BOC signal capturing and tracking method and system

Abstract

The invention relates to the field of GNSS (Global Navigation Satellite System) receivers and chips, and discloses a BOC signal capturing and tracking method, which comprises the following steps of: distributing and tracking; a frequency-locked loop tracking step: when identifying the carrier frequency, calculating the cross value and the dot value between two channels under a coherent integration time and a non-correlation integration number through accumulation so as to solve a frequency error; when the code phase is identified, the self-correlation amplitudes of the correlators of the two channels are accumulated respectively, and a code phase error is calculated; and after a discriminating result of the discriminator is obtained, filtering, adjusting and updating a loop are carried out subsequently, and when a carrier frequency error, a code phase error and signal power meet threshold requirements and frequency-locked loop tracking is completed, the loop is switched to phase-locked loop tracking. By adjusting the BOC (1, 1) signal tracking processing process, BOC modulation can be regarded as BPSK modulation, so that the size, cost and power consumption of a receiver are reduced, hardware resources are saved, 3dB carrier-to-noise ratio loss can be made up, and the positioning performance of the receiver is improved.

Description

Technical Field

[0001] The present invention relates to the field of GNSS receivers and chips, and in particular to a method and system for capturing and tracking a BOC signal. Background Art

[0002] In today's society where science and technology are developing rapidly, GNSS has been widely used in all aspects of social life, which has led to the overcrowding of various GNSS signal bands. Since traditional GNSS signals generally use BPSK modulation, in order to solve this problem and further improve the positioning accuracy of GNSS signals, binary offset carrier (BOC) modulation technology has emerged. Modern GPS new signals and Galileo signals have widely adopted BOC modulation, and BOC (1,1) modulation is the common benchmark for GPS and Galileo civil signals on the L1 / E1 band. Therefore, the use of BOC signals has a bright future.

[0003] The current mainstream GNSS chip integrates the baseband and RF parts. After receiving the signal transmitted by the GNSS satellite, it completes the signal capture, tracking, data demodulation and other processes, and provides satellite signal pseudo-range, carrier phase, navigation message and other information to achieve the positioning and speed measurement functions. The accuracy of the measurement result is closely related to the signal itself. The performance of the new BOC modulation signal is superior to the traditional BPSK-R modulation signal. It has better performance in improving positioning accuracy, anti-multipath interference and code tracking performance. Therefore, the processing of BOC modulation signals is a crucial part of the development of modern GNSS.

[0004] However, at present, some low-cost, small-size, and low-power GNSS chips mainly capture and track satellite signals based on BPSK-R modulation signals. Their hardware may not fully support BOC modulation signals. Since the BOC modulation signal spectrum is symmetrical around zero frequency, the spectrum on either side of the zero frequency already contains all the information that can be used for ranging and data demodulation. Most existing technologies only process the single-sided spectrum of the BOC modulation signal. In this sideband processing method, BOC modulation is essentially regarded as BPSK-R modulation, and its carrier frequency offset is the subcarrier frequency. However, this processing method has a very intuitive disadvantage: it only uses the single-sided spectrum of the BOC signal, wasting half of the spectrum information, resulting in a 3dB carrier-to-noise ratio loss and distortion of the spectrum shape, which will eventually lead to a reduction in the positioning performance of the satellite receiver. Summary of the invention

[0005] The main purpose of the present invention is to solve the technical problem that 3dB carrier-to-noise ratio loss occurs when BPSK signal processes the single-side spectrum of BOC (1,1) modulated signal in the prior art, which reduces the positioning performance of the receiver. A method for capturing and tracking BOC signals includes the following steps:

[0006] Assignment tracking steps:

[0007] Capture the right spectrum of the L1 frequency point broadcast by the satellite, and obtain the carrier Doppler frequency shift DopFreq and code phase CodePhase; calculate the left spectrum of the L1 frequency point, the right spectrum of the L2 frequency point, and the carrier Doppler frequency shift DopFreq and code phase CodePhase of the left spectrum of the L2 frequency point according to the following formula to obtain the signal parameter estimation value:

[0008] DopFreqL1L=DopFreq-2.046MHz–DopFreq*2.046 / fL1;

[0009] DopFreqL2R=DopFreq / fL1*fL2;

[0010] DopFreqL2L=DopFreqL2R-2.046MHz–DopFreqL2R*2.046 / fL2;

[0011] CodePhaseL2I=CodePhaseL2R=CodePhaseL1I=CodePhase;

[0012] Initialize the tracking channel steps:

[0013] Initializing a tracking loop according to the signal parameter estimation value, and allocating a tracking channel to achieve tracking of the BOC signal;

[0014] Frequency-locked loop tracking steps:

[0015] When identifying the carrier frequency, the frequency error can be obtained by accumulating the cross and dot values ​​between the two channels under a coherent integration time and a non-correlated integration number. When identifying the code phase, the autocorrelation amplitude of each correlator of the two channels is accumulated respectively to calculate the code phase error. After obtaining the identification result of the discriminator, filtering, adjustment and update loop are performed subsequently. When the carrier frequency error, code phase error and signal power meet the threshold requirements and the frequency-locked loop tracking is completed, the loop is switched to phase-locked loop tracking.

[0016] The step of initializing the tracking channel specifically includes:

[0017] The tracking channel that tracks the right single-side spectrum is marked as the main channel, and the other is the secondary channel. The main channel operates periodically and continuously in the form of closed-loop feedback to achieve continuous locking of the satellite signal. The secondary channel also operates periodically in the form of closed-loop feedback, but the secondary channel does not actively update the loop. Instead, the secondary channel carrier NCO and code NCO values ​​are updated synchronously with the loop parameters of the main channel only when the main channel updates the loop.

[0018] The frequency-locked loop tracking step also includes a phase adjustment step:

[0019] First, the cross and dot values ​​between the primary and secondary channels are calculated at each moment, and then the cross and dot values ​​are accumulated over a period of time, and then the carrier phase difference between the two tracking channels is calculated by the following formula;

[0020]

[0021] Finally, the IQ value of the secondary channel is rotated by this angle and added to the IQ value of the main channel to update the IQ value of the main channel for subsequent phase detection, filtering, and adjustment update loop processes.

[0022] The step of adjusting the phase also includes a step of demodulating the data bits:

[0023] After adjusting the phase of the IQ values ​​of the two tracking channels and adding them together, if IP(t) is positive, the current data code level is +1, otherwise, if the IP(t) value is negative, the current data code level is -1, and data bit demodulation can be completed according to the I / Q data demodulation method.

[0024] The data bit demodulation step also includes a positioning step:

[0025] After achieving frame synchronization, the demodulated data bits are decoded for navigation messages to obtain navigation message parameters with practical value. Combined with the code phase, carrier phase, and carrier frequency provided by the tracking loop, the receiver positioning of the BOC modulated signal is achieved.

[0026] A second aspect of the present invention provides a BOC signal acquisition and tracking system, comprising:

[0027] To assign a tracking unit:

[0028] It is used to capture the right side spectrum of the L1 frequency point broadcast by the satellite, and obtain the carrier Doppler frequency shift DopFreq and code phase CodePhase; the left side spectrum of the L1 frequency point, the right side spectrum of the L2 frequency point, and the carrier Doppler frequency shift DopFreq and code phase CodePhase of the left side spectrum of the L2 frequency point are calculated according to the following formula to obtain the signal parameter estimation value:

[0029] DopFreqL1L=DopFreq-2.046MHz–DopFreq*2.046 / fL1;

[0030] DopFreqL2R=DopFreq / fL1*fL2;

[0031] DopFreqL2L=DopFreqL2R-2.046MHz–DopFreqL2R*2.046 / fL2;

[0032] CodePhaseL2I=CodePhaseL2R=CodePhaseL1I=CodePhase;

[0033] Initialize the tracking channel unit:

[0034] Used to initialize the tracking loop according to the signal parameter estimation value, and allocate the tracking channel to achieve tracking of the BOC signal;

[0035] Frequency-locked loop tracking unit:

[0036] When identifying the carrier frequency, the frequency error can be obtained by accumulating the cross and dot values ​​between the two channels under a coherent integration time and a non-correlated integration number. When identifying the code phase, the autocorrelation amplitude of each correlator of the two channels is accumulated respectively to calculate the code phase error. After obtaining the identification result of the discriminator, filtering, adjustment and update loop are performed subsequently. When the carrier frequency error, code phase error and signal power meet the threshold requirements and the frequency-locked loop tracking is completed, the loop is switched to phase-locked loop tracking.

[0037] A third aspect of the present invention provides an electronic device, comprising: a memory and at least one processor, wherein instructions are stored in the memory, and the memory and the at least one processor are interconnected via lines; the at least one processor calls the instructions in the memory so that the electronic device executes the above-mentioned BOC signal capture and tracking method as described above.

[0038] A fourth aspect of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions, which, when executed on a computer, enable the computer to execute the above-mentioned method for acquiring and tracking the BOC signal.

[0039] The present invention has the following beneficial effects:

[0040] By adjusting the tracking process of the BOC (1,1) signal, the present invention can not only regard BOC modulation as BPSK modulation to reduce the size, cost, power consumption and hardware resources of the receiver, but also make up for the 3dB carrier-to-noise ratio loss and improve the receiver positioning performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A flowchart of a method for capturing and tracking a BOC signal provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" or "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0043] For ease of understanding, the specific process of the embodiment of the present invention is described below. Figure 1 The first embodiment of the method for capturing and tracking a BOC signal in the embodiment of the present invention includes:

[0044] Assignment tracking steps:

[0045] Capture the right spectrum of the L1 frequency point broadcast by the satellite, and obtain the carrier Doppler frequency shift DopFreq and code phase CodePhase; calculate the left spectrum of the L1 frequency point, the right spectrum of the L2 frequency point, and the carrier Doppler frequency shift DopFreq and code phase CodePhase of the left spectrum of the L2 frequency point according to the following formula to obtain the signal parameter estimation value:

[0046] DopFreqL1L=DopFreq-2.046MHz–DopFreq*2.046 / fL1;

[0047] DopFreqL2R=DopFreq / fL1*fL2;

[0048] DopFreqL2L=DopFreqL2R-2.046MHz–DopFreqL2R*2.046 / fL2;

[0049] CodePhaseL2I=CodePhaseL2R=CodePhaseL1I=CodePhase;

[0050] Initialize the tracking channel steps:

[0051] Initializing a tracking loop according to the signal parameter estimation value, and allocating a tracking channel to achieve tracking of the BOC signal;

[0052] Frequency-locked loop tracking steps:

[0053] When identifying the carrier frequency, the frequency error can be obtained by accumulating the cross and dot values ​​between the two channels under a coherent integration time and a non-correlated integration number. When identifying the code phase, the autocorrelation amplitude of each correlator of the two channels is accumulated respectively to calculate the code phase error. After obtaining the identification result of the discriminator, filtering, adjustment and update loop are performed subsequently. When the carrier frequency error, code phase error and signal power meet the threshold requirements and the frequency-locked loop tracking is completed, the loop is switched to phase-locked loop tracking.

[0054] Specifically, the following steps are included:

[0055] Step 1: RF front-end processing. The receiving antenna receives all visible low-orbit satellite signals. After filtering and amplification by the pre-filter and amplifier, the two frequency point signals L1 and L2 are mixed with the sine wave local oscillator signals f_lo1 / f_lo2 generated by the local oscillator and down-converted into intermediate frequency signals. The intermediate frequency signals are then sampled and quantized by the analog-to-digital converter and converted into digital intermediate frequency signals, which are then stored in different PP buffers for subsequent baseband signal processing.

[0056] Step 2: PP preprocessing. The digital intermediate frequency signal stored in the PP is then processed by down-conversion, anti-aliasing filter, downsampling and other data processing, and the results are stored in the data buffers AISB and TISB for subsequent baseband digital signal processing such as capture and tracking.

[0057] Step 3: BOC signal capture. After the same satellite broadcasts two BOC modulation signals with different frequencies (such as L1 and L2), in order to save the resources and power consumption of the positioning chip, only one side of the BOC signal spectrum needs to be captured, and only one frequency signal needs to be captured, such as the right side spectrum of the L1 frequency. Finally, based on the capture results, we can get the satellite's rough carrier frequency and code phase.

[0058] Step 4: Allocate tracking channels. This solution requires opening four tracking channels at the same time, tracking the right spectrum of the L1 frequency point, the left spectrum of the L1 frequency point, the right spectrum of the L2 frequency point, and the left spectrum of the L2 frequency point. After capturing the right spectrum of the L1 frequency point, the two key parameters of the carrier Doppler frequency shift DopFreq and the code phase CodePhase can be obtained, and then the parameters of the other three channels can be calculated by formulas (1)(2)(3)(4). In the formulas, fL1 and fL2 represent the frequencies of the carriers L1 and L2, and the subscripts L2I and L2R represent the left spectrum and the right spectrum of the L2 frequency point, respectively. It can be seen from the formulas that the carrier Doppler values ​​of the above four tracking channels are different because there is an offset carrier frequency value, but the code phase is the same.

[0059] DopFreqL1L=DopFreq-2.046MHz–DopFreq*2.046 / fL1; (1)

[0060] DopFreqL2R=DopFreq / fL1*fL2; (2)

[0061] DopFreqL2L=DopFreqL2R-2.046MHz–DopFreqL2R*2.046 / fL2; (3)

[0062] CodePhaseL2I = CodePhaseL2R = CodePhaseL1I = CodePhase; (4)

[0063] Step 5: Initialize the tracking channel. Initialize the tracking loop according to the signal parameter estimation value in step 4, and assign the tracking channel to track the BOC signal. Since each frequency signal has two tracking channels to track the right and left spectrum of the BOC modulated signal respectively, and the Doppler frequency shift and code phase of these two tracking channels are theoretically the same at all times, we adopt a new tracking scheme here to complete the tracking of the BOC modulated signal. Taking the L1 frequency point as an example, the tracking channel that tracks the right spectrum is marked as the main channel, and the other is the secondary channel. The main channel runs periodically in the form of closed-loop feedback to achieve continuous locking of the satellite signal. The secondary channel also runs periodically in the form of closed-loop feedback, but unlike the main channel: the secondary channel does not actively update the loop, but only when the main channel updates the loop, the secondary channel carrier NCO and code NCO values ​​are synchronously updated with the loop parameters of the main channel. The purpose is to ensure that the main and secondary channels are always consistent.

[0064] Step 6: Frequency-locked loop tracking. When identifying the carrier frequency, the frequency error can be obtained by accumulating the cross and dot values ​​between the two channels under a certain coherent integration time and non-correlated integration number. When identifying the code phase, the autocorrelation amplitude of each correlator of the two channels is accumulated respectively, so that the code phase error can be calculated more accurately. After obtaining the identification result of the discriminator, subsequent filtering, adjustment and update loops are performed. When the carrier frequency error, code phase error, and signal power meet the threshold requirements, the loop can be switched to phase-locked loop tracking.

[0065] Step 7: Adjust the phase and accumulate the channel iq values. When the carrier loop is a phase-locked loop, due to accidental factors such as carrier frequency accuracy limitations and loop update time errors, the carrier phases of the primary and secondary channels may not be exactly the same, but there is a phase difference that changes evenly over time. Therefore, in order to solve the above problems and improve the loop tracking quality, this solution adopts the following method: first calculate the cross and dot values ​​between the primary and secondary channels at each moment, then accumulate the cross and dot values ​​over a period of time (such as one second), and then use formula (5) to calculate the carrier phase difference between the two tracking channels. Finally, the iq value of the secondary channel is rotated by the angle and accumulated on the iq value of the primary channel, so as to update the iq value of the primary channel for subsequent phase detection, filtering, and loop adjustment and update processes.

[0066] φ 主 -φ 次 = arctan2(Cross,Dot) (5)

[0067] Step 8: Data bit demodulation. After adjusting the phase of the IQ values ​​of the two tracking channels and adding them together, if IP(t) is positive, the current data code level is +1, otherwise, if the IP(t) value is negative, the current data code level is -1, and data bit demodulation can be completed according to the I / Q data demodulation method. However, since the initial phase of the carrier is unknown, the demodulated data bits may all be in the opposite direction. At this time, you only need to search for the synchronization code or the inverse value of the synchronization code in the data bit stream to achieve frame synchronization to solve the 180° phase ambiguity problem of the data bit.

[0068] Step 9: Positioning. After achieving frame synchronization, the demodulated data bits can be decoded for navigation messages to obtain navigation message parameters with practical value. Combined with the code phase, carrier phase, carrier frequency and other observations provided by the tracking loop, the receiver positioning of the BOC (1,1) modulated signal can be achieved.

[0069] The main protection point of the present invention is a BOC signal capture and tracking solution provided in steps 3 to 6, with the focus on the process of opening two tracking channels after capture, updating the loop of the secondary channel through the main channel, and accumulating the iq values ​​of the two channels after adjusting the phase.

[0070] The above describes the acquisition and tracking method of the BOC signal in the embodiment of the present invention. The following describes the acquisition and tracking system of the BOC signal in the embodiment of the present invention:

[0071] To assign a tracking unit:

[0072] It is used to capture the right side spectrum of the L1 frequency point broadcast by the satellite, and obtain the carrier Doppler frequency shift DopFreq and code phase CodePhase; the left side spectrum of the L1 frequency point, the right side spectrum of the L2 frequency point, and the carrier Doppler frequency shift DopFreq and code phase CodePhase of the left side spectrum of the L2 frequency point are calculated according to the following formula to obtain the signal parameter estimation value:

[0073] DopFreqL1L=DopFreq-2.046MHz-DopFreq*2.046 / fL1;

[0074] DopFreqL2R=DopFreq / fL1*fL2;

[0075] DopFreqL2L=DopFreqL2R-2.046MHz-DopFreqL2R*2.046 / fL2;

[0076] CodePhaseL2I=CodePhaseL2R=CodePhaseL1I=CodePhase;

[0077] Initialize the tracking channel unit:

[0078] Used to initialize the tracking loop according to the signal parameter estimation value, and allocate the tracking channel to achieve tracking of the BOC signal;

[0079] Frequency-locked loop tracking unit:

[0080] When identifying the carrier frequency, the frequency error can be obtained by accumulating the cross and dot values ​​between the two channels under a coherent integration time and a non-correlated integration number. When identifying the code phase, the autocorrelation amplitude of each correlator of the two channels is accumulated respectively to calculate the code phase error. After obtaining the identification result of the discriminator, filtering, adjustment and update loop are performed subsequently. When the carrier frequency error, code phase error and signal power meet the threshold requirements and the frequency-locked loop tracking is completed, the loop is switched to phase-locked loop tracking.

[0081] Adjust the phase unit:

[0082] First, the cross and dot values ​​between the primary and secondary channels are calculated at each moment, and then the cross and dot values ​​are accumulated over a period of time, and then the carrier phase difference between the two tracking channels is calculated by the following formula;

[0083]

[0084] Finally, the IQ value of the secondary channel is rotated by the angle and added to the IQ value of the main channel to update the IQ value of the main channel for subsequent phase detection, filtering, and adjustment update loop processes.

[0085] Data bit demodulation unit:

[0086] After adjusting the phase of the IQ values ​​of the two tracking channels and adding them together, if IP(t) is positive, the current data code level is +1, otherwise, if the IP(t) value is negative, the current data code level is -1, and data bit demodulation can be completed according to the I / Q data demodulation method.

[0087] Positioning unit:

[0088] After achieving frame synchronization, the demodulated data bits are decoded for navigation messages to obtain navigation message parameters with practical value. Combined with the code phase, carrier phase, and carrier frequency provided by the tracking loop, the receiver positioning of the BOC modulated signal is achieved.

[0089] An embodiment of the present invention provides an electronic device, which may have relatively large differences due to different configurations or performances, and may include one or more processors (central processing units, CPU) (for example, one or more processors) and memories, and one or more storage media for storing applications or data (for example, one or more mass storage devices). Among them, the memories and storage media may be short-term storage or permanent storage. The program stored in the storage medium may include one or more modules (not shown in the figure), and each module may include a series of instruction operations in the electronic device. Furthermore, the processor may be configured to communicate with the storage medium and execute a series of instruction operations in the storage medium on the electronic device.

[0090] The electronic device may also include one or more power supplies, one or more wired or wireless network interfaces, one or more input and output interfaces, and / or one or more operating systems, such as Windows Serve, Mac OS X, Unix, Linux, FreeBSD, etc.

[0091] The structure of an electronic device provided by an embodiment of the present invention may have relatively large differences due to different configurations or performances, and may include one or more processors (central processing units, CPU) (for example, one or more processors) and memories, and one or more storage media for storing applications or data (for example, one or more mass storage devices). Among them, the memories and storage media may be short-term storage or permanent storage. The program stored in the storage medium may include one or more modules (not shown in the figure), and each module may include a series of instruction operations in the electronic device. Furthermore, the processor may be configured to communicate with the storage medium and execute a series of instruction operations in the storage medium on the electronic device.

[0092] The electronic device may also include one or more power supplies, one or more wired or wireless network interfaces, one or more input and output interfaces, and / or one or more operating systems, such as Windows Server, Mac OS X, Unix, Linux, FreeBSD, etc. Those skilled in the art will appreciate that the electronic device structure does not constitute a limitation on the electronic device, and may include more or less components than the aforementioned, or combine certain components, or arrange the components differently.

[0093] The present invention also provides a computer-readable storage medium, which may be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium. Instructions are stored in the computer-readable storage medium. When the instructions are executed on a computer, the computer executes the steps of the BOC signal capture and tracking method.

[0094] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system, device, or unit can refer to the corresponding process in the aforementioned method embodiment and will not be repeated here.

[0095] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program codes.

[0096] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for capturing and tracking a BOC signal, characterized in that: The following steps are involved: Assignment tracking steps: Capture the right side spectrum of the L1 frequency point broadcast by the satellite, and obtain the carrier Doppler frequency shift DopFreq and code phase CodePhase; The left spectrum of the L1 frequency point, the right spectrum of the L2 frequency point, and the carrier Doppler frequency shift DopFreq and code phase CodePhase of the left spectrum of the L2 frequency point are calculated according to the following formula to obtain the estimated values ​​of the signal parameters: DopFreqL1L=DopFreq-2.046MHz–DopFreq*2.046 / fL1; DopFreqL2R=DopFreq / fL1*fL2; DopFreqL2L=DopFreqL2R-2.046MHz–DopFreqL2R*2.046 / fL2; CodePhaseL2I=CodePhaseL2R=CodePhaseL1I=CodePhase; Initialize the tracking channel steps: Initializing a tracking loop according to the signal parameter estimation value, and allocating a tracking channel to achieve tracking of the BOC signal; Frequency-locked loop tracking steps: When identifying the carrier frequency, the frequency error can be obtained by accumulating the cross and dot values ​​between the two channels under a coherent integration time and a non-correlated integration number. When identifying the code phase, the autocorrelation amplitude of each correlator of the two channels is accumulated respectively to calculate the code phase error. After obtaining the identification result of the discriminator, filtering, adjustment and update loop are performed subsequently. When the carrier frequency error, code phase error and signal power meet the threshold requirements and the frequency-locked loop tracking is completed, the loop is switched to phase-locked loop tracking.

2. The method for capturing and tracking a BOC signal according to claim 1, characterized in that: The step of initializing the tracking channel specifically includes: The tracking channel that tracks the right single-side spectrum is marked as the main channel, and the other is the secondary channel. The main channel operates periodically and continuously in the form of closed-loop feedback to achieve continuous locking of the satellite signal. The secondary channel also operates periodically in the form of closed-loop feedback, but the secondary channel does not actively update the loop. Instead, the secondary channel carrier NCO and code NCO values ​​are updated synchronously with the loop parameters of the main channel only when the main channel updates the loop.

3. The method for capturing and tracking a BOC signal according to claim 2, characterized in that: The frequency-locked loop tracking step also includes a phase adjustment step: First, the cross and dot values ​​between the primary and secondary channels are calculated at each moment, and then the cross and dot values ​​are accumulated over a period of time, and then the carrier phase difference between the two tracking channels is calculated by the following formula; Finally, the IQ value of the secondary channel is rotated by the angle and added to the IQ value of the main channel to update the IQ value of the main channel for subsequent phase detection, filtering, and adjustment update loop processes.

4. The method for capturing and tracking a BOC signal according to claim 3, characterized in that: The step of adjusting the phase also includes a step of demodulating the data bits: After adjusting the phase of the IQ values ​​of the two tracking channels and adding them together, if IP(t) is positive, the current data code level is +1, otherwise, if the IP(t) value is negative, the current data code level is -1, and data bit demodulation can be completed according to the I / Q data demodulation method.

5. The method for capturing and tracking a BOC signal according to claim 4, characterized in that: The data bit demodulation step also includes a positioning step: After achieving frame synchronization, the demodulated data bits are decoded for navigation messages to obtain navigation message parameters with practical value. Combined with the code phase, carrier phase, and carrier frequency provided by the tracking loop, the receiver positioning of the BOC modulated signal is achieved.

6. A BOC signal acquisition and tracking system, characterized in that: The capture and tracking system comprises: To assign a tracking unit: It is used to capture the right side spectrum of the L1 frequency point broadcast by the satellite, and obtain the carrier Doppler frequency shift DopFreq and code phase CodePhase; the left side spectrum of the L1 frequency point, the right side spectrum of the L2 frequency point, and the carrier Doppler frequency shift DopFreq and code phase CodePhase of the left side spectrum of the L2 frequency point are calculated according to the following formula to obtain the signal parameter estimation value: DopFreqL1L=DopFreq-2.046MHz–DopFreq*2.046 / fL1; DopFreqL2R=DopFreq / fL1*fL2; DopFreqL2L=DopFreqL2R-2.046MHz–DopFreqL2R*2.046 / fL2; CodePhaseL2I=CodePhaseL2R=CodePhaseL1I=CodePhase; Initialize the tracking channel unit: Used to initialize the tracking loop according to the signal parameter estimation value, and allocate the tracking channel to achieve tracking of the BOC signal; Frequency-locked loop tracking unit: When identifying the carrier frequency, the frequency error can be obtained by accumulating the cross and dot values ​​between the two channels under a coherent integration time and a non-correlated integration number. When identifying the code phase, the autocorrelation amplitude of each correlator of the two channels is accumulated respectively to calculate the code phase error. After obtaining the identification result of the discriminator, filtering, adjustment and update loop are performed subsequently. When the carrier frequency error, code phase error and signal power meet the threshold requirements and the frequency-locked loop tracking is completed, the loop is switched to phase-locked loop tracking.

7. An electronic device, comprising a memory and at least one processor, wherein instructions are stored in the memory; The at least one processor calls the instructions in the memory to enable the electronic device to execute each step of the BOC signal acquisition and tracking method as described in any one of claims 1-5.

8. A computer-readable storage medium having instructions stored thereon, characterized in that: When the instructions are executed by a processor, the various steps of the method for acquiring and tracking a BOC signal as described in any one of claims 1 to 5 are implemented.

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