Foundation navigation signal receiver system and method based on time hopping pattern co-processing

Abstract

The invention relates to a ground-based navigation signal receiver system and method based on time-hopping pattern cooperative processing, and the method comprises the steps: a computer control module carries out parameter configuration and initial state setting, so as to provide support for subsequent signal capture and time-hopping pattern matching cooperation; executing signal search and time hopping pattern preliminary matching; after matching succeeds and a unique optimal matching bit is obtained, the receiver is switched into a traction and tracking stage guided by a time hopping pattern from a prior search state; and dynamically adjusting parameters and processing strategies according to a built-in self-adaptive processing mechanism, a time hopping pattern matching state and real-time signal quality. The time hopping pattern matching process is deeply embedded and cooperates with the navigation signal receiving process to construct an integrated processing architecture, so that the problems of processing link splitting and low resource utilization rate in the traditional scheme are effectively solved, the matching result is utilized to intelligently guide subsequent traction and tracking, the overall processing efficiency is greatly improved, and the method is suitable for large-scale popularization and application. And the first positioning time is shortened.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a ground-based navigation signal receiver system and method based on time-hopping pattern cooperative processing. Background Technology

[0002] To overcome the "near-far effect", ground-based navigation systems generally adopt the time hopping / direct sequence code division multiple access (TH / DS-CDMA) signal system. Under this system, each pseudo-satellite transmits signals in a specific time slot according to a known time hopping pattern with random characteristics. The receiving equipment must complete the matching of the time hopping pattern in order to achieve reliable signal acquisition and tracking.

[0003] Existing technologies capture transmission time slots by collecting sub-pattern samples and performing sliding matching with the target pattern; however, such methods are usually treated as independent signal detection post-processing steps, mainly considering false alarm situations, and are insufficient in handling the false alarm problem that inevitably occurs when strong and weak signals coexist, and are not linked with subsequent signal carrier stripping, code tracking and other reception processes.

[0004] A Chinese patent titled "A Baseband Reception System and Method for Ground-Based Navigation Signals" discloses a carrier numerically controlled oscillator, a digital down-converter, a correlator group, a code generator, and a time slot counting module, capable of acquiring and tracking spread spectrum signals. However, this system still follows the reception approach for continuous or fixed-period signals, requiring signal search and confirmation processes to be performed in each time slot, without fully exploring and utilizing the prior knowledge of time-hopping patterns to optimize the reception process. This technical solution is primarily designed for navigation signals with continuous or fixed-period structures, employing a time-slot-by-time search and confirmation process, requiring sequential detection and processing of each time slot during system operation. However, in application scenarios where ground-based navigation information adopts a time-hopping system, the above-mentioned receiving methods do not utilize the prior temporal information contained in the time-hopping pattern, making it difficult to form a collaborative processing mechanism guided by the time-hopping pattern during the acquisition, traction, and tracking stages. When facing engineering scenarios where the duty cycle of the time-hopping signal is low and the effective information appears at discrete and discontinuous times, the baseband receiving process it adopts still has room for further improvement in terms of computational resource utilization efficiency, processing timing optimization, and initial acquisition and confirmation speed.

[0005] Therefore, in practical applications, the two types of schemes mentioned above are usually used sequentially or in parallel. The receiving device needs to first determine the signal transmission time slot through a matching algorithm, and then initialize or guide the receiving channel to perform signal processing in that time slot. This separate architecture results in a lengthy processing link, with a delay between successful matching and stable tracking by the receiving channel, leading to low overall resource utilization efficiency and difficulty in responding quickly in dynamically changing signal environments. When strong signal interference causes false alarms, or when signals from multiple satellites overlap, the coordination of separate processing is insufficient, which can easily lead to erroneous acquisition or tracking loss. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a ground-based navigation signal processing method based on time-hopping pattern cooperative processing, which solves the deficiencies of the prior art.

[0007] The objective of this invention is achieved through the following technical solution: a ground-based navigation signal processing method based on time-hop pattern co-processing, the method comprising:

[0008] Initialization steps: The computer control module configures parameters and sets the initial state to provide support for subsequent signal acquisition and time-hopping pattern matching;

[0009] Collaborative capture and matching steps: Perform signal search and preliminary time-hopping pattern matching;

[0010] Match-guided traction and tracking steps: After a successful match and obtaining a unique best match bit, the receiver transitions from the prior search state to the traction and tracking phase guided by the time-hopping pattern.

[0011] Adaptive processing mechanism steps: Based on the built-in adaptive processing mechanism, parameters and processing strategies are dynamically adjusted according to the time-hopping pattern matching status and real-time signal quality.

[0012] The initialization steps specifically include the following:

[0013] The calculation and control module reads the time hop pattern information of the target pseudo-satellite to be captured from the non-volatile memory and loads it into the time hop pattern storage module. The time hop pattern uses an array of length L. This indicates that each element Represents the first in the pseudo-satellite launch sequence In a frame, the time slot number corresponding to the signal transmission window;

[0014] Write the initial carrier frequency control word to the carrier numerically controlled oscillator Write the initial code rate control word to the code numerically controlled oscillator and set its code phase jump range to [-1.5, +1.5] chips with a resolution of 0.5 chips;

[0015] The delay interval of the three local pseudocodes in the correlator group (early, instantaneous, and late) is initially set to 0.5 chips. The time slot calculation and terminal acquisition module is initialized to time slot mode, so that it performs continuous time slot counting based on the code period overflow signal and generates an interrupt request at the end of each time slot.

[0016] Set the threshold for successful time-skip pattern matching. Signal acquisition and detection threshold and signal tracking loss threshold .

[0017] The collaborative capture and matching steps specifically include the following:

[0018] The time slot calculation and interrupt request module operates in time slot mode, and its internal modules... The counter continuously counts each time slot based on the code period overflow signal output by the code generator, and the count value is... ,mold The counter counts the frames, and the count value is... The two combined constitute a complete continuous time slot count value. The time slot calculation and interrupt request module sends an interrupt request to the calculation control module at the end of each time slot;

[0019] The computational control module responds to each time slot interrupt by reading the early, immediate, and late I / Q integral values ​​output by the correlator group. , , And calculate the signal energy value of the instantaneous branch. ;

[0020] The calculation control module will With capture threshold In comparison, if If a signal is detected in the current time slot, the current time slot count value will be entered. As a valid element, it is fed into the sub-pattern sample buffer of the time-jump pattern matching module to form a continuously updated sub-pattern array. ,in ,like If the signal is not detected, it will be recorded as a time slot with no signal for subsequent timeout determination.

[0021] When the number of valid elements in the subpattern buffer reaches the preset initial matching length At that time, the jump pattern matching module starts the matching algorithm;

[0022] Calculate the normalized skip time slot distance of each element in the sub-pattern relative to the reference time slot to form a skip distance array. ;

[0023] The matching engine uses jump distance arrays As a probe, in the pre-stored target jump pattern array Perform sliding matching on top, for Each candidate start time slot The algorithm checks whether it can Find a set with The time slot corresponding to the zero-distance element in the Sino-African relationship, that is, for each Check if it exists Make mod Established, statistics meet the conditions Number as a matching degree ;

[0024] Each candidate start time slot Calculated matching degree With preset threshold In comparison, if Then the Mark it as a candidate qualified match. After traversing all L candidate start time slots, output the matching status based on the number of candidate qualified matches, and also output the best matching position.

[0025] The step of outputting the matching status based on the number of qualified candidate matches includes:

[0026] When there is only one qualified candidate match, the status is "match successful"; when there is no qualified candidate match, the status is "match failed"; when there are multiple qualified candidate matches, the status is "multiple candidate match". During this process, the calculation control module performs adaptive control based on the intermediate results of the time-jumping pattern matching module and the signal detection results.

[0027] The adaptive control module, based on the intermediate results of the time-hopping pattern matching module and the signal detection results, includes: during the search process, if no signal is detected in multiple consecutive time slots, and the waiting time slot number is... Exceeding the maximum possible interval calculated from the jump time pattern If the signal is not received, it is determined to be a timeout, and the control code digital oscillator will perform a code phase jump to quickly leave the current code phase where there is no signal.

[0028] The matching-guided traction and tracking steps specifically include the following:

[0029] The calculation control module sends a control command to the time slot counting and interrupt request module, switching it from time slot mode to frame mode. In frame mode, the time slot counting module counts consecutive time slots. It is compared in real time with the predicted transmission time slot sequence read from the time hop pattern storage module, only when An interrupt request is generated when the predicted launch time slot matches. The calculation and control module calculates the sub-pattern reference time slot based on the optimal matching position. Absolute superframe slot position in the target time-jump pattern And write the corresponding count correction value to the time slot counting module to align the time slot counter with the superframe timing of the pseudo-satellite transmitter, thereby establishing a time reference synchronized with the transmitter inside the receiver;

[0030] The calculation and control module uses the prior information obtained from the successful matching to preset the initial phase of the carrier numerically controlled oscillator and the code numerically controlled oscillator. Based on the optimal matching position and signal structure parameters, it calculates the approximate values ​​of the carrier phase and code phase at the current receiving time and writes them into the corresponding oscillators as initial values. This transforms the pulling process from blind pulling to initial pulling with prior information. After entering the pulling and tracking stage, the correlator group and control module are only activated within the transmission time slot window predicted by the time hopping pattern. Combined with the frequency-locked loop, phase-locked loop and delay-locked loop, the carrier frequency, carrier phase and code phase are tracked.

[0031] The adaptive processing mechanism specifically includes the following steps:

[0032] Handling strategy after matching failure: The calculation control module controls the code numerical control oscillator to perform large-step code phase jumps to quickly escape the current invalid search interval. The jump amount Δτ is determined according to the preset strategy.

[0033] Multi-candidate matching processing strategy: When the time-jump pattern matching module outputs the multi-candidate matching status, it indicates the length of the current sub-pattern sample. Insufficient to provide a unique starting point for matching the target pattern, the sub-pattern sample is expanded, and the control module instructs the time-slot pattern matching module to continue acquiring new time-slot samples, and the sub-pattern length is calculated. Extended to ;

[0034] Adaptive parameter adjustment based on signal quality: Continuously monitor the signal energy value of the instantaneous tributary. And the error estimate of the tracking loop, and dynamically adjust the processing parameters accordingly. In the signal search and confirmation stage, if a strong signal is continuously detected in the predicted time slot... Below the capture threshold However, above the noise floor, the computational control module increases the coherent integration time of the correlator array to improve the processing gain.

[0035] A ground-based navigation signal receiver system based on time-hopping pattern cooperative processing, the system comprising a time-hopping pattern matching module, a time slot counting and interrupt request module, a calculation control module, a correlator group, a code generator, a carrier numerically controlled oscillator, a code numerically controlled oscillator, and a digital downconverter;

[0036] The time-hopping pattern matching module is configured to provide control priors to the receiver front-end processing flow and output matching results for constraining time slot calculation, mid-terminal triggering timing, and traction and tracking processes.

[0037] The time slot counting and interrupt request module is configured to generate the system's time base and control the timing of interrupt requests.

[0038] The computational control module is configured to initialize all configurable parameters of the system via a configuration register interface, including the frequency control word of the carrier NCO. The rate control word of the NCO code, the delay interval d of the correlator, and the matching threshold. and capture threshold It is also responsible for responding to interrupt requests from the slot counting and interrupt request module.

[0039] The correlator group and digital downconverter are configured to perform despreading and coherent integration of the signal.

[0040] The carrier numerically controlled oscillator and the code numerically controlled oscillator are configured to generate local copy signals.

[0041] The time-jump pattern matching module includes a sub-pattern sample buffer, a reference time slot selection unit, a jump distance calculation unit, a sliding matching engine, and a decision and status output unit;

[0042] The sub-pattern sample buffer is used to cache the time slot numbers of continuously detected signals in chronological order. and its corresponding signal energy value , form and maintain a length of sub-pattern array ;

[0043] The reference time slot terminal unit reads the energy value recorded in each time slot of the sub-pattern sample buffer, and selects the time slot number corresponding to the maximum energy value as the reference time slot through a comparator circuit. ;

[0044] The jump distance calculation unit calculates the jump distance of each element in the sub-pattern. Relative to reference time slot Normalized jump distance , forming a jump distance array ;

[0045] The sliding matching engine consists of multiple parallel comparators and accumulators, used to process the jump distance array. With the target pattern array pre-read from the time-skip pattern memory Perform sliding matching for each candidate start time slot in the target pattern. Engine check Each non-zero distance Does a corresponding time slot exist in the target pattern? , making the relationship mod Established, for each Those that meet the above conditions The number of matches is accumulated to determine the matching degree. ,in, This represents the total number of time slots in the superframe.

[0046] The decision and status output unit: sets the matching degree of each candidate position. With preset threshold The system compares the results, counts the number of qualified matches, and outputs the final matching status flag and the best matching position.

[0047] The time slot counting and interrupt request module includes a module Counter, Modulus Counter, time-skipping pattern memory, comparator, and mode selector;

[0048] The module Counter: Using the code period overflow signal code_ov output by the code generator as the clock input, it counts the intra-frame time slots and outputs a count value n. Its overflow signal drives the module. counter;

[0049] The module Counter: Counts frames and outputs a count value m. The count value m and the count value n together constitute the complete continuous time slot calculation value. ;

[0050] The time-hopping pattern memory stores the time-hopping pattern of the target pseudo-satellite, with a depth of [insert depth here]. The memory cell corresponding to address m stores the transmission slot number of this frame. ;

[0051] The comparator: In frame mode, it calculates the intra-frame slot count value. Read from pattern memory The comparison is performed, and if they are equal, an interrupt request signal is generated.

[0052] The mode selector selects the interrupt source according to the configuration of the computing control module; in time slot mode, it directly uses the code_ov signal as the interrupt request, and in frame mode, it selects the output of the comparator as the interrupt request.

[0053] This invention has the following advantages: A ground-based navigation signal processing method based on time-hopping pattern co-processing constructs an integrated processing architecture by deeply embedding the time-hopping pattern matching process into the navigation signal receiving process, thereby effectively solving the problems of fragmented processing links and low resource utilization in traditional solutions; pattern matching is performed synchronously during the signal acquisition stage, and the matching results are used to intelligently guide subsequent traction and tracking, which greatly improves the overall processing efficiency and shortens the initial positioning time; at the same time, the sharing of hardware resources and dynamic power consumption management optimize the system power consumption, while the adaptive mechanism based on parameter presetting and real-time feedback of matching prior information significantly enhances the robustness and tracking accuracy of the system in complex signal environments; in addition, the modular design also provides flexibility for adapting to different signal systems and multi-channel expansion. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0055] Figure 2 This is a schematic diagram of the time-skip matching module. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is not intended to limit the scope of protection of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The present invention will be further described below with reference to the accompanying drawings.

[0057] like Figure 1One embodiment of this invention relates to a ground-based navigation signal receiver system based on time-hopping pattern cooperative processing. This system can be implemented using a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or a system-on-a-chip (SoC) containing a digital signal processor (DSP). Its hardware components mainly include core modules such as a time-hopping pattern matching module, a time slot counting and interrupt request module, a computational control module, a correlator group, a code generator, a carrier numerically controlled oscillator, and a digital downconverter. These modules are interconnected via a high-speed on-chip bus (such as an AXI bus) or shared memory, and work collaboratively under the unified scheduling of the computational control module to jointly complete the entire process from signal downconversion, despreading, time-hopping pattern matching to signal tracking.

[0058] like Figure 2 As shown, the time-hopping pattern matching module is implemented by dedicated logic circuits to execute the time-hopping pattern four-matching algorithm in real time. This module internally includes a sub-pattern sample buffer, a reference time slot selection unit, a hop distance calculation unit, a sliding four-matching engine, and a decision and status output unit. The time-hopping pattern matching module is configured to provide control priors to the receiver front-end processing flow, and its output matching results are used to constrain time slot counting, interrupt triggering timing, and subsequent traction and tracking processes.

[0059] Furthermore, the subpattern sample buffer is a depth of A first-in, first-out (FIFO) memory is used to buffer the time slot numbers of consecutively detected signals in chronological order. and its corresponding signal energy value , form and maintain a length of sub-pattern array .

[0060] The reference time slot selection unit reads the energy value recorded in each time slot of the sub-pattern sample buffer, and selects the time slot number corresponding to the maximum energy value as the reference time slot through the comparator circuit. ,Right now The jump distance calculation unit then calculates the jump distance for each element in the sub-pattern. Relative to reference time slot Normalized jump distance , forming a jump distance array The specific calculation is achieved through a subtractor, an adder, and a modular arithmetic circuit. The calculation formula is as follows:

[0061] ,

[0062] in, It is a value greater than 1 chosen for ease of modular arithmetic. Integers.

[0063] The sliding matching engine is the core processing unit of this module, consisting of multiple parallel comparators and accumulators that operate in a pipelined manner. It uses the jump distance array... With the target pattern array pre-read from the time-skip pattern memory Perform sliding matching. For each candidate start slot in the target pattern... Engine check Each non-zero distance Does a corresponding time slot exist in the target pattern? , making the relationship mod Established, among which This represents the total number of time slots in the superframe. For each... Those that meet the above conditions The number of matches is accumulated to determine the matching degree. .

[0064] The decision and status output unit will determine the matching degree of each candidate position. With preset threshold The system compares the results, counts the number of qualified matches, and outputs the final matching status flag and the best matching position (Best_Match_Index). The entire matching engine is designed to evaluate all L candidate positions within one or more time slots to meet real-time requirements.

[0065] The time slot counting and interrupt request module is responsible for generating the system's time base and controlling the timing of interrupt requests. Its internal structure includes modules... Counter, Modulus Counter, time-skipping pattern memory, comparator, and mode selector. The counter uses the code period overflow signal code_ov output by the code generator as its clock input to count intra-frame time slots and outputs a count value n. Its overflow signal drives the module Counter. Modulus The counter counts the frames and outputs the count value m. Together, they constitute a complete continuous time slot count value. The time-hop pattern memory (such as a two-port RAM) stores the time-hop pattern of the target pseudosatellite, with a depth of [missing information]. The memory cell corresponding to address m stores the transmission slot number of this frame. In frame mode, the comparator calculates the slot count value within the current frame. Read from pattern memory The comparison is performed, and if they are equal, an interrupt request signal is generated. The mode selector then selects the interrupt source according to the configuration of the computing control module: in time slot mode, the code_ov signal is directly used as the interrupt request; in frame mode, the output of the comparator is selected as the interrupt request.

[0066] The computational control module (CCD) is the control center of the system and can be implemented by an embedded microprocessor, a DSP core, or a custom hardware state machine. It initializes all configurable parameters of the system through a configuration register interface, including the frequency control word of the carrier NCO. The rate control word of the NCO code, the delay interval d of the correlator, and the matching threshold. Capture threshold This module contains the main control program or state machine, responsible for responding to interrupt requests from the time slot counting and interrupt request module. In each interrupt service routine, it reads the I / Q integral value output by the correlator group and calculates the signal energy. It reads the status flags output by the time-hopping pattern matching module. Based on this information, it executes the state transition logic for signal acquisition, confirmation, traction, and tracking, and implements the adaptive processing strategy described in section 4. During the signal tracking phase, it uses the following formula to estimate, in real time, the carrier phase error, etc. Code phase error :

[0067] ,

[0068] Then, the control words of the carrier NCO and code NCO are updated according to the loop filtering algorithm to achieve closed-loop tracking. At the same time, it is also responsible for writing the time slot count correction value to the time slot counting and interrupt request module after a successful match, and controlling its working mode switching.

[0069] The correlator group performs despreading and coherent integration of the signal. A digital downconverter typically consists of a multiplier and a low-pass filter, which converts the intermediate frequency sampling signal from the analog-to-digital converter (ADC) into a quadrature local carrier generated by the carrier NCO. and Frequency mixing yields baseband I and Q signals. Driven by the code clock output from the code NCO, the code generator produces a local pseudo-code sequence and generates early, immediate, and late pseudo-codes via a programmable delay line. Delay interval It can be configured by the computational control module. The correlator group contains three identical correlation channels, each consisting of a multiplier and an accumulator. These channels multiply the I and Q baseband signals with the three pseudocode signals respectively, and the results are processed within one time slot period (one pseudocode period). Accumulate within the range and output six integral values. The energy calculation unit consists of a squarer and an adder, performing real-time calculations. .

[0070] The carrier digitally controlled oscillator (NCO) and code digitally controlled oscillator are crucial for generating the local copy signal. The carrier NCO typically consists of a phase accumulator and a sine / cosine lookup table (LUT), whose output frequency... Frequency control word Decide: ,in For the system clock, This is the accumulator bit width. The code NCO structure is similar, generating the code clock that drives the code generator. Its code rate can be adjusted via a control word, and it supports phase-jumping functionality based on instructions from the computation control module to achieve fast search during acquisition.

[0071] Through the above modular hardware design, this invention deeply embeds the time-hopping pattern matching function into the front-end signal processing link of the traditional navigation receiver in the form of dedicated hardware, realizing hardware-level collaboration and pipelined operation of the matching process and the acquisition and tracking process, thereby significantly improving the overall processing efficiency and real-time performance of the system while ensuring high processing accuracy.

[0072] Another embodiment of the present invention provides a ground-based navigation signal processing method based on time-hopping pattern cooperative processing, which specifically includes the following:

[0073] S1. System Initialization: After the system is powered on, the computing control module is responsible for executing the initialization process, laying the foundation for subsequent signal acquisition and time-hopping pattern matching. This process mainly completes the parameter configuration and initial state setting of the hardware modules.

[0074] The calculation and control module reads the time hop pattern information of the target pseudo-satellite to be acquired from the non-volatile memory and loads it into the time hop pattern storage module. This time hop pattern information is used not only for subsequent matching decisions but also as a control prior for the receiver front-end processing, providing a unified timing constraint basis for time slot counting mode switching, interrupt triggering conditions, and traction initialization. This time hop pattern uses a length of... array This indicates that each element Represents the first in the pseudo-satellite launch sequence In a frame, the time slot number corresponding to the signal transmission window (The total number of time slots divided in each frame). To accelerate subsequent matching operations, the system can pre-calculate and store their "consecutive time slot numbers". This number is within a superframe period. The only one inside.

[0075] Configure carrier and code generation parameters: Write the initial carrier frequency control word to the carrier numerically controlled oscillator. Its output frequency ,in For system clock frequency, The accumulator word length is specified. An initial code rate control word is written to the code numerically controlled oscillator, and its code phase jump range is set to [-1.5, +1.5] chips with a resolution of 0.5 chips.

[0076] Configure the correlator and time slot module: Initially set the delay interval of the early, immediate, and late local pseudocodes in the correlator group to 0.5 chips. Initialize the time slot counting and interrupt request module to time slot mode, enabling it to perform continuous time slot counting based on the code period overflow signal, with the counting range covering the total number of time slots. And generate an interrupt request at the end of each time slot.

[0077] Set the algorithm decision threshold: Based on system performance requirements, set a threshold value for successful time-skip pattern matching. (For example (for sub-pattern sample length), signal acquisition and detection threshold and signal tracking loss threshold After completing the above configuration, the system enters a ready state and begins the collaborative capture and matching process.

[0078] S2, Cooperative Acquisition and Matching Phase: In this phase, the system performs signal search and preliminary time-hopping pattern matching in parallel. The specific process is as follows:

[0079] S201. After system startup, the time slot counting and interrupt request module operates in time slot mode, and its internal module... The counter continuously counts each time slot based on the code period overflow signal output by the code generator, and the count value is... ,mold The counter counts the frames, and the count value is... The two combined constitute a complete continuous time slot count value. This module sends an interrupt request to the computing control module at the end of each time slot.

[0080] S202. The calculation control module responds to each time slot interrupt and reads the early, immediate, and late I / Q integral values ​​output by the correlator group. , , And calculate the signal energy value of the instantaneous branch. .

[0081] S203, Signal detection and sub-pattern acquisition are performed simultaneously: The calculation and control module will... With capture threshold Comparison. If Then it is determined that a signal exists in the current time slot, and the current time slot count value is set. As a valid element, it is fed into the sub-pattern sample buffer (a buffer with a depth of) of the time-jump pattern matching module. In a FIFO (FIFO), a continuously updated array of subpatterns is formed. ,in .like If the signal is not received, it will be recorded as a time slot without signal and used for subsequent timeout determination.

[0082] S204. When the number of valid elements in the subpattern buffer reaches the preset initial matching length. At that time, the time-skip pattern matching module starts the matching algorithm. The algorithm first starts from... Selecting a reference time slot: Reading the signal energy value corresponding to each time slot element. (This value is related to step 3) (Associated storage), select the time slot with the highest energy value as the reference time slot. .

[0083] S205. Calculate the normalized jump time slot distance of each element in the sub-pattern relative to the reference time slot, forming a jump distance array. , in mod , is a value chosen for ease of modular arithmetic, greater than An integer. This operation converts the absolute time slot relationship of the subpatterns into a relative distance relationship.

[0084] S206, Sliding Matching and Decision: The matching engine uses a jump distance array As a "probe", it is used in a pre-stored array of target jump patterns. Perform sliding matching on top. For Each candidate start time slot The algorithm checks whether it can Find a set with The time slot corresponding to the zero-distance element in the Sino-African relationship, that is, for each Check if it exists Make mod Established ( (Total number of superframe slots). Statistical analysis of those meeting the conditions. Number as a matching degree .

[0085] S207, Set each candidate start time slot Calculated matching degree With preset threshold Comparison. If Then the Mark it as a candidate qualified match. Iterate through all... After selecting candidate starting time slots, the matching status is output based on the number of qualified matches: "Match Successful" if there is only one qualified match; "Match Failed" if there are no qualified matches; and "Multiple Candidate Matches" if there are multiple qualified matches. The optimal matching position is also output. During this process, the calculation and control module performs adaptive control based on the intermediate results from the time-skip pattern matching module and the signal detection results. For example, during the search process, if no signal is detected in multiple consecutive time slots (i.e., sub-pattern acquisition stagnates), and the waiting time slots are... Exceeding the maximum possible interval calculated from the jump time pattern If the signal is detected too late, it is considered a timeout, and the digitally controlled oscillator (DCO) is activated to perform a code phase jump (e.g., a jump of 1.5 chips) to quickly move away from the current code phase where there is no signal. This linkage between signal detection and matching processes constitutes the core of collaborative acquisition.

[0086] S3. Match-guided traction and tracking: Unlike the comparison file's processing flow that uses a blind traction method to gradually approach the synchronization state after successful acquisition, in this invention, when the time-hopping pattern matching module outputs "match successful" and provides a unique Best_Match_Index, the receiver transitions from a no-priority search state to a time-hopping pattern-guided traction and tracking stage. The system's operating mode and processing strategy change accordingly. The specific implementation of this stage is as follows:

[0087] First, the control module sends a control command to the slot counting and interrupt request module, switching it from slot mode to frame mode. In frame mode, the slot counting and interrupt request module calculates based on the continuous slot count value. It is compared in real time with the predicted transmission time slot sequence read from the time hop pattern storage module, only when An interrupt request is generated when the predicted transmission time slot matches, thus avoiding redundant processing of time slots without a signal and significantly reducing system computational load and power consumption. The calculation control module calculates the sub-pattern reference time slot based on Best_Match_Index. Absolute superframe slot position in the target time-jump pattern It writes the corresponding count correction value to the slot counting and interrupt request module to align the slot counter with the superframe timing of the pseudo-satellite transmitter, thereby establishing a time reference synchronized with the transmitter inside the receiver.

[0088] Based on this, the calculation and control module uses the prior time information obtained from successful matching to preset the initial phase of the carrier numerically controlled oscillator and the code numerically controlled oscillator. According to the Best_Match_Index and signal structure parameters, it calculates the approximate values ​​of the carrier phase and code phase at the current receiving time and writes them as initial values ​​into the corresponding oscillators, transforming the pulling process from blind pulling to prior-based initialization pulling, thus significantly shortening the pulling convergence time. After entering the pulling and tracking phase, the correlator group and control module are only activated within the transmission time slot window predicted by the time hop pattern. Combined with the frequency-locked loop, phase-locked loop, and delay-locked loop, it performs fine tracking of the carrier frequency, carrier phase, and code phase. Since the processing time is highly consistent with the actual arrival time of the signal, and the local copy is close to synchronization, the stability and accuracy of the tracking loop are improved. Because the navigation message and the superframe structure of the time hop pattern have a fixed timing relationship, after completing time hop matching and time slot count correction, the receiver can directly obtain the superframe boundary information. The calculation and control module quickly determines the data bit edges and the start position of the message frame, realizing rapid bit synchronization and frame synchronization, accelerating the navigation message decoding process, and shortening the initial positioning time.

[0089] S4. Adaptive Processing Mechanism: The system has a built-in adaptive processing mechanism that dynamically adjusts system parameters and processing strategies based on the time-hopping pattern matching status and real-time signal quality to handle complex situations such as matching failures, ambiguity, or changes in channel conditions. The specific process is as follows:

[0090] S401. Handling strategy after matching failure: Adjust and jump the code phase search step size. The calculation control module controls the code numerically controlled oscillator to perform a code phase jump with a relatively large step size to quickly escape the current invalid search interval. Here, a relatively large step size refers to a jump amount greater than the chip interval of the regular code phase search step size, preferably not less than one chip. The jump amount Δτ is determined according to a preset strategy, such as: .in, This is the current code phase search increment record; the jump direction is intended to advance the search forward. Meanwhile, Updated to + Simultaneously, the sub-pattern samples are updated, and the time-skip pattern matching module clears or partially updates its sub-pattern sample buffer (FIFO). Specifically, the oldest time slot element is deleted. And wait to acquire new time slot elements. Reference time slot Reselect the signal energy in the current buffer. The largest time slot is used to eliminate erroneous reference points that may be caused by false alarm signals.

[0091] S402. Multi-candidate matching processing strategy: When the time-jump pattern matching module outputs the "multi-candidate matching" status, it indicates the length of the current sub-pattern sample. Insufficient to provide a unique starting point for matching the target pattern. Expanding the sub-pattern sample, the control module instructs the time-slot pattern matching module to continue acquiring new time-slot samples, increasing the sub-pattern length. Extended to New subpattern array ( This includes more information on temporal relationships. Matching threshold. Can be followed Synchronous fine-tuning (e.g., maintaining) = This improves the discriminative power of the decision. By increasing the amount of observation data, the system can eliminate ambiguity among multiple candidate positions and converge to a unique match.

[0092] S403, Adaptive parameter adjustment based on signal quality: The system continuously monitors the signal energy value of the instantaneous branch. And the error estimates of the tracking loop (such as carrier phase error) Code phase error ), and dynamically adjust the processing parameters accordingly. During the signal search and confirmation phase, if a strong signal is continuously detected in the predicted time slot... Below the capture threshold However, above the noise floor, the computational control module can moderately increase the coherent integration time of the correlator array (doubling it in time slots) to improve processing gain. New integral value. , The calculation formula is:

[0093] ,

[0094] in, This is the adjusted number of integration time slots.

[0095] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and improvements, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A ground-based navigation signal processing method based on time-hopping pattern cooperative processing, characterized in that: The method includes: Initialization steps: The computer control module configures parameters and sets the initial state to provide support for subsequent signal acquisition and time-hopping pattern matching; Collaborative capture and matching steps: Perform signal search and preliminary time-hopping pattern matching; Match-guided traction and tracking steps: After a successful match and obtaining a unique best match bit, the receiver transitions from the prior search state to the traction and tracking phase guided by the time-hopping pattern. Adaptive processing mechanism steps: Based on the built-in adaptive processing mechanism, parameters and processing strategies are dynamically adjusted according to the time-hopping pattern matching status and real-time signal quality.

2. The ground-based navigation signal processing method based on time-hopping pattern cooperative processing according to claim 1, characterized in that: The initialization steps specifically include the following: The calculation and control module reads the time hop pattern information of the target pseudo-satellite to be captured from the non-volatile memory and loads it into the time hop pattern storage module. The time hop pattern uses an array of length L. This indicates that each element Represents the first in the pseudo-satellite launch sequence In a frame, the time slot number corresponding to the signal transmission window; Write the initial carrier frequency control word to the carrier numerically controlled oscillator Write the initial code rate control word to the code numerically controlled oscillator and set its code phase jump range to [-1.5, +1.5] chips with a resolution of 0.5 chips; The delay interval of the three local pseudocodes in the correlator group (early, instantaneous, and late) is initially set to 0.5 chips. The time slot calculation and terminal acquisition module is initialized to time slot mode, so that it performs continuous time slot counting based on the code period overflow signal and generates an interrupt request at the end of each time slot. Set the threshold for successful time-skip pattern matching. Signal acquisition and detection threshold and signal tracking loss threshold .

3. The ground-based navigation signal processing method based on time-hopping pattern cooperative processing according to claim 1, characterized in that: The collaborative capture and matching steps specifically include the following: The time slot calculation and interrupt request module operates in time slot mode, and its internal modules... The counter continuously counts each time slot based on the code period overflow signal output by the code generator, and the count value is... ,mold The counter counts the frames, and the count value is... The two combined constitute a complete continuous time slot count value. The time slot calculation and interrupt request module sends an interrupt request to the calculation control module at the end of each time slot; The computational control module responds to each time slot interrupt by reading the early, immediate, and late I / Q integral values ​​output by the correlator group. , , And calculate the signal energy value of the instantaneous branch. ; The calculation control module will With capture threshold In comparison, if If a signal is detected in the current time slot, the current time slot count value will be entered. As a valid element, it is fed into the sub-pattern sample buffer of the time-jump pattern matching module to form a continuously updated sub-pattern array. ,in ,like If the signal is not detected, it will be recorded as a time slot with no signal for subsequent timeout determination. When the number of valid elements in the subpattern buffer reaches the preset initial matching length At that time, the jump pattern matching module starts the matching algorithm; Calculate the normalized jump time slot distance of each element in the subpattern relative to the reference time slot to form a jump distance array. ; The matching engine uses jump distance arrays As a probe, in the pre-stored target jump pattern array Perform sliding matching on top, for Each candidate start time slot The algorithm checks whether it can Find a set with The time slot corresponding to the zero-distance element in the non-central region, that is, for each Check if it exists Make mod Established, statistics meet the conditions Number as a matching degree ; Each candidate start time slot Calculated matching degree With preset threshold In comparison, if Then the Mark it as a candidate qualified match. After traversing all L candidate start time slots, output the matching status based on the number of candidate qualified matches, and also output the best matching position.

4. The ground-based navigation signal processing method based on time-hopping pattern cooperative processing according to claim 3, characterized in that: The step of outputting the matching status based on the number of qualified candidate matches includes: When there is only one qualified candidate match, the status is "match successful"; when there is no qualified candidate match, the status is "match failed"; when there are multiple qualified candidate matches, the status is "multiple candidate match". During this process, the calculation control module performs adaptive control based on the intermediate results of the time-jumping pattern matching module and the signal detection results.

5. The ground-based navigation signal processing method based on time-hopping pattern cooperative processing according to claim 4, characterized in that: The adaptive control module, based on the intermediate results of the time-hopping pattern matching module and the signal detection results, includes: during the search process, if no signal is detected in multiple consecutive time slots, and the waiting time slot number is... Exceeding the maximum possible interval calculated from the jump time pattern If the signal is not received, it is determined to be a timeout, and the control code digital oscillator will perform a code phase jump to quickly leave the current code phase without signal.

6. The ground-based navigation signal processing method based on time-hopping pattern cooperative processing according to claim 1, characterized in that: The matching-guided traction and tracking steps specifically include the following: The calculation control module sends a control command to the time slot counting and interrupt request module, switching it from time slot mode to frame mode. In frame mode, the time slot counting module counts consecutive time slots. It is compared in real time with the predicted transmission time slot sequence read from the time hop pattern storage module, only when An interrupt request is generated when the predicted launch time slot matches. The calculation and control module calculates the sub-pattern reference time slot based on the optimal matching position. Absolute superframe slot position in the target time-jump pattern And write the corresponding count correction value to the time slot counting module to align the time slot counter with the superframe timing of the pseudo-satellite transmitter, thereby establishing a time reference synchronized with the transmitter inside the receiver; The calculation and control module uses the prior information obtained from the successful matching to preset the initial phase of the carrier numerically controlled oscillator and the code numerically controlled oscillator. Based on the optimal matching position and signal structure parameters, it calculates the approximate values ​​of the carrier phase and code phase at the current receiving time and writes them into the corresponding oscillators as initial values. This transforms the pulling process from blind pulling to initial pulling with prior information. After entering the pulling and tracking stage, the correlator group and control module are only activated within the transmission time slot window predicted by the time hopping pattern. Combined with the frequency-locked loop, phase-locked loop and delay-locked loop, the carrier frequency, carrier phase and code phase are tracked.

7. The ground-based navigation signal processing method based on time-hopping pattern cooperative processing according to claim 1, characterized in that: The adaptive processing mechanism specifically includes the following steps: Handling strategy after matching failure: The calculation control module controls the code numerical control oscillator to perform large-step code phase jumps to quickly escape the current invalid search interval. The jump amount Δτ is determined according to the preset strategy. Multi-candidate matching processing strategy: When the time-jump pattern matching module outputs the multi-candidate matching status, it indicates the length of the current sub-pattern sample. Insufficient to provide a unique starting point for matching the target pattern, the sub-pattern sample is expanded, and the control module instructs the time-slot pattern matching module to continue acquiring new time-slot samples, and the sub-pattern length is calculated. Extended to ; Adaptive parameter adjustment based on signal quality: Continuously monitor the signal energy value of the instantaneous tributary. And the error estimate of the tracking loop, and dynamically adjust the processing parameters accordingly. In the signal search and confirmation stage, if a strong signal is continuously detected in the predicted time slot... Below the capture threshold However, above the noise floor, the computational control module increases the coherent integration time of the correlator array to improve the processing gain.

8. A ground-based navigation signal receiver system based on time-hopping pattern cooperative processing, characterized in that: The system includes a time-hopping pattern matching module, a time slot counting and interrupt request module, a calculation and control module, a correlator group, a code generator, a carrier digitally controlled oscillator, a code digitally controlled oscillator, and a digital downconverter; The time-hopping pattern matching module is configured to provide control priors to the receiver front-end processing flow and output matching results for constraining time slot calculation, mid-terminal triggering timing, and traction and tracking processes. The time slot counting and interrupt request module is configured to generate the system's time base and control the timing of interrupt requests. The computational control module is configured to initialize all configurable parameters of the system via a configuration register interface, including the frequency control word of the carrier NCO. The rate control word of the NCO code, the delay interval d of the correlator, and the matching threshold. and capture threshold It is also responsible for responding to interrupt requests from the slot counting and interrupt request module. The correlator group and digital downconverter are configured to perform despreading and coherent integration of the signal. The carrier numerically controlled oscillator and the code numerically controlled oscillator are configured to generate local copy signals.

9. A ground-based navigation signal receiver system based on time-hopping pattern cooperative processing according to claim 8, characterized in that: The time-jump pattern matching module includes a sub-pattern sample buffer, a reference time slot selection unit, a jump distance calculation unit, a sliding matching engine, and a decision and status output unit; The sub-pattern sample buffer is used to cache the time slot numbers of continuously detected signals in chronological order. and its corresponding signal energy value , form and maintain a length of sub-pattern array ; The reference time slot terminal unit reads the energy value recorded in each time slot of the sub-pattern sample buffer, and selects the time slot number corresponding to the maximum energy value as the reference time slot through a comparator circuit. ; The jump distance calculation unit calculates the jump distance of each element in the sub-pattern. Relative to reference time slot Normalized jump distance , forming a jump distance array ; The sliding matching engine consists of multiple parallel comparators and accumulators, used to process the jump distance array. With the target pattern array pre-read from the time-skip pattern memory Perform sliding matching for each candidate start time slot in the target pattern. Engine check Each non-zero distance Does a corresponding time slot exist in the target pattern? , making the relationship mod Established, for each Those that meet the above conditions The number of matches is accumulated to determine the matching degree. ,in, This represents the total number of time slots in the superframe. The decision and status output unit: sets the matching degree of each candidate position. With preset threshold The system compares the results, counts the number of qualified matches, and outputs the final matching status flag and the best matching position.

10. A ground-based navigation signal receiver system based on time-hopping pattern cooperative processing according to claim 8, characterized in that: The time slot counting and interrupt request module includes a module Counter, Modulus Counter, time-skipping pattern memory, comparator, and mode selector; The module Counter: Using the code period overflow signal code_ov output by the code generator as the clock input, it counts the intra-frame time slots and outputs a count value n. Its overflow signal drives the module. counter; The module Counter: Counts frames and outputs a count value m. The count value m and the count value n together constitute the complete continuous time slot calculation value. ; The time-hopping pattern memory stores the time-hopping pattern of the target pseudo-satellite, with a depth of [insert depth here]. The memory cell corresponding to address m stores the transmission slot number of this frame. ; The comparator: In frame mode, it calculates the intra-frame slot count value. Read from pattern memory The comparison is performed, and if they are equal, an interrupt request signal is generated. The mode selector selects the interrupt source according to the configuration of the computing control module; in time slot mode, it directly uses the code_ov signal as the interrupt request, and in frame mode, it selects the output of the comparator as the interrupt request.

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