An eLoran signal acquisition and cycle identification method, system and apparatus

Abstract

This application belongs to the field of radio communication technology, specifically relating to a method, system, and device for eLoran signal acquisition and period identification. The method includes: acquiring an eLoran signal; squaring the signal based on its waveform characteristics and then low-pass filtering to obtain an envelope signal; performing GRI correlation on the envelope signal to obtain several sets of correlation peaks; accumulating the correlation peaks; and determining whether acquisition was successful based on the accumulation result. It exhibits good noise immunity, with all obtained correlation peaks being positive, ensuring correct accumulation and avoiding the influence of phase differences. After successful acquisition, the received eLoran signal is linearly averaged. Based on the peak value position of the first correlation peak, a multiple peak-to-peak ratio (PMR) decision is performed on the linearly averaged signal to identify the position of the third positive peak. The position of the zero-crossing point of the third cycle is then identified based on the position of the third positive peak. The use of multiple PMR decision reduces the influence of residual noise on the PMR decision and improves identification accuracy.

Description

Technical Field

[0001] This application belongs to the field of radio communication technology, and specifically relates to an eLoran signal acquisition and period identification method, system and device. Background Technology

[0002] eLoran (Enhanced Long Range Navigation) signal transmitters require the construction of corresponding timing monitoring stations to monitor timing integrity, ensure the quality of timing signal transmission, and improve the reliability of the eLoran timing system. Both eLoran signal monitoring and decoding require signal acquisition and period identification technologies. eLoran signal acquisition is a crucial step in ensuring the smooth progress of subsequent processes. This process requires confirming the repetition period of the pulse group, identifying the corresponding station chain, and acquiring the signal from that station. Period identification is the final step before measuring various signal parameters. This process requires determining the zero-crossing point of the third cycle. Accurate identification is essential for obtaining the parameters corresponding to each position, preparing for subsequent measurement or decoding processes. Therefore, eLoran signal acquisition and period identification technologies are indispensable for the smooth progress of subsequent decoding or parameter acquisition processes.

[0003] Currently, the main methods for eLoran signal acquisition include traditional acquisition, envelope delay correlation acquisition, coherent acquisition, and matched filtering acquisition. Traditional acquisition methods perform phase correlation accumulation only once per pulse group, requiring a long acquisition time and affecting reception efficiency. Coherent acquisition and matched filtering acquisition methods are affected by the new eLoran signal regime, with pulse position modulation affecting the accuracy of correlation peak decision. Delay correlation acquisition has certain requirements on the signal-to-noise ratio of the received signal, and this method is also affected by the new eLoran signal regime.

[0004] eLoran period identification methods mainly include derived pulse method, half-period peak method, joint period identification method, sequence polarity detection method, matched correlation method, waveform matching method, and delay addition method. The derived pulse method, waveform matching method, half-period peak method, sequence polarity detection method, delay addition method, joint period identification method, and peak-to-peak ratio method all require good signal-to-noise ratio conditions or accurate identification of the skywave position. The matched correlation method requires a high sampling rate and has a large computational load. Summary of the Invention

[0005] The purpose of this application is to provide an eLoran signal acquisition and period identification method, system and device to solve the technical problems of long acquisition time, high signal-to-noise ratio requirements and low identification accuracy in the prior art.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides an eLoran signal acquisition and period identification method, comprising:

[0008] Obtain the eLoran signal, square the signal according to its waveform characteristics, and then low-pass filter it to obtain the envelope signal.

[0009] The envelope signal is correlated with GRI (Group Repetition Interval) to obtain several sets of correlation peaks. The correlation peaks are accumulated to obtain the accumulation result. The eLoran signal acquisition is determined based on the accumulation result. If it is unsuccessful, the process returns to reacquire the eLoran signal.

[0010] After successful acquisition, the received eLoran signal is linearly averaged. Based on the peak position of the first relevant peak captured by the eLoran signal, multiple peak ratio decision is performed on the linearly averaged eLoran signal to identify the position of the positive peak of the third week. Based on the position of the positive peak of the third week, the position of the zero crossing point of the third week is identified.

[0011] Preferably, the step of acquiring the eLoran signal, which involves squaring the signal based on its waveform characteristics and then low-pass filtering to obtain the envelope signal, specifically includes:

[0012] Obtain the eLoran signal, assuming the envelope function of the eLoran signal is W(t), and the eLoran signals with phase encodings of 0° and 180° are S0(t) and S... π (t), as shown in the following formula:

[0013]

[0014]

[0015] The squared result is obtained by squaring the eLoran signals with phase encodings of 0° and 180°:

[0016]

[0017] The squared result is filtered through a low-pass filter to obtain the square of the envelope function, and the envelope signal is obtained from the square of the envelope function.

[0018] In the formula, This represents an eLoran signal with a phase code of 0°. This represents an eLoran signal with a phase encoding of 180°; W(t) represents the envelope function of the eLoran signal. Represents the carrier trigonometric function; Represents the angular frequency of the carrier trigonometric function; Indicates time.

[0019] Preferably, the plurality of correlation peaks are combinations of two positive correlation peaks, corresponding to the main station and the secondary station respectively. The main station has 9 positive correlation peaks, and the secondary station has 8 positive correlation peaks.

[0020] The cumulative result is obtained by accumulating several sets of related peaks. If the size and number of related peaks in the cumulative result correspond to the configuration of the main station and the auxiliary station, then the eLoran signal is judged to have been successfully captured.

[0021] Preferably, the step of performing multiple peak-to-peak ratio (PSR) determination on the linearly averaged signal specifically includes:

[0022] The ratio of adjacent positive peaks is detected for the linearly averaged signal. When the ratio of adjacent positive peaks falls within the preset threshold range of A4 / A3, it is considered that the position of the third positive peak has been preliminarily identified.

[0023] The linearly averaged signal is delayed by 10μs and superimposed on the original linearly averaged signal. The ratio of adjacent positive peaks is detected again. When the ratio of adjacent positive peaks falls within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third positive peak has been detected.

[0024] By using the positional relationship between the third week's positive peak and the third week's zero-crossing point, and the sampling rate, the peak ratio up to the third week's zero-crossing point is calculated. If the peak ratio does not fall within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third week's positive peak has been initially identified as incorrect, and the identification will start again from the place that was not detected. Here, A2 represents the second positive peak value at the beginning of the eLoran signal; A3 represents the third positive peak value at the beginning of the eLoran signal; and A4 represents the fourth positive peak value at the beginning of the eLoran signal.

[0025] Preferably, the value of (A4+A3) / (A3+A2) is calculated using the following formula:

[0026]

[0027] In the formula, To reach midnight, This indicates the positive peak value one week after midnight. This indicates the peak value of the week preceding midnight. This indicates the peak value two weeks prior to midnight; This indicates the time corresponding to the peak one week after midnight; This indicates the time corresponding to the peak one week before midnight; This indicates the time corresponding to the peak two weeks before midnight.

[0028] A second aspect of this application provides an eLoran signal acquisition and period identification system, comprising:

[0029] The acquisition unit is used to acquire the eLoran signal, and after squaring the eLoran signal according to its waveform characteristics, it performs low-pass filtering to obtain the envelope signal.

[0030] The judgment unit is used to perform GRI correlation on the envelope signal to obtain several sets of correlation peaks, accumulate the several sets of correlation peaks to obtain the accumulation result, and judge whether the eLoran signal acquisition is successful based on the accumulation result. If it is unsuccessful, it returns to reacquire the eLoran signal.

[0031] The identification unit is used to perform linear averaging on the received eLoran signal after successful acquisition, perform multiple peak ratio judgment on the linearly averaged eLoran signal based on the peak position of the first relevant peak captured by the eLoran signal, identify the position of the positive peak of the third week, and identify the position of the zero crossing point of the third week based on the position of the positive peak of the third week.

[0032] Preferably, in the acquisition unit, the eLoran signal is acquired, and the signal is squared and low-pass filtered according to the waveform characteristics of the eLoran signal to obtain the envelope signal, specifically including:

[0033] Obtain the eLoran signal, assuming the envelope function of the eLoran signal is W(t), and the pulse signals with phase encodings of 0° and 180° are S0(t) and S... π (t), as shown in the following formula:

[0034]

[0035]

[0036] The squared result is obtained by squaring the pulse signals whose phases are encoded as 0° and 180°:

[0037]

[0038] The squared result is filtered through a low-pass filter to obtain the square of the envelope function, and the envelope signal is obtained from the square of the envelope function.

[0039] Preferably, the identification unit performs multiple peak-to-peak ratio (PSR) determination on the linearly averaged signal, specifically including:

[0040] The ratio of adjacent positive peaks is detected for the linearly averaged signal. When the ratio of adjacent positive peaks falls within the preset threshold range of A4 / A3, it is considered that the position of the third positive peak has been preliminarily identified.

[0041] The linearly averaged signal is delayed by 10μs and superimposed on the original linearly averaged signal. The ratio of adjacent positive peaks is detected again. When the ratio of adjacent positive peaks falls within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third positive peak has been detected.

[0042] By using the positional relationship between the third week's positive peak and the third week's zero-crossing point, and the sampling rate, the peak ratio up to the third week's zero-crossing point is calculated. If the peak ratio does not fall within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third week's positive peak has been initially identified as incorrect, and the identification will start again from the place that was not detected. Here, A2 represents the second positive peak value at the beginning of the eLoran signal; A3 represents the third positive peak value at the beginning of the eLoran signal; and A4 represents the fourth positive peak value at the beginning of the eLoran signal.

[0043] In a third aspect, this application provides an electronic device including a processor and a memory, the processor being configured to execute a computer program stored in the memory to implement the eLoran signal capture and period identification method described in any one of the preceding claims.

[0044] In a fourth aspect, this application provides a computer-readable storage medium storing at least one instruction that, when executed by a processor, implements the eLoran signal capture and period recognition method described in any one of the preceding claims.

[0045] Compared with the prior art, the beneficial effects of this application are as follows:

[0046] This application provides an eLoran signal acquisition and period identification method. For signal acquisition, based on the signal's inherent characteristics, a squared-sum low-pass filter is used for envelope extraction. After envelope extraction, a GRI delay is applied for correlation and accumulation. This process exhibits good noise immunity, and all obtained correlation peaks are positive, ensuring accurate accumulation and avoiding the influence of phase differences. For eLoran signal period identification, multiple peak-to-peak ratio (PPR) identification is employed. Based on the eLoran signal acquisition marker, the PPR of nearby signals is identified. After identifying a PPR within a specified range, the signal is delayed by 10 μs and superimposed on the original signal. The PPR at the original position is then identified again. If the PPR at that position after delay and superposition falls within the specified range, identification is successful; otherwise, re-detection is performed. Linear averaging is applied to the successfully acquired eLoran signals. The output signal-to-noise ratio (SNR) after linear averaging increases logarithmically with the number of superpositions, with a rapid initial increase followed by a slower increase. This process effectively improves the output SNR. In subsequent testing, the use of two peak-to-peak ratio decisions reduced the impact of residual noise on the peak-to-peak ratio decision, which significantly reduced the probability of incorrect peak-to-peak ratio decisions and improved the accuracy of zero-crossing point identification in the third week. Attached Figure Description

[0047] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0048] Figure 1 This is a schematic diagram of the method flow of an embodiment of this application;

[0049] Figure 2 This is a flowchart illustrating the eLoran signal acquisition process according to an embodiment of this application.

[0050] Figure 3 This is a flowchart illustrating the eLoran period identification process according to an embodiment of this application.

[0051] Figure 4 This is a peak position identification diagram of an embodiment of this application;

[0052] Figure 5 This is a system structure block diagram of an embodiment of this application;

[0053] Figure 6 This is a structural block diagram of an electronic device according to an embodiment of this application. Detailed Implementation

[0054] The present application will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present application can be combined with each other.

[0055] The following detailed descriptions are exemplary and intended to provide further detailed explanation of this application. Unless otherwise specified, all technical terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application.

[0056] See Figure 1 This application discloses an eLoran signal acquisition and period identification method, including:

[0057] S1: Obtain the eLoran signal, square the eLoran signal according to its waveform characteristics, and then low-pass filter it to obtain the envelope signal;

[0058] S2: Perform GRI correlation on the envelope signal to obtain several sets of correlation peaks. Accumulate the several sets of correlation peaks to obtain the accumulation result. Determine whether the eLoran signal acquisition is successful based on the accumulation result. If it is unsuccessful, return to reacquire the eLoran signal.

[0059] S3: After successful acquisition, the received eLoran signal is linearly averaged. Based on the peak position of the first correlation peak captured by the eLoran signal, a multiple peak-to-peak ratio (PSR) decision is performed on the linearly averaged eLoran signal to identify the position of the third positive peak. The zero-crossing point position of the third cycle is then identified based on the position of the third positive peak. This application provides an eLoran signal acquisition and cycle identification method. In terms of signal acquisition, based on the signal's inherent characteristics, a squared-sum low-pass filter is used for envelope extraction. After envelope extraction, a GRI delay is applied for correlation and accumulation. This process has good noise immunity, and the obtained correlation peaks are all positive, allowing the correlation peaks to accumulate correctly and avoiding the influence of phase differences. For eLoran signal period identification, multiple peak-to-peak ratio (PPR) identification is employed. Based on the markers captured by the eLoran signal, the PPR of nearby locations is identified. After identifying a PPR falling within a specified range, the signal is delayed by 10μs and superimposed on the original signal. The PPR at the original position is then identified again. If the PPR at that position after delay and superposition falls within the specified range, identification is successful; otherwise, re-detection is performed. Linear averaging is applied to the successfully captured eLoran signals. The output signal-to-noise ratio (SNR) after linear averaging increases logarithmically with the number of superpositions, showing a rapid initial increase followed by a slower increase. This process effectively improves the output SNR. In subsequent detection, the use of two PPR decisions reduces the impact of residual noise on the PPR decision, significantly decreasing the probability of incorrect PPR decisions and improving the accuracy of zero-crossing point identification in the third cycle.

[0060] In some embodiments, obtaining the eLoran signal, which involves squaring the signal based on its waveform characteristics and then low-pass filtering to obtain the envelope signal, specifically includes:

[0061] Obtain the eLoran signal, assuming the envelope function of the eLoran signal is W(t), and the eLoran signals with phase encodings of 0° and 180° are S0(t) and S... π (t), as shown in the following formula:

[0062]

[0063]

[0064] The squared result is obtained by squaring the eLoran signals with phase encodings of 0° and 180°:

[0065]

[0066] The squared result is filtered through a low-pass filter to obtain the square of the envelope function, and the envelope signal is obtained from the square of the envelope function.

[0067] In the formula, This represents an eLoran signal with a phase code of 0°. This represents an eLoran signal with a phase encoding of 180°; W(t) represents the envelope function of the eLoran signal. Represents the carrier trigonometric function; Represents the angular frequency of the carrier trigonometric function; Indicates time.

[0068] In some embodiments, the plurality of correlation peaks are combinations of two positive correlation peaks, corresponding to the main station and the secondary station respectively. The main station has 9 positive correlation peaks, and the secondary station has 8 positive correlation peaks.

[0069] The cumulative result is obtained by accumulating several sets of related peaks. If the size and number of related peaks in the cumulative result correspond to the configuration of the main station and the auxiliary station, then the eLoran signal is judged to have been successfully captured.

[0070] In some embodiments, performing multiple peak-to-peak ratio (PSR) determination on the linearly averaged signal specifically includes:

[0071] The ratio of adjacent positive peaks is detected for the linearly averaged signal. When the ratio of adjacent positive peaks falls within the preset threshold range of A4 / A3, it is considered that the position of the third positive peak has been preliminarily identified.

[0072] The linearly averaged signal is delayed by 10μs and superimposed on the original linearly averaged signal. The ratio of adjacent positive peaks is detected again. When the ratio of adjacent positive peaks falls within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third positive peak has been detected.

[0073] By using the positional relationship between the third week's positive peak and the third week's zero-crossing point, and the sampling rate, the peak ratio up to the third week's zero-crossing point is calculated. If the peak ratio does not fall within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third week's positive peak has been initially identified as incorrect, and the identification will start again from the place that was not detected. Here, A2 represents the second positive peak value at the beginning of the eLoran signal; A3 represents the third positive peak value at the beginning of the eLoran signal; and A4 represents the fourth positive peak value at the beginning of the eLoran signal.

[0074] In some embodiments, the value of (A4+A3) / (A3+A2) is calculated using the following formula:

[0075]

[0076] In the formula, To reach midnight, This indicates the positive peak value one week after midnight. This indicates the peak value of the week preceding midnight. This indicates the peak value two weeks prior to midnight; This indicates the time corresponding to the peak one week after midnight; This indicates the time corresponding to the peak one week before midnight; This indicates the time corresponding to the peak two weeks before midnight.

[0077] See Figure 5 This application also discloses an eLoran signal acquisition and period recognition system, characterized in that it includes:

[0078] The acquisition unit is used to acquire the eLoran signal, and after squaring the eLoran signal according to its waveform characteristics, it performs low-pass filtering to obtain the envelope signal.

[0079] The judgment unit is used to perform GRI correlation on the envelope signal to obtain several sets of correlation peaks, accumulate the several sets of correlation peaks to obtain the accumulation result, and judge whether the eLoran signal acquisition is successful based on the accumulation result. If it is unsuccessful, it returns to reacquire the eLoran signal.

[0080] The identification unit is used to perform linear averaging on the received eLoran signal after successful acquisition, perform multiple peak ratio judgment on the linearly averaged eLoran signal based on the peak position of the first relevant peak captured by the eLoran signal, identify the position of the positive peak of the third week, and identify the position of the zero crossing point of the third week based on the position of the positive peak of the third week.

[0081] In some embodiments, the acquisition unit acquires the eLoran signal, squares the eLoran signal according to its waveform characteristics, and then performs a low-pass filter to obtain the envelope signal. Specifically, this includes:

[0082] Obtain the eLoran signal, assuming the envelope function of the eLoran signal is W(t), and the eLoran signals with phase encodings of 0° and 180° are S0(t) and S... π (t), as shown in the following formula:

[0083]

[0084]

[0085] The squared result is obtained by squaring the eLoran signals with phase encodings of 0° and 180°:

[0086]

[0087] The squared result is filtered through a low-pass filter to obtain the square of the envelope function, and the envelope signal is obtained from the square of the envelope function.

[0088] In the formula, This represents an eLoran signal with a phase code of 0°. This represents an eLoran signal with a phase encoding of 180°; W(t) represents the envelope function of the eLoran signal. Represents the carrier trigonometric function; Represents the angular frequency of the carrier trigonometric function; Indicates time.

[0089] In some embodiments, an eLoran signal acquisition and period identification method mainly consists of two parts: eLoran signal acquisition and eLoran signal period identification.

[0090] First, there's the eLoran signal acquisition section; the overall process is as follows: Figure 2 As shown.

[0091] The first step in this section is to obtain the envelope of the signal. Let the envelope function of the eLoran signal be W(t), and the eLoran signal be a pulse signal whose phase encoding is a pulse signal with 0° and 180° pulses S0(t) and S180° respectively. π If (t), then they can be represented as follows:

[0092]

[0093]

[0094] Squaring the eLoran signals of the two phase codes yields the following result:

[0095]

[0096] If we square the pulse signal and filter it through a low-pass filter, we will obtain the square of the envelope function. Using this method, we can obtain the envelope of the signal.

[0097]

[0098] In the formula, This represents an eLoran signal with a phase code of 0°. This represents the eLoran signal with a phase encoding of 180°; W(t) represents the envelope function of the eLoran signal. Represents the carrier trigonometric function; Represents the angular frequency of the carrier trigonometric function; Indicates time, This indicates a low-pass filter.

[0099] Based on this result, the resulting envelope signal is correlated according to GRI (Group Repetition Interval), which yields two combinations of positive correlation peaks, corresponding to the main station and the secondary station respectively. According to the Roland numbering system, the result of the main station is 9 positive correlation peaks, and the result of the secondary station is 8 positive correlation peaks.

[0100] The obtained correlation peaks are accumulated and superimposed, and then the result of accumulation and superposition is detected. If the size and number of correlation peaks are consistent with the configuration of the acquisition station at this time, it indicates that the eLoran signal is successfully acquired.

[0101] Finally, the eLoran signal period identification section is performed, which builds upon the eLoran signal acquisition process. Based on the peak position of the first relevant peak obtained during eLoran signal acquisition, the period of the signal preceding it is identified. The overall process is as follows: Figure 3 As shown.

[0102] The first step in this section is to perform a linear average on the received eLoran signal. Then, based on the peak position of the first relevant peak obtained during the eLoran signal acquisition process, a multiple peak-to-peak ratio (PSR) decision is made on the linearly averaged signal to identify the position of the positive peak in the third week, and thus identify the zero-crossing point in the third week.

[0103] The eLoran signal has positive peak values ​​before and after the zero-crossing point. Let the zero-crossing time be 'to', the time corresponding to the positive peak one week after the zero-crossing point is 'to+2.5μs', and the time corresponding to the positive peak one week before the zero-crossing point is 'to-7.5μs'. The ratio of their peak values ​​is constant. Let the ratio function be R(to), then we have:

[0104]

[0105] This indicates the positive peak value one week after midnight. This indicates the peak value one week prior to midnight; the time of midnight is... .

[0106] Let the positive peak values ​​be A1, A2, A3, A4, A5, etc., starting from the eLoran signal, and the negative peak values ​​be B1, B2, B3, etc., as shown in the specific diagram. Figure 4 As shown in the table below, the peak values ​​for the week following midnight and the week before midnight are as follows.

[0107] Table 1. Peak ratio of the week after midnight to the week before midnight

[0108]

[0109] The multiple peak ratio (PPR) decision method identifies the third-cycle zero-crossing point by detecting the PPR twice. The first detection checks the PPR without delay and superposition, while the second detection checks the PPR after delay and superposition. The specific process is as follows: When the adjacent positive PPR is detected to fall near A4 / A3, the position of the third-cycle positive peak is considered to have been initially identified. Then, the signal is delayed by 10μs and superimposed on the original signal. The adjacent positive PPR at this position is detected again. If its value falls near (A4+A3) / (A3+A2), the position of the third-cycle positive peak is considered to have been detected. The position of the third-cycle zero-crossing point can be calculated using the positional relationship between the third-cycle positive peak and the third-cycle zero-crossing point and the sampling rate. If its value does not fall near (A4+A3) / (A3+A2), the first step is considered to be incorrect, and the process restarts from the position not detected in the first step.

[0110] Since the ratio of the peak values ​​of the week after midnight to the week before midnight is a constant, the sum of the peak values ​​of the week after midnight and the week before midnight divided by the sum of the peak values ​​of the week before midnight and the two weeks before midnight is also a constant. Let this value be R2(to), then we have:

[0111]

[0112] In the formula, the time of crossing zero is , This indicates the positive peak value one week after midnight. This indicates the peak value of the week preceding midnight. This represents the peak value two weeks before midnight. The theoretical value of (A4+A3) / (A3+A2) calculated is 1.7846.

[0113] Regarding eLoran signal acquisition, the innovation of this application lies in the extraction of the eLoran signal envelope. Based on the waveform characteristics of the eLoran signal itself, the envelope of the eLoran signal is obtained through a squared low-pass filter. Regarding eLoran signal period identification, the innovation of this application lies in the multiple identification of peak-to-peak ratio. Based on the eLoran signal acquisition marker, the peak-to-peak ratio of the vicinity is identified. After the peak-to-peak ratio is identified to fall within the specified range, the signal is delayed by 10μs and superimposed with the original signal. The peak-to-peak ratio at the original position is identified again. If the peak-to-peak ratio at that position falls within the specified range after the delay and superposition, the identification is successful. If it is not within the specified range, the detection is repeated.

[0114] In some embodiments, in an eLoran signal acquisition and period identification system, the identification unit performs multiple peak-to-mass ratio (PSR) determination on the linearly averaged signal, specifically including:

[0115] The ratio of adjacent positive peaks is detected for the linearly averaged signal. When the ratio of adjacent positive peaks falls within the preset threshold range of A4 / A3, it is considered that the position of the third positive peak has been preliminarily identified.

[0116] The linearly averaged signal is delayed by 10μs and superimposed on the original linearly averaged signal. The ratio of adjacent positive peaks is detected again. When the ratio of adjacent positive peaks falls within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third positive peak has been detected.

[0117] By using the positional relationship between the third week's positive peak and the third week's zero-crossing point, and the sampling rate, the peak ratio up to the third week's zero-crossing point is calculated. If the peak ratio does not fall within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third week's positive peak has been initially identified as incorrect, and the identification will start again from the place that was not detected. Here, A2 represents the second positive peak value at the beginning of the eLoran signal; A3 represents the third positive peak value at the beginning of the eLoran signal; and A4 represents the fourth positive peak value at the beginning of the eLoran signal.

[0118] In terms of signal acquisition, envelope extraction is performed using a squared low-pass filter based on the signal's characteristics. After envelope extraction, a GRI delay is applied to correlate and accumulate the signal. This process has good noise immunity, and all the obtained correlation peaks are positive, allowing the correlation peaks to accumulate correctly and avoiding the effects of phase differences.

[0119] For period identification, linear averaging uses GRI correlation as the cumulative time interval. Let S be the i-th GRI sampling result of the first pulse signal in the pulse group. i The i-th GRI sample result of the Gaussian white noise here is G. i The i-th GRI sample result of the mixed signal at this point is MIX. i Furthermore, the expectation of Gaussian white noise is 0, and its variance is σ. 2 Then we have:

[0120]

[0121]

[0122]

[0123] Where N is the number of sampling points, and let the power of the eLoran signal be P. Si The noise power is P Gi The input signal-to-noise ratio is SNR. in Then there are:

[0124]

[0125]

[0126]

[0127] Since the first pulse in a pulse group has no change in phase or amplitude, and sampling is generally continuous, it can be assumed that:

[0128]

[0129] After averaging, we get the following result:

[0130]

[0131]

[0132] Where M represents the number of stacking operations, then the output signal-to-noise ratio (SNR) after linear averaging is... out for:

[0133]

[0134] According to the above formula, the output signal-to-noise ratio after linear averaging increases logarithmically with the number of averaging iterations. The growth trend of the output signal-to-noise ratio is fast at first and then slows down. This process can effectively improve the output signal-to-noise ratio.

[0135] In subsequent testing, the use of two peak-to-peak ratio decisions reduced the impact of residual noise on the peak-to-peak ratio decision, which significantly reduced the probability of incorrect peak-to-peak ratio decisions and improved the accuracy of zero-crossing point identification in the third week.

[0136] eLoran (Enhanced Long Range Navigation) is a modern, high-precision land-based long-range radio navigation system. It is designed as a critical backup and complement to global satellite navigation systems such as GPS, GLONASS, and Galileo, with significant advantages, particularly in terms of anti-jamming, anti-spoofing, and signal availability.

[0137] In some embodiments, such as Figure 6 As shown, this application also provides an electronic device 100 for implementing the eLoran signal acquisition and period identification method described in any one of the above claims;

[0138] The electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and executable on at least one processor 102, and at least one communication bus 104.

[0139] The memory 101 can be used to store the computer program 103. The processor 102 implements the eLoran signal capture and period recognition method steps by running or executing the computer program stored in the memory 101 and calling the data stored in the memory 101.

[0140] The memory 101 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required for at least one function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created based on the use of the electronic device 100 (such as audio data), etc. In addition, the memory 101 may include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other non-volatile solid-state storage device.

[0141] At least one processor 102 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Processor 102 may be a microprocessor or any conventional processor. Processor 102 is the control center of electronic device 100, connecting various parts of electronic device 100 via various interfaces and lines.

[0142] The memory 101 in the electronic device 100 stores multiple instructions to implement an eLoran signal capture and period identification method, and the processor 102 can execute multiple instructions to achieve the following:

[0143] Obtain the eLoran signal, square it according to the waveform characteristics of the eLoran signal, and then low-pass filter it to obtain the envelope signal;

[0144] GRI correlation is performed on the envelope signal to obtain several sets of correlation peaks. The correlation peaks are accumulated to obtain the accumulation result. The eLoran signal acquisition is determined based on the accumulation result. If it is unsuccessful, the process returns to reacquire the eLoran signal.

[0145] After successful acquisition, the received eLoran signal is linearly averaged. Based on the peak position of the first relevant peak captured by the eLoran signal, multiple peak ratio decision is performed on the linearly averaged eLoran signal to identify the position of the positive peak of the third week. Based on the position of the positive peak of the third week, the position of the zero crossing point of the third week is identified.

[0146] In some embodiments, if the modules / units integrated in the electronic device 100 are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, and read-only memory (ROM).

[0147] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0148] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0149] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0150] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0151] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0152] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this application. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of the claims of this application.

Claims

1. A method for eLoran signal acquisition and period identification, characterized in that, include: Obtain the eLoran signal, square it according to the waveform characteristics of the eLoran signal, and then low-pass filter it to obtain the envelope signal; GRI correlation is performed on the envelope signal to obtain several sets of correlation peaks. The correlation peaks are accumulated to obtain the accumulation result. The eLoran signal acquisition is determined based on the accumulation result. If it is unsuccessful, the process returns to reacquire the eLoran signal. After successful acquisition, the received eLoran signal is linearly averaged. Based on the peak position of the first relevant peak captured by the eLoran signal, multiple peak ratio decision is performed on the linearly averaged eLoran signal to identify the position of the third positive peak. Based on the position of the third positive peak, the position of the third zero crossing point is identified. The process of performing multiple peak-to-peak ratio (PSR) determination on the linearly averaged signal specifically includes: The ratio of adjacent positive peaks is detected for the linearly averaged signal. When the ratio of adjacent positive peaks falls within the preset threshold range of A4 / A3, it is considered that the position of the third positive peak has been preliminarily identified. The linearly averaged signal is delayed by 10μs and superimposed on the original linearly averaged signal. The ratio of adjacent positive peaks is detected again. When the ratio of adjacent positive peaks falls within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third positive peak has been detected. By using the positional relationship between the third week's positive peak and the third week's zero-crossing point, and the sampling rate, the peak ratio up to the third week's zero-crossing point is calculated. If the peak ratio does not fall within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third week's positive peak has been initially identified as incorrect, and the identification will start again from the place that was not detected. Here, A2 represents the second positive peak value at the beginning of the eLoran signal; A3 represents the third positive peak value at the beginning of the eLoran signal; and A4 represents the fourth positive peak value at the beginning of the eLoran signal.

2. The eLoran signal acquisition and period identification method according to claim 1, characterized in that, The process of acquiring the eLoran signal, which involves squaring the signal based on its waveform characteristics and then low-pass filtering to obtain the envelope signal, specifically includes: Obtain the eLoran signal, assuming the envelope function of the eLoran signal is W(t), and the eLoran signals with phase encodings of 0° and 180° are S0(t) and S... π (t), as shown in the following formula: The squared result is obtained by squaring the eLoran signals with phase encodings of 0° and 180°: The squared result is filtered through a low-pass filter to obtain the square of the envelope function, and the envelope signal is obtained from the square of the envelope function. In the formula, This represents an eLoran signal with a phase code of 0°. This represents an eLoran signal with a phase encoding of 180°; W(t) represents the envelope function of the eLoran signal. Represents the carrier trigonometric function; Represents the angular frequency of the carrier trigonometric function; Indicates time.

3. The eLoran signal acquisition and period identification method according to claim 1, characterized in that, The aforementioned sets of correlation peaks are combinations of two types of positive correlation peaks, corresponding to the main station and the secondary station respectively. The main station has 9 positive correlation peaks, and the secondary station has 8 positive correlation peaks. The cumulative result is obtained by accumulating several sets of related peaks. If the size and number of related peaks in the cumulative result correspond to the configuration of the main station and the auxiliary station, then the eLoran signal is judged to have been successfully captured.

4. The eLoran signal acquisition and period identification method according to claim 1, characterized in that, The value of (A4+A3) / (A3+A2) is calculated using the following formula: In the formula, To reach midnight, This indicates the positive peak value one week after midnight. This indicates the peak value of the week preceding midnight. This indicates the peak value two weeks prior to midnight; This indicates the time corresponding to the peak one week after midnight; This indicates the time corresponding to the peak one week before midnight; This indicates the time corresponding to the peak two weeks before midnight.

5. An eLoran signal acquisition and period recognition system, characterized in that, include: The acquisition unit is used to acquire the eLoran signal, and after squaring the eLoran signal according to its waveform characteristics, it performs low-pass filtering to obtain the envelope signal. The judgment unit is used to perform GRI correlation on the envelope signal to obtain several sets of correlation peaks, accumulate the several sets of correlation peaks to obtain the accumulation result, and judge whether the eLoran signal acquisition is successful based on the accumulation result. If it is unsuccessful, it returns to reacquire the eLoran signal. The identification unit is used to perform linear averaging on the received eLoran signal after successful acquisition, perform multiple peak ratio judgment on the linearly averaged eLoran signal based on the peak position of the first relevant peak captured by the eLoran signal, identify the position of the third positive peak, and identify the position of the third zero crossing point based on the position of the third positive peak. The identification unit performs multiple peak-to-peak ratio (PSR) determination on the linearly averaged signal, specifically including: The ratio of adjacent positive peaks is detected for the linearly averaged signal. When the ratio of adjacent positive peaks falls within the preset threshold range of A4 / A3, it is considered that the position of the third positive peak has been preliminarily identified. The linearly averaged signal is delayed by 10μs and superimposed on the original linearly averaged signal. The ratio of adjacent positive peaks is detected again. When the ratio of adjacent positive peaks falls within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third positive peak has been detected. By using the positional relationship between the third week's positive peak and the third week's zero-crossing point, and the sampling rate, the peak ratio up to the third week's zero-crossing point is calculated. If the peak ratio does not fall within the preset threshold range of (A4+A3) / (A3+A2), it is considered that the position of the third week's positive peak has been initially identified as incorrect, and the identification will start again from the place that was not detected. Here, A2 represents the second positive peak value at the beginning of the eLoran signal; A3 represents the third positive peak value at the beginning of the eLoran signal; and A4 represents the fourth positive peak value at the beginning of the eLoran signal.

6. The eLoran signal acquisition and periodicity identification system according to claim 5, characterized in that, The acquisition unit acquires the eLoran signal, squares the eLoran signal according to its waveform characteristics, and then performs a low-pass filter to obtain the envelope signal. Specifically, this includes: Obtain the eLoran signal, assuming the envelope function of the eLoran signal is W(t), and the eLoran signals with phase encodings of 0° and 180° are S0(t) and S... π (t), as shown in the following formula: The squared result is obtained by squaring the eLoran signals with phase encodings of 0° and 180°: The squared result is filtered through a low-pass filter to obtain the square of the envelope function, and the envelope signal is obtained from the square of the envelope function. In the formula, This represents an eLoran signal with a phase code of 0°. This represents an eLoran signal with a phase encoding of 180°; W(t) represents the envelope function of the eLoran signal. Represents the carrier trigonometric function; Represents the angular frequency of the carrier trigonometric function; Indicates time.

7. An electronic device, characterized in that, It includes a processor and a memory, the processor being used to execute a computer program stored in the memory to implement the eLoran signal capture and period identification method as described in any one of claims 1 to 4.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction, which, when executed by a processor, implements the eLoran signal capture and period identification method as described in any one of claims 1 to 4.

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