A spread spectrum capture method, device, electronic device and storage medium

Abstract

The present invention relates to the field of satellite communications and discloses a spread spectrum capture method, device, electronic device, and storage medium, belonging to the technical field of spread spectrum capture in the field of wireless communications. The spread spectrum capture method includes: dividing the satellite movement speed range into grades; in each grade, compensating the spread spectrum received signal and then performing sliding correlation to determine the grade with the largest correlation peak, and recording a first time offset estimate and a first frequency offset estimate to complete initial capture; after compensating the spread spectrum received signal based on the first time offset estimate and the first frequency offset estimate, performing time domain capture to obtain a second time offset estimate; after compensating the spread spectrum received signal based on the second time offset estimate and the first frequency offset estimate, performing frequency domain capture to obtain a second frequency offset estimate. The present invention solves the accuracy and sensitivity problems in the spread spectrum signal capture process.

Description

Technical Field

[0001] The present application belongs to the field of spread spectrum capture technology in the field of satellite communications, and in particular relates to a spread spectrum capture method, device, electronic equipment and storage medium. Background Art

[0002] Low-orbit satellites and ground terminals typically experience significant relative motion. The radial velocity and acceleration of these satellites cause the carrier frequencies of the signals received by both receivers to exhibit large Doppler frequencies and Doppler frequency variations, resulting in high dynamics. To demodulate useful information from highly dynamic spread-spectrum signals, accurate and rapid acquisition of the spread-spectrum signal's carrier frequency and pseudo-code phase is essential. Therefore, acquiring highly dynamic spread-spectrum signals is essentially a two-dimensional search process for the received signal's carrier frequency and pseudo-code phase. The goal of carrier acquisition is to ensure that the difference between the local signal's carrier frequency and the received signal's carrier frequency falls within the limits of the automatic frequency control (AFC) (or the fast acquisition band of the phase-locked loop (PLL)). The goal of pseudo-code acquisition is to ensure that the difference between the local signal's pseudo-code phase and the received signal's pseudo-code phase is less than 1 chip.

[0003] Traditional acquisition algorithms can be categorized into two types based on their signal processing methods: time-domain and frequency-domain. Time-domain algorithms are primarily based on massively parallel correlators, detecting multiple code phase bins in parallel. Frequency-domain algorithms utilize the Fast Fourier Transform (FFT) for correlation operations. These algorithms include segmented zero-padding, single-folding, double-folding, direct averaging, and overlapping averaging. These algorithms are designed for normal received signals. However, when signals are obscured by mountains, forests, tall buildings, and other factors, attenuation can reach 20dB. In such situations, a longer pre-detection integration time is required to capture weak signals. This extended pre-detection integration time significantly increases the impact of code Doppler. Code Doppler can cause code phase slip between the received signal (i.e., the satellite signal) and the local signal. Traditional spread-spectrum acquisition algorithms, which do not account for this effect, are therefore ineffective. Summary of the Invention

[0004] The embodiments of the present application provide a spread spectrum capture method to solve the problems of low accuracy and sensitivity in the signal spread spectrum capture process.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0006] According to the first aspect of the embodiment of the present application, a spread spectrum capture method is provided, comprising: dividing the satellite moving speed range into bins; in each bin, compensating the spread spectrum received signal and then performing sliding correlation, determining the bin with the largest correlation peak, and recording the first time offset estimate and the first frequency offset estimate to complete the initial capture; after compensating the spread spectrum received signal based on the first time offset estimate and the first frequency offset estimate, performing time domain capture to obtain a second time offset estimate; after compensating the spread spectrum received signal based on the second time offset estimate and the first frequency offset estimate, performing frequency domain capture to obtain a second frequency offset estimate. The present application utilizes code Doppler binning to compensate for the code received signal, which greatly reduces the code phase slip between the received signal and the local signal caused by code Doppler, greatly extends the pre-detection integration time, and can significantly improve the capture sensitivity.

[0007] In one embodiment of the present application, at each gear position, the spread spectrum received signal is compensated and then sliding correlation is performed to determine the gear position with the largest correlation peak, and the first time offset estimation value and the first frequency offset estimation value are recorded, specifically including: frequency offset compensation for the spread spectrum received signal; code offset compensation and rearrangement of the spread spectrum received signal after frequency offset compensation according to time slot granularity; sliding correlation of the rearranged spread spectrum received signal with the local pilot sequence; accumulating the sliding correlation results according to time slots, and performing peak search on the accumulated results to obtain the position and peak size corresponding to the maximum correlation peak in the current gear position; comparing the sizes of the maximum correlation peaks at each gear position, and taking the maximum value and corresponding position of each maximum peak as the first frequency offset estimation value and the first time offset estimation value, respectively.

[0008] In one embodiment of the present application, the frequency offset compensation is performed using the Doppler frequency shift amount corresponding to each gear position.

[0009] In one embodiment of the present application, the code deviation compensation includes: calculating a code Doppler offset according to a Doppler frequency shift corresponding to each gear position, and performing code deviation compensation using the code Doppler offset.

[0010] In one embodiment of the present application, the accumulating the sliding correlation results by time slot specifically includes: performing segmented accumulation of the sliding correlation results within the time slot; and performing non-coherent accumulation of the sliding correlation results after segmented accumulation of each time slot between time slots.

[0011] In one embodiment of the present application, the segmented accumulation of the sliding correlation results within the time slot includes: segmenting the sliding correlation results within the time slot, and coherently accumulating the data in each segment; and incoherently accumulating the coherently accumulated segments of data.

[0012] In one embodiment of the present application, the time domain capture is completed using the same process as the initial capture.

[0013] In one embodiment of the present application, after compensating the spread spectrum received signal based on the first time offset estimation value and the first frequency offset estimation value, time domain capture is performed to obtain the second time offset estimation value, which specifically includes: compensating the spread spectrum received signal based on the first time offset estimation value and the first frequency offset estimation value; rearranging the compensated spread spectrum received signal according to time slot granularity; sliding correlation of the rearranged compensated spread spectrum received signal with a local pilot sequence; accumulating the sliding correlation results according to time slots, and performing peak search on the accumulated results, and taking the position corresponding to the maximum correlation peak as the second time offset estimation value.

[0014] In one embodiment of the present application, after compensating the spread spectrum received signal based on the second time offset estimation value and the first frequency offset estimation value, frequency domain capture to obtain the second frequency offset estimation value specifically includes: compensating the spread spectrum received signal based on the second time offset estimation value and the first frequency offset estimation value; performing matched filtering and channel estimation on the compensated spread spectrum received signal to obtain channel data; after performing fast Fourier transform on the channel data, performing peak search on the spectrum, and taking the position of the peak as the second frequency offset estimation value.

[0015] In one embodiment of the present application, a real-time data source is used to process data at different gears, and the data obtained after sliding correlation is cached.

[0016] According to a second aspect of an embodiment of the present application, a spread spectrum capture device is provided, including: a binning module for binning the satellite moving speed range and calculating the Doppler frequency shift corresponding to each bin; a primary capture module for performing sliding correlation on the spread spectrum received signal at each bin, determining the bin with the largest correlation peak, and recording a first time offset estimate and a first frequency offset estimate; a secondary time domain capture module for compensating the spread spectrum received signal based on the first time offset estimate and the first frequency offset estimate, and then performing time domain capture to obtain a second time offset estimate; and a secondary frequency domain capture module for compensating the spread spectrum received signal based on the second time offset estimate and the first frequency offset estimate, and then performing frequency domain capture to obtain a second frequency offset estimate.

[0017] According to a third aspect of an embodiment of the present application, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and executes the spread spectrum capture method described in the first aspect.

[0018] According to a fourth aspect of an embodiment of the present application, a computer-readable storage medium is provided, on which computer program instructions are stored. When the program instructions are executed by a processor, they are used to implement the process corresponding to the spread spectrum capture method described in the first aspect.

[0019] The aforementioned main solution of this application and its further options can be freely combined to form multiple solutions, all of which can be adopted and protected by this application. After understanding the solution of this application, those skilled in the art will understand that there are many combinations based on existing technology and common knowledge, all of which are technical solutions to be protected by this application, and these are not exhaustive here. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0021] Figure 1 It is a flowchart of the spread spectrum capture method according to an embodiment of the present application.

[0022] Figure 2 It is a schematic diagram of an electronic device according to an embodiment of the present application.

[0023] Figure 3 It is a structural diagram of a computer system suitable for implementing the electronic device of the embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0025] All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in this application without creative effort are within the scope of protection of this application. The embodiments and features in the embodiments in this application may be combined with each other in any manner unless there is a conflict. Furthermore, although a logical order is shown in the flowcharts, in some cases, the steps shown or described may be performed in an order different from that shown.

[0026] The term "comprising" and any variations thereof in the specification and claims of this application and the accompanying drawings are intended to cover non-exclusive protection. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to the process, method, product, or apparatus.

[0027] In this application, "multiple" can mean at least two, for example, two, three or more, and this embodiment of the application does not limit this. In the technical solution of this application, the collection, dissemination, and use of data are in compliance with the requirements of relevant national laws and regulations.

[0028] The relative motion between the satellite and the receiver will cause not only carrier frequency offset but also code Doppler. Assume that the carrier frequency offset is , then the corresponding code Doppler is:

[0029]

[0030] in, is the code rate, is the carrier frequency.

[0031] For conventional signals (non-spread spectrum signals), although the maximum carrier frequency offset caused by LEO satellite motion can reach up to 30kHz, the symbol rate is relatively low, resulting in a code Doppler shift of only 1.6Hz, meaning it takes 625ms to cause a single symbol shift. Therefore, the impact of code Doppler can be ignored in conventional mode. However, spread spectrum mode features a high code rate, with a chip rate typically exceeding 10MHz. For highly dynamic LEO satellites, the code Doppler in spread spectrum mode can reach as high as 200Hz, causing a code phase slip in just 5ms. The spread spectrum acquisition algorithm must account for the impact of code Doppler.

[0032] On the other hand, the core of spread spectrum communication technology is to map narrowband source signals onto wideband pseudo-random codes. This enables transmission with a very low signal-to-noise ratio, improving the system's anti-interference capabilities. Furthermore, due to distance and obstruction, the path loss between satellites and the ground is typically large.

[0033] In summary, low-Earth orbit satellites are not only highly dynamic but also have low signal-to-noise ratios (SNRs). To improve the sensitivity and accuracy of spread-spectrum acquisition in low SNR conditions, it is often necessary to increase the pre-detection integration time, such as by extending the coherent integration time or increasing the number of incoherent accumulations. While increasing the integration period can improve sensitivity, it also introduces new challenges. Firstly, the high dynamics of low-Earth orbit satellites make the effects of code Doppler significant when the integration period is extended. Once the pre-detection integration time exceeds 5ms, code phase slippage prevents the integrated energy from accumulating at the same code phase, preventing coherent energy accumulation and significantly reducing the combining gain achieved by extending the detection integration time. Secondly, from an engineering implementation perspective, whether using frequency-domain or time-domain acquisition, increasing the detection integration time significantly increases the amount of data buffered during acquisition.

[0034] Therefore, the technical difficulties of spread spectrum capture that need to be solved include: overcoming the influence of code Doppler, extending the effective detection integration time, and improving the sensitivity and accuracy of spread spectrum capture; solving the problems of high load and high cache of weak signal high-sensitivity capture algorithm, and realizing low-complexity spread spectrum signal capture.

[0035] While existing technologies reduce the impact of code Doppler through Doppler pre-compensation, their implementation is highly complex. Firstly, they cache sampled data, significantly increasing the amount of data required when the integration length is increased. Secondly, their detection algorithms utilize a high-point FFT, which is difficult to implement in practical engineering or chip applications. Furthermore, the data cached within the capture detection time in existing technologies requires the capture processing of all Doppler pre-compensation levels to be completed one by one within the detection time, significantly increasing the processing speed of the capture system.

[0036] Based on this, the embodiment of the present application proposes a spread spectrum capture method, which uses the relationship between carrier Doppler and code Doppler to perform code Doppler compensation according to the carrier frequency grid of each search, thereby reducing the code phase slip between the received signal and the local signal caused by code Doppler, extending the pre-detection integration time, and significantly improving the capture sensitivity. In addition, in the capture method of the embodiment of the present application, a secondary capture is added on the basis of a single capture, and after compensation using the time-frequency deviation value of the initial capture, the initial capture process is reused, which greatly improves the capture accuracy while also having excellent module reusability. Please refer to Figure 1 The specific plan is as follows:

[0037] S100: Divide the satellite moving speed range into grades.

[0038] In order to reduce the code phase slip between the received signal and the local signal caused by code Doppler, in the embodiment of the present application, the satellite moving speed range is divided into grades, and the Doppler frequency shift corresponding to each grade is calculated for subsequent compensation of the spread spectrum received signal.

[0039] Theoretically, the more gears the better, but in practice, it is necessary to comprehensively consider the computational complexity and performance. In one embodiment, in order to ensure that the code deviation does not exceed 0.5 chips within the cumulative time and take into account the computational complexity, the satellite movement speed range is divided into bins according to the speed of 1 km / s, and the Doppler frequency shift of the kth bin is recorded as .

[0040] S200 , performing sliding correlation after compensating the spread spectrum received signal at each gear position, determining the gear position with the largest correlation peak, and recording a first time offset estimation value and a first frequency offset estimation value, thereby completing initial capture.

[0041] In the embodiment of the present application, sliding correlation processing is performed on the spread spectrum received signal at each gear position, and a capture result is preliminarily determined.

[0042] It should be noted that in this embodiment, the processing for each gear position is real-time, that is, each gear position is processed using a different real-time data source. This reduces the computational load within each gear position and ensures that the execution time of the capture processing module is less than each detection cycle. Compared to traditional solutions that require the completion of compensation and capture processing for all Doppler gear positions within a single detection cycle, in this embodiment, only one Doppler gear position needs to be compensated and captured within a single detection cycle, significantly reducing the hardware processing speed requirements in actual implementation.

[0043] The following is a detailed description of the gear search process:

[0044] First, the Doppler frequency shift corresponding to each gear is used to complete the frequency offset compensation. Assuming that the signal after matched filtering is , then the signal after frequency offset compensation for the kth gear is expressed as:

[0045]

[0046] in, j Indicates plural, i Indicates the number of received sampling points, The length of the received data. Indicates the sampling rate; Indicates the delay sample point adjustment amount. During the initial capture, toa is 0. During the secondary capture process, toa is , that is, the time offset estimate determined by the initial capture is used to perform timing compensation.

[0047] Then, in order to reduce the impact of code Doppler on spread spectrum acquisition performance, code offset compensation needs to be performed on the received data. At the same time, in order to facilitate subsequent processing, this embodiment rearranges the spread spectrum received signals of the selected gear according to the time slot granularity, and calculates the code Doppler of each time slot of the current gear to complete the code offset compensation of the time slot granularity. The first gear speed The code Doppler shift of time slots is calculated as follows:

[0048]

[0049] The signal after compensating the code deviation and rearranging according to the time slot granularity is: :

[0050]

[0051] in, is the center frequency of the carrier frequency, is the number of chips in each time slot, is the upsampling multiple, and are the known speed and frequency deviation of the current gear respectively, Indicates the k In the gear, the received j The first time slot i The sliding sampling point corresponds to the m received signals, round() means rounding to the nearest integer.

[0052] Since the amount of spread spectrum data is large, if the traditional solution of performing code offset compensation on each code chip one by one is adopted, the amount of calculation is extremely large. The embodiment of the present application adopts a time slot-level code offset compensation method, which approximates the code offset adjustment amount of a time slot to the same value, and uses the offset of the first code chip of each time slot as the code offset adjustment amount of all code chips in the time slot. In this way, the first code chip of all time slots is aligned with the first code chip of the first time slot, ensuring that the timing boundaries of all time slots are aligned. The time slot-level code offset compensation method greatly reduces the complexity of spread spectrum code offset compensation. At the same time, after the code chips between time slots are aligned, it can also effectively reduce the impact of code Doppler on the correlation of subsequent synchronization signals, increase the merging gain between time slots, and thus improve the performance of spread spectrum capture.

[0053] Then, the rearranged spread spectrum received signal is sliding correlated with the local pilot sequence. The details are as follows:

[0054]

[0055] in, Indicates in k Next gear j The first time slot i The sliding sampling point corresponds to the m The signal after the pilot signal is eliminated from the received signal, that is, the sliding correlation result, represents the conjugate of the local pilot sequence.

[0056] Next, the sliding correlation results are accumulated according to the time slots, and the accumulated results are searched for peak values ​​to obtain the position and peak value corresponding to the maximum correlation peak value of the current gear.

[0057] In the embodiment of the present application, the process of accumulating the sliding correlation results by time slot is divided into two parts: accumulation processing within the time slot and between time slots.

[0058] For the time slot, the sliding correlation results are mainly accumulated in segments within the time slot. Specifically, the M-point sliding correlation results of each time slot are accumulated. Divide into N segments, each segment length P = M / N; perform coherent accumulation on the data in each segment:

[0059]

[0060] in, Indicates the k In the first speed gear, j Time slot n The result of coherent accumulation of the signal after the modulation signal is eliminated in each segment. Then, the data after coherent accumulation of each segment is non-coherently accumulated:

[0061]

[0062] in, It represents the non-coherent accumulation result of each point in each time slot.

[0063] For time slots, the main thing is to accumulate the sliding correlation results after the segmented accumulation of each time slot. Taking into account the code Doppler shift, according to the k The Doppler frequency shift of each time slot is calculated by the code Doppler shift of each time slot. Before performing sliding correlation on the spread spectrum received signal, code offset compensation is performed at the time slot granularity, so that the sliding correlation results between time slots are equivalent to staggered accumulation during accumulation, ensuring that the same code chips are aligned and superimposed when accumulating and merging between time slots, eliminating the impact of code chip expansion and contraction caused by code Doppler. Specifically, in this embodiment, the sliding correlation results between time slots are accumulated using a non-coherent accumulation method to obtain the first k Under the gear position, the sliding correlation result after the accumulation and merging between time slots is .

[0064] The embodiment of the present application can effectively improve the capture performance under low signal-to-noise ratio and reduce the impact of noise on detection by combining coherent and incoherent accumulation.

[0065] Perform peak search on the accumulated sliding correlation results of the kth gear to obtain the corresponding position of the maximum correlation peak and peak size , and then get the timing value Toa(k) and frequency offset estimation value under this gear (k):

[0066]

[0067]

[0068]

[0069]

[0070] Repeat this process to obtain the maximum correlation peak size and position under all gears.

[0071] It's important to note that subsequent data is based on the results of inter-slot accumulation and merging; the original data is never reused. Therefore, in this embodiment, the data cache only needs to store the results of inter-slot accumulation and merging, eliminating the need to retain all matched filtered data as in traditional solutions. This allows the cache capacity to be dependent solely on the length of the correlation function, independent of the detection period. In other words, by decoupling the cache from the integration period length, the data cache capacity remains solely dependent on the length of the correlation sequence, regardless of how long the detection period is extended. This does not increase the system's data cache capacity, significantly reducing the system's memory overhead.

[0072] Finally, compare the size of the maximum correlation peak under each gear, and use the maximum value and corresponding position of each maximum peak as the first frequency offset estimation value and the first time offset estimation value respectively. Specifically, traverse all gears and determine the gear with the largest maximum correlation peak under all gears , and then determine the time-frequency offset estimate as the initial capture result. The maximum correlation peak value of the gear is the first frequency offset estimate, and the position of the maximum correlation peak value is the first time offset estimate:

[0073]

[0074]

[0075] in, is the time-biased estimate, is the estimated value of frequency offset.

[0076] In practical applications, to balance processing complexity and effectiveness, the gear granularity is designed to be coarse. Furthermore, satellites are highly dynamic, with PSC (Primary Synchronization Code) and SSC (Secondary Synchronization Code) detection data segments spaced far apart, leading to significant variations in time-frequency offset. Therefore, in the embodiments of the present application, after completing initial capture, secondary capture is performed using the initial capture results to improve capture accuracy and sensitivity. Secondary capture primarily includes time-domain capture and frequency-domain capture processes. The time-domain capture process is identical to the initial capture process, while the frequency-domain capture process is partially identical to the initial capture process. In practical applications, secondary capture utilizes the same algorithm as the initial capture algorithm, modularizing the initial capture algorithm and enabling module reuse by configuring different parameters. This significantly improves capture accuracy and sensitivity while also offering excellent module reusability, facilitating practical engineering implementation or chip integration.

[0077] S300: After compensating the spread spectrum received signal based on the first time offset estimation value and the first frequency offset estimation value, perform time domain capture to obtain a second time offset estimation value.

[0078] For time domain capture, this embodiment primarily utilizes the initial capture results to compensate for the timing, frequency, and code offsets of the spread-spectrum received signal. The sliding correlation operation in S200 is then repeated to obtain a second time offset estimate. Specifically, the spread-spectrum received signal is first compensated based on the first time offset estimate and the first frequency offset estimate. The compensated spread-spectrum received signal is then rearranged at a time slot granularity. Next, the rearranged, compensated spread-spectrum received signal is subjected to sliding correlation with a local pilot sequence. Finally, the sliding correlation results are accumulated by time slot, and a peak search is performed on the accumulated results. The position corresponding to the maximum correlation peak is used as the second time offset estimate. This second time offset estimate enables time synchronization between the payload and the terminal.

[0079] S400: After compensating the spread spectrum received signal based on the second time offset estimation value and the first frequency offset estimation value, frequency domain capture is performed to obtain a second frequency offset estimation value.

[0080] For frequency domain capture, this embodiment first uses the first frequency offset estimate from the initial capture result and the second time offset estimate from the secondary time domain capture to compensate for the timing, frequency, and code offsets of the spread spectrum received signal. Then, the compensated spread spectrum received signal undergoes matched filtering and least squares (LS) channel estimation to obtain channel data. Finally, after performing a fast Fourier transform on the channel data, the spectrum is peak-searched, and the peak location is used as the second frequency offset estimate. This second frequency offset estimate enables frequency synchronization between the payload and the terminal.

[0081] It is worth noting that the secondary capture process composed of S300 and S400 in the embodiment of the present application is not only to improve the accuracy of capture, but also to ensure the consistency of the time-frequency offset estimated during time slot synchronization and the time-frequency offset value of subframe synchronization. As mentioned above, since the data of each gear is received serially and processed in real time, and in order to reduce the cache volume, only the result of the time slot accumulation and merging is retained, and the original data is not saved. Therefore, under the influence of the high dynamics of low-orbit satellites, if the data of subsequent frame synchronization (SSC synchronization or auxiliary synchronization) is the same as the first k If the data intervals for slot synchronization (PSC synchronization or main synchronization) are far apart, the estimated time-frequency offset during slot synchronization has exceeded the allowable error range for subframe synchronization. Therefore, after completing initial slot synchronization, a secondary acquisition is performed using the results of the initial acquisition to ensure that the frequency and timing of the initial acquisition are close to the time-frequency offset of the subsequent subframe synchronization data segments, further improving the accuracy and sensitivity of spread spectrum acquisition.

[0082] In the engineering implementation of the spread spectrum capture method proposed in the embodiment of the present application, since only sliding window and real-time processing are used for the received data, only the relevant data needs to be cached, and there is no need to cache all the received data, which greatly reduces the amount of data cached.

[0083] In order to improve the accuracy of capture, the traditional solution uses multiple large-point FFTs, which is extremely unfriendly to actual engineering. In addition, most of its modules are independent algorithms, and the module reusability is not high. For the two capture processes proposed in the embodiment of the present application, the initial capture process can be integrated into an algorithm module, and the parameters can be adjusted during the second capture and the algorithm module of the initial capture can be reused, which has good module reusability. In addition, the detection algorithm mainly used in this application can be completed by a simple multiplication accelerator. Not only is it easy to implement and has high development efficiency, but its actual processing efficiency in engineering applications will also be better than that of FFTs with ultra-large points.

[0084] An embodiment of the present application also provides a spread spectrum capture device, including: a binning module, used to bin the satellite movement speed range and calculate the Doppler frequency shift corresponding to each bin; a primary capture module, used to perform sliding correlation on the spread spectrum received signal at each bin, determine the bin with the largest correlation peak, and record a first time offset estimate and a first frequency offset estimate; a secondary time domain capture module, used to compensate the spread spectrum received signal based on the first time offset estimate and the first frequency offset estimate, and then perform time domain capture to obtain a second time offset estimate; and a secondary frequency domain capture module, used to compensate the spread spectrum received signal based on the second time offset estimate and the first frequency offset estimate, and then perform frequency domain capture to obtain a second frequency offset estimate.

[0085] The following describes an electronic device embodiment of the present application, which can be used to perform the high-precision frequency offset estimation method in the above embodiment of the present application. For details not disclosed in the electronic device embodiment, please refer to the above embodiment of the method of the present application.

[0086] Reference Figure 2 As shown, an electronic device 500 according to an embodiment of the present application includes: a memory 501 and a processor 502, wherein the memory 501 stores a computer program corresponding to the spread spectrum capture method described in the first aspect that can be loaded and executed by the processor 502.

[0087] Figure 3 A schematic diagram of the structure of a computer system suitable for implementing an electronic device according to an embodiment of the present application is shown.

[0088] It should be noted that Figure 3 The computer system 600 of the electronic device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0089] like Figure 3 As shown, computer system 600 includes a central processing unit (CPU) 601, which can perform various appropriate actions and processes, such as the methods described in the above embodiments, based on programs stored in read-only memory (ROM) 602 or programs loaded from storage 608 into random access memory (RAM) 603. RAM 603 also stores various programs and data required for system operation. CPU 601, ROM 602, and RAM 603 are interconnected via bus 604. An input / output (I / O) interface 605 is also connected to bus 604.

[0090] The following components are connected to the I / O interface 605: an input section 606 including a keyboard, mouse, and the like; an output section 607 including devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), and speakers; a storage section 608 including a hard disk; and a communication section 609 including a network interface card such as a LAN (Local Area Network) card or a modem. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to the I / O interface 605 as needed. A removable storage medium 611, such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, is installed in the drive 610 as needed, so that computer programs read from the removable storage medium can be installed in the storage section 608 as needed.

[0091] In particular, according to embodiments of the present application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for executing the methods illustrated in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via the communication section 609 and / or installed from a removable storage medium 611. When executed by the central processing unit (CPU) 601, the computer program performs the various functions defined in the system of the present application.

[0092] It should be noted that the computer-readable medium described in the embodiments of this application may be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to, an electrical connection having one or more conductors, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal transmitted in baseband or as part of a carrier wave, which carries computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, or any suitable combination thereof.

[0093] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present application. Among them, each box in the flowchart or block diagram can represent a module, program segment, or part of the code, and the above-mentioned module, program segment, or part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0094] The units involved in the embodiments described in this application may be implemented by software or hardware, and the units described may also be set in a processor. In some cases, the names of these units do not constitute limitations on the units themselves.

[0095] As another aspect, the present application further provides a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the spread spectrum acquisition method described in the above embodiments.

[0096] As another aspect, the present application further provides a computer-readable medium, which may be included in the electronic device described in the above embodiments, or may exist independently and not be incorporated into the electronic device. The computer-readable medium carries one or more programs, and when the one or more programs are executed by the electronic device, the electronic device implements the spread spectrum acquisition method described in the above embodiments.

[0097] It should be noted that, although several modules or units of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiment of the application, the features and functions of two or more modules or units described above can be concretized in one module or unit. On the contrary, the features and functions of one module or unit described above can be further divided into multiple modules or units to be concretized.

[0098] Through the description of the above embodiments, it is easy for those skilled in the art to understand that the example embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solution according to the embodiments of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, and includes a number of instructions to enable a computing device (which can be a personal computer, a server, a touch terminal, or a network device, etc.) to execute the method according to the embodiments of the present application.

[0099] Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances. The drawings in the embodiments are used to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0100] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

[0101] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A spread spectrum acquisition method, characterized in that: include: Divide the range of satellite movement speed into bins; At each gear position, frequency deviation compensation is performed on the spread spectrum received signal; Perform code offset compensation and rearrangement on the spread spectrum received signal after frequency offset compensation according to time slot granularity; Perform sliding correlation between the rearranged spread spectrum received signal and the local pilot sequence; accumulate the sliding correlation results by time slot, and perform peak search on the accumulated results to obtain the position and peak value corresponding to the maximum correlation peak in the current gear; Comparing the magnitudes of the maximum correlation peaks at each gear position, and taking the maximum value and the corresponding position of each maximum peak as the first frequency offset estimation value and the first time offset estimation value, respectively; After compensating for timing, frequency offset, and code offset of the spread spectrum received signal based on the first time offset estimate and the first frequency offset estimate, performing time domain capture to obtain a second time offset estimate; After performing timing, frequency offset, and code offset compensation on the spread spectrum received signal based on the second time offset estimation value and the first frequency offset estimation value, frequency domain capture is performed to obtain a second frequency offset estimation value.

2. The spread spectrum acquisition method according to claim 1, wherein: The frequency deviation compensation is completed using the Doppler frequency shift corresponding to each gear position.

3. The spread spectrum acquisition method according to claim 1, wherein: The code deviation compensation includes: calculating a code Doppler offset according to a Doppler frequency shift corresponding to each gear position, and using the code Doppler offset to complete the code deviation compensation.

4. The spread spectrum acquisition method according to claim 1, wherein: The accumulating the sliding correlation results by time slot specifically includes: Segment-wise accumulation of sliding correlation results within the time slot; The sliding correlation results after the segmented accumulation of each time slot are non-coherently accumulated between time slots.

5. The spread spectrum acquisition method according to claim 4, wherein: The step of accumulating the sliding correlation results in sections within the time slot includes: The sliding correlation results within the time slot are divided into segments, and the data within each segment are coherently accumulated; The data of each segment after coherent accumulation are non-coherently accumulated.

6. The spread spectrum acquisition method according to claim 1, wherein: The time domain capture is completed using the same process as the initial capture.

7. The spread spectrum acquisition method according to claim 1 or 6, wherein: The method further comprises: performing time domain capture to obtain a second time offset estimate value after performing timing, frequency offset, and code offset compensation on the spread spectrum received signal based on the first time offset estimate value and the first frequency offset estimate value; Performing timing, frequency offset, and code offset compensation on the spread spectrum received signal based on the first time offset estimation value and the first frequency offset estimation value; Rearrange the compensated spread spectrum received signal according to the time slot granularity; Sliding correlation is performed between the spread spectrum received signal after rearrangement compensation and the local pilot sequence; The sliding correlation results are accumulated according to the time slots, and a peak search is performed on the accumulated results. The position corresponding to the maximum correlation peak is used as the second time offset estimation value.

8. The spread spectrum acquisition method according to claim 1, wherein: The performing frequency domain capture to obtain the second frequency offset estimate value after performing timing, frequency offset, and code offset compensation on the spread spectrum received signal based on the second time offset estimate value and the first frequency offset estimate value specifically includes: Performing timing, frequency offset, and code offset compensation on the spread spectrum received signal based on the second time offset estimation value and the first frequency offset estimation value; Perform matched filtering and channel estimation on the compensated spread spectrum received signal to obtain channel data; After performing fast Fourier transform on the channel data, a peak search is performed on the spectrum, and the position of the peak is used as the second frequency offset estimation value.

9. The spread spectrum acquisition method according to claim 1, wherein: Use real-time data sources to process data at different gears and cache the data obtained after sliding correlation.

10. A spread spectrum acquisition device, characterized in that: include: The binning module is used to bin the satellite's moving speed range and calculate the Doppler frequency shift corresponding to each bin; A primary capture module is used to perform frequency offset compensation on the spread spectrum received signal at each gear position; The code offset compensation and rearrangement of the spread spectrum received signal after frequency offset compensation are performed at the time slot granularity; the rearranged spread spectrum received signal is sliding correlated with the local pilot sequence; the sliding correlation results are accumulated by time slot and the accumulated results are peak searched to obtain the position and peak value corresponding to the maximum correlation peak in the current gear; Comparing the magnitudes of the maximum correlation peaks at each gear position, and taking the maximum value and the corresponding position of each maximum peak as the first frequency offset estimation value and the first time offset estimation value, respectively; A secondary time domain capture module is configured to perform time domain capture to obtain a second time offset estimate after performing timing, frequency offset, and code offset compensation on the spread spectrum received signal based on the first time offset estimate and the first frequency offset estimate; The secondary frequency domain capture module performs timing, frequency offset and code offset compensation on the spread spectrum received signal based on the second time offset estimation value and the first frequency offset estimation value, and then performs frequency domain capture to obtain the second frequency offset estimation value.

11. An electronic device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and execute the spread spectrum acquisition method according to any one of claims 1 to 9.

12. A computer-readable storage medium having computer program instructions stored thereon, characterized in that: When the program instructions are executed by a processor, they are used to implement the process corresponding to the spread spectrum capture method according to any one of claims 1 to 9.

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