GNSS tracking loop bandwidth switching method and device based on multi-observation hysteresis state machine, equipment and medium

Abstract

The application discloses a GNSS tracking loop bandwidth switching method and device based on multi-observation hysteresis state machine, equipment and medium, relates to the wireless electric navigation signal processing technical field, the method includes: initializing current bandwidth state, evidence integral, confirmation count and keeping count; obtaining loop observation according to the related output and discriminator output of GNSS spread spectrum signal tracking channel, and normalizing into main criterion risk quantity and auxiliary criterion risk quantity, then determining promotion evidence, strong dynamic evidence and stable evidence; updating state control quantity based on each evidence; obtaining target bandwidth state through step-by-step switching among three bandwidth states through hysteresis state machine; obtaining target bandwidth combination through table lookup, updating tracking loop filter coefficient and numerically controlled oscillator control quantity. The application can adaptively switch the bandwidth state of code tracking loop, frequency tracking loop and phase tracking loop according to the loop internal multi-observation in the GNSS spread spectrum signal tracking process.

Description

Technical Field

[0001] This application relates to the field of radio navigation signal processing technology, and in particular to a GNSS tracking loop bandwidth switching method, apparatus, equipment and medium based on a multi-observation hysteresis state machine. Background Technology

[0002] After a GNSS (Global Navigation Satellite System) receiver acquires a signal, it needs to continuously maintain synchronization between the local spreading code and the local carrier and the received signal through a spread spectrum signal tracking channel. For GNSS spread spectrum signals such as GPS L1 C / A (L1 Coarse Acquisition), code phase, carrier frequency, and carrier phase tracking are typically maintained through code tracking loops, frequency tracking loops, and phase tracking loops. In dynamic disturbance scenarios, Doppler frequency, carrier phase, and correlation peak quality may change rapidly, posing adaptive requirements for the tracking loop bandwidth configuration.

[0003] Existing GNSS tracking loops typically employ a fixed bandwidth approach, or utilize model-driven optimal bandwidth solutions, fuzzy control for variable bandwidth, adaptive gain FLL (Frequency Locked Loop) / PLL (Phase Locked Loop), FLL-assisted PLL, multi-loop joint operation, vector tracking, and DLL (Delay Locked Loop) adaptive bandwidth to adjust tracking loop parameters. These methods can improve tracking performance in some scenarios, but their implementation paths and dependencies differ.

[0004] However, fixed low bandwidth is insufficient for dynamic disturbances, while fixed high bandwidth amplifies steady-state noise and frequency estimation jitter. Relying solely on phase error, frequency error, or related amplitude for switching is susceptible to instantaneous noise, amplitude fluctuations, and outliers. Two-state bandwidth switching lacks a transition state, easily leading to excessive high bandwidth occupancy or repeated state oscillations. Some adaptive schemes also rely on external motion models, navigation solution feedback, or complex controllers. Therefore, how to adaptively switch the bandwidth states of the code tracking loop, frequency tracking loop, and phase tracking loop based on multiple internal observations during GNSS spread spectrum signal tracking has become an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a GNSS tracking loop bandwidth switching method, apparatus, device and medium based on a multi-observation hysteresis state machine, aiming to solve the technical problem of how to adaptively switch the bandwidth state of the code tracking loop, frequency tracking loop and phase tracking loop according to the multi-observation inside the loop during GNSS spread spectrum signal tracking.

[0006] To achieve the above objectives, this application proposes a GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine, the method comprising: Initialize the state control variables, which include the current bandwidth state, evidence integral, acknowledgment count, and hold count; Based on the correlation output and discriminator output of the GNSS spread spectrum signal tracking channel, loop observations are obtained, and the loop observations are normalized to obtain the loop risk quantity, which includes the primary criterion risk quantity and the auxiliary criterion risk quantity. The upgrade evidence, strong dynamic evidence, and stable evidence are determined based on the risk amount of the primary criterion and the risk amount of the auxiliary criterion. Based on the upgrade evidence, the strong dynamic evidence, and the stability evidence, the evidence integral, the confirmation count, and the hold count are updated to obtain the updated state control quantity. Based on the updated state control quantity, the target bandwidth state is obtained by switching between the first bandwidth state, the second bandwidth state, and the third bandwidth state through a hysteresis state machine. The first bandwidth state, the second bandwidth state, and the third bandwidth state correspond to different tracking loop bandwidth combinations in the preset bandwidth table. The target bandwidth combination corresponding to the target bandwidth state is found in the preset bandwidth table, and the tracking loop filter coefficients and numerically controlled oscillator control quantities are updated according to the target bandwidth combination.

[0007] Furthermore, to achieve the above objectives, this application also proposes a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine, the device comprising: An initialization module is used to initialize state control variables, which include current bandwidth state, evidence integral, acknowledgment count, and hold count. The risk acquisition module is used to obtain loop observations based on the relevant outputs and discriminator outputs of the GNSS spread spectrum signal tracking channel, and to normalize the loop observations to obtain the loop risk quantity, which includes the primary criterion risk quantity and the auxiliary criterion risk quantity. The evidence determination module is used to determine upgraded evidence, highly dynamic evidence, and stable evidence based on the risk level of the primary criterion and the risk level of the auxiliary criterion. The control update module is used to update the evidence integral, the confirmation count, and the hold count based on the upgrade evidence, the strong dynamic evidence, and the stable evidence, so as to obtain the updated state control quantity; The state switching module is used to switch between the first bandwidth state, the second bandwidth state and the third bandwidth state step by step according to the updated state control quantity, through a hysteresis state machine to obtain the target bandwidth state. The first bandwidth state, the second bandwidth state and the third bandwidth state correspond to different tracking loop bandwidth combinations in a preset bandwidth table. The bandwidth switching module is used to find the target bandwidth combination corresponding to the target bandwidth state from the preset bandwidth table, and update the tracking loop filter coefficients and the numerically controlled oscillator control quantities according to the target bandwidth combination.

[0008] Furthermore, to achieve the above objectives, this application also proposes a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine. The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The computer program is configured to implement the steps of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine as described above.

[0009] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine as described above.

[0010] One or more technical solutions proposed in this application have at least the following technical effects: When initializing the state control variables, values ​​are assigned to the current bandwidth state, evidence integral, confirmation count, and hold count to provide initial data for subsequent state judgments and avoid residual states from the previous tracking process affecting the current bandwidth switching. Then, loop observations are obtained based on the relevant outputs of the GNSS spread spectrum signal tracking channel and the discriminator output. These loop observations are normalized into primary criterion risk quantities and auxiliary criterion risk quantities, enabling observation information of different dimensions to participate in judgment at the same scale. Next, upgrade evidence, strong dynamic evidence, and stability evidence are determined based on the primary and auxiliary criterion risk quantities to distinguish between different state change bases such as general upgrades, strong dynamic upgrades, and stable downgrades, reducing the impact of fluctuations in single observations. To prevent misjudgments, this application updates the evidence integral, confirmation count, and hold count based on upgraded evidence, strong dynamic evidence, and stable evidence, transforming the judgment result within a single cycle into a continuous state control quantity, reducing frequent switching caused by instantaneous disturbances. Subsequently, based on the updated state control quantity, a hysteresis state machine switches stepwise between the first bandwidth state, the second bandwidth state, and the third bandwidth state to obtain the target bandwidth state, giving bandwidth state changes a transitional hierarchy. Finally, the target bandwidth combination corresponding to the target bandwidth state is found from the preset bandwidth table, and the tracking loop filter coefficients and numerically controlled oscillator control quantities are updated according to the target bandwidth combination, ensuring that bandwidth state switching is implemented in the tracking loop control parameter update. This application can adaptively switch the bandwidth state of the code tracking loop, frequency tracking loop, and phase tracking loop based on multiple observations within the loop during GNSS spread spectrum signal tracking. Attached Figure Description

[0011] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a flowchart illustrating the first embodiment of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in this application. Figure 2 This is a schematic diagram of the GNSS spread spectrum signal tracking loop structure provided in the first embodiment of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in this application. Figure 3This is a schematic diagram of the three-state bandwidth lookup table and step-by-step switching provided in the first embodiment of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in this application. Figure 4 This is a flowchart illustrating the second embodiment of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in this application. Figure 5 This is a schematic diagram of the bandwidth switching structure of the multi-observation hysteresis state machine provided in the second embodiment of the GNSS tracking loop bandwidth switching method based on the multi-observation hysteresis state machine of this application. Figure 6 This is a schematic diagram of the loop observation processing and state control quantity update process provided in the second embodiment of the GNSS tracking loop bandwidth switching method based on multi-observation hysteresis state machine of this application. Figure 7 This is a schematic diagram of the module structure of the GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine according to an embodiment of this application; Figure 8 This is a schematic diagram of the hardware operating environment involved in the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in the embodiments of this application.

[0014] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0015] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0016] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0017] It should be noted that the embodiments of this application can be applied to GNSS receivers, navigation terminals, vehicle navigation devices, or tracking channel processors in GNSS receivers. The following description uses a tracking channel processor in a GNSS receiver as an example to illustrate this embodiment and the subsequent embodiments.

[0018] In this example, the GNSS spread spectrum signal can be a Global Positioning System (GPS) L1 coarse acquisition code (L1 C / A) signal, and the tracking channel can include a delay-locked loop (DLL), a frequency-locked loop (FLL), and a phase-locked loop (PLL).

[0019] Based on this, the first embodiment of this application provides a GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine according to this application.

[0020] In this embodiment, the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine includes steps S10 to S60: Step S10: Initialize state control variables, which include current bandwidth state, evidence integral, acknowledgment count, and hold count; It should be noted that the state control quantity refers to the control data used to record the switching process of the tracking loop bandwidth state, the current bandwidth state refers to the bandwidth level used in the current coherent integration cycle, the evidence integral refers to the value used to accumulate the duration of dynamic or stable signs, the confirmation count refers to the count value used to confirm that the upshift or downshift conditions are continuously met, and the hold count refers to the count value used to limit the switching again after the state switch.

[0021] Understandably, upon entering the GNSS spread spectrum signal tracking channel, initial values ​​are assigned to the current bandwidth state, evidence integration, confirmation count, and hold count. The current bandwidth state can be set to the first bandwidth state, or it can be set to the third bandwidth state during the towing phase after acquisition. The evidence integration and confirmation count are usually set to 0. The hold count can be set to 0, or its initial value can be set according to the ratio of the preset hold time to the coherent integration period. The preset hold time can be determined based on the receiver platform's integration period, loop filter update time, and allowed state switching frequency. This step provides the initial control basis for subsequent state judgments, preventing historical channel states or residual counts from the previous round of processing from affecting the bandwidth switching judgment of the current tracking channel.

[0022] Please refer to Figure 2 , Figure 2 This diagram illustrates the GNSS spread spectrum signal tracking loop structure provided in the first embodiment of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine according to this application. The diagram shows the closed-loop processing relationship between the local carrier, local code, correlator, discriminator, loop filter, and numerically controlled oscillator in the GNSS spread spectrum signal tracking loop. In this example, the bandwidth switching process does not change the basic tracking structure of the early, prompt, and late branches correlators, discriminators, and loop filters. Instead, it reads the correlation output and discriminator output within the tracking channel and updates the loop filter parameters according to the bandwidth status.

[0023] After L1 carrier and code acquisition, the digital intermediate frequency sampling signal is input to the local carrier mixing downconverter module. The local carrier is generated by a numerically controlled carrier oscillator (NCO). The sine / cosine signal output from the NCO (Network Oscillator) is provided. The down-converted signal, along with the leading, instantaneous, and lagging local codes generated by the code numerically controlled oscillator and pseudocode generator, enters the correlator and integrator zeroing module to obtain the leading, instantaneous, and lagging correlation results. The correlation results are fed into the discriminator group to obtain the code phase error of the delay-locked loop, the residual frequency error of the frequency-locked loop, and the carrier phase error of the phase-locked loop, respectively. On the other hand, internal observations are formed, including the in-phase (I) and quadrature (Q) components of the instantaneous branch, signal amplitude, phase error, and frequency error. The discriminator error is processed by the loop filter group to form the discriminant value output, which is fed back to generate code control and carrier feedback frequency words. The code control is used to adjust the code numerically controlled oscillator and pseudocode generator, and the carrier feedback frequency word is used to adjust the carrier NCO. At the same time, the internal observations can be used as the basis for bandwidth switching judgment. The loop control quantity output by the loop filter is used to update the numerically controlled oscillator, and the final output tracking result includes code phase, carrier frequency, and carrier phase.

[0024] Step S20: Based on the relevant output and discriminator output of the GNSS spread spectrum signal tracking channel, the loop observation is obtained, and the loop observation is normalized to obtain the loop risk quantity, which includes the primary criterion risk quantity and the auxiliary criterion risk quantity. It should be noted that the GNSS spread spectrum signal tracking channel refers to the signal processing channel used to keep the local spreading code and local carrier synchronized with the received signal. The correlation output can be the complex correlation results of the Early branch, Prompt branch and Late branch. The discriminator output can be the output of the code phase discriminator, the carrier frequency discriminator and the carrier phase discriminator. The loop observation refers to the tracking state quantity obtained from the correlation output and the discriminator output. The loop risk quantity refers to the value after converting the loop observation to a unified risk scale.

[0025] Understandably, in each coherent integration cycle, the correlation output and discriminator output are read from the GNSS spread spectrum signal tracking channel, and observation data reflecting carrier phase, carrier frequency changes, and correlation peak amplitude changes are obtained accordingly. Subsequently, observation data of different dimensions are converted into risk quantities according to corresponding thresholds. For example, phase-type observation data are converted according to the phase normalization threshold, frequency-type observation data are converted according to the frequency normalization threshold, and the correlation amplitude of the Prompt branch is first converted into amplitude attenuation, and then converted according to the amplitude attenuation normalization threshold.

[0026] The normalization threshold can be obtained from the initial statistical calibration window or a threshold pre-calibrated by the receiver platform. The length of the initial statistical calibration window can be determined based on the coherent integration period and the start-up stabilization time, for example, covering several hundred coherent integration periods. The primary criterion risk measure represents the risk related to carrier phase and carrier frequency, while the secondary criterion risk measure represents the risk related to frequency variation and associated amplitude attenuation. This step, through normalization processing, transforms the phase, frequency, and amplitude observation data to a comparable scale, facilitating subsequent unified judgment using the primary and secondary criterion risk measures, while preserving the hierarchical relationship between the primary and secondary criteria.

[0027] Step S30: Determine the upgrade evidence, strong dynamic evidence, and stable evidence based on the primary criterion risk quantity and the auxiliary criterion risk quantity; It should be noted that "upgrade evidence" refers to the judgment result indicating that the current tracking channel has a need to increase its bandwidth level, "strong dynamic evidence" refers to the judgment result indicating that the current tracking channel has a need to enter the third bandwidth state, "stability evidence" refers to the judgment result indicating that the current tracking channel has the conditions to reduce its bandwidth level, and "comprehensive risk quantity" refers to the risk assessment quantity obtained by weighting the primary criterion risk quantity and the auxiliary criterion risk quantity.

[0028] Understandably, a comprehensive risk quantity is calculated based on the primary and secondary criterion risk quantities, and then judged in conjunction with preset primary criterion anomaly conditions, preset escalation conditions, preset strong dynamic conditions, and preset stability conditions. Preset primary criterion anomaly conditions can be determined based on whether the phase or frequency risk quantity exceeds the corresponding threshold; preset escalation conditions can be determined based on whether the comprehensive risk quantity exceeds the escalation threshold; preset strong dynamic conditions can be determined based on whether the primary criterion risk quantity reaches the strong dynamic threshold, or whether the secondary criterion risk quantity reaches the strong dynamic auxiliary threshold and the primary criterion risk quantity is close to the anomaly threshold; preset stability conditions can be determined based on whether the primary criterion risk quantity and the comprehensive risk quantity are below the stability threshold. Each threshold can be preset according to the receiver platform, coherent integration period, signal quality, and target dynamic range. The escalation and stability thresholds should preferably be set to different values ​​to form a hysteresis interval. This step, by using the primary and secondary criterion risk quantities together to form evidence judgment, can reduce misjudgments caused by instantaneous phase fluctuations, frequency spikes, or short-term amplitude attenuation when relying solely on a single observation.

[0029] Step S40: Based on the upgrade evidence, the strong dynamic evidence, and the stability evidence, update the evidence integral, the confirmation count, and the hold count to obtain the updated state control quantity; It should be noted that dynamic evidence score can be an integral value that records the degree of persistence of upgrade evidence, stable evidence score can be an integral value that records the degree of persistence of stable evidence, upgrade confirmation count can be a count value that records the degree of continuous satisfaction of upgrade conditions, and downgrade confirmation count can be a count value that records the degree of continuous satisfaction of downgrade conditions.

[0030] Understandably, the evidence score is divided into dynamic evidence score and stable evidence score, and the confirmation count is divided into upgrade confirmation count and downgrade confirmation count. When strong dynamic evidence is established, the dynamic evidence score is accumulated according to a preset enhancement step size; when strong dynamic evidence is not established but upgrade evidence is established, the dynamic evidence score is accumulated according to a preset dynamic step size; when both upgrade evidence and strong dynamic evidence are not established, the dynamic evidence score decreases according to a preset dynamic decay step size and is limited to a non-negative range. When stable evidence is established, the stable evidence score is accumulated according to a preset stable step size; when stable evidence is not established, the stable evidence score decreases according to a preset stable decay step size and is limited to a non-negative range.

[0031] Once the hold count reaches the decision-making condition, the upgrade confirmation count and downgrade confirmation count are updated based on the dynamic evidence integral and stable evidence integral. If the hold count does not reach the decision-making condition, the hold count is updated according to the preset hold step size. This step converts the judgment result of a single coherent integration cycle into a continuous judgment result through evidence integral and confirmation count, which can reduce bandwidth state jumps caused by single-point outlier data; by limiting the re-decision after state switching through the hold count, the repeated changes in bandwidth state can be reduced.

[0032] Step S50: Based on the updated state control quantity, the target bandwidth state is obtained by switching between the first bandwidth state, the second bandwidth state, and the third bandwidth state through a hysteresis state machine. The first bandwidth state, the second bandwidth state, and the third bandwidth state correspond to different tracking loop bandwidth combinations in the preset bandwidth table. It should be noted that a hysteresis state machine refers to a state control structure with state maintenance, step-by-step switching, and different up / down conditions. The first bandwidth state, second bandwidth state, and third bandwidth state correspond to different bandwidth levels in the preset bandwidth table, and the target bandwidth state refers to the bandwidth state selected after the state judgment is completed in the current coherent integration cycle. The tracking loop bandwidth combination includes code tracking loop bandwidth, frequency tracking loop bandwidth, and phase tracking loop bandwidth.

[0033] Understandably, the updated state control variables are used to determine whether the current bandwidth state needs to be switched. If the current bandwidth state is the first bandwidth state and the upgrade condition is met, the switch proceeds to the second bandwidth state; if the current bandwidth state is the second bandwidth state and both the upgrade condition and strong dynamic evidence are met, the switch proceeds to the third bandwidth state; if the current bandwidth state is the third bandwidth state and the downgrade condition is met, the switch proceeds to the second bandwidth state; if the current bandwidth state is the second bandwidth state and the downgrade condition is met, the switch proceeds to the first bandwidth state. If neither the upgrade nor downgrade condition is met, the current bandwidth state is maintained. The first, second, and third bandwidth states correspond to different bandwidth levels of the tracking loop bandwidth combinations in the preset bandwidth table, with the second bandwidth state located between the first and third bandwidth states. This step, through three bandwidth states and a step-by-step switching method, provides a transitional layer for bandwidth state switching, reducing the loop parameter changes caused by direct jumps between the first and third bandwidth states; by using hysteresis judgment, different trigger conditions are used for upgrades and downgrades, reducing repeated switching near critical states.

[0034] Step S60: Find the target bandwidth combination corresponding to the target bandwidth state from the preset bandwidth table, and update the tracking loop filter coefficients and numerically controlled oscillator control quantities according to the target bandwidth combination.

[0035] It should be noted that the preset bandwidth table refers to the correspondence between bandwidth status and tracking loop bandwidth combination, the target bandwidth combination refers to the code tracking loop bandwidth, carrier frequency tracking loop bandwidth and carrier phase tracking loop bandwidth corresponding to the target bandwidth status, the tracking loop filter coefficients refer to the parameters used for filtering processing by the code tracking loop, carrier frequency tracking loop and carrier phase tracking loop, and the numerically controlled oscillator control quantity can be the control word, frequency correction quantity or phase correction quantity used to adjust the local code generator or local carrier generator.

[0036] Understandably, after determining the target bandwidth state, the corresponding target bandwidth combination is looked up from the preset bandwidth table. The preset bandwidth table can record the code tracking loop bandwidth, carrier frequency tracking loop bandwidth, and carrier phase tracking loop bandwidth according to the first bandwidth state, the second bandwidth state, and the third bandwidth state, respectively; each bandwidth value can be pre-configured according to the signal system, coherent integration period, receiver platform, and target dynamic range.

[0037] After identifying the target bandwidth combination, the filter coefficients of the code tracking loop, carrier frequency tracking loop, and carrier phase tracking loop are updated according to the mapping relationship between the target bandwidth combination and the preset filter coefficients. Then, based on the updated filter coefficients, the discriminator output of the GNSS spread spectrum signal tracking channel is filtered to obtain the loop control quantity, and the numerically controlled oscillator control quantity is updated according to the loop control quantity. This step converts the target bandwidth state into the bandwidth combination of the code tracking loop, carrier frequency tracking loop, and carrier phase tracking loop through a preset bandwidth table, and further converts it into filter coefficients, so that the bandwidth state switching can be implemented in the tracking loop filter parameter update and the local code and local carrier control update.

[0038] This embodiment constructs loop observations through the correlation output and discriminator output within the GNSS spread spectrum signal tracking channel. The primary and secondary criterion risk quantities are used for escalation, strong dynamics, and stability assessments, respectively. Evidence integration, confirmation counting, and hold counting drive a hysteresis state machine for step-by-step bandwidth switching. Finally, the tracking loop filter coefficients and numerically controlled oscillator control quantities are updated according to the target bandwidth combination. This process does not rely on external motion models or navigation solution feedback, enabling switching to the appropriate bandwidth level during dynamic disturbances and returning to the appropriate bandwidth level during stable conditions. This reduces false triggering of single observations and frequent bandwidth state changes, improving the dynamic adaptability and steady-state tracking stability during GNSS spread spectrum signal tracking.

[0039] As an example, the step of updating the evidence integral, the confirmation count, and the hold count based on the upgrade evidence, the strong dynamic evidence, and the stable evidence to obtain the updated state control quantity includes: dividing the evidence integral into dynamic evidence integral and stable evidence integral; dividing the confirmation count into upgrade confirmation count and downgrade confirmation count; updating the dynamic evidence integral based on the upgrade evidence and the strong dynamic evidence, wherein, when the strong dynamic evidence is valid, it is accumulated according to a preset enhancement step size; when the strong dynamic evidence is invalid but the upgrade evidence is valid, it is accumulated according to a preset dynamic step size; and when neither the strong dynamic evidence nor the upgrade evidence is valid, it is accumulated according to a preset dynamic step size. The system employs a preset dynamic decay step size for decreasing and non-negative limiting. It updates the stable evidence integral based on the stable evidence, whereby it accumulates according to a preset stable step size when the stable evidence is valid, and decreases according to a preset stable decay step size for decreasing and non-negative limiting when the stable evidence is invalid. When the hold count meets a preset decision-making condition, the system updates the upshift confirmation count based on the comparison between the dynamic evidence integral and a preset dynamic trigger value, and updates the downshift confirmation count based on the comparison between the stable evidence integral and the preset stable trigger value. When the hold count does not meet the preset decision-making condition, the system updates the hold count according to a preset hold step size, resulting in an updated state control quantity.

[0040] It should be noted that dynamic evidence score refers to the cumulative value used to record the persistence of escalating evidence or strong dynamic evidence; stable evidence score refers to the cumulative value used to record the persistence of stable evidence; escalation confirmation count refers to the count value used to confirm the persistence of escalation after the dynamic evidence score reaches the trigger requirement; escalation confirmation count refers to the count value used to confirm the persistence of escalation after the stable evidence score reaches the trigger requirement; non-negative threshold means that when the result after the score decreases is less than 0, the score value is set to 0; the preset decision condition can be to keep the count equal to 0, or to keep the count not greater than the preset decision threshold.

[0041] Understandably, the evidence score is first split into dynamic evidence score and stable evidence score, and the confirmation count is split into upgrade confirmation count and downgrade confirmation count. The dynamic evidence score is used for upgrade-side judgment, and the stable evidence score is used for downgrade-side judgment; both are updated separately to avoid the same score value being used for both upgrade and downgrade judgments simultaneously. The upgrade confirmation count corresponds to the dynamic evidence score, and the downgrade confirmation count corresponds to the stable evidence score. The hold count is used to record whether the hold phase after a state switch has ended.

[0042] When updating the dynamic evidence integral based on upgrade evidence and strong dynamic evidence, the validity of the strong dynamic evidence is first determined. If the strong dynamic evidence is valid, the dynamic evidence integral is accumulated according to a preset enhancement step size; if the strong dynamic evidence is invalid but the upgrade evidence is valid, the dynamic evidence integral is accumulated according to a preset dynamic step size; if neither type of evidence is valid, the dynamic evidence integral is decreased according to a preset dynamic decay step size, and non-negative limiting is applied. The preset enhancement step size can be greater than the preset dynamic step size, for example, the preset enhancement step size can be 2 to 4, and the preset dynamic step size can be 1 to 2; the preset dynamic decay step size can be 1 to 2, and the specific values ​​can be set according to the coherent integration period, the duration of the dynamic disturbance, and the allowable upgrade response speed.

[0043] When updating the stability evidence integral based on stable evidence, if the stable evidence is valid, it is incremented by a preset stability step size; if the stable evidence is invalid, it is decremented by a preset stability decay step size, and a non-negative limit is applied. The preset stability step size and preset stability decay step size can be set according to the stable observation time required for downgrading; for example, in a 1ms coherent integration period, if it is desired that the stable state lasts for several tens of milliseconds before triggering downgrading confirmation, the preset stability trigger value can be set to a count value of the corresponding order of magnitude.

[0044] Based on this, it is determined whether the hold count meets the preset decision-making conditions. When the hold count meets the preset decision-making conditions, updating the upgrade confirmation count and downgrade confirmation count is allowed. If the dynamic evidence integral reaches the preset dynamic trigger value, the upgrade confirmation count is accumulated by the preset confirmation step size. If the dynamic evidence integral does not reach the preset dynamic trigger value, the upgrade confirmation count is reset to zero or decreased by the preset confirmation decay step size. If the stable evidence integral reaches the preset stable trigger value, the downgrade confirmation count is accumulated by the preset confirmation step size. If the stable evidence integral does not reach the preset stable trigger value, the downgrade confirmation count is reset to zero or decreased by the preset confirmation decay step size. The preset dynamic trigger value, preset stable trigger value, and preset confirmation step size can be set according to the state switching sensitivity. The confirmation count usually needs to meet the conditions for several consecutive coherent integration cycles before proceeding to the subsequent state decision.

[0045] If the hold count does not meet the preset decision-making conditions, the upshift confirmation count and downshift confirmation count are not updated, or they are kept at their current values; simultaneously, the hold count is updated according to the preset hold step size. The preset hold step size can correspond to the coherent integration period, for example, decreasing by 1 after each coherent integration period until the hold count meets the preset decision-making conditions. After the update, the current dynamic evidence integral, the current stable evidence integral, the current upshift confirmation count, the current downshift confirmation count, and the current hold count together constitute the updated state control quantity.

[0046] This example records the evidence persistence on the upshift and downshift sides using dynamic evidence integration and stable evidence integration, respectively. It reconfirms the integration triggering result by using upshift confirmation count and downshift confirmation count, and reduces the impact of instantaneous fluctuations within a single coherent integration cycle on the bandwidth state by maintaining the count limit after the state switch. This improves the continuity and stability of bandwidth state switching.

[0047] As an example, the bandwidth level corresponding to the second bandwidth state is located between the first bandwidth state and the third bandwidth state. The step of obtaining the target bandwidth state by switching between the first bandwidth state, the second bandwidth state, and the third bandwidth state step by step using a hysteresis state machine based on the updated state control quantity includes: when the current bandwidth state is the first bandwidth state and the updated state control quantity meets the preset upgrade condition, the second bandwidth state is determined as the target bandwidth state; when the current bandwidth state is the second bandwidth state, the updated state control quantity meets the preset upgrade condition, and the strong dynamic evidence is established, the third bandwidth state is determined as the target bandwidth state; when the current bandwidth state is the third bandwidth state and the updated state control quantity meets the preset downgrade condition, the second bandwidth state is determined as the target bandwidth state; when the current bandwidth state is the second bandwidth state and the updated state control quantity meets the preset downgrade condition, the first bandwidth state is determined as the target bandwidth state; when the updated state control quantity does not meet the preset upgrade condition and the preset downgrade condition, the current bandwidth state is determined as the target bandwidth state.

[0048] It should be noted that the bandwidth level refers to the state level corresponding to the tracking loop bandwidth combination in the preset bandwidth table. The tracking loop bandwidth combination can include code tracking loop bandwidth, carrier frequency tracking loop bandwidth, and carrier phase tracking loop bandwidth. The first bandwidth state can correspond to a narrower bandwidth combination, the second bandwidth state can correspond to a transitional bandwidth combination, and the third bandwidth state can correspond to a wider bandwidth combination. The preset upgrade condition refers to the combination of conditions used to determine the bandwidth state to switch to a higher bandwidth level, which can include the hold count meeting the decision-making requirement, the dynamic evidence integral reaching the dynamic trigger value, and the upgrade confirmation count reaching the upgrade confirmation value. The preset downgrade condition refers to the combination of conditions used to determine the bandwidth state to switch to a lower bandwidth level, which can include the hold count meeting the decision-making requirement, the stability evidence integral reaching the stability trigger value, and the downgrade confirmation count reaching the downgrade confirmation value.

[0049] Please refer to Figure 3 , Figure 3This diagram illustrates the three-state bandwidth lookup table and step-by-step switching of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine, as provided in the first embodiment of this application. The diagram shows the initial pull, bandwidth lookup table configuration, and step-by-step bandwidth state switching relationship of the GNSS spread spectrum signal tracking loop after acquisition: After acquisition, the initial pull phase begins, using a high-bandwidth configuration during the forced high-bandwidth maintenance period; the frequency-locked loop can activate an independent pull bandwidth of 80 Hz. After pull ends, the bandwidth combination of the delay-locked loop, frequency-locked loop, and phase-locked loop is selected according to the state table. The low bandwidth corresponds to a delay-locked loop of 1.8 Hz, a frequency-locked loop of 6 Hz, and a phase-locked loop of 8 Hz, suitable for steady-state low-noise tracking; the medium bandwidth corresponds to a delay-locked loop of 2.4 Hz, a frequency-locked loop of 20 Hz, and a phase-locked loop of 16 Hz, suitable for transitional and medium-dynamic scenarios; and the high bandwidth corresponds to a delay-locked loop of 3.2 Hz, a frequency-locked loop of 45 Hz, and a phase-locked loop of 28 Hz, suitable for high-dynamic scenarios.

[0050] During the state switching process, the low bandwidth mode enters the medium bandwidth mode when the medium dynamic condition judgment is met, the medium bandwidth mode enters the high bandwidth mode when the high dynamic condition judgment is met, the high bandwidth mode returns to the medium bandwidth mode when the steady-state judgment condition is met, and the medium bandwidth mode returns to the low bandwidth mode when it is continuously stable. After the bandwidth mode decision is completed, the hold count is assigned to the hold duration threshold to suppress frequent bandwidth state switching in a short period of time and prevent the loop filter coefficients from being repeatedly updated.

[0051] Understandably, the hierarchical relationship between the first, second, and third bandwidth states is first determined based on a preset bandwidth table. The bandwidth level corresponding to the second bandwidth state lies between the first and third bandwidth states; therefore, the state machine only allows switching between adjacent bandwidth states—that is, switching between the first and second bandwidth states, and between the second and third bandwidth states—but not directly between the first and third bandwidth states. The specific bandwidth values ​​corresponding to each bandwidth state can be pre-configured based on the GNSS signal system, coherent integration period, receiver loop order, and target dynamic range.

[0052] When the current bandwidth state is the first bandwidth state, the updated state control value is read. If the updated state control value meets the preset upgrade conditions, the second bandwidth state is determined as the target bandwidth state; if the preset upgrade conditions are not met, the first bandwidth state continues to be determined as the target bandwidth state. The upgrade here only enters the second bandwidth state and does not directly enter the third bandwidth state.

[0053] In this example, the third bandwidth state is used for strong dynamic response and is not considered a steady-state tracking state. If only the auxiliary criterion risk increases, but the primary criterion risk does not meet the near-abnormal condition, the system will not enter the third bandwidth state. If the updated state control quantity meets the preset upgrade condition and the strong dynamic evidence is valid, the third bandwidth state is determined as the target bandwidth state. If the updated state control quantity meets the preset downgrade condition, the first bandwidth state is determined as the target bandwidth state. If neither of the two switching conditions is met, the second bandwidth state is determined as the target bandwidth state. Strong dynamic evidence is used to restrict the second bandwidth state from entering the third bandwidth state, preventing entry into the third bandwidth state based solely on general upgrade evidence.

[0054] When the current bandwidth state is the third bandwidth state, the updated state control value is read. If the updated state control value meets the preset downgrading conditions, the second bandwidth state is determined as the target bandwidth state; if the preset downgrading conditions are not met, the third bandwidth state continues to be determined as the target bandwidth state. Here, downgrading first enters the second bandwidth state, and does not directly downgrade to the first bandwidth state.

[0055] Furthermore, when the updated state control quantity does not meet either the preset upgrade condition or the preset downgrade condition, the target bandwidth state remains the current bandwidth state. If a state transition has already occurred, the hold count can be set to a preset hold value. The preset hold value can be determined based on the coherent integration period and the minimum allowable state hold time, for example, by converting it according to "minimum hold time / coherent integration period".

[0056] This example uses a step-by-step switching between a first bandwidth state, a second bandwidth state, and a third bandwidth state to create a transitional state for the change in tracking loop bandwidth. By controlling the switching in different directions through preset upscaling conditions, strong dynamic evidence, and preset downscaling conditions, the direct jump between the first and third bandwidth states is reduced, as are the back-and-forth switching under critical conditions, which can improve the stability of the bandwidth state control of the GNSS spread spectrum signal tracking channel.

[0057] As an example, the step of finding the target bandwidth combination corresponding to the target bandwidth state from the preset bandwidth table and updating the tracking loop filter coefficients and the numerically controlled oscillator control quantity according to the target bandwidth combination includes: finding the target bandwidth combination corresponding to the target bandwidth state from the preset bandwidth table, wherein the target bandwidth combination includes the target code tracking loop bandwidth, the target carrier frequency tracking loop bandwidth, and the target carrier phase tracking loop bandwidth; determining the target filter coefficient combination according to the mapping relationship between the target bandwidth combination and the preset filter coefficients, wherein the target filter coefficient combination includes the code tracking loop target filter coefficients, the carrier frequency tracking loop target filter coefficients, and the carrier phase tracking loop target filter coefficients; updating the tracking loop filter coefficients to the target filter coefficient combination; and filtering the discriminator output of the GNSS spread spectrum signal tracking channel based on the updated tracking loop filter coefficients to obtain the loop control quantity, and updating the numerically controlled oscillator control quantity according to the loop control quantity.

[0058] It should be noted that the target bandwidth combination refers to the code tracking loop bandwidth, carrier frequency tracking loop bandwidth, and carrier phase tracking loop bandwidth corresponding to the target bandwidth state in the preset bandwidth table. The preset filter coefficient mapping relationship refers to the correspondence between the tracking loop bandwidth and the loop filter coefficients; this can be achieved using a lookup table or by using existing bandwidth coefficient conversion formulas in the receiver loop filter design. The target filter coefficient combination refers to the code tracking loop target filter coefficients, carrier frequency tracking loop target filter coefficients, and carrier phase tracking loop target filter coefficients corresponding to the target bandwidth combination. The loop control quantity refers to the code phase correction, carrier frequency correction, or carrier phase correction quantity obtained after the discriminator output has been processed by the loop filter.

[0059] Understandably, once the target bandwidth state is determined, it is used as an index to look up the corresponding record in the preset bandwidth table to obtain the target bandwidth combination. The preset bandwidth table can record the code tracking loop bandwidth, carrier frequency tracking loop bandwidth, and carrier phase tracking loop bandwidth according to the first bandwidth state, the second bandwidth state, and the third bandwidth state, respectively; the unit of each bandwidth can be Hz, and the value can be determined based on the GNSS signal system, coherent integration period, loop order, and target dynamic range.

[0060] After obtaining the target bandwidth combination, the target filter coefficient combination is obtained according to the preset filter coefficient mapping relationship. If the preset filter coefficient mapping relationship uses a lookup table, the target code tracking loop bandwidth, target carrier frequency tracking loop bandwidth, and target carrier phase tracking loop bandwidth are used as indices to read the corresponding filter coefficients respectively; if a formula conversion is used, the corresponding filter coefficients are calculated based on the bandwidth, coherent integration period, and loop order. The preset filter coefficient mapping relationship can be generated during the receiver platform calibration stage or pre-configured according to the loop filter structure.

[0061] Then, the current tracking loop filter coefficients are replaced with the target filter coefficient combination. The code tracking loop uses the code tracking loop target filter coefficients, the carrier frequency tracking loop uses the carrier frequency tracking loop target filter coefficients, and the carrier phase tracking loop uses the carrier phase tracking loop target filter coefficients. If the target bandwidth state is consistent with the current bandwidth state, the current filter coefficients can remain unchanged; if the target bandwidth state changes, the target filter coefficient combination is activated in the current coherent integration cycle or the next coherent integration cycle.

[0062] Based on this, the discriminator output of the GNSS spread spectrum signal tracking channel is input to the updated loop filter to obtain the loop control quantity. The code tracking-related loop control quantity is used to update the code numerically controlled oscillator control quantity, and the carrier frequency or carrier phase-related loop control quantity is used to update the carrier numerically controlled oscillator control quantity, so that the local spreading code and local carrier continue to track the received signal according to the loop parameters corresponding to the target bandwidth state.

[0063] This example converts the target bandwidth state into a target bandwidth combination through a preset bandwidth table, and then converts the target bandwidth combination into a target filter coefficient combination through a preset filter coefficient mapping relationship. This enables the bandwidth state switching to be implemented in the filter coefficient updates of the code tracking loop, carrier frequency tracking loop, and carrier phase tracking loop. At the same time, the numerically controlled oscillator control quantity is generated based on the updated filter coefficients, which enables the GNSS spread spectrum signal tracking channel to continue operating according to the target bandwidth state, improving the connection between bandwidth switching and loop tracking control.

[0064] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to the first embodiment described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 4 , Figure 4 This is a flowchart illustrating the second embodiment of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine according to this application. Step S20 of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine includes steps S21 to S24: Step S21: Extract the current Prompt branch correlation output, carrier phase discriminator output, and frequency discriminator output from the current coherent integration cycle correlation output and discriminator output of the GNSS spread spectrum signal tracking channel, and read the historical tracking quantity to obtain the loop correlation quantity. The historical tracking quantity includes the Prompt branch correlation output of the previous coherent integration cycle, the estimated residual frequency error of the current carrier in the previous coherent integration cycle, and the Prompt amplitude reference value. Step S22: Based on the loop correlation quantities, obtain the loop observations, which include carrier phase error, current carrier residual frequency error estimate, frequency error change, and amplitude attenuation. Step S23: Normalize the loop observations according to the corresponding normalization thresholds to obtain the phase risk quantity, frequency risk quantity, frequency change risk quantity, and amplitude attenuation risk quantity. Step S24: Determine the phase risk quantity and the frequency risk quantity as the primary criterion risk quantities, and determine the frequency change risk quantity and the amplitude attenuation risk quantity as the auxiliary criterion risk quantities to obtain the loop risk quantity.

[0065] It should be noted that the current Prompt branch correlation output refers to the complex correlation value output by the Prompt correlator within the current coherent integration period, which may include in-phase and quadrature components. Historical tracking data refers to the tracking data saved from the previous coherent integration period and used for current period determination. Loop correlation data refers to the intermediate data set obtained by processing the current coherent integration period correlation output, discriminator output, and historical tracking data, used to calculate loop observations. The normalization threshold can be a threshold obtained from the initial statistical calibration window or a threshold pre-calibrated by the GNSS receiver platform; for example, the phase normalization threshold can be determined based on the quantiles and limiting range of the carrier phase error, the frequency normalization threshold can be determined based on the quantiles and limiting range of the current carrier residual frequency error estimate, and the amplitude attenuation normalization threshold can be determined based on the statistical results of the amplitude stability segment of the Prompt branch.

[0066] Understandably, firstly, the current Prompt branch correlation output is read from the current coherent integration cycle correlation output of the GNSS spread spectrum signal tracking channel, and the carrier phase discriminator output and frequency discriminator output are read from the discriminator output; simultaneously, the previous coherent integration cycle Prompt branch correlation output, the previous coherent integration cycle current carrier residual frequency error estimate, and the Prompt amplitude reference value are read from the storage unit, and these data are used as loop correlation quantities. The Prompt amplitude reference value can be the median of the instantaneous branch correlation amplitude within the initial statistical calibration window, or a smoothed updated reference value can be used, for example: in, This indicates the reference value of the Prompt amplitude for the current coherent integration period. This represents the Prompt amplitude reference value of the previous coherent integration cycle. Indicates the current real-time branch correlation amplitude. This indicates the preset smoothing coefficient. It can be set according to the channel amplitude change rate and the requirement to resist instantaneous attenuation, for example, from 0.9 to 0.999.

[0067] When the real-time branch correlation amplitude is lower than the preset amplitude lower limit, the update of the Prompt amplitude reference value can be paused, or the amplitude sample of the current coherent integration cycle can be skipped.

[0068] Loop observations are obtained based on loop correlation quantities. The carrier phase error can be directly obtained from the carrier phase discriminator output, or from the phase discrimination result of the current Prompt branch correlation output; the Prompt branch correlation amplitude can be obtained from the magnitude of the current Prompt branch correlation output. The current carrier residual frequency error estimate can be obtained from the phase difference between the current Prompt branch correlation output and the previous coherent integration period's Prompt branch correlation output, or from the frequency discriminator output. The frequency error change can be obtained from the difference between the current carrier residual frequency error estimate and the previous coherent integration period's current carrier residual frequency error estimate; the amplitude attenuation can be obtained from the decrease ratio of the current Prompt branch correlation amplitude relative to the Prompt amplitude reference value. The carrier phase error, the current carrier residual frequency error estimate, the frequency error change, and the amplitude attenuation are collectively considered as loop observations.

[0069] The phase risk can be obtained by the ratio of the absolute value of the carrier phase error to the phase normalization threshold; the frequency risk can be obtained by the ratio of the absolute value of the estimated carrier residual frequency error in the current coherent integration period to the frequency normalization threshold; the frequency variation risk can be obtained by the ratio of the absolute value of the frequency error variation to the frequency variation normalization threshold; and the amplitude attenuation risk can be obtained by the ratio of the amplitude attenuation to the amplitude attenuation normalization threshold. For example, satisfying: in, Indicates carrier phase error, This represents the estimate of the carrier residual frequency error. This represents the change in frequency error. Indicates the amplitude attenuation. This indicates a preset risk upper limit. This represents the phase normalization threshold. Indicates the frequency normalization threshold. This represents the normalized threshold for frequency variation. This represents the amplitude decay normalization threshold. The threshold can be set according to the state machine criteria, for example, from 1.5 to 3.

[0070] Based on this, phase risk and frequency risk are used as the primary criterion risk quantities, while frequency change risk and amplitude attenuation risk are used as secondary criterion risk quantities, resulting in the loop risk quantity. The primary and secondary criterion risk quantities participate in the subsequent evaluation of upgrade evidence, strong dynamic evidence, and stable evidence, respectively.

[0071] This embodiment uses the correlation output and discriminator output of the current coherent integration cycle, combined with historical tracking data, to form loop observations that reflect carrier phase, carrier frequency, frequency changes, and correlation peak amplitude changes. Loop observations with different dimensions are then converted into risk quantities of the same scale, and the primary criterion risk quantity and auxiliary criterion risk quantity are distinguished. This facilitates the subsequent bandwidth state switching judgment of the hysteresis state machine based on multiple types of internal observation information, improving the GNSS spread spectrum signal tracking channel's ability to distinguish between dynamic changes and stable states.

[0072] As an example, the step of obtaining loop observations based on the loop correlation quantities, wherein the loop observations include carrier phase error, current carrier residual frequency error estimate, frequency error change, and amplitude attenuation, comprises: obtaining carrier phase error and Prompt branch correlation amplitude based on the current Prompt branch correlation output and the carrier phase discriminator output; obtaining current carrier residual frequency error estimate based on the phase difference between the current Prompt branch correlation output and the Prompt branch correlation output of the previous coherent integration cycle, or based on the frequency discriminator output; obtaining frequency error change based on the current carrier residual frequency error estimate and the current carrier residual frequency error estimate of the previous coherent integration cycle; and obtaining amplitude attenuation based on the Prompt branch correlation amplitude and the Prompt amplitude reference value.

[0073] It should be noted that the current Prompt branch correlation output refers to the complex correlation value output by the Prompt correlator within the current coherent integration period, while the Prompt branch correlation output of the previous coherent integration period refers to the complex correlation value of the Prompt correlator stored in the previous coherent integration period. The carrier phase error can be the output of the carrier phase discriminator, or it can be the phase discrimination result obtained from the in-phase and quadrature components of the current Prompt branch correlation output. The current carrier residual frequency error estimate refers to the estimated frequency deviation that still exists after carrier frequency tracking. The Prompt amplitude reference value can be the median of the Prompt branch correlation amplitude within the initial statistical calibration window, or it can be the amplitude reference value obtained through smoothing updates.

[0074] Understandably, firstly, based on the current Prompt branch correlation output and the carrier phase discriminator output, the carrier phase error and the Prompt branch correlation amplitude are obtained. The current Prompt branch correlation output can be denoted as... The relevant amplitude of the Prompt branch can be taken as... The modulus value; the carrier phase error can be directly taken from the output of the carrier phase discriminator, or it can be obtained from... The in-phase and quadrature components are obtained through phase discrimination. If the receiver uses a Costas discriminator or a two-parameter arctangent function atan2 discriminator, the carrier phase error is output according to the principal value range of the corresponding discriminator and is consistent with the direction of loop frequency correction.

[0075] Secondly, the estimated residual frequency error of the current carrier is obtained. If the phase difference method of the instantaneous tributary correlation output is used, it can be obtained based on the current instantaneous tributary correlation output. The output of the instantaneous branch related to the previous coherent integration cycle The phase difference between them yields an estimate of the current carrier residual frequency error, for example: in, This represents the estimate of the current carrier residual frequency error in the current coherent integration period. This represents the conjugate of the correlation output of the Prompt branch in the previous coherent integration cycle, and T represents the coherent integration cycle.

[0076] If the receiver has already output the frequency discriminator result, the frequency discriminator output can also be used as an estimate of the current carrier residual frequency error. The coherent integration period can be determined according to the GNSS signal system and receiver tracking configuration; for example, it can be 1 ms in GPS L1 C / A signals.

[0077] Then, based on the current carrier residual frequency error estimate in the current coherent integration cycle and the current carrier residual frequency error estimate in the previous coherent integration cycle, the frequency error change is obtained. The frequency error change can be taken as the difference between the two estimates, which represents the trend of carrier residual frequency error change between adjacent coherent integration cycles. The current carrier residual frequency error estimate in the previous coherent integration cycle can be written to the cache after the previous tracking update and read in the current coherent integration cycle.

[0078] The amplitude attenuation is obtained based on the relevant amplitude of the Prompt branch and the Prompt amplitude reference value. The amplitude attenuation can be expressed as the percentage decrease in the current relevant amplitude of the Prompt branch relative to the Prompt amplitude reference value, for example: in, Indicates the amplitude attenuation. This indicates the current relative magnitude of the Prompt branch. This represents the Prompt amplitude reference value. The Prompt amplitude reference value can be obtained within the initial stabilization window or updated during tracking according to a preset smoothing coefficient; the preset smoothing coefficient can be set according to the channel amplitude change rate and the requirement for resistance to instantaneous attenuation, for example, a value between 0.9 and 0.999.

[0079] This example uses the current Prompt branch correlation output, carrier phase discriminator output, frequency discriminator output, and historical tracking data to obtain the carrier phase error, the current carrier residual frequency error estimate, the frequency error change, and the amplitude attenuation. This allows the loop observations to simultaneously reflect the carrier phase deviation, carrier frequency deviation, short-time frequency variation, and correlation peak amplitude variation, improving the completeness of the observation information on which subsequent bandwidth status judgments are based.

[0080] As an example, the step of determining upgrade evidence, strong dynamic evidence, and stable evidence based on the primary criterion risk quantity and the auxiliary criterion risk quantity includes: performing a weighted summation of the phase risk quantity, the frequency risk quantity, the frequency change risk quantity, and the amplitude attenuation risk quantity to obtain a comprehensive risk quantity; determining that upgrade evidence is established when at least one of the phase risk quantity and the frequency risk quantity satisfies a preset primary criterion anomaly condition, or when the comprehensive risk quantity satisfies a preset upgrade condition; determining that strong dynamic evidence is established when the primary criterion risk quantity satisfies a preset strong dynamic primary criterion condition, or when the auxiliary criterion risk quantity satisfies a preset strong dynamic auxiliary condition and the primary criterion risk quantity satisfies a preset near-anomaly condition; and determining that stable evidence is established when the primary criterion risk quantity satisfies a preset primary criterion stability condition and the comprehensive risk quantity satisfies a preset stability condition.

[0081] It should be noted that the comprehensive risk quantity refers to the risk assessment quantity synthesized from phase risk quantity, frequency risk quantity, frequency change risk quantity, and amplitude attenuation risk quantity according to preset weights. The preset weights can be set according to the sensitivity of each type of risk quantity to changes in the tracking loop state. Typically, the weights of phase risk quantity and frequency risk quantity are greater than the weights of frequency change risk quantity and amplitude attenuation risk quantity. For example, the preset weights are all non-negative values, and the sum of the weights is 1.

[0082] The preset primary criterion anomaly condition can be that the phase risk quantity or frequency risk quantity reaches the corresponding anomaly threshold; the preset upgrade condition can be that the comprehensive risk quantity reaches the upgrade threshold; the preset strong dynamic primary criterion condition can be that the phase risk quantity or frequency risk quantity reaches the strong dynamic primary criterion threshold; the preset strong dynamic auxiliary condition can be that the frequency change risk quantity or amplitude attenuation risk quantity reaches the strong dynamic auxiliary threshold; the preset near anomaly condition can be that the phase risk quantity or frequency risk quantity reaches the near anomaly threshold; the preset primary criterion stability condition can be that both the phase risk quantity and frequency risk quantity are below the stability threshold; the preset stability condition can be that the comprehensive risk quantity is below the stability risk threshold.

[0083] It is understandable that the phase risk, frequency risk, frequency change risk, and amplitude attenuation risk are first weighted and synthesized to obtain a comprehensive risk quantity, which satisfies the following: in, Indicates the overall risk level. This represents the phase risk quantity. Indicates the frequency risk level. This indicates the risk level of frequency variation. This indicates the magnitude of the risk of attenuation. , , and These represent the corresponding preset weights.

[0084] Preset weights can be set according to the principle of priority of the primary criterion, for example... and Take the larger weight. and The smaller weights are selected; in one embodiment, the four preset weights can be 0.45, 0.35, 0.10 and 0.10 respectively.

[0085] Next, the validity of the upgrade evidence is determined. If at least one of the phase risk quantity and frequency risk quantity reaches the preset primary criterion anomaly threshold, or the combined risk quantity reaches the preset upgrade threshold, the upgrade evidence is deemed valid; if neither condition is met, the upgrade evidence is deemed invalid. The preset primary criterion anomaly threshold can be a value near 1, indicating that the phase risk quantity or frequency risk quantity has reached the corresponding normalization threshold; the preset upgrade threshold can be set according to the upgrade sensitivity allowed by the GNSS receiver, for example, a value between 0.8 and 1.2.

[0086] Determine whether strong dynamic evidence is valid. If the phase risk or frequency risk reaches the preset primary criterion threshold for strong dynamics, then strong dynamic evidence is established. If the frequency change risk or amplitude decay risk reaches the preset auxiliary threshold for strong dynamics, and the phase risk or frequency risk reaches the preset near-abnormal threshold, then strong dynamic evidence is also established. If only the frequency change risk or amplitude decay risk increases, while neither the phase risk nor the frequency risk reaches the near-abnormal threshold, then this situation is not considered strong dynamic evidence. The preset primary criterion threshold for strong dynamics can be greater than the preset anomalous threshold for the primary criterion, the preset near-abnormal threshold can be less than the preset anomalous threshold for the primary criterion, and the preset auxiliary threshold for strong dynamics can be set based on the fluctuation range of the frequency change risk and amplitude decay risk.

[0087] Further determine whether the stability evidence is valid. If both the phase risk and frequency risk are lower than the preset primary criterion stability threshold, and the overall risk is lower than the preset stability risk threshold, then the stability evidence is considered valid; otherwise, the stability evidence is considered invalid. The preset stability risk threshold can be lower than the preset escalation threshold. For example, if the preset escalation threshold is 0.90, the preset stability risk threshold can be around 0.70, thus creating a hysteresis interval between escalation and escalation judgments.

[0088] This example summarizes multiple types of loop risk quantities by integrating risk quantities, and uses phase risk quantity and frequency risk quantity as the main criteria, and frequency change risk quantity and amplitude attenuation risk quantity as auxiliary criteria. This can avoid directly triggering strong dynamic evidence by only a short-term increase in auxiliary risk quantities. At the same time, different threshold conditions are used for upgrade evidence, strong dynamic evidence and stable evidence, forming a basis for hysteresis judgment between upgrade and downgrade, reducing the bandwidth state erroneous switching caused by instantaneous disturbances.

[0089] For example, to help understand the implementation flow of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine obtained by combining the second embodiment with the first embodiment described above, please refer to... Figure 5 , Figure 5 This is a schematic diagram of the bandwidth switching structure of the multi-observation hysteresis state machine provided in the second embodiment of the GNSS tracking loop bandwidth switching method based on the multi-observation hysteresis state machine of this application.

[0090] This figure illustrates the processing relationships in the GNSS spread spectrum signal tracking channel, from initial statistical calibration, acquisition of loop internal observations, construction of risk quantities, hierarchical classification of primary and secondary criteria, to the output bandwidth parameters from the hysteresis state machine lookup table: Initial statistical calibration forms a threshold reference based on the 80th quantile, amplitude limiting, and median or exponential smoothing of the reference amplitude, and provides the threshold reference to the loop internal observations and the calculation of normalized risk quantities; The delay-locked loop, frequency-locked loop, and phase-locked loop in the GNSS spread spectrum signal tracking channel operate continuously under closed-loop control, reading the loop internal observations, where the primary criteria include phase error and frequency error, and the secondary criteria include frequency change and amplitude attenuation; The loop internal observations are normalized to obtain the phase risk quantity, frequency risk quantity, frequency change risk quantity, amplitude attenuation risk quantity, and comprehensive risk quantity.

[0091] Subsequently, a hierarchical judgment is made using primary and secondary criteria. When the primary criterion is abnormal or close to abnormal, the risk level of the secondary criterion is considered to determine the escalation evidence, strong dynamic evidence, and stable evidence. Dynamic and stable evidence are fed into a hysteresis state machine, which determines the state based on the dynamic evidence integral, stable evidence integral, escalation confirmation count, de-escalation confirmation count, and hold count. The state determination result is used to query the bandwidth state table, which includes low, medium, and high escalation levels, and outputs the bandwidth of the delay-locked loop, frequency-locked loop, and phase-locked loop. The updated bandwidth parameters are used to update the loop filter and numerically controlled oscillator, enabling the tracking channel to enter the next coherent integration cycle.

[0092] Please refer to Figure 6 , Figure 6 This is a schematic diagram of the loop observation processing and state control quantity update process provided in the second embodiment of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in this application. The diagram shows the cycle-by-cycle processing flow of the GNSS spread spectrum signal tracking channel after acquisition and fine alignment: First, the tracking loop, bandwidth table, and state machine variables are initialized. High bandwidth is used in the initial traction phase, and the frequency-locked loop traction bandwidth can be set to 80 Hz. Then, calibration samples are collected, including phase, frequency, frequency change, and prompt amplitude. If the calibration window is not completed, the collection continues. If the calibration window is completed, the threshold and reference quantity are calculated based on the 80th quantile, amplitude limiting, and median reference amplitude. After entering normal tracking, the data of the leading branch, instantaneous branch, and lagging branch are read in each coherent integration cycle to obtain the carrier phase error, carrier residual frequency error estimate, frequency error change, and instantaneous branch related amplitude. The above observations are normalized into phase risk quantity, frequency risk quantity, frequency change risk quantity, amplitude attenuation risk quantity, and comprehensive risk quantity.

[0093] The system then uses a tiered approach based on primary and secondary criteria to determine the dynamic and stable evidence integrals, and identifies strong dynamic evidence. Subsequently, it updates the upgrade confirmation count, downgrade confirmation count, and hold count, and verifies the upgrade or downgrade conditions. Upgrade conditions include both the dynamic evidence integral reaching a preset dynamic trigger value and the upgrade confirmation count reaching a preset upgrade confirmation value; switching from the second bandwidth state to the third bandwidth state also requires strong dynamic evidence to be established. Downgrade conditions include both the stable evidence integral reaching a preset stable trigger value and the downgrade confirmation count reaching a preset downgrade confirmation value. After the state decision is completed, the bandwidths of the delay-locked loop, frequency-locked loop, and phase-locked loop are selected by looking up tables, the loop filter and numerically controlled oscillator are updated, and the system enters the next integration cycle.

[0094] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the GNSS tracking loop bandwidth switching method based on multi-observation hysteresis state machine of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0095] This application also provides a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine. Please refer to [link / reference]. Figure 7 The GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine includes: Initialization module 10 is used to initialize state control variables, which include current bandwidth state, evidence integral, acknowledgment count and hold count; The risk acquisition module 20 is used to obtain loop observations based on the relevant outputs and discriminator outputs of the GNSS spread spectrum signal tracking channel, and to normalize the loop observations to obtain the loop risk quantity, which includes the primary criterion risk quantity and the auxiliary criterion risk quantity. The evidence determination module 30 is used to determine upgraded evidence, highly dynamic evidence, and stable evidence based on the risk amount of the primary criterion and the risk amount of the auxiliary criterion. The control update module 40 is used to update the evidence integral, the confirmation count and the hold count based on the upgrade evidence, the strong dynamic evidence and the stable evidence, so as to obtain the updated state control quantity; The state switching module 50 is used to switch between the first bandwidth state, the second bandwidth state and the third bandwidth state step by step according to the updated state control quantity through a hysteresis state machine to obtain the target bandwidth state. The first bandwidth state, the second bandwidth state and the third bandwidth state correspond to different tracking loop bandwidth combinations in a preset bandwidth table. The bandwidth switching module 60 is used to find the target bandwidth combination corresponding to the target bandwidth state from the preset bandwidth table, and update the tracking loop filter coefficients and the numerically controlled oscillator control quantities according to the target bandwidth combination.

[0096] The GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine provided in this application employs the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in the above embodiments. It solves the technical problem of how to adaptively switch the bandwidth states of the code tracking loop, frequency tracking loop, and phase tracking loop based on internal multi-observation measurements during GNSS spread spectrum signal tracking. Compared with the prior art, the beneficial effects of the GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine provided in this application are the same as those of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine provided in the above embodiments. Furthermore, other technical features in the GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0097] This application provides a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine. The GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in the first embodiment described above.

[0098] The following is for reference. Figure 8 This document illustrates a schematic diagram of a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine, suitable for implementing embodiments of this application. The GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine in the embodiments of this application may include a GNSS receiver, a navigation terminal, an in-vehicle navigation device, an embedded navigation processing device, or an electronic device configured with GNSS baseband processing capabilities. Figure 8 The GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0099] like Figure 8As shown, the GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in ROM 1002 (Read Only Memory) or a program loaded from storage device 1003 into RAM 1004 (Random Access Memory). RAM 1004 also stores various programs and data required for the operation of the GNSS tracking loop bandwidth switching device based on the multi-observation hysteresis state machine. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via bus 1005. I / O interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, LCDs (Liquid Crystal Displays), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine to communicate wirelessly or wiredly with other devices to exchange data. Although the figure shows a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine with various systems, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems can be implemented alternatively.

[0100] The GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine provided in this application adopts the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in the above embodiments. It solves the technical problem of how to adaptively switch the bandwidth states of the code tracking loop, frequency tracking loop, and phase tracking loop based on internal multi-observation measurements during GNSS spread spectrum signal tracking. Compared with the prior art, the beneficial effects of the GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine provided in this application are the same as those of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine provided in the above embodiments. Furthermore, other technical features of this GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0101] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, which are used to execute the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine in the above embodiments.

[0102] The computer-readable storage medium provided in this application can be a tangible medium capable of storing computer programs, such as a hard disk, random access memory, read-only memory, flash memory, optical storage device, or magnetic storage device. When the computer program is executed by a processor, it implements the above-described GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine.

[0103] The aforementioned computer-readable storage medium may be included in a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine; or it may exist independently and not be assembled into a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine.

[0104] The aforementioned computer-readable storage medium carries one or more programs that, when executed by a GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine, cause the GNSS tracking loop bandwidth switching device based on the multi-observation hysteresis state machine to: initialize state control quantities, including the current bandwidth state, evidence integral, confirmation count, and hold count; obtain loop observations based on the correlation output and discriminator output of the GNSS spread spectrum signal tracking channel, and normalize the loop observations to obtain loop risk quantities, including a primary criterion risk quantity and an auxiliary criterion risk quantity; and determine an upgrade certificate based on the primary criterion risk quantity and the auxiliary criterion risk quantity. Based on the upgraded evidence, strong dynamic evidence, and stable evidence, the evidence integral, the confirmation count, and the hold count are updated to obtain the updated state control quantity. Based on the updated state control quantity, a hysteresis state machine is used to switch between a first bandwidth state, a second bandwidth state, and a third bandwidth state to obtain a target bandwidth state. The first bandwidth state, the second bandwidth state, and the third bandwidth state correspond to different tracking loop bandwidth combinations in a preset bandwidth table. The target bandwidth combination corresponding to the target bandwidth state is found from the preset bandwidth table, and the tracking loop filter coefficients and the numerically controlled oscillator control quantity are updated according to the target bandwidth combination.

[0105] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including LAN (Local Area Network) or WAN (Wide Area Network)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0106] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0107] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine. This solves the technical problem of how to adaptively switch the bandwidth states of the code tracking loop, frequency tracking loop, and phase tracking loop based on internal multi-observation measurements during GNSS spread spectrum signal tracking. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine provided in the above embodiments, and will not be repeated here.

[0108] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine, characterized in that, The method includes: Initialize state control variables, which include current bandwidth state, evidence integral, confirmation count, and hold count. The evidence integral is a value used to accumulate the persistence of dynamic or stable indicators. The confirmation count is a count value used to confirm that the conditions for upgrading or downgrading are continuously met. The hold count is a count value used to limit the switching of states after the state switch. Based on the correlation output and discriminator output of the GNSS spread spectrum signal tracking channel, loop observations are obtained, and the loop observations are normalized to obtain loop risk quantities. The loop risk quantities include primary criterion risk quantities and secondary criterion risk quantities. The loop risk quantities refer to the values ​​after converting the loop observations to a unified risk scale. The primary criterion risk quantities are used to represent the risks related to carrier phase and carrier frequency, and the secondary criterion risk quantities are used to represent the risks related to frequency changes and correlation amplitude attenuation. The upgrade evidence, strong dynamic evidence, and stable evidence are determined based on the primary criterion risk quantity and the auxiliary criterion risk quantity. The upgrade evidence refers to the judgment result that indicates that the current tracking channel has a need to increase the bandwidth level. The strong dynamic evidence refers to the judgment result that indicates that the current tracking channel has a need to enter the third bandwidth state. The stable evidence refers to the judgment result that indicates that the current tracking channel has the conditions to reduce the bandwidth level. Based on the upgrade evidence, the strong dynamic evidence, and the stability evidence, the evidence integral, the confirmation count, and the hold count are updated to obtain the updated state control quantity. Based on the updated state control quantity, the target bandwidth state is obtained by switching between the first bandwidth state, the second bandwidth state, and the third bandwidth state through a hysteresis state machine. The first bandwidth state, the second bandwidth state, and the third bandwidth state correspond to different tracking loop bandwidth combinations in the preset bandwidth table. The target bandwidth combination corresponding to the target bandwidth state is found in the preset bandwidth table, and the tracking loop filter coefficients and numerically controlled oscillator control quantities are updated according to the target bandwidth combination.

2. The method as described in claim 1, characterized in that, The steps of obtaining loop observations based on the correlation output and discriminator output of the GNSS spread spectrum signal tracking channel, and normalizing the loop observations to obtain the loop risk quantity, wherein the loop risk quantity includes the primary criterion risk quantity and the auxiliary criterion risk quantity, include: From the current coherent integration cycle correlation output and discriminator output of the GNSS spread spectrum signal tracking channel, extract the current Prompt branch correlation output, carrier phase discriminator output and frequency discriminator output, and read the historical tracking quantity to obtain the loop correlation quantity. The historical tracking quantity includes the Prompt branch correlation output of the previous coherent integration cycle, the estimated residual frequency error of the current carrier in the previous coherent integration cycle and the Prompt amplitude reference value. Based on the loop correlation quantities, loop observations are obtained, including carrier phase error, current carrier residual frequency error estimate, frequency error change, and amplitude attenuation. The loop observations are normalized according to the corresponding normalization thresholds to obtain the phase risk quantity, frequency risk quantity, frequency change risk quantity, and amplitude attenuation risk quantity. The phase risk quantity and the frequency risk quantity are determined as the primary criterion risk quantities, and the frequency change risk quantity and the amplitude attenuation risk quantity are determined as the auxiliary criterion risk quantities, thus obtaining the loop risk quantity.

3. The method as described in claim 2, characterized in that, The step of obtaining loop observations based on the loop correlation quantities, wherein the loop observations include carrier phase error, current carrier residual frequency error estimate, frequency error change, and amplitude attenuation, includes: Based on the current Prompt branch correlation output and the carrier phase discriminator output, the carrier phase error and the Prompt branch correlation amplitude are obtained; Based on the phase difference between the current Prompt branch correlation output and the Prompt branch correlation output of the previous coherent integration period, or based on the frequency discriminator output, the current carrier residual frequency error estimate is obtained. The frequency error change is obtained based on the current carrier residual frequency error estimate and the current carrier residual frequency error estimate of the previous coherent integration period. The amplitude attenuation is obtained based on the relevant amplitude of the Prompt branch and the reference value of the Prompt amplitude.

4. The method as described in claim 2, characterized in that, The steps for determining upgrade evidence, strong dynamic evidence, and stable evidence based on the primary criterion risk quantity and the auxiliary criterion risk quantity include: The comprehensive risk quantity is obtained by weighted summation of the phase risk quantity, the frequency risk quantity, the frequency change risk quantity, and the amplitude attenuation risk quantity. When at least one of the phase risk quantity and the frequency risk quantity satisfies the preset main criterion anomaly condition, or when the comprehensive risk quantity satisfies the preset upgrade condition, the upgrade evidence is determined to be valid. When the risk amount of the primary criterion meets the preset strong dynamic primary criterion condition, or when the risk amount of the auxiliary criterion meets the preset strong dynamic auxiliary condition and the risk amount of the primary criterion meets the preset near-abnormal condition, the strong dynamic evidence is determined to be valid. When the risk quantity of the primary criterion meets the preset stability condition of the primary criterion, and the comprehensive risk quantity meets the preset stability condition, the stable evidence is determined to be valid. The overall risk level satisfies: in, Indicates the overall risk level. This represents the phase risk quantity. Indicates the frequency risk level. This indicates the risk level of frequency variation. This indicates the magnitude of the risk of attenuation. , , and These represent the corresponding preset weights.

5. The method as described in claim 1, characterized in that, The step of updating the evidence integral, the confirmation count, and the hold count based on the upgrade evidence, the strong dynamic evidence, and the stability evidence to obtain the updated state control quantity includes: The evidence score is divided into dynamic evidence score and stable evidence score, and the confirmation count is divided into upgrade confirmation count and downgrade confirmation count. The dynamic evidence score is updated based on the upgrade evidence and the strong dynamic evidence. When the strong dynamic evidence is valid, the score is accumulated according to a preset enhancement step size. When the strong dynamic evidence is invalid but the upgrade evidence is valid, the score is accumulated according to a preset dynamic step size. When neither the strong dynamic evidence nor the upgrade evidence is valid, the score is decreased according to a preset dynamic decay step size and non-negative amplitude is applied. The stable evidence integral is updated based on the stable evidence, wherein when the stable evidence is valid, it is accumulated according to a preset stable step size, and when the stable evidence is invalid, it is decreased according to a preset stable decay step size and non-negative amplitude is applied. When the retention count meets the preset decision-making condition, the upshift confirmation count is updated according to the comparison result of the dynamic evidence score and the preset dynamic trigger value, and the downshift confirmation count is updated according to the comparison result of the stable evidence score and the preset stable trigger value. When the hold count does not meet the preset decision-making condition, the hold count is updated according to the preset hold step size to obtain the updated state control quantity.

6. The method as described in claim 1, characterized in that, The bandwidth level corresponding to the second bandwidth state is located between the first bandwidth state and the third bandwidth state; The step of obtaining the target bandwidth state by sequentially switching between the first bandwidth state, the second bandwidth state, and the third bandwidth state using a hysteresis state machine based on the updated state control quantity includes: When the current bandwidth state is the first bandwidth state and the updated state control quantity meets the preset upgrade conditions, the second bandwidth state is determined as the target bandwidth state. When the current bandwidth state is the second bandwidth state, and the updated state control quantity meets the preset upgrade conditions, and the strong dynamic evidence is established, the third bandwidth state is determined as the target bandwidth state. When the current bandwidth state is the third bandwidth state and the updated state control quantity meets the preset downgrade condition, the second bandwidth state is determined as the target bandwidth state. When the current bandwidth state is the second bandwidth state and the updated state control quantity meets the preset downgrading conditions, the first bandwidth state is determined as the target bandwidth state. When the updated state control quantity does not meet the preset upgrade condition and the preset downgrade condition, the current bandwidth state is determined as the target bandwidth state.

7. The method according to any one of claims 1 to 6, characterized in that, The step of finding the target bandwidth combination corresponding to the target bandwidth state from the preset bandwidth table, and updating the tracking loop filter coefficients and the numerically controlled oscillator control quantities according to the target bandwidth combination includes: The target bandwidth combination corresponding to the target bandwidth state is found from the preset bandwidth table. The target bandwidth combination includes the target code tracking loop bandwidth, the target carrier frequency tracking loop bandwidth, and the target carrier phase tracking loop bandwidth. Based on the target bandwidth combination and the preset filter coefficient mapping relationship, the target filter coefficient combination is determined, which includes code tracking loop target filter coefficients, carrier frequency tracking loop target filter coefficients and carrier phase tracking loop target filter coefficients; Update the tracking loop filter coefficients to the target filter coefficient combination; Based on the updated tracking loop filter coefficients, the discriminator output of the GNSS spread spectrum signal tracking channel is filtered to obtain the loop control quantity, and the numerically controlled oscillator control quantity is updated according to the loop control quantity.

8. A GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine, characterized in that, The device employs the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine as described in any one of claims 1 to 7, and the device comprises: An initialization module is used to initialize state control variables, which include current bandwidth state, evidence integral, acknowledgment count, and hold count. The risk acquisition module is used to obtain loop observations based on the relevant outputs and discriminator outputs of the GNSS spread spectrum signal tracking channel, and to normalize the loop observations to obtain the loop risk quantity, which includes the primary criterion risk quantity and the auxiliary criterion risk quantity. The evidence determination module is used to determine upgraded evidence, highly dynamic evidence, and stable evidence based on the risk level of the primary criterion and the risk level of the auxiliary criterion. The control update module is used to update the evidence integral, the confirmation count, and the hold count based on the upgrade evidence, the strong dynamic evidence, and the stable evidence, so as to obtain the updated state control quantity; The state switching module is used to switch between the first bandwidth state, the second bandwidth state and the third bandwidth state step by step according to the updated state control quantity, through a hysteresis state machine to obtain the target bandwidth state. The first bandwidth state, the second bandwidth state and the third bandwidth state correspond to different tracking loop bandwidth combinations in a preset bandwidth table. The bandwidth switching module is used to find the target bandwidth combination corresponding to the target bandwidth state from the preset bandwidth table, and update the tracking loop filter coefficients and the numerically controlled oscillator control quantities according to the target bandwidth combination.

9. A GNSS tracking loop bandwidth switching device based on a multi-observation hysteresis state machine, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine as described in any one of claims 1 to 7.

10. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it implements the steps of the GNSS tracking loop bandwidth switching method based on a multi-observation hysteresis state machine as described in any one of claims 1 to 7.

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