A high-precision capture system and method for BeiDou-3 baseband

Abstract

The present invention belongs to the field of Beidou navigation communication technology, and particularly relates to a high-precision capture system and method applied to Beidou-3 baseband, including a capture engine, connected to a tracking arbitration module, a peak detection module, and a Doppler frequency / phase conversion module, for capturing digital intermediate frequency signals and generating synchronization signals and integral values, etc. The present invention realizes a high-precision capture method by introducing a power accumulation smoothing module, a peak detection module, and a Doppler frequency / phase conversion module, and combining a capture arbitration and a tracking arbitration mechanism. The method significantly improves the accuracy of the Doppler frequency and pseudo-code phase estimated by the capture engine when converted to a tracking channel, effectively enhances the capture probability, and thus optimizes the dynamic performance of the baseband algorithm. At the same time, the scheme also realizes efficient resource utilization, avoids complex calculations to correct the pseudo-code phase, and reduces the consumption of logic resources.

Description

Technical Field

[0001] The present invention belongs to the field of Beidou navigation communication technology, and in particular relates to a high-precision capture system and method applied to Beidou-3 baseband. Background Art

[0002] As the BeiDou-3 satellite system is being globalized, it is designed to improve data transmission and anti-interference capabilities, so a longer pseudo code length and larger signal bandwidth are adopted. This technology upgrade places higher demands on satellite signal acquisition and tracking algorithms, especially requiring efficient and accurate parallel acquisition strategies. However, in the traditional acquisition-to-tracking process, the acquisition engine faces challenges in processing cached data;

[0003] After the acquisition process is completed, the pseudo code phase and Doppler frequency Cache data time and capture engine working time The direct impact of this correction is that it needs to be corrected to match the actual signal change. for: ,in, is the pseudo code length in one chip period, is the pseudo code rate in one chip period, is the carrier frequency; although it can compensate for time delay to a certain extent, its calculation complexity is high, which not only consumes a lot of resources, but also easily introduces additional calculation errors when implementing in hardware;

[0004] In addition, when applying the corrected pseudo code phase to the pseudo code generator and clock generator of the tracking channel, if a pseudo code generation method other than a lookup table (LUT) is used, the pseudo code phase adjustment (such as advance or lag) must be implemented through a D flip-flop; this process is not only time-consuming, but also requires the pseudo code phase to be constantly readjusted according to the new time delay and set again in the pseudo code generator, forming a cycle of continuous iteration and prone to time accumulation errors;

[0005] This traditional capture-to-tracking process is often difficult to achieve fine phase synchronization due to its inherent computational precision and time limitations. In extreme cases, the phase difference may exceed one chip length, resulting in a significant decrease in capture accuracy, especially considering that one chip period contains multiple carrier periods (specifically ), the receiver's pseudo-code Doppler frequency Carrier Doppler frequency There is a specific conversion relationship between If the influence of the Doppler effect on the pseudo-code phase is not effectively corrected, the pseudo-code phase will deviate to more than 1 code chip, making it impossible to smoothly pull in and stably track the signal, thereby affecting the performance and reliability of the entire navigation system. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In order to overcome the defects of the traditional capture-to-tracking system in the above-mentioned background technology, the present invention proposes a high-precision capture system and method applied to the BeiDou-3 baseband, which significantly improves the accuracy of the Doppler frequency and pseudo-code phase estimated by the capture engine when converted to the tracking channel, effectively enhances the capture probability, and thus optimizes the dynamic performance of the baseband algorithm. At the same time, the scheme also realizes efficient resource utilization, avoids complex calculations to correct the pseudo-code phase, and reduces the consumption of logical resources.

[0008] (II) Technical solution

[0009] The present invention is implemented by the following technical solution: The present invention proposes a high-precision capture system applied to BeiDou-3 baseband, comprising:

[0010] A capture engine, connected to the tracking arbitration module, the peak detection module, and the Doppler frequency / phase conversion module, for capturing the digital intermediate frequency signal and generating a synchronization signal and an integral value;

[0011] A tracking arbitration module, connected to the tracking module, for controlling the tracking channel;

[0012] A peak detection module, connected to the capture arbitration module, is used to detect and record the maximum peak information of the integral value;

[0013] A capture arbitration module, connected to the Doppler frequency / phase conversion module, is used to compare the average power and the integral value and control the capture process;

[0014] The Doppler frequency / phase conversion module is provided with 2N+1 pseudo code clock generators, a selector and a difference calculator, connected to the tracking arbitration module, and is used to calculate the pseudo code Doppler frequency and correct the pseudo code phase according to the captured Doppler frequency;

[0015] A power accumulation and smoothing module is connected to the capture arbitration module and is used to calculate the average power of the digital intermediate frequency signal;

[0016] The tracking module is provided with a plurality of tracking channels, each tracking channel includes a local carrier generator, a pseudo code clock generator and a pseudo code generator;

[0017] The value of N is dynamically calculated according to the range of pseudo code Doppler frequency, and the calculation formula is: N = f doppler ＿ ca ＿ max =round[ f d_max f c f ca ] ; is the maximum carrier Doppler frequency, which is determined by the acquisition system; round is the rounding function; is the carrier frequency, is the pseudo code rate, , They are all determined by the satellite Beidou signal system of the digital intermediate frequency signal captured by the capture engine before the frequency is converted.

[0018] The present invention also provides a high-precision capture method applied to the BeiDou-3 baseband, and the capture method is implemented based on the capture system described above:

[0019] The capture method comprises the following steps:

[0020] a. The capture engine captures the digital intermediate frequency signal, generates a synchronization signal and an integral value, and sends the synchronization signal to the tracking arbitration module, and the integral value to the peak detection module; at the same time, the digital intermediate frequency signal is continuously input to the power accumulation smoothing module, which counts and accumulates the input digital intermediate frequency signal to calculate the average power , and send it to the capture arbitration module;

[0021] b. The tracking arbitration module sets the pseudo code clock generator and pseudo code generator in the idle tracking channel to the corresponding pseudo code parameters through control information according to the synchronization signal and the state of the tracking channel in the tracking module, and starts them so that the tracking channel generates pseudo code signals synchronously with the capture engine;

[0022] c. The peak detection module continuously detects and records the maximum peak information, which includes the integral value corresponding to the maximum peak. , Doppler frequency, pseudo code phase, and send the peak information to the capture arbitration module;

[0023] d. The capture arbitration module continuously compares the average power and integral value , and the capture arbitration module is set with a preset ratio ,when When the maximum peak value is reached, a stop signal is sent to the capture engine, and the Doppler frequency and pseudo code phase corresponding to the maximum peak value are sent to the Doppler frequency / phase conversion module;

[0024] e. The Doppler frequency / phase conversion module calculates the pseudo code Doppler frequency according to the received Doppler frequency and preset parameters, selects the closest pseudo code clock generator from 2N+1 pseudo code clock generators, and corrects the pseudo code phase through the phase accumulator and the difference calculator, that is, each pseudo code clock generator is from The pseudo code rate is generated in 1 Hz increments, and a rising edge sensitive phase accumulator is provided to calculate the phase accumulation value phase. The selector selects the accumulated value phase to be sent to the difference calculator, which adds the accumulated value phase to the difference calculator. The difference is made by the reference value phase to correct the captured pseudo code phase;

[0025] f. The tracking arbitration module sets the corrected pseudo code phase and the calculated pseudo code Doppler frequency to the corresponding tracking channel for subsequent tracking processing.

[0026] Preferably, the synchronization signal includes a pseudo code number and a pseudo code start mark of the digital intermediate frequency signal.

[0027] The "rising edge sensitive" mentioned above refers to a triggering mode of a circuit or logic element, which is only sensitive to the rising edge of the signal (i.e., the moment when it changes from a low level to a high level). In the Doppler frequency / phase conversion module, the rising edge sensitive phase accumulator is used to increase the phase value at the rising edge of each pseudo code clock generator. This method ensures the accuracy and synchronization of phase accumulation, because each cycle of the pseudo code clock generator corresponds to a specific point in the pseudo code signal. By being sensitive only to the rising edge, unnecessary phase changes can be avoided during the stable period of the signal or at the falling edge, thereby improving the accuracy of capture and tracking.

[0028] (III) Beneficial effects

[0029] The present invention realizes a high-precision capture method by introducing a power accumulation smoothing module, a peak detection module, and a Doppler frequency / phase conversion module, and combining the capture arbitration and tracking arbitration mechanisms. The method significantly improves the accuracy of the Doppler frequency and pseudo-code phase estimated by the capture engine when converted to the tracking channel, effectively enhances the capture probability, and thus optimizes the dynamic performance of the baseband algorithm. At the same time, the solution also realizes efficient resource utilization, avoids complex calculations to correct the pseudo-code phase, and reduces the consumption of logic resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0031] Figure 1 It is a system structure block diagram of the present invention.

[0032] Figure 2 The Doppler frequency / phase conversion module is a Doppler frequency / phase conversion module of the present invention. DETAILED DESCRIPTION

[0033] Reference Figure 1-2As shown, the present invention proposes a high-precision capture system applied to BeiDou-3 baseband, including:

[0034] A capture engine, connected to the tracking arbitration module, the peak detection module, and the Doppler frequency / phase conversion module, for capturing the digital intermediate frequency signal and generating a synchronization signal and an integral value;

[0035] A tracking arbitration module, connected to the tracking module, for controlling the tracking channel;

[0036] A peak detection module, connected to the capture arbitration module, is used to detect and record the maximum peak information of the integral value;

[0037] A capture arbitration module, connected to the Doppler frequency / phase conversion module, is used to compare the average power and the integral value and control the capture process;

[0038] The Doppler frequency / phase conversion module is provided with 2N+1 pseudo code clock generators, a selector and a difference calculator, connected to the tracking arbitration module, and is used to calculate the pseudo code Doppler frequency and correct the pseudo code phase according to the captured Doppler frequency;

[0039] A power accumulation and smoothing module is connected to the capture arbitration module and is used to calculate the average power of the digital intermediate frequency signal;

[0040] The tracking module is provided with a plurality of tracking channels, each tracking channel includes a local carrier generator, a pseudo code clock generator and a pseudo code generator;

[0041] The value of N is dynamically calculated according to the range of pseudo code Doppler frequency, and the calculation formula is: N = f doppler ＿ ca ＿ max =round[ f d_max f c f ca ] ; is the maximum carrier Doppler frequency, which is determined by the acquisition system; round is the rounding function; is the carrier frequency, is the pseudo code rate, , They are all determined by the satellite Beidou signal system of the digital intermediate frequency signal captured by the capture engine before the frequency is converted.

[0042] The present invention also provides a high-precision capture method applied to the BeiDou-3 baseband, and the capture method is implemented based on the capture system described above:

[0043] The capture method comprises the following steps:

[0044] a. The capture engine captures the digital intermediate frequency signal, generates a synchronization signal and an integral value, and sends the synchronization signal to the tracking arbitration module, and the integral value to the peak detection module; at the same time, the digital intermediate frequency signal is continuously input to the power accumulation smoothing module, which counts and accumulates the input digital intermediate frequency signal to calculate the average power (This step provides a benchmark for subsequent peak detection and capture arbitration, and by calculating the average power in real time, it avoids complex phase correction based on the capture engine working time and cache time, improving the real-time and accuracy of capture), and sends it to the capture arbitration module; this step can avoid correcting the pseudo code phase captured by the capture engine according to the capture engine working time and cache time;

[0045] b. The tracking arbitration module sets the pseudo code clock generator and pseudo code generator in the idle tracking channel to the corresponding pseudo code parameters through control information according to the synchronization signal and the state of the tracking channel in the tracking module, and starts them so that the tracking channel generates pseudo code signals synchronously with the capture engine;

[0046] c. The peak detection module continuously detects and records the maximum peak information, which includes the integral value corresponding to the maximum peak. , Doppler frequency, pseudo code phase (these information are crucial for subsequent capture arbitration and Doppler frequency / phase conversion, because they represent the strongest point and the best capture point of the signal), and send the peak information to the capture arbitration module;

[0047] In steps a, b, and c, the power accumulation smoothing module calculates the average power of the input signal , used for subsequent integration with the capture engine Comparison is made to determine whether to stop the capture process and switch to tracking. This method avoids complex time-based corrections and improves capture efficiency.

[0048] d. The capture arbitration module continuously compares the average power and integral value , and the capture arbitration module is set with a preset ratio ,when When the maximum peak value is reached, a stop signal is sent to the capture engine, and the Doppler frequency and pseudo code phase corresponding to the maximum peak value are sent to the Doppler frequency / phase conversion module; this step ensures that resource allocation and tracking channel initialization are performed only when the signal quality is good enough;

[0049] e. The Doppler frequency / phase conversion module calculates the pseudo code Doppler frequency according to the received Doppler frequency and preset parameters, selects the closest pseudo code clock generator from 2N+1 pseudo code clock generators, and corrects the pseudo code phase through the phase accumulator and the difference calculator, that is, each pseudo code clock generator is from The pseudo code rate is generated in 1 Hz increments, and a rising edge sensitive phase accumulator is provided to calculate the phase accumulation value phase. The selector selects the accumulated value phase to be sent to the difference calculator, which adds the accumulated value phase to the difference calculator. The reference value phase is used to correct the captured pseudo code phase; this step uses multiple pseudo code clock generators and a selector. The module can select the clock generator closest to the calculated pseudo code Doppler frequency, and correct the captured pseudo code phase through the difference calculator to improve the tracking accuracy and stability;

[0050] f. The tracking arbitration module sets the corrected pseudo code phase and the calculated pseudo code Doppler frequency to the corresponding tracking channel for subsequent tracking processing; this process ensures a smooth transition from capture to tracking, reducing resource waste and error accumulation.

[0051] Among them, the synchronization signal includes the pseudo code number and pseudo code start mark of the digital intermediate frequency signal, which is crucial for subsequent signal processing.

[0052] The "rising edge sensitive" mentioned above refers to a triggering mode of a circuit or logic element, which is only sensitive to the rising edge of the signal (i.e., the moment when it changes from a low level to a high level). In the Doppler frequency / phase conversion module, the rising edge sensitive phase accumulator is used to increase the phase value at the rising edge of each pseudo code clock generator. This method ensures the accuracy and synchronization of phase accumulation, because each cycle of the pseudo code clock generator corresponds to a specific point in the pseudo code signal. By being sensitive only to the rising edge, unnecessary phase changes can be avoided during the stable period of the signal or at the falling edge, thereby improving the accuracy of capture and tracking.

[0053] The present invention achieves the following significant effects by introducing a power accumulation smoothing module, a peak detection module and a Doppler frequency / phase conversion module, and combining a capture arbitration and tracking arbitration mechanism:

[0054] 1. Improve the accuracy of Doppler frequency and pseudo code phase: In the capture stage, by calculating the average power of the digital intermediate frequency signal in real time and comparing it with the integral value, the present invention can accurately screen out the moment when the signal quality is good enough for capture; then, in the Doppler frequency / phase conversion module, the pseudo code Doppler frequency and the difference calculator obtained by accurate calculation are used to correct the pseudo code phase, which significantly improves the accuracy of the Doppler frequency and pseudo code phase estimated by the capture engine when converted to the tracking channel;

[0055] 2. Enhanced capture probability: Since the present invention adopts a more sophisticated signal quality assessment method and precise pseudo code phase correction technology in the capture process, the system can more accurately identify and capture effective satellite signals, thereby effectively enhancing the capture probability;

[0056] 3. Optimize the dynamic performance of the baseband algorithm: By improving the accuracy and efficiency of capture, the present invention provides a more stable and reliable signal source for subsequent tracking processing, so that the baseband algorithm can maintain better performance in a dynamic environment (such as high-speed satellite movement, signal interference, etc.), and optimizes the dynamic performance of the baseband algorithm;

[0057] 4. Realize efficient resource utilization: The solution of the present invention avoids complex time-based corrections and additional computing resource consumption; through real-time power statistics and peak detection, the system can quickly determine the signal quality and respond, reducing unnecessary calculations and resource waste; at the same time, the selector mechanism in the Doppler frequency / phase conversion module enables the system to select the clock generator closest to the calculated pseudo-code Doppler frequency, further improving resource utilization efficiency;

[0058] 5. Reduce the consumption of logic resources: By simplifying the correction process of the pseudo code phase (avoiding complex calculations to correct the pseudo code phase), the present invention reduces the consumption of logic resources, so that the system can adopt a more compact and economical hardware architecture when designing, reducing the overall cost;

[0059] In summary, the present invention, through a series of innovative technical means, not only improves the accuracy and efficiency of the capture engine, but also optimizes the dynamic performance of the baseband algorithm, and realizes efficient utilization of resources and reduction of logical resources, providing strong technical support for the development of satellite communications and navigation and positioning fields.

[0060] Example:

[0061] Taking the BeiDou-3 S2C frequency as an example, The carrier frequency is 2491.75MHz, the pseudo code rate The capture arbitration module is set to a preset ratio of 8.16MHz. 1.5, the acquisition engine searches for the maximum carrier Doppler frequency is 5KHz, tracking channel 1 is idle;

[0062] a. The capture engine generates a synchronization signal and an integral value. The synchronization signal contains the pseudo code number 01 of the digital intermediate frequency and the pseudo code start mark. At the same time, the digital intermediate frequency signal is continuously input into the power accumulation smoothing module. The smoothing window is 5ms (i.e., the accumulated values ​​before and after 5ms are averaged to obtain the accumulated values ​​within 1ms). This module counts and accumulates the input digital intermediate frequency signal to calculate the average power. (like );

[0063] b. The capture engine sends the synchronization signal to the tracking arbitration module. The tracking arbitration module sets the pseudo code clock generator and pseudo code generator in tracking channel 1 to the corresponding pseudo code parameters through control information according to the synchronization signal (pseudo code number 01 and pseudo code start mark) and the idle channel 1 in the tracking module, and starts them, so that the tracking channel and the capture engine generate pseudo code signals synchronously;

[0064] c. The capture engine sends the integral value to the peak detection module, which continuously detects and records the maximum peak information. The peak information includes the integral value corresponding to the maximum peak. , Doppler frequency, pseudo code phase (such as integral value , Doppler frequency is 0Hz, pseudo code phase is 4501), and the peak information is sent to the capture arbitration module;

[0065] d. The capture arbitration module continuously compares the average power and integral value , and the capture arbitration module is set with a preset ratio ,when (For example, when the carrier Doppler frequency is 1000Hz and the pseudo code phase is 120, ), a stop signal is sent to the capture engine, and the Doppler frequency and pseudo code phase corresponding to the maximum peak are sent to the Doppler frequency / phase conversion module;

[0066] e. Calculate the acquisition pseudo code Doppler based on the above information: ; The maximum pseudo-code Doppler frequency can also be calculated as f doppler ＿ ca ＿ max =round[ f d_max f c f ca ]=round[ 5000 2491750000 8160000 ]=16Hz , so N is 16. The Doppler frequency / phase conversion module contains 33 pseudo code clock generators, and the pseudo code rates they generate are 8159984Hz, 8159985Hz, 8159986Hz, ..., 8160000Hz, 8160001Hz, ..., 8160016Hz. If the phase obtained by accumulating 8160000Hz is 5671, and the accumulated value phase corresponding to the pseudo code generator rate 8160003Hz of the capture engine input carrier Doppler is 5673, the difference between these two accumulated values ​​is 2;

[0067] f. The tracking arbitration module delays the tracking channel 1 pseudo code by 2 chips and sets the pseudo code clock generator to a Doppler frequency of 3 Hz.

[0068] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A high-precision acquisition system applied to BeiDou-3 baseband, characterized by: Included are: A capture engine, connected to the tracking arbitration module, the peak detection module, and the Doppler frequency / phase conversion module, for capturing the digital intermediate frequency signal and generating a synchronization signal and an integral value; A tracking arbitration module, connected to the tracking module, for controlling the tracking channel; A peak detection module, connected to the capture arbitration module, is used to detect and record the maximum peak information of the integral value; A capture arbitration module, connected to the Doppler frequency / phase conversion module, is used to compare the average power and the integral value and control the capture process; The Doppler frequency / phase conversion module is provided with 2N+1 pseudo code clock generators, a selector and a difference calculator, connected to the tracking arbitration module, and is used to calculate the pseudo code Doppler frequency and correct the pseudo code phase according to the captured Doppler frequency; A power accumulation and smoothing module is connected to the capture arbitration module and is used to calculate the average power of the digital intermediate frequency signal; The tracking module is provided with a plurality of tracking channels, each tracking channel includes a local carrier generator, a pseudo code clock generator and a pseudo code generator; The value of N is dynamically calculated according to the range of pseudo code Doppler frequency, and the calculation formula is: ; is the maximum carrier Doppler frequency, which is determined by the acquisition system; round is the rounding function; is the carrier frequency, is the pseudo code rate, , They are all determined by the Beidou satellite signal system before the digital intermediate frequency signal captured by the capture engine is converted.

2. A high-precision acquisition method applied to BeiDou-3 baseband, characterized in that: The capture method is implemented based on the capture system according to claim 1; The capture method comprises the following steps: a. The capture engine captures the digital intermediate frequency signal, generates a synchronization signal and an integral value, and sends the synchronization signal to the tracking arbitration module, and the integral value to the peak detection module; at the same time, the digital intermediate frequency signal is continuously input to the power accumulation smoothing module, which counts and accumulates the input digital intermediate frequency signal to calculate the average power , and send it to the capture arbitration module; b. The tracking arbitration module sets the pseudo code clock generator and pseudo code generator in the idle tracking channel to the corresponding pseudo code parameters through control information according to the synchronization signal and the state of the tracking channel in the tracking module, and starts them so that the tracking channel generates pseudo code signals synchronously with the capture engine; c. The peak detection module continuously detects and records the maximum peak information, which includes the integral value corresponding to the maximum peak. , Doppler frequency, pseudo code phase, and send the peak information to the capture arbitration module; d. The capture arbitration module continuously compares the average power and integral value , and the capture arbitration module is set with a preset ratio ,when When the maximum peak value is reached, a stop signal is sent to the capture engine, and the Doppler frequency and pseudo code phase corresponding to the maximum peak value are sent to the Doppler frequency / phase conversion module; e. The Doppler frequency / phase conversion module calculates the pseudo code Doppler frequency according to the received Doppler frequency and preset parameters, selects the closest pseudo code clock generator from 2N+1 pseudo code clock generators, and corrects the pseudo code phase through the phase accumulator and the difference calculator, that is, each pseudo code clock generator is from The pseudo code rate is generated in 1 Hz increments, and a rising edge sensitive phase accumulator is provided to calculate the phase accumulation value phase. The selector selects the accumulated value phase to be sent to the difference calculator, which adds the accumulated value phase to the difference calculator. The difference is made by the reference value phase to correct the captured pseudo code phase; f. The tracking arbitration module sets the corrected pseudo code phase and the calculated pseudo code Doppler frequency to the corresponding tracking channel for subsequent tracking processing.

3. A high-precision acquisition method applied to BeiDou-3 baseband according to claim 2, characterized in that: The synchronization signal includes the pseudo code number and pseudo code start mark of the digital intermediate frequency signal.

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