chip, for example, in the range of 0.05 to 0.5 chips, to ensure sufficient sensitivity to short-delay multipath.
[0011] At each code delay position, the receiver performs correlation integration on the in-phase component I and the quadrature component Q, respectively, to obtain... , , , , , The superscripts "E" and "L" correspond to respectively , The relevant outputs, with "P" superscript corresponding to the Prompt point. The relevant output. Incoherent correlation amplitudes at each delay location can be constructed based on the I / Q components, for example: , , The correlation output can be integrated over one or more code periods, and the integration time can be adaptively set according to conditions such as carrier-to-noise ratio.
[0012] Step 2 (Multipath Feature Index Calculation Steps): Based on the above multipath correlation outputs, construct a multipath feature index M to characterize the degree of asymmetry in the correlation function. First, calculate the local asymmetry index for each pair of symmetrical delay positions. Its definition is: in, This is a small constant used to prevent the denominator from approaching zero. When ground multipath is weak and the correlation function is approximately symmetric, ,but Approaching zero; when significant multipath events cause asymmetric distortion of the correlation function on both sides of the Prompt point. The absolute value increases. Subsequently, a weighted combination of each local asymmetry index is performed to obtain the global multipath characteristic index M, which can be expressed in the form of a weighted L2 norm: in, The weights at each symmetrical delay position satisfy the following condition: It can be normalized to The weights can be the same, or they can be set according to the different sensitivities to short-delay or long-delay multipath propagation at different delay locations. For example, the weights can be set for those closer to the Prompt point. Greater weighting is assigned to enhance the representation of short-delay multipath signals. A larger value for M indicates a more pronounced asymmetry of the correlation function on the code delay axis, meaning the signal is more susceptible to multipath interference.
[0013] Furthermore, the multipath characteristic index M can be further expanded by combining information on the slope of the correlation function and sidelobe energy, for example: Slope difference index: Calculate the local slope of the correlation function at the delay positions adjacent to Prompt, and construct the slope difference normalization index S, for example: To measure the asymmetry of the slope of the correlation function on both sides of the Prompt point.
[0014] Side lobe energy ratio index: Within the preset main lobe delay range and side lobe delay range Calculate the relevant energies separately: And construct an index for the ratio of side lobe energy to main lobe energy. Used to identify long-delay multipath or sidelobe enhancement conditions.
[0015] The aforementioned asymmetry index M, slope difference index S, and sidelobe energy ratio index Linear or nonlinear combinations can be performed to form a comprehensive multipath characteristic index, for example: in, These are non-negative weighting coefficients. By appropriately selecting the weights, the comprehensive characterization capability for different types of multipaths can be enhanced.
[0016] In the basic embodiment of the present invention, the multipath characteristic index can be directly taken as M; in the extended embodiment, the above-mentioned comprehensive index can be used. .
[0017] Step 3 (Code Tracking Loop Adaptive Control Steps): The receiver uses the multipath characteristic index M or the comprehensive multipath characteristic index. The size of this value is used to adaptively adjust the key parameters of the code tracking loop. In practical applications, the selection... or One of them is sufficient. It provides a more refined characterization of multipath interference, but increases computational complexity. Taking the multipath feature index M as an example, the details are as follows: Specifically, when the multipath feature index M satisfies When the current multipath interference is determined to be weak, the code tracking loop switches to a first operating mode and adopts a first parameter configuration. Under this configuration, for example, the Early-Late interval of the correlator adopts a first predetermined value. Its value is relatively large; the loop bandwidth adopts a first predetermined value. Its value is relatively wide to improve the loop's robustness in tracking dynamic stress and noise.
[0018] When satisfied If a certain degree of multipath interference is detected, the code tracking loop switches to a second operating mode and adopts a second parameter configuration. Under this configuration, for example, the correlator interval is adjusted to a second predetermined value. Its value is less than the first predetermined value; the loop bandwidth is adjusted to the second predetermined value. Its value is less than the first predetermined value, thereby achieving a balance between multipath suppression capability and dynamic tracking performance in the loop.
[0019] When satisfied If the multipath interference is deemed severe, the code tracking loop switches to a third operating mode and adopts a third parameter configuration. Under this configuration, for example, the correlator interval uses a third predetermined value. Its value is the preset minimum value; the loop bandwidth adopts a third preset value. Its value is a preset minimum value, and a high-resolution anti-multipath discriminator structure can be further enabled to suppress the impact of multipath effects on code tracking lock points to the greatest extent.
[0020] Wherein, the correlator interval satisfies The loop bandwidth satisfies The specific parameter values for each operating mode can be preset or adaptively configured according to the target application scenario and system performance requirements of the receiver.
[0021] threshold , Parameters such as correlator spacing and loop bandwidth in each mode can be preset according to the target application scenario and performance requirements of the receiver.
[0022] This invention discloses a loop-adaptive GNSS anti-multipath method based on multicorrelator output, the advantages of which are: (1) This invention utilizes the correlation outputs of multiple symmetric code delay positions on both sides of the Prompt point to construct a multipath feature index M that characterizes the degree of asymmetry of the correlation function. This allows the receiver to measure the impact of multipath on the shape of the correlation function without significantly increasing the number of correlators and computational complexity. Compared with the traditional DLL that relies solely on a single Early-Late difference, this index can more comprehensively reflect the correlation peak distortion caused by short-delay multipath.
[0023] (2) This invention adaptively controls the correlator spacing and loop bandwidth of the code tracking loop based on the multipath characteristic index M, enabling the code tracking loop parameters to be dynamically adjusted according to changes in multipath conditions. It maintains good dynamic performance and noise robustness when multipath is weak, and enhances the suppression capability of short-delay multipath when multipath is strong, thereby improving the overall performance of the receiver under different environments and operating conditions.
[0024] (3) The multipath characteristic index M proposed in this invention has normalization characteristics and is not sensitive to changes in the overall signal amplitude, making it easy to uniformly set thresholds and control strategies under different signal power conditions. At the same time, this index can be combined and extended with indices such as slope difference index and sidelobe energy ratio index to further improve the ability to identify different types of multipath.
[0025] (4) This invention can improve the locking accuracy of the code tracking loop in a multipath environment and reduce pseudorange measurement deviation while maintaining a relatively simple structure and controllable computational load. Furthermore, by weighting or eliminating observations, it reduces the impact of multipath-contaminated observations on navigation solution results, thereby improving overall positioning accuracy and stability. This method is applicable to various GNSS systems and receiver platforms, demonstrating good versatility and engineering application value. Attached Figure Description
[0026] Figure 1 This is a general structural block diagram of a GNSS receiver and multipath interference suppression device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a single-channel tracking loop provided in an embodiment of the present invention; Figure 3 This refers to the shape of the correlation function when multiple paths exist, as provided in the embodiments of the present invention, and the position of the symmetrical correlation sampling points in the present invention; Figure 4 This is a flowchart of the multipath feature index M calculation provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the code tracking loop adaptive control process provided in an embodiment of the present invention. Detailed Implementation
[0027] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.
[0028] like Figure 1 The diagram shows the overall structural block diagram of a GNSS receiver and multipath interference suppression device provided in this embodiment of the invention. The GNSS receiver module includes: a radio frequency front-end module, an AD conversion module, a baseband signal processing module, a navigation calculation module, and a storage control module, wherein the baseband signal processing module integrates the multipath interference suppression module of this invention.
[0029] The radio frequency front-end module receives radio frequency signals from various GNSS satellites and performs low-noise amplification, bandpass filtering, down-conversion, and other processing. The analog-to-digital conversion module samples the down-converted intermediate frequency (IF) or baseband signal to obtain a digital IF signal. The baseband processing module performs acquisition, tracking, and generation of observations such as pseudorange, carrier phase, and Doppler. The navigation calculation module calculates position, velocity, and time based on the observations. The storage and control module stores programs and parameters and schedules and manages each module.
[0030] The multipath interference suppression device of this invention is housed within the baseband processing module and can be implemented as a software program executed by a hardware circuit, a programmable logic device, a digital signal processor, or an embedded processor. Those skilled in the art can choose the specific implementation method based on system resources and application requirements.
[0031] Figure 2 A schematic diagram of a single-channel tracking loop in an embodiment of the present invention is shown. Each satellite corresponds to one tracking channel, which includes a carrier tracking loop, a code tracking loop, and the multicorrelator unit 310, multipath feature extraction unit 320, and loop control unit 330 proposed in this invention.
[0032] In traditional DLL structures, the received signal is typically correlated only at three code delay positions: early, immediate, and late, yielding Early, Prompt, and Late correlation outputs, respectively. The DLL uses only the Early-Late difference to form the discriminator output, controlling the local pseudocode generator. This structure, utilizing only the differential information of a single Early-Late pair, has limited capacity to characterize the shape distortion of the correlation function caused by short-delay multipath propagation.
[0033] In this embodiment of the invention, the multiple correlator unit 310, based on the fact that the code delay corresponding to the precise timing is 0, has multiple pairs of symmetrical code delay positions set on both sides of it. For example, K pairs of symmetrical delay positions can be set: , k=1,2,…,n in, For multiple pre-set chip intervals, One chip width, To separate digital segments, and preferably set as follows: The fractional interval is less than one chip, for example, in the range of 0.05 to 0.5 chips, to ensure sufficient sensitivity to short-delay multipath propagation. Correspondingly, the multicorrelator unit 310 correlates with the local pseudocode at each delay position to obtain multipath correlation outputs. Specifically, at each delay position, the in-phase component and the quadrature component can be calculated: , , , , , The superscripts "E" and "L" correspond to respectively , The relevant outputs, with "P" superscript corresponding to the Prompt point. The relevant output. In practical implementation, to avoid the impact of carrier phase reversal on the performance indicators, this embodiment preferably uses incoherent correlation amplitude or incoherent accumulated energy constructed based on I / Q components as the input for subsequent processing. For example, incoherent correlation amplitudes at each delay position can be constructed based on I / Q components, for example: , , The aforementioned related outputs can be integrated and accumulated over one or more code periods. The integration time can be adaptively set according to conditions such as the carrier-to-noise ratio C / N0 to balance noise immunity and time-varying response capability.
[0034] Figure 3 The diagram schematically illustrates the shape of the correlation function in the presence of multipath and the location of the symmetrical correlation sampling points in this invention. Under the ideal multipath-free condition, the correlation function centered at Prompt is approximately symmetrical about a zero delay, i.e., it satisfies... However, when short-delay multipaths exist, the multipaths tend to concentrate on one side of the main peak, causing the correlation function to exhibit obvious asymmetry.
[0035] Figure 4 The flowchart of multipath feature index M calculation is shown. The multipath feature extraction unit 320 of this invention constructs multipath feature index M by utilizing the differences between each symmetrical sampling point, which is used to quantitatively characterize the degree of asymmetry of the correlation function on the code delay axis and the current degree of multipath interference.
[0036] Specifically, for the k-th pair of symmetric delay positions, its local asymmetry index It can be calculated using the following formula: in, and These are the relevant outputs corresponding to the delay positions of the lead and lag symmetric codes, respectively. To prevent the denominator from approaching zero, a small constant can be selected, which is much smaller than the relevant output amplitude, depending on the noise level.
[0037] To integrate the asymmetric information at each symmetric delay location, this embodiment uses local asymmetry indices. By performing a weighted combination, the global multipath feature index M is obtained: in, The weights corresponding to the delay positions of the k-th pair of symmetric codes satisfy the following conditions: ,and The sensitivity to short-delay multipath can be weighted according to different delay locations. For example, a larger weight can be given to delay locations closer to the Prompt to enhance the sensitivity to short-delay multipath distortion.
[0038] As can be seen from the above definition, in the case of ideal symmetry or very weak multipath, Then each When the multipath is strong and concentrated on one side of the correlation function, M approaches 0; and As the difference increases, the corresponding M value also increases significantly. Therefore, M can be used as an indicator to measure the current degree of multipath interference in the channel.
[0039] Furthermore, the multipath feature extraction unit 320 can also introduce correlation function slope difference index and sidelobe energy ratio index based on the above. For example: (1) Calculate the local slope of the correlation function at adjacent delay positions on both sides of Prompt (e.g., k=1) and construct a slope difference normalization index: To measure the asymmetry of the slope of the correlation function on both sides of the Prompt point; (2) Within the preset main lobe delay range and side lobe delay range Calculate the relevant energies separately: And construct the ratio of side lobe energy to main lobe energy: Used to identify long-delay multipath interference or sidelobe delay enhancement.
[0040] The aforementioned asymmetry index M, slope difference index S, and sidelobe energy ratio index Linear or nonlinear combinations can be performed to form a comprehensive multipath characteristic index, for example: in, , , These are non-negative weighting coefficients. By appropriately selecting the weights, M or... As a multipath characteristic index for subsequent loop control and observation quality control.
[0041] Figure 4 A schematic diagram of the code tracking loop adaptive control flow according to an embodiment of the present invention is shown. Figure 4 As shown, the loop control unit 330 reads the current multipath characteristic index M at a certain period (e.g., every or every several integral periods) and selects the corresponding loop working mode according to the interval where M is located, thereby realizing automatic parameter adjustment based on multipath sensing.
[0042] To achieve adaptive control based on multipath sensing, a first threshold is preset in this embodiment. Second threshold and satisfy Depending on the magnitude of the multipath characteristic index, the code tracking loop can be configured to different operating modes, for example: (1) First working mode: when When the multipath interference is determined to be weak, the loop control unit 330 configures the code tracking loop to the first operating mode. In this mode, a first predetermined value for the correlator interval is used. and the first predetermined value of loop bandwidth To maintain robustness to dynamic changes and noise.
[0043] (2) Second working mode: when When multipath interference is detected to be present, the loop control unit 330 configures the code tracking loop to a second operating mode. In this mode, a second predetermined correlator interval is used. The second predetermined value of loop bandwidth This makes the locking point of the delay-locked loop closer to the steep region of the relevant main peak, thereby suppressing code tracking deviation caused by short-delay multipath.
[0044] (3) Third working mode: when When the multipath interference is deemed severe, the loop control unit 330 configures the code tracking loop to the third operating mode. In this mode, a third predetermined value for the correlator interval is used. and the third predetermined value of loop bandwidth It also enables high-resolution anti-multipath discriminator structures, such as discriminators built based on multi-point correlation combinations, to minimize the impact of multipath effects on locking points.
[0045] Among them, the correlator interval satisfies The loop bandwidth meets The specific parameter values for each mode can be configured according to the receiver's target application scenario and performance requirements, such as static measurement, vehicle navigation, or high dynamic platforms. To avoid loop oscillation caused by frequent mode switching, the loop control unit 330 can set a buffer zone or minimum dwell time near the threshold.
[0046] The parameters such as correlator spacing and loop bandwidth in the first, second, and third operating modes mentioned above can be configured according to the target application scenario and performance requirements of the receiver; meanwhile, the first threshold Second threshold The parameters of each mode can also be adaptively adjusted by combining information such as satellite elevation angle, carrier-to-noise ratio (C / N0), and receiver motion status.
[0047] The above embodiments illustrate a typical implementation path of the multipath interference suppression method and apparatus of the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the relevant module divisions, parameter configurations, and index combinations without departing from the spirit and substance of the present invention should be included within the protection scope of the present invention.
Claims
1. A loop-adaptive GNSS anti-multipath method based on multicorrelator output, characterized in that, Includes the following steps: S1: For the GNSS intermediate frequency or baseband digital signal obtained by downconversion and analog-to-digital conversion from the RF front-end, the local pseudocode phase corresponding to zero delay on the code delay axis is... Centered on the periphery, several pairs of symmetrical code delay positions are set on both sides. , ,in , These represent the lead code phase and the lag code phase, respectively, and are correlated with the local pseudocode at each delay position to obtain the corresponding lead correlation output. Lag-related output and code phase The corresponding Prompt correlator output That is, timely and relevant output; S2: Based on the correlation output at each symmetric code delay position, calculate the local asymmetry index at each symmetric code delay position. We then weighted and combined the local asymmetry indices to obtain the multipath feature index M, which characterizes the degree of asymmetry of the correlation function on the code delay axis. S3: Compare the multipath feature index M with a preset threshold, select the working mode of the code tracking loop according to the interval where M is located, and adaptively adjust the correlator interval and loop bandwidth of the code tracking loop to suppress multipath interference.
2. The loop adaptive GNSS anti-multipath method based on multicorrelator output according to claim 1, characterized in that, In step S1, the in-phase component I and the quadrature component Q are calculated at each code delay position. This is typically done by performing corresponding integration and sum of squares on the in-phase and quadrature components to obtain the incoherent correlation amplitude, as shown in the formula: ， ， in, and Corresponding to the leading in-phase and quadrature components, and Corresponding to the lagging in-phase and quadrature components, and This corresponds to the in-phase and quadrature components with zero delay. And the local asymmetry index... Both the multipath characteristic index M and the multipath characteristic index M are based on and Calculated.
3. The loop adaptive GNSS anti-multipath method based on multicorrelator output according to claim 1, characterized in that, In step S2, the local asymmetry index Defined as: in, and These are the relevant outputs at the delay positions of the k-th pair of symmetric codes. To prevent the denominator from approaching a tiny positive constant; the multipath characteristic index M is defined as: in, The weights of the delay positions of each symmetric code satisfy the following conditions: And for Furthermore, a larger weight is assigned to the minimum code delay position near zero delay to enhance sensitivity to short-delay multipath interference; the multipath feature synthesis index also includes additional indices based on the correlation function slope and sidelobe energy, specifically: (1) In code phase The local slope of the correlation function is calculated at the delay positions of the left and right adjacent codes, and a slope difference normalization index is constructed, where k=1: (2) Calculate the relevant energy within the preset main lobe delay range and side lobe delay range respectively. and And construct the side lobe energy ratio index: (3) The multipath feature comprehensive index is based on M, S and Linear combination: in, , , These are non-negative weighting coefficients.
4. The loop adaptive GNSS anti-multipath method based on multicorrelator output according to claim 1, characterized in that, In step S3, a first threshold is preset. Second threshold and satisfy Based on the multipath characteristic index M or the multipath characteristic comprehensive index The size of the code tracking loop will configure it into one of three operating modes. In practical applications, the selection will be... or One of them is sufficient. It provides a more refined characterization of multipath interference, but increases computational complexity. Taking the multipath feature index M as an example, the details are as follows: (1) When At this time, the code tracking loop is in the first working mode, and the correlator interval adopts a first predetermined value. The loop bandwidth adopts a first predetermined value. ; (2) When At this time, the code tracking loop is in the second operating mode, and the correlator interval adopts a second predetermined value. The loop bandwidth adopts the second predetermined value. ; (3) When At this time, the code tracking loop is in the third operating mode, and the correlator interval adopts the third predetermined value. The loop bandwidth adopts a third predetermined value. ; Wherein, the correlator interval satisfies The loop bandwidth satisfies .
5. A multipath interference suppression device for a satellite navigation receiver, used to implement a loop-adaptive GNSS anti-multipath method based on multiple correlator output as described in any one of claims 1-4, characterized in that, include: (1) A multicorrelator unit (310) is used to set several pairs of symmetrical code delay positions on the code delay axis with the zero-delay code phase as the center, and to correlate with the local pseudocode at each code delay position to obtain the corresponding correlation output and the timely correlation output; (2) Multipath feature extraction unit (320) is used to calculate the local asymmetry index based on the correlation output of each symmetric code delay position, and to perform weighted combination of each local asymmetry index to obtain the multipath feature index M or multipath feature comprehensive index that characterizes the degree of asymmetry of the correlation function on the code delay axis. ; (3) Loop control unit (330), used to... or Compare with a preset threshold, based on multipath characteristic indicators or or The operating mode of the code tracking loop is selected based on the interval, and the correlator interval and loop bandwidth of the code tracking loop are adaptively adjusted.