A satellite high-precision traction method and system

Abstract

The present invention discloses a high-precision satellite traction method and system, the method comprising: calculating the pseudo-code frequency by capturing the carrier Doppler; calculating the error below half a chip by capturing the integrated peak value before and after the chip integral value, and updating the pseudo-code instantaneous phase by the error below half a chip and the captured pseudo-code instantaneous phase; calculating the sampling clock for pseudo-code phase conversion by the pseudo-code frequency and the pseudo-code instantaneous phase; calculating the pseudo-code period based on the pseudo-code frequency, and finding the remainder of the pseudo-code period by capturing the captured capture time and the tracking DUMP time; calculating the clock difference between capture and tracking based on the remainder result and the sampling clock for pseudo-code phase conversion, which is used to configure the tracking channel clock waiting value. Without increasing resources, the capture and traction calculation efficiency and success rate are greatly improved, and the frequency point with a higher chip frequency or a BOC modulation signal can be directly pulled.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation technology, and more particularly to a high-precision satellite traction method and system. Background Art

[0002] Satellite signal acquisition technologies mainly include combined search technology of Doppler frequency, pseudo code phase, time and DFT frequency domain search technology. Two-dimensional or three-dimensional combined search technology can be roughly divided into frequency parallel pseudo code serial acquisition, frequency serial pseudo code parallel acquisition, etc. Whether it is combined search or frequency domain search results, the instantaneous code phase is the most resource-saving with half-chip accuracy. On this basis, the instantaneous code phase error used for tracking after traction calculation can only be an error of half-chip order.

[0003] The capture result is in units of half a chip, that is, the instantaneous phase is half a chip error, which cannot be eliminated during the traction calculation. Moreover, for signals with BOC modulation, the only tracking method that can be used is to tug to BOC (1, 1) based on the capture result. Satellite signal tracking traction is divided into a carrier loop and a code loop. The carrier loop can expand the traction range in the early stage according to the adjustment of the carrier coefficient to solve the problem of insufficient capture accuracy, while increasing the amount of calculation. The traction range of the code loop must have an accuracy greater than the half-chip error, otherwise the traction success rate will not be high.

[0004] Therefore, how to provide a satellite traction algorithm that can reduce the amount of calculation while improving the success rate of capture and traction is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of this, the present invention provides a satellite high-precision traction method and system, which greatly improves the capture and traction calculation efficiency and success rate without increasing resources, and can directly traction a frequency point with a higher chip frequency or a BOC modulated signal.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A high-precision satellite traction method, comprising:

[0008] Calculate the pseudo code frequency by capturing the acquired carrier Doppler;

[0009] Calculate the error below half a chip by capturing the integrated value of the preceding and following chips of the integrated peak value, and update the pseudo code instantaneous phase by the error below half a chip and the pseudo code instantaneous phase acquired by the capture;

[0010] Calculate a sampling clock for pseudo-code phase conversion by using the pseudo-code frequency and the pseudo-code instantaneous phase;

[0011] Calculate the pseudo code period based on the pseudo code frequency, and find the modulus of the pseudo code period by capturing the acquired capture time and tracking the DUMP time;

[0012] The clock difference between capture and tracking is calculated based on the remainder result and the sampling clock converted from the pseudo code phase, and is used to configure the tracking channel clock wait value.

[0013] Preferably, the specific calculation formula for calculating the pseudo code frequency by capturing the acquired carrier Doppler is:

[0014]

[0015] Code Rate=Code Base Rate+Carrier Doppler*Carrier2 Code

[0016] Wherein, Code Base Rate is the nominal frequency value of the pseudo code chip, Carrier Base Rate is the nominal frequency value of the carrier Doppler, Carrier Doppler represents the carrier Doppler frequency, and Code Rate represents the pseudo code frequency.

[0017] Preferably, the error below half a chip is calculated by capturing the integrated value of the preceding and following chips of the integrated peak value, and the pseudo code instantaneous phase is updated by the error below half a chip and the captured pseudo code instantaneous phase. The specific calculation formula is:

[0018]

[0019] Code Chip PhaseF=Code Chip Phase+Code Chip Difference

[0020] Among them, E Code Integral is the leading code integral value, L Code Integral is the lagging code integral value, CodeChip Phase is the pseudo code instantaneous phase containing only the integer part, and Code Chip PhaseF is the pseudo code instantaneous phase containing both the fractional part and the integer part.

[0021] Preferably, the sampling clock for pseudo-code phase conversion is calculated by the pseudo-code frequency and the pseudo-code instantaneous phase, and the specific calculation formula is:

[0022]

[0023] Among them, Sample Rate is the satellite signal intermediate frequency sampling rate, Code Chip PhaseF is the instantaneous phase of the pseudo code including the fractional part and the integer part, Code Rate represents the pseudo code frequency, and Phase Clock Number is the sampling clock.

[0024] Preferably, the pseudocode period is calculated based on the pseudocode frequency, and the pseudocode period is modulo the captured capture time and the tracked DUMP time. The specific calculation formula is:

[0025]

[0026] Time Difference=Capture Time-DUMP Time

[0027] Clock Difference = MOD (Time Difference, Code Period Clock) where CodeLength is the length of the pseudocode chip period, Code Rate represents the pseudocode frequency, Sample Rate is the satellite signal intermediate frequency sampling rate, Code Period Clock represents the pseudocode period, Capture Time is the capture time for storing captured data, DUMPTime is the tracking DUMP time, MOD is the remainder function, and Clock Difference represents the remainder result.

[0028] Preferably, the clock difference between capture and tracking is calculated based on the remainder result and the sampling clock converted from the pseudo code phase, and is used to configure the tracking channel clock waiting value. The specific calculation formula is:

[0029] Clock wait=Phase Clock Number-Clock Difference

[0030] Clock wait Uint=Clock wait+Code Period Clock

[0031] Among them, Clock Difference represents the remaining results, Clock wait Uint represents the non-negative integer waiting value of the sampling clock finally obtained for pulling the satellite signal, Code Period Clock represents the number of sampling clocks of the pseudo code period, and Phase Clock Number is the number of sampling clocks converted by the pseudo code phase.

[0032] Preferably, the preceding and following code chip integral values ​​of the integral peak value include an advanced code integral value and a delayed code integral value.

[0033] A high-precision satellite traction system, comprising:

[0034] Capture module: used to capture carrier Doppler, the integrated value of the preceding and following chips of the integrated peak, the instantaneous phase of the chip and the capture time;

[0035] Traction module: used to calculate the pseudo code frequency by capturing the carrier Doppler;

[0036] Calculate the error below half a chip by capturing the integrated value of the preceding and following chips of the integrated peak value, and update the pseudo code instantaneous phase by the error below half a chip and the pseudo code instantaneous phase acquired by the capture;

[0037] Calculating a sampling clock for pseudo-code phase conversion by using the pseudo-code frequency and the pseudo-code instantaneous phase; and

[0038] Tracking module: used for calculating the pseudo code period based on the pseudo code frequency, and finding the remainder of the pseudo code period by capturing the acquired capture time and tracking the DUMP time;

[0039] The clock difference between capture and tracking is calculated based on the remainder result and the sampling clock converted from the pseudo code phase, and is used to configure the tracking channel clock wait value.

[0040] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a high-precision satellite traction method and system. The satellite signal needs to capture the carrier Doppler and instantaneous code chip phase through calculation for satellite signal tracking. The traction calculation is to complete the process from satellite signal capture to tracking. The present invention reduces the calculation amount of sampling rate and code chip rate conversion by converting half-code chip accuracy into sampling clock accuracy and adding the preceding and following code chips of the peak code chip into the calculation, while improving the success rate of capture and traction. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0042] Figure 1 The accompanying drawing is a flow chart of the satellite traction calculation method provided by the present invention.

[0043] Figure 2 The accompanying drawing is a block diagram of the satellite traction system provided by the present invention.

[0044] Figure 3 The accompanying drawing is a diagram showing the relationship between the capture time and the DUMP time used in the traction calculation provided by the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] The embodiment of the present invention discloses a high-precision satellite traction method, such as Figure 1 As shown, the specific steps are as follows:

[0047] Step 1: Calculate the pseudo code frequency by capturing the carrier Doppler.

[0048] The Doppler effect caused by relative motion between the carrier frequency and the pseudo code frequency is linear, so the pseudo code frequency value can be calculated based on the carrier Doppler. The specific formula is as follows:

[0049]

[0050] Code Rate=Code Base Rate+Carrier Doppler*Carrier2 Code

[0051] Wherein, Code Base Rate is the nominal frequency value of the pseudo code chip, Carrier Base Rate is the nominal frequency value of the carrier Doppler, Carrier Doppler represents the carrier Doppler frequency, and Code Rate represents the pseudo code frequency.

[0052] Step 2: Use the integrated value of the code chips before and after the peak to calculate the error below half a code chip, and add it to the instantaneous phase value of the captured code chip to update the instantaneous phase of the pseudo code.

[0053] The peak value of the capture result is the instantaneous phase of the pseudo code. The integral value of the preceding and following code bits is the integral value of the leading code and the lagging code. The integral value of the leading code (E) and the lagging code (L) can be used to calculate the error below half a code bit. The specific formula is as follows:

[0054]

[0055] Code Chip PhaseF=Code Chip Phase+Code Chip Difference

[0056] Among them, E Code Integral is the leading code integral value, L Code Integral is the lagging code integral value, CodeChip Phase is the pseudo code instantaneous phase containing only the integer part, and Code Chip PhaseF is the pseudo code instantaneous phase containing both the fractional part and the integer part.

[0057] Step 3: Convert the captured accurate pseudo code instantaneous phase (including integers and decimals) into the number of sampling clocks.

[0058] The pseudo code phase unit of the capture result is half a chip value. After converting it into the number of sampling clocks, it becomes the sampling clock value during the traction calculation. The specific formula is as follows:

[0059]

[0060] Among them, Sample Rate is the satellite signal intermediate frequency sampling rate, Code Chip PhaseF is the instantaneous phase of the pseudo code including the fractional part and the integer part, Code Rate represents the pseudo code frequency, and Phase Clock Number is the sampling clock.

[0061] Step 4: Calculate the pseudo code period based on the pseudo code frequency, and calculate the modulo value of the difference between the capture time and the tracking DUMP time minus the pseudo code period.

[0062] Since the pseudo code Doppler value changes, the pseudo code period is not an accurate millisecond value, so it is necessary to calculate the remainder of the sampling clock difference caused by the code phase difference between tracking and capture to the pseudo code period clock.

[0063]

[0064] Time Difference=Capture Time-DUMP Time

[0065] Clock Difference = MOD (Time Difference, Code Period Clock) where CodeLength is the length of the pseudocode chip period, Code Rate represents the pseudocode frequency, Sample Rate is the satellite signal intermediate frequency sampling rate, Code Period Clock represents the pseudocode period, Capture Time is the capture time for storing captured data, DUMPTime is the tracking DUMP time, MOD is the remainder function, and Clock Difference represents the remainder result.

[0066] Step 5: Calculate the accurate capture and tracking clock difference based on the remainder result and the sampling clock converted from the pseudo code phase, which is used to configure the tracking channel clock wait value.

[0067] The calculation accuracy of the phase difference value of the capture and tracking has reached the sampling clock accuracy. If a positive integer is required, it is accumulated with the chip frequency value periodically until it reaches a positive integer. The final result can greatly improve the traction success rate and can directly pull the frequency point with a higher chip frequency, such as F1's BOC (6, 1). The specific formula is as follows:

[0068] Clock wait=Phase Clock Number-Clock Difference

[0069] Clock wait Uint=Clock wait+Code Period Clock

[0070] Among them, Clock Difference represents the remainder result, Clock wait Uint represents the non-negative integer waiting value of the sampling clock finally used to pull the satellite signal, Code Period Clock represents the number of sampling clocks of the pseudo code period, and Phase Clock Number is the number of sampling clocks converted by the pseudo code phase.

[0071] The embodiment of the present invention discloses a high-precision satellite traction system, such as Figure 2 As shown, the specific steps are as follows: including:

[0072] Capture module: used to capture carrier Doppler, chip integral values ​​before and after the integral peak, chip instantaneous phase and capture time; specifically: mix according to the nominal intermediate frequency value of the satellite signal, then downsample to half the chip frequency, store the data and record the start time of storage; then configure different Dopplers to repeatedly read out the stored data and perform carrier stripping, matched filtering and integration operations with the Doppler waveform data; finally, based on the comparison, the carrier Doppler with the highest signal-to-noise ratio and exceeding the preset value threshold, the chip instantaneous phase and the chip integral values ​​before and after the integral peak are obtained for traction calculation.

[0073] Traction module: used to calculate the pseudo code frequency by capturing the carrier Doppler;

[0074] Calculate the error below half a chip by capturing the integrated value of the preceding and following chips of the integrated peak value, and calculate the pseudo code instantaneous phase by the error below half a chip and the instantaneous phase of the chip acquired by the capture;

[0075] Calculating a sampling clock by using the pseudo code frequency and the pseudo code instantaneous phase; and

[0076] Tracking module: used for calculating the pseudo code period based on the pseudo code frequency, and finding the remainder of the pseudo code period by capturing the acquired capture time and tracking the DUMP time;

[0077] The clock difference between capture and tracking is calculated based on the remainder result and the sampling clock converted from the pseudo code phase, which is used to configure the tracking channel clock waiting value so that the tracking module is aligned with the signal phase and the carrier loop and code loop can be used to complete traction and stable satellite signal tracking.

[0078] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0079] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-precision satellite traction method, characterized in that: include: Calculate the pseudo code frequency by capturing the acquired carrier Doppler; Calculate the error below half a chip by capturing the integrated value of the preceding and following chips of the integrated peak value, and update the pseudo code instantaneous phase by the error below half a chip and the pseudo code instantaneous phase acquired by the capture; Calculate a sampling clock for pseudo-code phase conversion by using the pseudo-code frequency and the pseudo-code instantaneous phase; Calculate the pseudo code period based on the pseudo code frequency, and find the modulus of the pseudo code period by capturing the acquired capture time and tracking the DUMP time; The clock difference between capture and tracking is calculated based on the remainder result and the sampling clock converted from the pseudo code phase, and is used to configure the tracking channel clock wait value.

2. A satellite high-precision traction method according to claim 1, characterized in that: The specific calculation formula for calculating the pseudo code frequency by capturing the carrier Doppler is: Code Rate=Code Base Rate+Carrier Doppler*Carrier2Code Wherein, Code Base Rate is the nominal frequency value of the pseudo code chip, Carrier Base Rate is the nominal frequency value of the carrier Doppler, Carrier Doppler represents the carrier Doppler frequency, and Code Rate represents the pseudo code frequency.

3. A satellite high-precision traction method according to claim 1, characterized in that: The error below half a chip is calculated by capturing the integrated value before and after the integrated peak, and the pseudo code instantaneous phase is updated by the error below half a chip and the pseudo code instantaneous phase obtained by the capture. The specific calculation formula is: CodeChip PhaseF=CodeChip Phase+CodeChip Difference Wherein, E Code Integral is the leading code integral value, L Code Integral is the lagging code integral value, CodeChipPhase is the pseudo code instantaneous phase including only the integer part, and CodeChip PhaseF is the pseudo code instantaneous phase including the fractional part and the integer part.

4. A satellite high-precision traction method according to claim 1, characterized in that: The sampling clock for pseudo code phase conversion is calculated by the pseudo code frequency and the pseudo code instantaneous phase. The specific calculation formula is: Wherein, Sample Rate is the satellite signal intermediate frequency sampling rate, CodeChip PhaseF is the instantaneous phase of the pseudo code including the fractional part and the integer part, Code Rate indicates the pseudo code frequency, and Phase Clock Number is the number of sampling clocks converted to the pseudo code phase.

5. A satellite high-precision traction method according to claim 1, characterized in that: The pseudo code period is calculated based on the pseudo code frequency, and the pseudo code period is modulo the captured capture time and the tracked DUMP time. The specific calculation formula is: Time Difference=Capture Time-DUMP Time Clock Difference=MOD (Time Difference, Code Period Clock) Wherein, Clde Length is the length of the pseudo code chip period, Code Rate indicates the pseudo code frequency, Sample Rate is the satellite signal intermediate frequency sampling rate, Code Period Clock indicates the number of sampling clocks of the pseudo code period, Capture Time is the capture time for capturing data storage, DUMP Time is the tracking DUMP time, MOD is the remainder function, and Clock Difference indicates the remainder result.

6. A satellite high-precision traction method according to claim 1, characterized in that: The clock difference between capture and tracking is calculated based on the remainder result and the sampling clock converted from the pseudo code phase, and is used to configure the tracking channel clock wait value. The specific calculation formula is: Clockwait=Phase Clock Number-Clock Difference Clock wait Uint=Clock wait+Code Period Clock Among them, Clock Difference represents the remainder result, Clock value Uint represents the non-negative integer waiting value of the sampling clock used to pull the satellite signal, Code Period Clock represents the number of sampling clocks in the pseudo code period, and Phase Clock Number is the number of sampling clocks converted by the pseudo code phase.

7. A satellite high-precision traction method according to claim 2, characterized in that: The integrated values ​​of the preceding and following code bits of the integrated peak value include the advanced code integrated value and the delayed code integrated value.

8. A high-precision satellite traction system, characterized in that: include: Capture module: used to capture carrier Doppler, the integrated value of the preceding and following chips of the integrated peak, the instantaneous phase of the chip and the capture time; Traction module: used to calculate the pseudo code frequency by capturing the carrier Doppler; Calculate the error below half a chip by capturing the integrated value of the preceding and following chips of the integrated peak value, and update the pseudo code instantaneous phase by the error below half a chip and the pseudo code instantaneous phase acquired by the capture; Calculate a sampling clock for pseudo-code phase conversion by using the pseudo-code frequency and the pseudo-code instantaneous phase; as well as Tracking module: used for calculating the pseudo code period based on the pseudo code frequency, and finding the remainder of the pseudo code period by capturing the acquired capture time and tracking the DUMP time; The clock difference between capture and tracking is calculated based on the remainder result and the sampling clock converted from the pseudo code phase, and is used to configure the tracking channel clock wait value.

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