Loss-of-lock re-acquisition method and apparatus based on short-time burst synchronization signals

Abstract

This application relates to a method and apparatus for re-acquiring a lost-lock signal based on a short-time burst synchronization signal. The method includes: designing a short-time burst synchronization signal based on a short-time burst system; reading a certain length of baseband received signal from the starting position of the short-time burst synchronization signal and generating a corresponding local modulation sequence; calculating a carrier signal; performing coherent integration on the carrier signal to obtain the amplitude; determining whether the carrier Doppler frequency range search is complete; if not, recalculating the amplitude according to the Doppler search step; if complete, determining whether the phase search in the time domain is complete; if not, shifting the starting position forward by a certain distance and calculating a new amplitude; if complete, finding the maximum amplitude; and determining whether the maximum amplitude of the acquisition search is greater than a preset threshold; if greater, the signal is considered successfully acquired; otherwise, the signal is considered not acquired. This method can improve the success rate of acquisition.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of space electronic information technology, in particular to a method and device for reacquiring a lost lock based on a short-time burst synchronization signal. BACKGROUND

[0002] In the field of space electronic information technology represented by satellite communication and satellite navigation, data transmission, positioning and timing observation information need to be carried by radio electromagnetic signals. The prerequisite for users to realize the basic functions of communication and navigation is the acquisition and time-frequency synchronization of received signals. Especially when there is a large time delay and Doppler uncertainty in the received signal, blind acquisition and time-frequency synchronization of the received signal is one of the important key technologies of space electronic information systems, and directly affects the service performance of user terminals.

[0003] Traditional medium and high orbit satellite navigation signals mainly use continuous spread spectrum signal system. User terminals need to search for signals in three-dimensional space of time domain, frequency domain and code domain. The computational complexity of single acquisition is large, but when the signal acquisition is successful, the user terminal can enter the tracking state and does not need to continuously acquire the same signal. The dynamic range of traditional medium and high orbit satellite communication signals is relatively small, mainly in time division and frequency division system. User terminals usually search for signals in time domain and frequency domain, and the search dimension and space of acquisition are relatively small. However, for the low-orbit constellation with development potential, both navigation signals and communication signals will face greater satellite dynamics and more mutual interference, so it is necessary to design time-frequency synchronization signals based on short-time burst system and to study the receiving and acquisition method of the signals. SUMMARY

[0004] Therefore, it is necessary to provide a method and device for reacquiring a lost lock based on a short-time burst synchronization signal, which can improve the success probability of acquisition.

[0005] A method for reacquiring a lost lock based on a short-time burst synchronization signal, the method comprising:

[0006] A short-time burst synchronization signal is designed based on a short-time burst system. The short-time burst synchronization signal includes synchronization signal paradigm one, synchronization signal paradigm two, synchronization signal paradigm three and synchronization signal paradigm four.

[0007] A baseband received signal of a certain length is read from the starting position of the short-time burst synchronization signal and a corresponding local modulation sequence is generated. A signal stripped of the modulation sequence is obtained by calculating the baseband received signal and the local modulation sequence.

[0008] A carrier signal is calculated according to the signal stripped of the modulation sequence and the carrier Doppler frequency. The carrier signal is coherently integrated to obtain an amplitude.

[0009] Determine whether the carrier Doppler frequency range search is complete. If the carrier Doppler frequency range search is not complete, search the next carrier Doppler grid, update the carrier Doppler frequency according to the Doppler search step, recalculate the amplitude, and update the corresponding index of the amplitude.

[0010] If the carrier Doppler frequency range search has been completed, determine whether the time domain phase search has been completed. If the time domain phase search has not been completed, search the next time domain phase grid, move the starting position of the short burst synchronization signal forward by a preset distance, update the amplitude index, and calculate the new amplitude. If the time domain phase search has been completed, find the largest amplitude value from multiple amplitude values.

[0011] Determine whether the maximum amplitude of the capture search is greater than a preset threshold. If it is greater than the preset threshold, the signal is considered to have been successfully captured; otherwise, the signal is considered not to have been captured.

[0012] In one embodiment, synchronization signal paradigm one consists of a periodic sequence of all "1" symbols and a unique word, wherein the local modulation sequence is a sequence of all "1" symbols; synchronization signal paradigm two consists of a periodic sequence of "01" symbols and a unique word, wherein the local modulation sequence is a periodic sequence of "01" symbols; synchronization signal paradigm three consists of several relatively short unique words repeated periodically, wherein the local modulation sequence is a unique word with a short period; synchronization signal paradigm four consists of a unique word with a relatively long period, wherein the local modulation sequence is a unique word with a complete long period.

[0013] In one embodiment, a baseband received signal of a certain length is read from the starting position of the short-time burst synchronization signal, and a corresponding local modulation sequence is generated; a signal stripped of the modulation sequence is calculated based on the baseband received signal and the local modulation sequence, including:

[0014] Starting from the signal start position N0, read the baseband received signal s1 of length N1 and generate a local modulation sequence c1 of length N1. Multiply the local modulation sequence c1 with the baseband received signal s1 to obtain the stripped modulation sequence signal s2 of length N1.

[0015] In one embodiment, the carrier signal is calculated based on the signal of the stripped modulation sequence and the carrier Doppler frequency, including:

[0016] The carrier signal is calculated based on the signal obtained from the stripped modulation sequence and the carrier Doppler frequency.

[0017] s3=s2·exp(-2πf d n / f s )

[0018] Among them, f dwhere f is the carrier Doppler frequency, n represents the serial number of the digital signal, f s where f is the carrier Doppler frequency, n represents the serial number of the digital signal, f

[0019] In one embodiment, the carrier Doppler frequency is updated according to the step of Doppler search, including:

[0020] The carrier Doppler frequency is updated according to the step of Doppler search, f d ′ = f d + d, where d represents the step of Doppler search.

[0021] In one embodiment, the serial number of the amplitude is updated after the starting position of the short-time burst synchronization signal is moved forward by a preset distance, including:

[0022] The starting position N0 of the short-time burst synchronization signal is moved forward by y points, i.e. N0′ = N0 + y, and the serial number i of the amplitude is updated to i + 1, where y represents the size of one time-domain grid in the acquisition search.

[0023] A lock-loss reacquisition device based on a short-time burst synchronization signal, the device comprising:

[0024] A short-time burst synchronization signal design module for designing a short-time burst synchronization signal based on a short-time burst system; the short-time burst synchronization signal comprises a synchronization signal paradigm one, a synchronization signal paradigm two, a synchronization signal paradigm three and a synchronization signal paradigm four;

[0025] A signal stripping module for reading a certain length of baseband received signal from the starting position of the short-time burst synchronization signal and generating a corresponding local modulation sequence; a stripped modulation sequence signal is obtained by calculation based on the baseband received signal and the local modulation sequence;

[0026] An amplitude calculation module for calculating a carrier signal based on the stripped modulation sequence signal and the carrier Doppler frequency; a coherent integration is performed on the carrier signal to obtain an amplitude;

[0027] A frequency search module for judging whether the search of the carrier Doppler frequency range is completed, if not, searching the next carrier Doppler grid, updating the carrier Doppler frequency according to the step of Doppler search, recalculating the amplitude and updating the serial number corresponding to the amplitude;

[0028] A time-domain search module for judging whether the phase search in the time domain is completed if the search of the carrier Doppler frequency range is completed, if not, searching the next time-domain phase grid, moving the starting position of the short-time burst synchronization signal forward by a preset distance, updating the serial number of the amplitude and calculating a new amplitude; if the phase search in the time domain is completed, finding the maximum amplitude from a plurality of amplitudes.

[0029] a capture decision module, configured to determine whether a maximum amplitude of the capture search is greater than a preset threshold, and if greater than the preset threshold, consider that a signal is successfully captured, and otherwise consider that a signal is not captured.

[0030] The short-burst synchronization signal-based loss-of-lock recapturing method and device, the application first designs a short-burst synchronization signal based on a short-burst system, gives four typical synchronization signal design structure paradigms, which can take into account the calculation complexity and high reliable reception, effectively meet the application requirements of large time delay variation and wide Doppler range for low-orbit satellite signal acquisition; then designs a loss-of-lock recapturing method based on the short-burst synchronization signal, uses the periodic broadcasting characteristics of the short-burst synchronization signal, determines the shrinkage range in the frequency domain first, then performs time domain shrinkage based on the frequency domain search, and searches in a very small range, which can greatly reduce the unnecessary search range to compress the time-frequency search space, further improve the acquisition probability, and through simulation experiments, the simulation results show that under the conditions of signal duration of 1.5 ms, time delay deviation of 0.2 ms, carrier deviation of 250 Hz, false alarm probability of 0.1%, and acquisition probability of 90%, the acquisition sensitivity of the received signal can still be 42 dB-Hz. In the application, a structure similar to a classical receiver is maintained, and complex operations such as matrix inversion and eigenvalue decomposition are not involved, so the application is simple to implement, has small amount of calculation, and is very convenient to implement. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A flowchart of a short-burst synchronization signal-based loss-of-lock recapturing method in one embodiment;

[0032] Figure 2 A structure diagram of a short-burst synchronization signal in one embodiment;

[0033] Figure 3 A framework flowchart of a loss-of-lock recapturing method in one embodiment;

[0034] Figure 4 A relationship diagram of a signal acquisition decision threshold and a false alarm probability in one embodiment;

[0035] Figure 5 A relationship diagram of a short-burst signal duration and a signal acquisition probability in one embodiment;

[0036] Figure 6 A relationship diagram of a short-burst signal time delay deviation and a signal acquisition probability in one embodiment;

[0037] Figure 7 A relationship diagram of a short-burst signal carrier deviation and a signal acquisition probability in one embodiment;

[0038] Figure 8 Figure 6 is a diagram of the relationship between short burst signal delay / carrier offset and signal acquisition probability in one embodiment;

[0039] Figure 9 Figure 7 is a block diagram of a lock-loss reacquisition device based on a short burst synchronization signal in one embodiment. DETAILED DESCRIPTION

[0040] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0041] In one embodiment, as shown in Figure 1 a lock-loss reacquisition method based on a short burst synchronization signal is provided, including the following steps:

[0042] Step 102, a short burst synchronization signal is designed based on a short burst system; the short burst synchronization signal includes a synchronization signal paradigm one, a synchronization signal paradigm two, a synchronization signal paradigm three and a synchronization signal paradigm four.

[0043] The initial acquisition of a traditional continuous spread spectrum system signal needs to search in a three-dimensional space of time domain, frequency domain and code domain, which does not meet the application requirements of large time delay variation and wide Doppler range of low-orbit satellite signals. A short burst synchronization signal is designed based on a short burst system of low-orbit satellite, in which four typical synchronization signal design structure paradigms are given, which is a synchronization signal system considering both the calculation complexity and the high reliable reception requirement, as shown in Figure 2 synchronization signal paradigm one: composed of a periodic sequence of all "1" symbols and a unique word, in which the periodic sequence of all "1" symbols is a single carrier signal after modulating the carrier, and the user can complete the initial acquisition of the signal by using frequency domain search. The unique word can be used to further determine the data type and accurate time synchronization after the initial acquisition of the signal. Synchronization signal paradigm two: composed of a periodic sequence of "01" symbols and a unique word, in which the periodic sequence of "01" symbols exhibits a double carrier characteristic after modulating the carrier, and the user can perform two-dimensional search in time-frequency domain when capturing, and only needs to search for "01" two phases in time domain. The unique word can be used to further determine the data type and accurate time synchronization after the initial acquisition of the signal. Synchronization signal paradigm three: composed of a periodic repetition of a plurality of relatively short unique words, the user searches and captures in a three-dimensional space of time, frequency and code, and the time domain search needs to be performed within a week of a unique word; when different users or different information types use unique words for differentiation, the list of unique words also needs to be searched when capturing for the first time.

[0044] Synchronization signal paradigm four: composed of a relatively long unique word, the user searches in the time-frequency code three-dimensional space, the time domain search needs to traverse the entire length of the special word, when different users or different information types are distinguished by unique words, the first time the user needs to search the list of unique words.

[0045] From synchronization signal paradigm one to synchronization signal paradigm four, the complexity of the user receiving terminal's capture reception gradually increases, and the adaptability to the challenging environment also gradually increases. When designing the system synchronization signal system, the user receiving complexity and safety reliability indicators need to be weighed according to the specific needs.

[0046] Step 104, read a certain length of baseband received signal from the starting position of the short-time burst synchronization signal and generate the corresponding local modulation sequence; calculate the signal stripped of the modulation sequence according to the baseband received signal and the local modulation sequence.

[0047] As shown in Figure 3 , input the short-time burst synchronization signal s0, initialize i=0, read the baseband received signal s1 of length N1 from the starting position N0 of the signal, generate the local modulation sequence c1 of length N1, and multiply it with the baseband received signal s1 to get the signal s2=s1*c1 of length N1 stripped of the modulation sequence.

[0048] Step 106, calculate the carrier signal according to the signal stripped of the modulation sequence and the carrier Doppler frequency; perform coherent integration on the carrier signal to get the amplitude.

[0049] According to the carrier Doppler frequency f d , the carrier on the stripped signal is removed to get the signal s3=s2·exp(-2πf d n / f s ) of length N1. Perform coherent integration on the signal s3 of length N1 stripped of the modulation sequence to get the integrated amplitude A i , corresponding to the Doppler frequency , and the signal delay is

[0050] Step 108, judge whether the search of the carrier Doppler frequency range is completed, if not, search the next carrier Doppler grid, update the carrier Doppler frequency according to the Doppler search step, recalculate the amplitude and update the sequence number corresponding to the amplitude.

[0051] It is prior art to determine whether the search of the carrier Doppler frequency range is completed, which will not be described in detail in the present application. Generally, the range is determined according to the time delay of the signal and the uncertainty of the carrier Doppler frequency. If the search of the carrier Doppler frequency range is not completed, the next carrier Doppler grid is searched, i.e. the carrier Doppler frequency is updated to f d ′ = f d +d, where d represents the step of the Doppler search, and i is updated to i+1.

[0052] If the search of the carrier Doppler frequency range is completed, it is determined whether the search of the time domain phase is completed. If the search of the time domain phase is not completed, the next time domain phase grid is searched, the starting position of the short-time burst synchronization signal is moved forward by a preset distance, the order of the amplitude is updated, and a new amplitude is calculated. If the search of the time domain phase is completed, the maximum amplitude is found from the multiple amplitudes.

[0053] It is prior art to determine whether the search of the time domain phase is completed if the search of the carrier Doppler frequency range is completed, which will not be described in detail in the present application. Generally, the range is determined according to the time delay of the signal and the uncertainty of the carrier Doppler frequency. If the search of the time domain phase is not completed, the next time domain phase grid is searched, i.e. the starting position N0 of the received signal is moved forward by y points, i.e. N0=N0+y, and i is updated to i+1. y is the size of a time domain grid in the acquisition search, which can be set by the user according to the requirement. The smaller y is, the denser the search is, the higher the precision is, and the larger the calculation amount is.

[0054] The maximum amplitude is found from the acquisition results [A0 A1 A2 A3 A4……]. j The corresponding acquisition frequency is f j The maximum amplitude is used to make the acquisition decision.

[0055] In step 112, it is determined whether the maximum amplitude of the acquisition search is greater than a preset threshold. If the maximum amplitude is greater than the preset threshold, it is considered that the signal is successfully acquired. Otherwise, it is considered that the signal is not acquired.

[0056] In the above method for reacquiring a loss of lock based on a short-burst synchronization signal, the application first designs a short-burst synchronization signal based on a short-burst system, and four typical design structures of the synchronization signal are given, which can take into account the calculation complexity and high reliable reception, and effectively meet the application requirements of large time delay variation and wide Doppler range for low-orbit satellite signal acquisition. Then, a method for reacquiring a loss of lock is designed based on the short-burst synchronization signal. By using the periodic broadcasting feature of the short-burst synchronization signal, the contraction range in the frequency domain is first determined, and then the time domain is contracted based on the frequency domain search, and the search is performed in a very small range, which can greatly reduce the unnecessary search range to compress the time-frequency search space, and further improve the acquisition probability. Simulation results show that, under the conditions of a signal duration of 1.5 ms, a time delay deviation of 0.2 ms, a false alarm probability of 0.1% and an acquisition probability of 90%, the acquisition sensitivity of the received signal can still be 42 dB-Hz. In the application, a structure similar to that of a classical receiver is maintained, and complex operations such as matrix inversion and eigenvalue decomposition are not involved, so the application is simple to implement, has small calculation amount, and is very convenient to implement.

[0057] In one embodiment, the synchronization signal paradigm one is composed of a periodic sequence of all "1" symbols and a unique word, wherein the local modulation sequence is a periodic sequence of all "1" symbols; the synchronization signal paradigm two is composed of a periodic sequence of "01" symbols and a unique word, wherein the local modulation sequence is a periodic sequence of "01" symbols; the synchronization signal paradigm three is composed of a plurality of unique words with relatively short lengths repeated periodically, wherein the local modulation sequence is a unique word with a short period; and the synchronization signal paradigm four is composed of a unique word with a relatively long length, wherein the local modulation sequence is a unique word with a complete long period.

[0058] In one embodiment, a baseband received signal of a certain length is read from the starting position of the short-burst synchronization signal to generate a corresponding local modulation sequence; and a signal stripped of modulation sequence is obtained by calculation based on the baseband received signal and the local modulation sequence, including:

[0059] The baseband received signal s1 of length N1 is read from the starting position N0 of the signal to generate the local modulation sequence c1 of length N1, the local modulation sequence c1 is multiplied by the baseband received signal s1 to obtain the signal s2 stripped of modulation sequence of length N1.

[0060] In one embodiment, a carrier signal is calculated based on the signal stripped of modulation sequence and the carrier Doppler frequency, including:

[0061] The carrier signal calculated based on the signal stripped of modulation sequence and the carrier Doppler frequency is

[0062] s3=s2·exp(-2πf d n / f s )

[0063] Among them, f d Here, f is the carrier Doppler frequency, n represents the sequence number of the digital signal, and f is the frequency of the carrier Doppler. s s1 represents the sampling frequency, and s2 is the signal stripped of the modulation sequence.

[0064] In one embodiment, updating the carrier Doppler frequency according to the Doppler search steps includes:

[0065] The carrier Doppler frequency is updated stepwise based on the Doppler search, with frequency f. d ′=f d +d, where d represents the step size of the Doppler search.

[0066] In one embodiment, updating the amplitude sequence number after shifting the starting position of the short-time burst synchronization signal forward by a predetermined distance includes:

[0067] Move the starting position N0 of the short burst synchronization signal forward by y points, i.e., N0′=N0+y, and update the amplitude index i=i+1 at the same time. y represents the size of a time-domain grid in the capture search.

[0068] In one embodiment, Figure 4 The relationship between the signal acquisition decision threshold and the false alarm probability is shown in the figure. In this embodiment, a Monte Carlo simulation was performed with 100,000 repetitions. The simulation settings included a signal symbol rate of 32 kHz, a coherent integration time of 1.5 ms, a sampling frequency of 250 kHz, and normalization of the coherent integration by the number of points. The acquisition decision threshold range was considered to be 2.0–3.0. Simulation results show that as the decision threshold increases, the false alarm probability of the received signal acquisition continuously decreases; when the false alarm probability is controlled at 0.1%, the acquisition decision threshold is approximately 2.6.

[0069] In one embodiment, Figure 5The simulation plots the relationship between the duration of short burst signals and the signal acquisition probability. In this embodiment, a Monte Carlo simulation was used, repeated 100,000 times. The simulation settings included a signal symbol rate of 32 kHz, a sampling frequency of 250 kHz, and normalization of the coherent integral by the number of points. The acquisition decision threshold was set to 2.6. The simulation considered four cases: a received signal carrier-to-noise ratio (CNR) ranging from 30 dB-Hz to 45 dB-Hz, and received signal durations of 0.5 ms, 1.0 ms, 1.5 ms, and 2.0 ms. The simulation results show that as the received signal CNR increases, the signal acquisition probability gradually increases and eventually approaches 1. Taking an acquisition probability greater than 90% as the decision threshold for signal acquisition sensitivity, the longer the signal duration, the higher the acquisition sensitivity. The capture sensitivity is approximately 44 dB-Hz when the signal duration is 0.5 ms; approximately 41 dB-Hz when the signal duration is 1.0 ms; approximately 39 dB-Hz when the signal duration is 1.5 ms; and approximately 38 dB-Hz when the signal duration is 2.0 ms.

[0070] In one embodiment, Figure 6 This diagram illustrates the relationship between short burst signal delay deviation and signal acquisition probability. In this embodiment, a Monte Carlo simulation was conducted with 100,000 repetitions. The simulation settings included a signal symbol rate of 32 kHz, a received signal duration of 1.5 ms, a sampling frequency of 250 kHz, and normalization of the coherent integral by the number of points. The acquisition decision threshold was set to 2.6. The simulation considered five cases: received signal carrier-to-noise ratio (CNR) ranging from 30 dB-Hz to 45 dB-Hz, and received signal delay deviations of ±0.2 ms, ±0.1 ms, and 0 ms. Simulation results show that a larger received signal delay deviation leads to lower acquisition sensitivity. When the received signal delay deviation is 0 ms, the acquisition sensitivity is approximately 39 dB-Hz; when the received signal delay deviation is ±0.1 ms, the acquisition sensitivity is approximately 39.5 dB-Hz; and when the received signal delay deviation is ±0.2 ms, the acquisition sensitivity is approximately 40 dB-Hz.

[0071] In one embodiment, Figure 7This diagram illustrates the relationship between carrier deviation and signal acquisition probability for short burst signals. In this embodiment, a Monte Carlo simulation was performed with 100,000 repetitions. The simulation settings included a signal symbol rate of 32 kHz, a received signal duration of 1.5 ms, a sampling frequency of 250 kHz, and normalization of the coherent integral by the number of points. The acquisition decision threshold was set to 2.6. The simulation considered five scenarios: a received signal carrier-to-noise ratio (CNR) ranging from 30 dB-Hz to 45 dB-Hz, and received signal carrier deviations of ±250 Hz, ±125 Hz, and 0 Hz. Simulation results show that a larger received signal delay deviation leads to lower acquisition sensitivity. When the received signal carrier deviation is 0 Hz, the acquisition sensitivity is approximately 39 dB-Hz; when the received signal carrier deviation is ±125 Hz, the acquisition sensitivity is approximately 39.5 dB-Hz; and when the received signal carrier deviation is ±250 Hz, the acquisition sensitivity is approximately 41 dB-Hz.

[0072] In one embodiment, Figure 8 The diagram illustrates the relationship between short burst signal delay / carrier deviation and signal acquisition probability. In this embodiment, a Monte Carlo simulation was performed with 100,000 repetitions. The simulation settings included a signal symbol rate of 32 kHz, a received signal duration of 1.5 ms, a sampling frequency of 250 kHz, and normalization of the coherent integral by the number of points. The acquisition decision threshold was set to 2.6. Considering a received signal carrier-to-noise ratio range of 30 dB-Hz to 45 dB-Hz, three levels of received signal delay and carrier deviation were set: (0 ms, 0 Hz), (0.1 ms, 125 Hz), and (0.2 ms, 250 Hz). Simulation results show that when the received signal delay and carrier deviation are (0 ms, 0 Hz), the acquisition sensitivity is approximately 39 dB-Hz; when the received signal delay and carrier deviation are (0.1 ms, 125 Hz), the acquisition sensitivity is approximately 40 dB-Hz; and when the received signal delay and carrier deviation are (0.2 ms, 250 Hz), the acquisition sensitivity is approximately 42 dB-Hz.

[0073] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0074] In one embodiment, such as Figure 9 As shown, a lock-out re-acquisition device based on a short-time burst synchronization signal is provided, comprising: a short-time burst synchronization signal design module 902, a signal stripping module 904, an amplitude calculation module 906, a frequency search module 908, a time-domain search module 910, and an acquisition decision module 912, wherein:

[0075] The short-time burst synchronization signal design module 902 is used to design and obtain a short-time burst synchronization signal based on the short-time burst system; the short-time burst synchronization signal includes synchronization signal paradigm one, synchronization signal paradigm two, synchronization signal paradigm three and synchronization signal paradigm four;

[0076] The signal stripping module 904 is used to read a certain length of baseband received signal starting from the beginning position of the short burst synchronization signal and generate a corresponding local modulation sequence; and to calculate the stripped modulation sequence signal based on the baseband received signal and the local modulation sequence.

[0077] The amplitude calculation module 906 is used to calculate the carrier signal based on the signal stripped of the modulation sequence and the carrier Doppler frequency; and to perform coherent integration on the carrier signal to obtain the amplitude.

[0078] The frequency search module 908 is used to determine whether the search of the carrier Doppler frequency range has been completed. If the search of the carrier Doppler frequency range has not been completed, the next carrier Doppler grid is searched, the carrier Doppler frequency is updated according to the step of the Doppler search, the amplitude is recalculated, and the corresponding index of the amplitude is updated.

[0079] The time-domain search module 910 is used to determine whether the time-domain phase search is completed if the carrier Doppler frequency range search has been completed. If the time-domain phase search is not completed, it searches the next time-domain phase grid, moves the starting position of the short-time burst synchronization signal forward by a preset distance, updates the amplitude sequence number, and calculates the new amplitude. If the time-domain phase search is completed, it finds the largest amplitude value from multiple amplitude values.

[0080] The capture decision module 912 is used to determine whether the maximum amplitude of the capture search is greater than a preset threshold. If it is greater than the preset threshold, the signal is considered to have been successfully captured; otherwise, the signal is considered not to have been captured.

[0081] Specific limitations regarding the lock-loss recapture device based on short-time burst synchronization signals can be found in the limitations of the lock-loss recapture method based on short-time burst synchronization signals mentioned above, and will not be repeated here. Each module in the aforementioned lock-loss recapture device based on short-time burst synchronization signals can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in the computer device, or stored in software in the memory of the computer device, so that the processor can call and execute the operations corresponding to each module.

[0082] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for lock-loss reacquisition based on a short-time burst synchronization signal, characterized in that, The method includes: Short-time burst synchronization signals are obtained based on the design of the short-time burst system; the short-time burst synchronization signals include synchronization signal paradigm one, synchronization signal paradigm two, synchronization signal paradigm three and synchronization signal paradigm four; A certain length of baseband received signal is read from the starting position of the short-time burst synchronization signal, and a corresponding local modulation sequence is generated; the signal stripped of the modulation sequence is calculated based on the baseband received signal and the local modulation sequence. The carrier signal is calculated based on the signal of the stripped modulation sequence and the carrier Doppler frequency; the amplitude is obtained by coherent integration of the carrier signal. Determine whether the carrier Doppler frequency range search is complete. If the carrier Doppler frequency range search is not complete, search the next carrier Doppler grid, update the carrier Doppler frequency according to the Doppler search step, recalculate the amplitude, and update the corresponding index of the amplitude. If the carrier Doppler frequency range search has been completed, determine whether the time domain phase search has been completed. If the time domain phase search has not been completed, search the next time domain phase grid, move the starting position of the short burst synchronization signal forward by a preset distance, update the amplitude index, and calculate the new amplitude. If the time domain phase search has been completed, find the largest amplitude value from multiple amplitude values. Determine whether the maximum amplitude of the capture search is greater than a preset threshold. If it is greater than the preset threshold, the signal is considered to have been successfully captured; otherwise, the signal is considered not to have been captured. The synchronization signal paradigm one consists of a periodic sequence of all "1" symbols and a unique word, wherein the local modulation sequence is a sequence of all "1" symbols; the synchronization signal paradigm two consists of a periodic sequence of "01" symbols and a unique word, wherein the local modulation sequence is a periodic sequence of "01" symbols; the synchronization signal paradigm three consists of several relatively short unique words repeated periodically, wherein the local modulation sequence is a unique word with a short period; the synchronization signal paradigm four consists of a unique word with a relatively long period, wherein the local modulation sequence is a unique word with a complete long period.

2. The method of claim 1, wherein, A certain length of baseband received signal is read from the starting position of the short burst synchronization signal and a corresponding local modulation sequence is generated; The signal obtained by calculating the stripped modulation sequence based on the baseband received signal and the local modulation sequence includes: from the signal start position N 0, read the length of N 1 baseband received signal s 1 and generate a length of N 1 local modulation sequence c 1, multiply the local modulation sequence c 1 with the baseband received signal s 1 to obtain a length of N 1 signal of the stripped modulation sequence s 2.

3. The method of claim 1, wherein, The carrier signal is calculated based on the signal of the stripped modulation sequence and the carrier Doppler frequency, including: The carrier signal is calculated based on the signal of the stripped modulation sequence and the carrier Doppler frequency. wherein f d is the carrier Doppler frequency, n denotes the sequence number of the digital signal, f s denotes the sampling frequency, s 2 is the signal of the stripping modulation sequence.

4. The method of claim 3, wherein, The carrier Doppler frequency is updated stepwise based on the Doppler search, including: The carrier Doppler frequency is updated in steps according to a Doppler search as wherein, d denotes a step of the Doppler search.

5. The method according to any one of claims 1 to 4, characterized in that, The sequence number of the amplitude is updated after moving the starting position of the short-time burst synchronization signal forward by a preset distance, including: Starting position of short burst synchronization signal N 0 is shifted forward y point, i.e. the sequence number of the amplitude is updated at the same time i = i + 1, y denotes the size of one time domain bin in the acquisition search.

6. A device for re-acquiring a lost-lock signal based on a short-time burst synchronization signal, characterized in that, The device includes: The short burst synchronization signal design module is configured to design a short burst synchronization signal based on a short burst system; the short burst synchronization signal comprises a synchronization signal paradigm one, a synchronization signal paradigm two, a synchronization signal paradigm three and a synchronization signal paradigm four; the synchronization signal paradigm one is composed of a periodic sequence with all "1" symbols and a unique word, wherein the local modulation sequence is the periodic sequence with all "1" symbols; the synchronization signal paradigm two is composed of a periodic sequence with "01" symbols and a unique word, wherein the local modulation sequence is the periodic sequence with "01" symbols; the synchronization signal paradigm three is composed of a plurality of unique word periods with relatively short lengths, wherein the local modulation sequence is a unique word with a short period; and the synchronization signal paradigm four is composed of a unique word with a relatively long length, wherein the local modulation sequence is the unique word with a complete long period. The signal stripping module is configured to read a baseband receiving signal with a certain length from a starting position of the short burst synchronization signal and generate a corresponding local modulation sequence; and calculate a stripped modulation sequence signal based on the baseband receiving signal and the local modulation sequence. The amplitude calculation module is configured to calculate a carrier signal based on the stripped modulation sequence signal and a carrier Doppler frequency; and perform coherent integration on the carrier signal to obtain an amplitude. The frequency search module is configured to determine whether the search of a carrier Doppler frequency range is completed; if the search of the carrier Doppler frequency range is not completed, search a next carrier Doppler grid, update the carrier Doppler frequency based on a Doppler search step, recalculate the amplitude and update a sequence number corresponding to the amplitude. The time domain search module is configured to determine whether the phase search in the time domain is completed if the search of the carrier Doppler frequency range is completed; if the phase search in the time domain is not completed, search a next time domain phase grid, update the sequence number of the amplitude and calculate a new amplitude after the starting position of the short burst synchronization signal is moved by a preset distance; and find a maximum amplitude from a plurality of amplitudes if the phase search in the time domain is completed. The acquisition decision module is configured to determine whether the maximum amplitude of the acquisition search is greater than a preset threshold; if the maximum amplitude is greater than the preset threshold, it is considered that the signal is successfully acquired; otherwise, it is considered that the signal is not acquired.

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