Self-adaptive GNSS (Global Navigation Satellite System) signal capturing method and system, terminal and medium

Abstract

The invention provides a self-adaptive GNSS (Global Navigation Satellite System) signal capturing method and system, a terminal and a medium, in an earlier debugging stage, capturing is graded by utilizing simulation experience, information of each gear is recorded, and during formal capturing, coherent integration and incoherent accumulation are carried out on a received intermediate frequency signal and a defined reference satellite pseudo code to obtain a maximum correlation value; and according to the capture gear information, determining an incoherent accumulation frequency and a capture threshold of formal capture. Meanwhile, synchronous coherent integration is carried out on the intermediate frequency signal and a known aerial satellite pseudo code, and non-coherent accumulation of determined times is also carried out to obtain another maximum correlation value. And finally, judging the capture condition of the current satellite by combining the two maximum correlation values and a capture threshold. According to the invention, a reference satellite is introduced as a threshold discrimination reference in a single capture process, and corresponding capture durations are set for different signal intensities, so that the problems that a single detection threshold algorithm is poor in performance in a weak signal environment and is difficult to adapt to all signal intensities are effectively solved; and meanwhile, unnecessary capture time waste under the condition of relatively strong signals is also remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the field of satellite positioning and navigation, and particularly to an adaptive GNSS signal acquisition method, system, terminal, and medium. Background Art

[0002] In existing detection technologies, the single-shot acquisition threshold detection algorithm is the starting point of the detection process, which is divided into two categories: hard threshold and soft threshold. The hard threshold algorithm determines the presence of a signal by comparing the squared modulus of the correlation value with a preset fixed threshold, which requires the receiver to flexibly adjust the threshold value according to the carrier-to-noise ratio of the acquired satellite signal to ensure the desired detection probability. However, the reliability of this method is challenged in a weak signal environment. Soft threshold algorithms, such as peak-to-average ratio detection and peak-to-peak ratio detection, although having the characteristic of constant false alarm probability and being able to improve the detection performance to a certain extent, the setting of their threshold values is equally complex and lacks a theoretically closed-form solution, resulting in difficulty in determining a unified ratio threshold under different carrier-to-noise ratios and non-coherent integration times.

[0003] To overcome the limitations of single-shot detection in a weak signal environment, a multi-shot acquisition detector has emerged. The M-out-of-N detector determines the presence of a signal through a fixed number of detections, but this method has a long acquisition time, especially in the case of only noise, with low efficiency. The Tong detector reduces the false alarm rate and improves the detection probability in weak signals through a variable dwell time and counter mechanism. However, the Tong detector may also fall into a wandering state, resulting in an overly long dwell time. The scheme of combining the two detectors can solve these problems to a certain extent, but it is relatively complex to implement and still requires careful parameter adjustment for different signal strengths. Especially when the satellite signal is weak, during the non-coherent integration process after coherent integration, the balance between the false alarm rate and the miss detection rate becomes particularly difficult, and an unreasonable threshold value setting often directly leads to acquisition failure. Therefore, although many improvement schemes have been proposed, there are still obvious defects and limitations between single-shot detection and multi-shot detection in traditional acquisition detection technologies. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide an adaptive GNSS signal acquisition method, system, terminal, and medium, which are used to solve the technical problems that the acquisition detection technology using a single-shot detection algorithm has poor performance in a weak signal environment and is difficult to adapt to all signal strengths, and there is a waste of acquisition time in a strong signal environment.

[0005] To achieve the above and other related objectives, the present invention provides an adaptive GNSS signal acquisition method, which includes: synchronously performing coherent integration on the received intermediate-frequency signal and a defined reference satellite pseudo-code to obtain a correlation value, and performing non-coherent accumulation on the correlation value according to the acquisition gear information determined in the simulation and debugging stage before the start of acquisition to obtain the maximum correlation value, determining the acquisition gear for the formal acquisition, and obtaining the non-coherent accumulation times and acquisition threshold for the formal acquisition; wherein, the reference satellite pseudo-code is defined as a pseudo-random sequence with the same generation method as the in-air satellite pseudo-code, and the sequences are inconsistent but orthogonal; the intermediate-frequency signal is obtained by a low-intermediate-frequency receiver receiving the in-air satellite signal; synchronously performing coherent integration on the intermediate-frequency signal and the known in-air satellite pseudo-code to obtain a correlation value, and performing non-coherent accumulation for the non-coherent accumulation times of the formal acquisition on the correlation value to obtain the maximum correlation value; according to the maximum correlation value obtained based on the reference satellite pseudo-code, the maximum correlation value obtained based on the in-air satellite pseudo-code, and the acquisition threshold for the formal acquisition, obtaining the acquisition situation of the current in-air satellite signal.

[0006] In an embodiment of the present invention, the method for determining the acquisition gear information in the simulation and debugging stage before the start of acquisition includes: respectively synchronously performing coherent integration on the debugging intermediate-frequency signal and the defined reference satellite pseudo-code, and the debugging intermediate-frequency signal and the in-air satellite pseudo-code to obtain correlation values, and performing non-coherent accumulation for corresponding times on their respective correlation values at different carrier-to-noise ratios to obtain the maximum correlation value, and obtaining the statistical information at different carrier-to-noise ratios; wherein, the statistical information includes: the non-coherent accumulation times at the corresponding carrier-to-noise ratio, the maximum correlation value obtained based on the reference satellite pseudo-code, and the maximum correlation value obtained based on the in-air satellite pseudo-code; dividing multiple acquisition gears according to the statistical information at each carrier-to-noise ratio, and determining the acquisition gear information; wherein, the acquisition gear information includes: the reference satellite noise energy, non-coherent accumulation times, maximum correlation value ratio, and acquisition threshold of all acquisition gears.

[0007] In an embodiment of the present invention, the dividing multiple acquisition gears according to the statistical information at each carrier-to-noise ratio and determining the acquisition gear information includes: dividing the statistical information into multiple acquisition gears in descending order of the carrier-to-noise ratio; using the smaller value among the multiple maximum correlation value ratios obtained based on the reference satellite pseudo-code and the in-air satellite pseudo-code in the statistical information corresponding to each acquisition gear as the maximum correlation value ratio of the corresponding acquisition gear, and setting the acquisition threshold and reference satellite noise energy of the corresponding acquisition gear according to the maximum correlation value ratio, and using the non-coherent accumulation times in the statistical information corresponding to the maximum correlation value ratio as the non-coherent accumulation times of the acquisition gear.

[0008] In an embodiment of the present invention, the method for setting the acquisition threshold includes: using the maximum correlation value ratio of non - lowest acquisition gears as the respective optimal thresholds for the corresponding acquisition gears, setting the maximum correlation value ratio of the lowest acquisition gear as the normal threshold of the lowest acquisition gear, and setting a value less than the normal threshold as the rejection threshold of the lowest acquisition gear.

[0009] In an embodiment of the present invention, non - coherently accumulating the correlation values according to the acquisition gear information determined in the simulation and debugging stage before the start of acquisition to obtain the maximum correlation value, determining the acquisition gear for formal acquisition, and obtaining the non - coherent accumulation times and acquisition threshold for formal acquisition includes: non - coherently accumulating the correlation values one by one for the non - coherent accumulation times of each acquisition gear until the maximum correlation value obtained after accumulating through the corresponding non - coherent accumulation times is not less than the reference satellite noise energy of the acquisition gear corresponding to the non - coherent accumulation times, then stopping the accumulation, and taking this acquisition gear as the acquisition gear for formal acquisition, and taking the non - coherent accumulation times and acquisition threshold of this acquisition gear as the non - coherent accumulation times and acquisition threshold for formal acquisition.

[0010] In an embodiment of the present invention, obtaining the acquisition situation of the current in - air satellite signal according to the maximum correlation value obtained based on the reference satellite pseudo - code, the maximum correlation value obtained based on the in - air satellite pseudo - code, and the acquisition threshold for formal acquisition includes: calculating the ratio of the maximum correlation value obtained based on the reference satellite pseudo - code to the maximum correlation value obtained based on the in - air satellite pseudo - code; comparing this ratio with the acquisition threshold for formal acquisition to obtain the acquisition situation of the current satellite.

[0011] In an embodiment of the present invention, the step of comparing this ratio with the acquisition threshold for formal acquisition to obtain the acquisition situation of the current satellite includes: when the acquisition gear for formal acquisition is a non - lowest gear, comparing this ratio with the optimal threshold of the corresponding acquisition gear. If the ratio is greater than the optimal threshold, it is determined that the acquisition is successful; otherwise, it is determined that the acquisition fails, and the signal acquisition of the next satellite is performed. When the acquisition gear for formal acquisition is the lowest gear, comparing this ratio with the normal threshold and the rejection threshold. If the ratio is greater than the normal threshold, it is determined that the acquisition is successful; if the ratio is less than the rejection threshold, it is determined that the acquisition fails; if the ratio is not less than the rejection threshold and not greater than the normal threshold, a secondary acquisition determination operation is performed. The secondary acquisition determination operation includes: performing secondary acquisition when the ratio is not less than the rejection threshold and not greater than the normal threshold. If the maximum correlation values obtained from both acquisitions are not less than the rejection threshold, it is determined that the acquisition is successful; otherwise, it is determined that the acquisition fails.

[0012] To achieve the above object and other related objects, the present invention provides an adaptive GNSS signal acquisition system, the system comprising: a reference satellite maximum correlation value acquisition module, configured to perform coherent integration on the received intermediate frequency signal and a defined reference satellite pseudo-code to obtain a correlation value, and perform non-coherent accumulation on the correlation value according to the acquisition gear information determined in the simulation and debugging stage before the start of acquisition to obtain the maximum correlation value, determine the acquisition gear for formal acquisition, and obtain the non-coherent accumulation times and acquisition threshold for formal acquisition; wherein, the reference satellite pseudo-code is defined as a pseudo-random sequence with the same generation method as the in-air satellite pseudo-code, and the sequences are inconsistent but orthogonal; the intermediate frequency signal is obtained by a low intermediate frequency receiver receiving the in-air satellite signal; an in-air satellite maximum correlation value acquisition module, connected to the reference satellite maximum correlation value acquisition module, configured to perform coherent integration on the intermediate frequency signal and a known in-air satellite pseudo-code to obtain a correlation value, and perform non-coherent accumulation of the non-coherent accumulation times for formal acquisition on the correlation value to obtain the maximum correlation value; an acquisition decision module, connected to the reference satellite maximum correlation value acquisition module and the in-air satellite maximum correlation value acquisition module, configured to obtain the acquisition situation of the current in-air satellite signal according to the maximum correlation value obtained based on the reference satellite pseudo-code, the maximum correlation value obtained based on the in-air satellite pseudo-code, and the acquisition threshold for formal acquisition.

[0013] To achieve the above object and other related objects, the present invention provides an electronic terminal, comprising: one or more memories and one or more processors; the one or more memories are configured to store computer programs; the one or more processors, connected to the memories, are configured to run the computer programs to execute the adaptive GNSS signal acquisition method.

[0014] To achieve the above object and other related objects, the present invention provides a computer-readable storage medium storing a computer program, and the computer program, when run by one or more processors, executes the method.

[0015] As described above, the present invention is an adaptive GNSS signal acquisition method, system, terminal, and medium, which has the following beneficial effects: In the early debugging stage of the present invention, simulation experience is used to divide the acquisition into bins and record the information of each bin. During the formal acquisition, the intermediate frequency signal received by the receiver is coherently integrated with the defined reference satellite pseudo-code and non-coherently accumulated to obtain the maximum correlation value. According to the acquisition bin information, the non-coherent accumulation times and acquisition threshold for formal acquisition are determined. At the same time, the intermediate frequency signal is also synchronously coherently integrated with the known in-air satellite pseudo-code, and non-coherently accumulated a certain number of times to obtain another maximum correlation value. Finally, based on the maximum correlation values based on the reference satellite pseudo-code and the in-air satellite pseudo-code and the acquisition threshold, the acquisition situation of the current satellite is determined. The present invention introduces a reference satellite as the benchmark for threshold discrimination in a single acquisition process, and sets corresponding acquisition durations for different signal strengths, effectively solving the problem that the single detection threshold algorithm has poor performance in weak signal environments and is difficult to adapt to all signal strengths, and also significantly reducing the unnecessary waste of acquisition time in strong signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It shows a schematic flow chart of the adaptive GNSS signal acquisition method in an embodiment of the present invention.

[0017] Figure 2 It shows a schematic flow chart of determining the acquisition bin information before the start of acquisition in an embodiment of the present invention.

[0018] Figure 3 It shows a schematic flow chart of obtaining the acquisition situation of the current satellite during the acquisition process in an embodiment of the present invention.

[0019] Figure 4 It shows a schematic structural diagram of the adaptive GNSS signal acquisition system in an embodiment of the present invention.

[0020] Figure 5 It shows a schematic structural diagram of the electronic terminal in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0022] It should be noted that in the following description, with reference to the accompanying drawings, several embodiments of the present invention are described. It should be understood that other embodiments may also be used, and mechanical composition, structure, electrical, and operational changes may be made without departing from the spirit and scope of the present invention. The following detailed description should not be considered restrictive, and the scope of the embodiments of the present invention is only defined by the claims of the published patent. The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. Spatially related terms, such as "upper", "lower", "left", "right", "below", "beneath", "lower part", "above", "upper part", etc., may be used in the text to facilitate the description of the relationship between one element or feature shown in the figure and another element or feature.

[0023] Throughout the specification, when it is said that a part is "connected" to another part, this includes not only the case of "direct connection" but also the case of "indirect connection" with other elements placed therebetween. In addition, when it is said that a certain part "includes" a certain constituent element, unless there is a particularly contrary record, it does not exclude other constituent elements, but means that other constituent elements may also be included.

[0024] The first, second, and third, etc. terms mentioned therein are used to describe various parts, components, regions, layers, and / or segments, but are not limited thereto. These terms are only used to distinguish one part, component, region, layer, or segment from other parts, components, regions, layers, or segments. Therefore, the first part, component, region, layer, or segment described below may refer to the second part, component, region, layer, or segment within the scope not exceeding the present invention.

[0025] Furthermore, as used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms "comprising", "including" indicate the presence of the described features, operations, elements, components, items, kinds, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, operations, elements, components, items, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or meaning any one or any combination. Thus, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A, B, and C". An exception to this definition only occurs when the combination of elements, functions, or operations is inherently mutually exclusive in some way.

[0026] The present invention provides an adaptive GNSS signal acquisition method. In the preliminary preparation stage, through a large number of simulations, the acquisition is divided into several levels, so that signals of different intensities correspond to different acquisition durations, and appropriate level information is set for formal acquisition. After the acquisition of airborne satellites is started, the airborne signal is converted into an intermediate-frequency signal by a low-intermediate-frequency receiver, and synchronous coherent integration and non-coherent accumulation are performed with the defined reference satellite pseudo-code to obtain the maximum correlation value, and the number of non-coherent accumulations and the acquisition threshold are determined according to the acquisition level information preset before the acquisition starts. At the same time, synchronous coherent integration is also performed on the intermediate-frequency signal and the known airborne satellite pseudo-code, and non-coherent accumulation is performed the same number of times to obtain another maximum correlation value. Finally, the acquisition situation of the current satellite is determined by combining the maximum correlation values based on the reference satellite pseudo-code and the airborne satellite pseudo-code and the acquisition threshold. In the single acquisition process of the present invention, a reference satellite is introduced as the benchmark for threshold discrimination, and corresponding acquisition durations are set for different signal intensities, effectively solving the problem that the single detection threshold algorithm has poor performance in a weak signal environment and is difficult to adapt to all signal intensities, and at the same time significantly reducing the unnecessary waste of acquisition time in a strong signal environment.

[0027] The following takes the attached drawings as a reference to elaborate on the embodiments of the present invention, so that those skilled in the technical field of the present invention can easily implement it. The present invention can be embodied in many different forms and is not limited to the embodiments described herein.

[0028] As Figure 1 shows a schematic flow chart of an adaptive GNSS signal acquisition method in an embodiment of the present invention.

[0029] GNSS (Global Navigation Satellite System) signal acquisition refers to the receiver identifying and locking the signal from the satellite in the received signal, which is the basis for subsequent signal tracking, positioning, and navigation. During the acquisition process, the receiver needs to search for and determine key parameters such as the carrier frequency and code phase of the satellite signal. The adaptive GNSS signal acquisition method includes:

[0030] Step S1: Synchronously perform coherent integration on the received intermediate-frequency signal and the defined reference satellite pseudo-code to obtain a correlation value, and perform non-coherent accumulation on the correlation value according to the acquisition level information determined in the simulation and debugging stage before the acquisition starts to obtain the maximum correlation value, determine the acquisition level for formal acquisition, and obtain the number of non-coherent accumulations and the acquisition threshold for formal acquisition.

[0031] Specifically, the intermediate frequency signal is received by a low-intermediate frequency receiver near the corresponding frequency point of the airborne satellite signal. And the present invention adds a reference satellite pseudo-code, defined as a noise spreading code; this noise spreading code is a pseudo-random sequence, generated in the same way as the airborne satellite pseudo-code. This means it has similar characteristics to the conventional satellite spreading code, such as having a certain periodicity, randomness, and pseudo-random characteristics. The sequence of this noise spreading code is inconsistent with but orthogonal to the airborne satellite pseudo-code. Orthogonality is an important characteristic. In signal processing, two signals being orthogonal means that their result is zero under a certain inner product operation. This indicates that although the noise spreading code is different from the airborne satellite pseudo-code, they have an orthogonal relationship. Such a characteristic enables the use of this noise spreading code as a reference satellite pseudo-code to avoid interference with the airborne satellite pseudo-code, and when performing various signal correlation operations, it can be distinguished from the airborne satellite pseudo-code.

[0032] In one embodiment, the method for determining the acquisition gear information in the simulation and debugging stage before the start of acquisition includes:

[0033] Before formal acquisition, a large number of simulations are carried out. Respectively, the coherent integration of the intermediate frequency signal for debugging with the defined reference satellite pseudo-code and the coherent integration of the intermediate frequency signal for debugging with the airborne satellite pseudo-code are synchronized to obtain correlation values, and the non-coherent accumulation of the respective correlation values is carried out the corresponding number of times at different carrier-to-noise ratios to obtain the maximum correlation value, and the statistical information at different carrier-to-noise ratios is obtained;

[0034] Specifically, as Figure 2 , first, the coherent integration operation of the intermediate frequency signal for debugging with the defined reference satellite pseudo-code and the coherent integration operation of the intermediate frequency signal for debugging with the airborne satellite pseudo-code are respectively carried out. The airborne satellite pseudo-code before acquisition is the pseudo-code set for the preliminary simulation and debugging to determine the acquisition gear information. Synchronous coherent integration is a signal processing technology that synchronizes the intermediate frequency signal and the airborne satellite pseudo-code in time and frequency and calculates their correlation through coherent integration. Through this operation, the correlation values between the intermediate frequency signal and the reference satellite pseudo-code and between the intermediate frequency signal and the airborne satellite pseudo-code can be obtained, and these correlation values reflect the similarity or relevance between them. Fix the coherent integration time, and use any pseudo-code synchronization algorithm to calculate the integral, such as sliding correlation, parallel code phase, piecewise matched filter based on fast Fourier transform (PMF-FFT, Piecewise Matched Filter-Fast Fourier Transform), double-block zero-padding (DBZP, Double-Block Zero-Padding), etc. search methods.

[0035] At different carrier-to-noise ratios, perform non-coherent integration on the obtained correlation values for corresponding times, and observe the correlation peak curve. The correlation peak curve refers to a curve plotted with the correlation value as the ordinate and certain variables (such as time, frequency, code phase, etc.) as the abscissa. It should be noted that the number of non-coherent integration times at each carrier-to-noise ratio can be appropriately selected according to requirements. At different carrier-to-noise ratios, the correlation peak curves will exhibit different characteristics and variation laws. Non-coherent integration is to accumulate the energies of multiple uncorrelated signal samples, aiming to enhance signal characteristics and improve the reliability of signal detection. Through multiple non-coherent integration operations, observe the correlation peak to obtain the maximum correlation value at different carrier-to-noise ratios. The intermediate frequency signal for debugging here involves signals with multiple carrier-to-noise ratios, that is, the above operations will be performed in different carrier-to-noise environments to simulate the actual complex signal propagation environment.

[0036] For each carrier-to-noise ratio, collect corresponding statistical information, including:

[0037] Number of non-coherent integration times: The number of non-coherent integration performed to achieve the maximum correlation value at different carrier-to-noise ratios. This reflects the processing intensity required to achieve better signal characteristics at this carrier-to-noise ratio.

[0038] Maximum correlation value obtained based on the reference satellite pseudo-code: At this carrier-to-noise ratio, after coherent integration and non-coherent accumulation, the maximum correlation value between the intermediate frequency signal and the reference satellite pseudo-code. This value can be used as one of the bases for subsequent judgment.

[0039] Maximum correlation value obtained based on the in-air satellite pseudo-code: Similarly at this carrier-to-noise ratio, the maximum correlation value between the intermediate frequency signal and the in-air satellite pseudo-code, which helps to compare and analyze the situations of different signal sources.

[0040] Divide multiple acquisition gears according to the statistical information at each carrier-to-noise ratio, and determine the acquisition gear information; wherein, the acquisition gear information includes: the reference satellite noise energy, the number of non-coherent integration times, the maximum correlation value ratio, and the acquisition threshold of all acquisition gears.

[0041] In one embodiment, the dividing multiple acquisition gears according to the statistical information at each carrier-to-noise ratio and determining the acquisition gear information includes:

[0042] First, calculate the ratio of the maximum correlation value obtained based on the reference satellite pseudo-code to the maximum correlation value obtained based on the in-air satellite pseudo-code at each carrier-to-noise ratio, and based on the magnitudes of the non-coherent integration times and the maximum correlation value ratios at each carrier-to-noise ratio, divide the statistical information into multiple acquisition gears in descending order of carrier-to-noise ratio. The purpose is to group the statistical information with similar maximum correlation value ratios into the same gear, and at the same time ensure that the statistical information with a higher carrier-to-noise ratio is divided into higher gears. The carrier-to-noise ratio step between each gear does not have to be the same, and the number of coherent integration times increases gradually with each gear;

[0043] For each acquisition bin, based on the smaller value among the ratios of multiple maximum correlation values obtained from the reference satellite pseudo-code and the on-air satellite pseudo-code within that bin, set the maximum correlation value ratio corresponding to the acquisition bin. For example, the minimum value among the ratios of multiple maximum correlation values can be selected. This ratio can be used as a characteristic value for that bin, denoted as the acquisition threshold, and used for subsequent signal processing decisions. The reference satellite noise energy for the acquisition bin can be obtained based on the maximum correlation value obtained from the reference satellite pseudo-code in the statistical information corresponding to the above ratio. The maximum correlation value can be directly used as the reference satellite noise energy for the acquisition bin, or a small numerical adjustment can be made based on this value to obtain the reference satellite noise energy for the acquisition bin. To a certain extent, this maximum correlation value can reflect the noise equivalent situation of the reference satellite signal in that bin, providing a reference for subsequent signal analysis and processing. Take the non-coherent accumulation count in the corresponding statistical information as the non-coherent accumulation count for the acquisition bin. This count is obtained based on previous signal processing operations and reflects the number of non-coherent accumulation operations required to achieve a good processing effect in that bin, providing a reference for the processing intensity of subsequent acquisition operations.

[0044] In one embodiment, the method for setting the acquisition threshold includes: using the maximum correlation value ratios of non-lowest acquisition bins as the respective optimal thresholds for the corresponding acquisition bins. When the correlation detection value of the acquired signal in a non-lowest acquisition bin exceeds this threshold, it can be considered that the signal strength is high enough to reliably declare acquisition success. Set the maximum correlation value ratio of the lowest acquisition bin as the normal threshold; and directly set a value smaller than the normal threshold as the rejection threshold, which is used to handle the situation of the weakest signal bin. Use the two thresholds as the judgment criteria for the lowest acquisition bin. If the correlation detection value is greater than the normal threshold, it means the satellite signal strength is acceptable and the acquisition is successful. If the correlation detection value is not greater than the normal threshold and not less than the rejection threshold, secondary acquisition is required, and only when both are not less than the rejection threshold is the current satellite acquisition considered successful, so as to reduce the false alarm caused by mis-acquisition and ensure the accuracy of acquisition. When the detection value of this bin is less than the rejection threshold, it can be considered that there is no signal from the corresponding satellite, and there is no need for further processing. Just directly search for the next satellite.

[0045] The above steps of determining the acquisition bin information before the start of acquisition all belong to the preliminary preparation stage. Using simulation experience to use different acquisition durations for strong and weak signal intensities can not only ensure sufficient detection ability in a weak signal environment, improve acquisition reliability, but also save acquisition time in a high signal intensity environment, avoid unnecessary time waste, and effectively balance the reliability and efficiency of acquisition.

[0046] In one embodiment, as Figure 3, during the acquisition process of satellite signals, first, a GNSS frequency point signal that has been acquired is converted to obtain an intermediate frequency signal. The correlation value of this intermediate frequency signal and a defined reference satellite pseudo-code is obtained by means of coherent integration.

[0047] Next, the detection work will be carried out for each acquisition gear one by one. The specific operations are as follows:

[0048] First, according to the non-coherent accumulation times set for the first acquisition gear, the non-coherent accumulation operation is performed on the correlation value obtained through coherent integration, so as to obtain the maximum correlation value. Then, this maximum correlation value is compared with the reference satellite noise energy corresponding to this acquisition gear to perform the noise energy decision operation. If the maximum correlation value obtained after the corresponding non-coherent accumulation times is not less than the reference satellite noise energy corresponding to this acquisition gear, the accumulation operation is stopped. At this time, this acquisition gear is determined as the acquisition gear used for formal acquisition, and at the same time, the non-coherent accumulation times and acquisition threshold corresponding to this acquisition gear are used as the non-coherent accumulation times and acquisition threshold used during formal acquisition.

[0049] If the maximum correlation value obtained after the accumulation of the corresponding non-coherent accumulation times is less than the reference satellite noise energy corresponding to this acquisition gear, the non-coherent accumulation is performed according to the non-coherent accumulation times set for the next acquisition gear. After that, the newly obtained maximum correlation value is compared with the reference satellite noise energy corresponding to this acquisition gear. Similarly, if the new maximum correlation value is not less than the reference satellite noise energy corresponding to this acquisition gear, the accumulation is stopped and this acquisition gear is determined as the acquisition gear for formal acquisition; if it is still less, the non-coherent accumulation is continued according to the non-coherent accumulation times of the next acquisition gear, and so on in a loop until the obtained maximum correlation value is not less than the reference satellite noise energy corresponding to the corresponding acquisition gear.

[0050] Step S2: Synchronously perform coherent integration on the intermediate frequency signal and a known in-air satellite pseudo-code to obtain a correlation value, and perform non-coherent accumulation of the non-coherent accumulation times for formal acquisition on the correlation value to obtain the maximum correlation value.

[0051] Specifically, first, as Figure 3 , the synchronous coherent integration operation is performed on the intermediate frequency signal and a known in-air satellite pseudo-code. The non-coherent accumulation operation is performed on the correlation value obtained through synchronous coherent integration. The number of non-coherent accumulations has been determined in the previous process. In this process, the non-coherent accumulation operation of the non-coherent accumulation times for formal acquisition determined in step S1 will be performed on the correlation value, and finally a maximum correlation value is obtained. The known in-air satellite pseudo-code in formal acquisition is the pseudo-code sequence corresponding to the actual satellite signal received by the receiver, which carries information such as the actual satellite operation and signal transmission.

[0052] Step S3: Obtain the acquisition status of the current satellite signal in the air according to the maximum correlation value obtained based on the reference satellite pseudo-code, the maximum correlation value obtained based on the satellite pseudo-code in the air, and the acquisition threshold for formal acquisition.

[0053] In one embodiment, obtaining the acquisition status of the current satellite signal in the air according to the maximum correlation value obtained based on the reference satellite pseudo-code, the maximum correlation value obtained based on the satellite pseudo-code in the air, and the acquisition threshold for formal acquisition includes:

[0054] As Figure 3 , calculate the ratio of the maximum correlation value obtained based on the reference satellite pseudo-code to the maximum correlation value obtained based on the satellite pseudo-code in the air; then compare this ratio with the acquisition threshold for formal acquisition to make a judgment on the acquisition status of the current satellite. The acquisition threshold here has been determined in the previous steps. The acquisition thresholds for different acquisition gears correspond to different signal strength ranges and acquisition statuses. By comparing the ratio with these thresholds, it can be determined whether the current satellite is successfully acquired.

[0055] In one embodiment, the comparing this ratio with the acquisition threshold for formal acquisition and making a judgment on the acquisition status of the current satellite includes:

[0056] When the acquisition gear for formal acquisition determined by using the noise energy judgment in step S1 is not the lowest gear, compare this ratio with the optimal threshold of the acquisition gear for formal acquisition. If this ratio is greater than the optimal threshold, it is determined that the acquisition is successful, and record the number of the visible satellite and the required phase and frequency information. It is necessary to record the number of the visible satellite and the required phase and frequency information. These information are crucial for subsequent satellite signal processing and use. For example, these information can be stored in a database or data structure for subsequent satellite tracking, data transmission and other operations. If this ratio is not greater than the optimal threshold, it is determined that the acquisition fails, indicating that the signal of the current satellite is too weak or does not exist, which is not sufficient to meet the acquisition conditions. At this time, the continuous acquisition of the current satellite should be abandoned and the signal acquisition of the next satellite should be carried out to improve the overall satellite search efficiency.

[0057] When the acquisition gear for formal acquisition is at the lowest gear, compare this ratio with the normal threshold and the exclusion threshold;

[0058] If this ratio is greater than the normal threshold, it is determined that the acquisition is successful, and record the number of the visible satellite and the required phase and frequency information;

[0059] If the ratio is not less than the ejection threshold and not greater than the normal threshold, a secondary acquisition determination operation is performed; when the ratio is between the two thresholds, it means that for satellite signals in this situation, their strength may be at a medium level. To ensure the accuracy and reliability of acquisition, a secondary acquisition determination operation, i.e., secondary acquisition, is required to prevent misacquisition. If the maximum correlation values obtained from both acquisitions are not less than the ejection threshold, the acquisition is determined to be successful; otherwise, the acquisition is determined to be failed, and the signal acquisition of the next satellite is performed.

[0060] If the ratio is less than the ejection threshold, the acquisition is determined to be failed; when the ratio is less than the ejection threshold, it indicates that the signal of the current satellite is too weak or does not exist, which is insufficient to meet the acquisition conditions. At this time, the continuous acquisition of the current satellite should be abandoned, and the signal acquisition of the next satellite should be performed to improve the overall satellite search efficiency.

[0061] Similar to the principle of the above embodiment, the present invention provides an adaptive GNSS signal acquisition system.

[0062] The following provides specific embodiments in conjunction with the accompanying drawings:

[0063] As Figure 4 shows the structural schematic diagram of the adaptive GNSS signal acquisition system in the embodiment of the present invention.

[0064] The system includes:

[0065] A reference satellite maximum correlation value acquisition module 1, which is used to perform coherent integration on the received intermediate frequency signal and the defined reference satellite pseudo-code to obtain a correlation value, and perform non-coherent accumulation on the correlation value according to the acquisition gear information determined in the simulation and debugging stage before the start of acquisition to obtain the maximum correlation value, determine the acquisition gear for formal acquisition, and obtain the non-coherent accumulation times and acquisition threshold for formal acquisition; wherein, the reference satellite pseudo-code is defined as a pseudo-random sequence with the same generation method as the in-air satellite pseudo-code, and the sequences are inconsistent but orthogonal; the intermediate frequency signal is obtained by a low intermediate frequency receiver receiving the in-air satellite signal.

[0066] An in-air satellite maximum correlation value acquisition module 2, connected to the reference satellite maximum correlation value acquisition module 1, which is used to perform coherent integration on the intermediate frequency signal and the known in-air satellite pseudo-code to obtain a correlation value, and perform non-coherent accumulation on the correlation value for the non-coherent accumulation times of formal acquisition to obtain the maximum correlation value.

[0067] An acquisition decision module 3, connected to the reference satellite maximum correlation value acquisition module 1 and the in-air satellite maximum correlation value acquisition module 2, which is used to obtain the acquisition situation of the current in-air satellite signal according to the maximum correlation value obtained based on the reference satellite pseudo-code, the maximum correlation value obtained based on the in-air satellite pseudo-code, and the acquisition threshold for formal acquisition.

[0068] Since the implementation principle of the adaptive GNSS signal acquisition system has been described in the foregoing embodiments, it will not be repeated here.

[0069] The adaptive GNSS signal acquisition method provided by the embodiments of the present invention can be implemented on the terminal side or the server side. In terms of the hardware structure of the electronic terminal, please refer to Figure 5 , which is an optional schematic diagram of the hardware structure of the adaptive GNSS signal acquisition terminal 1000 provided by the embodiments of the present invention. The terminal 1000 may be a mobile phone, a computer device, a tablet device, a personal digital processing device, a factory background processing device, etc. The terminal 1000 includes: at least one processor 1001, a memory 1002, at least one network interface 10010, and a user interface 1009. Each component in the device is coupled together through a bus system 1005. It can be understood that the bus system 1005 is used to realize the connection and communication between these components. In addition to the data bus, the bus system 1005 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clarity, in Figure 5 all kinds of buses are labeled as the bus system.

[0070] Among them, the user interface 1009 may include a display, a keyboard, a mouse, a trackball, a click gun, a key, a button, a touchpad, or a touch screen, etc.

[0071] It can be understood that the memory 1002 may be a volatile memory or a non-volatile memory, and may also include both a volatile memory and a non-volatile memory. Among them, the non-volatile memory may be a read-only memory (ROM, Read Only Memory), a programmable read-only memory (PROM, Programmable Read-Only Memory), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM, Static Random Access Memory), synchronous static random access memory (SSRAM, Synchronous Static Random Access Memory). The memory described in the embodiments of the present invention is intended to include but not be limited to these and any other suitable categories of memory.

[0072] The memory 1002 in the embodiments of the present invention is used to store various types of data to support the operation of the terminal 1000. Examples of such data include: any executable programs for operating on the terminal 1000, such as the operating system 10021 and application programs 10022; the operating system 10021 contains various system programs, such as the framework layer, core library layer, driver layer, etc., for implementing various basic services and processing hardware-based tasks. The application programs 10022 can include various application programs, such as a MediaPlayer, a Browser, etc., for implementing various application services. The adaptive GNSS signal acquisition method provided by the embodiments of the present invention can be included in the application programs 10022.

[0073] The method disclosed in the above embodiments of the present invention can be applied to the processor 1001 or implemented by the processor 1001. The processor 1001 may be an integrated circuit chip with signal processing capabilities. During implementation, the steps of the above method can be completed by the integrated logic circuit in the hardware of the processor 1001 or instructions in software form. The above-mentioned processor 1001 can be a general-purpose processor, a digital signal processor (DSP, Digital Signal Processor), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 1001 can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. The processor 1001 can be a microprocessor or any conventional processor, etc. Combining the steps of the accessory optimization method provided by the embodiments of the present invention can be directly embodied as being completed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium, and this storage medium is located in the memory. The processor reads the information in the memory and combines its hardware to complete the steps of the foregoing method.

[0074] In an exemplary embodiment, the terminal 1000 can be one or more application-specific integrated circuits (ASICs, Application Specific Integrated Circuit), DSPs, programmable logic devices (PLDs, ProgrammableLogic Device), complex programmable logic devices (CPLDs, Complex Programmable LogicDevice) for executing the foregoing method.

[0075] Those of ordinary skill in the art can understand that all or part of the steps to implement the above method embodiments can be completed by hardware related to a computer program. The aforementioned computer program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps including those of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk, or optical disc, etc., various media that can store program codes.

[0076] In the embodiments provided in the present application, the computer-readable and writable storage medium may include a read-only memory, a random access memory, an EEPROM, a CD-ROM, or other optical disc storage devices, a magnetic disk storage device, or other magnetic storage devices, a flash memory, a USB flash drive, a portable hard drive, or any other medium that can be used to store the desired program code in the form of instructions or data structures and can be accessed by a computer. Additionally, any connection may be properly termed a computer-readable medium. For example, if the instructions are sent from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the medium. However, it should be understood that the computer-readable and writable storage medium and the data storage medium do not include connections, carrier waves, signals, or other transient media, but are intended to refer to non-transient, tangible storage media. As used in the application, magnetic disks and optical discs include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while optical discs reproduce data optically using a laser.

[0077] In summary, for the adaptive GNSS signal acquisition method, system, terminal and medium of the present invention, during the preliminary debugging stage, the acquisition is divided into different levels based on simulation experience and the information of each level is recorded. During the formal acquisition, the in-phase integration and non-coherent accumulation are performed on the intermediate frequency signal received by the receiver and the defined reference satellite pseudo-code to obtain the maximum correlation value, and according to the acquisition level information, the non-coherent accumulation times and acquisition threshold for the formal acquisition are determined. At the same time, the in-phase integration of the intermediate frequency signal and the known in-air satellite pseudo-code is also performed, and the non-coherent accumulation for a certain number of times is also carried out to obtain another maximum correlation value. Finally, based on the maximum correlation values based on the reference satellite pseudo-code and the in-air satellite pseudo-code and the acquisition threshold, the acquisition situation of the current satellite is judged. The present invention introduces a reference satellite as the benchmark for threshold discrimination in the single acquisition process, and sets corresponding acquisition durations for different signal strengths, effectively solving the problems that the single detection threshold algorithm has poor performance in weak signal environments and is difficult to adapt to all signal strengths, and also significantly reducing the unnecessary waste of acquisition time in strong signal situations. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0078] The above embodiments are only used to exemplarily illustrate the principles and effects of the present invention, rather than to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An adaptive GNSS signal acquisition method, characterized in that: The method comprises: The received intermediate frequency signal and the defined reference satellite pseudo code are synchronously coherently integrated to obtain a correlation value, and the correlation value is incoherently accumulated according to the capture gear information determined in the simulation debugging stage before the capture begins to obtain a maximum correlation value, the capture gear for formal capture is determined, and the number of incoherent accumulations and the capture threshold for formal capture are obtained; wherein the reference satellite pseudo code is defined as a pseudo-random sequence generated in the same manner as the satellite pseudo code in the air, and the sequences are inconsistent but orthogonal; The intermediate frequency signal is obtained by receiving the satellite signal in the air with a low intermediate frequency receiver; Synchronously performing coherent integration on the intermediate frequency signal and the known satellite pseudo code in the air to obtain a correlation value, and performing incoherent accumulation of the formally captured incoherent accumulation times on the correlation value to obtain a maximum correlation value; The capture status of the current satellite signal in the air is obtained according to the maximum correlation value obtained based on the reference satellite pseudo code, the maximum correlation value obtained based on the satellite pseudo code in the air and the capture threshold of the formal capture.

2. The adaptive GNSS signal acquisition method according to claim 1, characterized in that: The methods for determining the gear information to be captured during the simulation debugging phase before the capture begins include: The intermediate frequency signal for debugging and the defined reference satellite pseudo code, and the intermediate frequency signal for debugging and the airborne satellite pseudo code are synchronously calculated to obtain correlation values, and the respective correlation values ​​are incoherently accumulated for a corresponding number of times under different carrier-to-noise ratios to obtain a maximum correlation value, so as to obtain statistical information under different carrier-to-noise ratios; wherein the statistical information includes: the number of incoherent accumulations under the corresponding carrier-to-noise ratio, the maximum correlation value obtained based on the reference satellite pseudo code, and the maximum correlation value obtained based on the airborne satellite pseudo code; A plurality of capture gears are divided according to statistical information at each carrier-to-noise ratio, and capture gear information is determined; wherein the capture gear information includes: reference satellite noise energy, incoherent accumulation times, maximum correlation value ratio and capture threshold of all capture gears.

3. The adaptive GNSS signal acquisition method according to claim 2, characterized in that: The dividing a plurality of capture gears according to the statistical information at each carrier-to-noise ratio and determining the capture gear information comprises: Divide each statistical information into multiple capture levels according to the carrier-to-noise ratio from high to low; A smaller value among multiple maximum correlation value ratios obtained based on the reference satellite pseudocode and the air satellite pseudocode in the statistical information corresponding to each capture gear is used as the maximum correlation value ratio of the corresponding capture gear, and a capture threshold and reference satellite noise energy of the corresponding capture gear are set according to the maximum correlation value ratio, and the number of incoherent accumulations in the statistical information corresponding to the maximum correlation value ratio is used as the incoherent accumulation number of the capture gear.

4. The adaptive GNSS signal acquisition method according to claim 3, characterized in that: The capture threshold setting methods include: The maximum correlation value ratios of non-lowest capture gears are used as the optimal thresholds of the corresponding capture gears, the maximum correlation value ratio of the lowest capture gear is set as the regular threshold of the lowest capture gear, and a value less than the regular threshold is set as the exclusion threshold of the lowest capture gear.

5. The adaptive GNSS signal acquisition method according to claim 2, characterized in that: The method of performing incoherent accumulation of correlation values ​​according to the capture gear information determined in the simulation debugging stage before the capture starts to obtain the maximum correlation value, determining the capture gear for formal capture, and obtaining the incoherent accumulation number and capture threshold for formal capture includes: The incoherent accumulation of the incoherent accumulation times of each capture gear is performed on the correlation values ​​one by one, and the accumulation is stopped when the maximum correlation value obtained after the corresponding incoherent accumulation times is not less than the reference satellite noise energy of the capture gear corresponding to the incoherent accumulation times, and the capture gear is used as the capture gear for formal capture, and the incoherent accumulation times and the capture threshold of the capture gear are used as the incoherent accumulation times and the capture threshold for formal capture.

6. The adaptive GNSS signal acquisition method according to claim 5, characterized in that: According to the maximum correlation value obtained based on the reference satellite pseudo code, the maximum correlation value obtained based on the air satellite pseudo code and the acquisition threshold of the formal acquisition, the acquisition status of the current air satellite signal is obtained, including: Calculate the ratio of the maximum correlation value obtained based on the reference satellite pseudo code and the maximum correlation value obtained based on the air satellite pseudo code; The ratio is compared with the formal capture threshold to obtain the current satellite capture status.

7. The adaptive GNSS signal acquisition method according to claim 6, characterized in that: The step of comparing the ratio with the formally captured capture threshold to obtain the current satellite capture status includes: When the acquisition gear of the formal acquisition is not the lowest gear, the ratio is compared with the optimal threshold of the corresponding acquisition gear. If the ratio is greater than the optimal threshold, it is determined that the acquisition is successful, otherwise it is determined that the acquisition fails and the signal acquisition of the next satellite is carried out; When the capture gear of the formal capture is the lowest gear, the ratio is compared with the normal threshold and the rejection threshold. If the ratio is greater than the normal threshold, the capture is determined to be successful. If the ratio is less than the rejection threshold, the capture is determined to be unsuccessful. If the ratio is not less than the rejection threshold and not greater than the normal threshold, a secondary capture determination operation is performed. The secondary capture determination operation includes: performing secondary capture when the ratio is not less than the rejection threshold and not greater than the normal threshold; if the maximum correlation values ​​obtained from the two captures are not less than the rejection threshold, the capture is determined to be successful; otherwise, the capture is determined to be unsuccessful.

8. An adaptive GNSS signal acquisition system, characterized in that: The system comprises: The reference satellite maximum correlation value acquisition module is used to synchronously calculate the coherent integration of the received intermediate frequency signal and the defined reference satellite pseudo code to obtain the correlation value, and to perform non-coherent accumulation of the correlation value according to the capture gear information determined in the simulation debugging stage before the capture starts to obtain the maximum correlation value, determine the capture gear for formal capture, and obtain the number of non-coherent accumulations and capture threshold for formal capture; wherein the reference satellite pseudo code is defined as a pseudo-random sequence generated in the same way as the airborne satellite pseudo code, and the sequences are inconsistent but orthogonal; the intermediate frequency signal is obtained by receiving the airborne satellite signal by a low intermediate frequency receiver; An air satellite maximum correlation value acquisition module is connected to the reference satellite maximum correlation value acquisition module and is used to synchronously obtain a coherent integration of the intermediate frequency signal and a known air satellite pseudo code to obtain a correlation value, and to perform a non-coherent accumulation of the number of formally captured non-coherent accumulations on the correlation value to obtain a maximum correlation value; The capture judgment module is connected to the reference satellite maximum correlation value acquisition module and the air satellite maximum correlation value acquisition module, and is used to obtain the capture status of the current air satellite signal based on the maximum correlation value obtained based on the reference satellite pseudo code, the maximum correlation value obtained based on the air satellite pseudo code and the capture threshold of formal capture.

9. An electronic terminal, characterized in that: include: one or more memories and one or more processors; The one or more memories are used to store computer programs; The one or more processors, connected to the memory, are configured to run the computer program to perform the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is executed by one or more processors, the method according to any one of claims 1 to 7 is performed.

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