A short wave 2FSK signal symbol synchronization system and method

Abstract

The application discloses a short-wave 2FSK signal symbol synchronization system and method in the technical field of signal burst detection, which comprises the following steps: detecting the short-wave 2FSK signal through signal energy detection to determine whether there is a signal burst; in response to the existence of the signal burst, performing synchronization signal burst starting index; after the synchronization signal burst starting index, performing summation calculation on the signal starting part data in a single step mode to determine the burst starting position; performing cross-correlation calculation on the burst from the burst starting position through a characteristic sequence to determine the position index of the frame header; calculating the length of each frame based on the position index of the frame header; calculating the actual symbol rate based on the length of each frame and combining the theoretical symbol rate; and performing symbol synchronization through the actual symbol rate. The application improves the synchronization accuracy, performs synchronization through the accurate symbol rate, and is convenient for subsequent code word judgment.

Description

Technical Field

[0001] This invention relates to a shortwave 2FSK signal symbol synchronization system and method, belonging to the field of signal burst detection technology. Background Technology

[0002] In shortwave signals, there are many factors that affect reception, such as noise and multipath. Generally, the early and late gate method is used to synchronize shortwave signals. When synchronizing using the known theoretical symbol rate, the data accumulation within a certain symbol range before and after the synchronization point is calculated and adjusted.

[0003] In shortwave signals, the actual symbol rate deviates from the theoretical value due to various factors such as noise and propagation distance. This is especially true when using a late-late gate method; if the synchronization point is off during the initial symbol adjustment, subsequent adjustments will fail. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a shortwave 2FSK signal symbol synchronization system and method. This invention performs synchronization by calculating the accurate symbol rate, which facilitates subsequent codeword decision-making.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] In a first aspect, the present invention provides a shortwave 2FSK signal symbol synchronization method, comprising:

[0007] The presence of signal bursts is determined by detecting the signal energy of shortwave 2FSK signals.

[0008] In response to the presence of a signal burst, a synchronization signal burst initiation index is performed;

[0009] After the synchronization signal burst start index, the initial part of the signal data is accumulated in a single step manner to determine the burst start position;

[0010] The position index of the frame header is determined by cross-correlation calculation of the burst based on the feature sequence from the burst's starting position.

[0011] The length of each frame is calculated based on the position index of the frame header;

[0012] The actual symbol rate is calculated based on the length of each frame and the theoretical symbol rate.

[0013] Symbol synchronization is performed using the actual symbol rate.

[0014] Furthermore, the burst start position is the starting index under the maximum value of the step-cumulative calculation result, and the step-cumulative calculation formula includes:

[0015] A(SUM)_1=A(1)+A(2)+…+A(19)+A(20)

[0016] A(SUM)_2=A(2)+A(3)+…+A(20)+A(21)

[0017] ``````

[0018] A(SUM)_51=A(51)+A(52)+…+A(69)+A(70)

[0019] In the formula, A(n) represents the nth data in the initial part of the signal, and A(SUM)_n represents the step summation calculation result of the nth data.

[0020] Furthermore, the feature sequence is the frame header data of the shortwave 2FSK signal, and multiple frame header data exist in the signal burst. The cross-correlation calculation represents the sum of products. When the frame header data are the same, the result of the sum of products is the largest, that is, multiple peaks are obtained, and the index of each peak is the position index of the frame header.

[0021] Furthermore, the cross-correlation calculation formula is as follows:

[0022] B(SUM)_n=B(n1)*1+B(n2)*1+B(n3)*1+B(n4)*1+B(n5)*1+B(n6)*0+B(n7)*0+B(n8)*0

[0023] In the formula, B(n1)~B(n8) are frame header data, which are taken from the signal burst in sequence, and B(SUM)_n represents the cross-correlation calculation result.

[0024] Furthermore, the length of each frame is:

[0025] n_length=n a -n b

[0026] In the formula, n_length is the length of each frame, n a n is the position index of the next frame header. b This is the position index of the previous frame header.

[0027] Furthermore, the actual symbol rate is:

[0028] Nn_symbolRate=n_length / (floor(n+length / (a*b))*b)

[0029] Where Nn_symbolRate is the actual symbol rate, n_length is the length of each frame, floor indicates rounding down, n is the position index of the frame header, a is the theoretical actual symbol rate, and b is the length of the feature sequence.

[0030] Furthermore, the theoretical actual symbol rate a is 20, and the length b of the feature sequence is 8 bits "11111000".

[0031] Secondly, the present invention provides a shortwave 2FSK signal symbol synchronization system, comprising:

[0032] Burst detection module: used to detect the signal energy of shortwave 2FSK signals to determine whether a signal burst exists;

[0033] Synchronization Index Module: Used to perform synchronization signal burst initiation indexing in response to the presence of a signal burst;

[0034] Accumulation Calculation Module: After synchronizing the burst start index of the signal, it performs accumulation calculation on the initial part of the signal data in a single step manner to determine the burst start position;

[0035] Cross-correlation calculation module: used to perform cross-correlation calculation on bursts from the burst start position using feature sequences to determine the position index of the frame header;

[0036] Frame length calculation module: used to calculate the length of each frame based on the position index of the frame header;

[0037] Real-rate calculation module: used to calculate the actual symbol rate based on the length of each frame and the theoretical symbol rate;

[0038] Symbol synchronization module: Used for symbol synchronization based on the actual symbol rate.

[0039] Thirdly, the present invention provides a shortwave 2FSK signal symbol synchronization device, including a processor and a storage medium;

[0040] The storage medium is used to store instructions;

[0041] The processor is configured to operate according to the instructions to perform the steps of the method according to any of the foregoing.

[0042] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0043] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0044] I. This invention synchronizes the signal bursts by starting the signal burst index, then determines the frame header position index through summation and cross-correlation calculations, and determines the length of each frame. Then, it calculates the actual symbol rate and performs symbol synchronization, thus avoiding deviations in the synchronization point during the first symbol adjustment. This improves the synchronization accuracy. Calculating accurate symbol rates for synchronization facilitates subsequent codeword decisions.

[0045] Second, this invention targets specific signal types, where characteristic sequences exist within specific signals. Symbol synchronization is performed using these characteristic sequences, ensuring that the calculated symbol start position is the most accurate from the beginning. This avoids errors that occur during the first synchronization attempt, as is the case with early and late gates. Therefore, this solution offers higher accuracy and efficiency in symbol synchronization for specific signal types, extracting more and more accurate signal information. Attached Figure Description

[0046] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0047] Figure 1 This is a flowchart illustrating a shortwave 2FSK signal symbol synchronization method provided in Embodiment 1 of the present invention. Detailed Implementation

[0048] The present invention 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 herein can be combined with each other.

[0049] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0050] Example 1:

[0051] 2FSK (Frequency Shift Keying) is a binary digital frequency modulation (BFSK) system that uses the carrier frequency to transmit digital information; that is, the transmitted digital information controls the carrier frequency. A 2FSK signal is a modulated waveform where the symbol "0" corresponds to carrier frequency f1, and the symbol "1" corresponds to carrier frequency f2 (a different carrier frequency than f1), and the change between f1 and f2 is instantaneous. When transmitting a "0" signal, a carrier with frequency f1 is sent; when transmitting a "1" signal, a carrier with frequency f2 is sent. It is clear that FSK uses carriers of different frequencies to transmit digital messages. Research has revealed a discrepancy between the theoretical and actual symbol rates of shortwave 2FSK signals, necessitating symbol synchronization during the decision-making process.

[0052] This embodiment proposes a shortwave 2FSK signal symbol synchronization method, which specifically includes the following steps:

[0053] First, signal bursts are obtained from the shortwave 2FSK signal through signal energy detection. These bursts contain information (non-noise). Then, the starting index of the signal burst is synchronized; here, this is time synchronization, i.e., confirming the symbol decision starting index (position). The symbol starting point is obtained by accumulating the peak value of the initial data portion of the signal burst using a single-step method (the initial data portion is the first half of the signal burst). The starting index at the maximum value of the accumulated result is the starting point of the signal symbol position, as shown in the following formula:

[0054] A(SUM)_1=A(1)+A(2)+…+A(19)+A(20)

[0055] A(SUM)_2=A(2)+A(3)+…+A(20)+A(21)

[0056] ``````

[0057] A(SUM)_51=A(51)+A(52)+…+A(69)+A(70)

[0058] In the formula, A(n) represents the nth data in the initial part of the signal, and A(SUM)_n represents the step summation calculation result of the nth data. It is assumed that between A(SUM)_1 and A(SUM)_51, the value of A(SUM)_35 is the largest, that is, A(35) is the starting position of the first symbol in the signal burst, which is the burst start position.

[0059] Next, cross-correlation is performed on the burst starting from the burst's initial position using the feature sequence. Here, the feature sequence refers to the frame header data of the signal, specifically "F8" in hexadecimal ("11111000" in binary). The feature sequence is known, and multiple frame header data exist within the burst. Cross-correlation calculation represents the sum of products; when the data are identical, the sum of products is maximized, resulting in multiple peaks. The index of each peak is the position index of the frame header. The cross-correlation calculation formula is as follows:

[0060] B(SUM)_n=B(n1)*1+B(n2)*1+B(n3)*1+B(n4)*1+B(n5)*1+B(n6)*0+B(n7)*0+B(n8)*0

[0061] In the formula, B(n1)~B(n8) are the frame header data, which are taken from the signal burst in order. B(SUM)_n represents the cross-correlation calculation result. The step is 1 to traverse the entire signal burst and calculate all B(SUM)_n. There will be multiple B(SUM)_n with very large values. The value of small n represents the position index of each frame header.

[0062] After obtaining the position index of each frame header, the length of each frame is calculated based on the position of each frame header. The formula is as follows:

[0063] n_length=n a -n b

[0064] In the formula, n_length is the length of each frame, n a n is the position index of the next frame header. b The position index of the previous frame header is used to obtain the length of each frame by subtracting the value of the previous n from the value of the next n in B(SUM)_n.

[0065] After obtaining the length of each frame, the actual symbol rate is calculated using the length of each frame and the theoretical symbol rate. Assuming the theoretical actual symbol rate is 20, the formula is as follows:

[0066] Nn_symbolRate=n_length / (floor(n+length / (20*8))*8)

[0067] Where Nn_symbolRate is the actual symbol rate, n_length is the length of each frame, floor indicates rounding down, n is the position index of the frame header, and 8 is the length of the feature sequence, which is 8 bits "11111000".

[0068] After obtaining the actual symbol rate, symbol synchronization is performed using this actual symbol rate. The symbol rate is the number of sampling points occupied by one symbol. For example, one bit of a signal without noise occupies 20 sampling points. However, the actual number of sampling points occupied by one bit of a signal is not an integer of 20. The "01" decision is made according to the actual symbol rate, and symbol synchronization is performed to make the demodulation decision result more accurate.

[0069] Because this method targets a specific signal type, the characteristic sequence exists within that signal. Symbol synchronization using this characteristic sequence ensures the most accurate calculation of the symbol start position from the very beginning, avoiding errors that occur during the initial synchronization process, as is often the case with early and late gates. Therefore, this scheme offers higher accuracy and efficiency in symbol synchronization for specific signal types. Without symbol synchronization, demodulation decisions ("01") will be incorrect, leading to poorer results and further decoding errors—incomplete and erroneous information. Thus, symbol synchronization extracts more and more accurate signal information.

[0070] Example 2:

[0071] A shortwave 2FSK signal symbol synchronization system, which can implement the shortwave 2FSK signal symbol synchronization method described in Embodiment 1, includes:

[0072] Burst detection module: used to detect the signal energy of shortwave 2FSK signals to determine whether a signal burst exists;

[0073] Synchronization Index Module: Used to perform synchronization signal burst initiation indexing in response to the presence of a signal burst;

[0074] Accumulation Calculation Module: After synchronizing the burst start index of the signal, it performs accumulation calculation on the initial part of the signal data in a single step manner to determine the burst start position;

[0075] Cross-correlation calculation module: used to perform cross-correlation calculation on bursts from the burst start position using feature sequences to determine the position index of the frame header;

[0076] Frame length calculation module: used to calculate the length of each frame based on the position index of the frame header;

[0077] Real-rate calculation module: used to calculate the actual symbol rate based on the length of each frame and the theoretical symbol rate;

[0078] Symbol synchronization module: Used for symbol synchronization based on the actual symbol rate.

[0079] Example 3:

[0080] This invention also provides a shortwave 2FSK signal symbol synchronization device, which can realize the shortwave 2FSK signal symbol synchronization method described in Embodiment 1, including a processor and a storage medium;

[0081] The storage medium is used to store instructions;

[0082] The processor is configured to operate according to the instructions to perform the steps of the following method:

[0083] The presence of signal bursts is determined by detecting the signal energy of shortwave 2FSK signals.

[0084] In response to the presence of a signal burst, a synchronization signal burst initiation index is performed;

[0085] After the synchronization signal burst start index, the initial part of the signal data is accumulated in a single step manner to determine the burst start position;

[0086] The position index of the frame header is determined by cross-correlation calculation of the burst based on the feature sequence from the burst's starting position.

[0087] The length of each frame is calculated based on the position index of the frame header;

[0088] The actual symbol rate is calculated based on the length of each frame and the theoretical symbol rate.

[0089] Symbol synchronization is performed using the actual symbol rate.

[0090] Example 4:

[0091] This invention also provides a computer-readable storage medium that implements the shortwave 2FSK signal symbol synchronization method described in Embodiment 1. The medium stores a computer program that, when executed by a processor, performs the steps of the following method:

[0092] The presence of signal bursts is determined by detecting the signal energy of shortwave 2FSK signals.

[0093] In response to the presence of a signal burst, a synchronization signal burst initiation index is performed;

[0094] After the synchronization signal burst start index, the initial part of the signal data is accumulated in a single step manner to determine the burst start position;

[0095] The position index of the frame header is determined by cross-correlation calculation of the burst based on the feature sequence from the burst's starting position.

[0096] The length of each frame is calculated based on the position index of the frame header;

[0097] The actual symbol rate is calculated based on the length of each frame and the theoretical symbol rate.

[0098] Symbol synchronization is performed using the actual symbol rate.

[0099] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative and not exhaustive. All modifications within the scope of this invention or its equivalents are included in this invention.

[0100] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention 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.

[0101] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. 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 illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0102] 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.

[0103] 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.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention 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 the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A shortwave 2FSK signal symbol synchronization method, characterized in that, include: The presence of signal bursts is determined by detecting the signal energy of shortwave 2FSK signals. In response to the presence of a signal burst, a synchronization signal burst initiation index is performed; After the synchronization signal burst start index, the initial part of the signal data is accumulated in a single step manner to determine the burst start position; The burst's position is determined by cross-correlation calculation of the burst using feature sequences from its initial position. The burst's initial position is the starting index at the maximum value of the step-cumulative calculation result. The step-cumulative calculation formula includes: A(SUM)_1=A(1)+A(2)+…+A(19)+A(20) A(SUM)_2=A(2)+A(3)+…+A(20)+A(21) `````` A(SUM)_51=A(51)+A(52)+…+A(69)+A(70) In the formula, A(n) represents the nth data in the initial part of the signal, and A(SUM)_n represents the step-by-step cumulative sum calculation result of the nth data; The length of each frame is calculated based on the position index of the frame header; The actual symbol rate is calculated based on the length of each frame and the theoretical symbol rate. Symbol synchronization is performed using the actual symbol rate.

2. The shortwave 2FSK signal symbol synchronization method according to claim 1, characterized in that, The feature sequence is the frame header data of the shortwave 2FSK signal, and multiple frame header data exist in the signal burst. The cross-correlation calculation represents the sum of products. When the frame header data are the same, the result of the sum of products is the largest, that is, multiple peaks are obtained, and the index of each peak is the position index of the frame header.

3. The shortwave 2FSK signal symbol synchronization method according to claim 1, characterized in that, The formula for calculating the cross-correlation is: B(SUM)_n=B(n1)*1+B(n2)*1+B(n3)*1+B(n4)*1+B(n5)*1+B(n6)*0+B(n7)*0+B(n8)*0 In the formula, B(n1)~B(n8) are frame header data, which are taken from the signal burst in sequence, and B(SUM)_n represents the cross-correlation calculation result.

4. The shortwave 2FSK signal symbol synchronization method according to claim 1, characterized in that, The length of each frame is: n_length=n a -n b In the formula, n_length is the length of each frame, n a n is the position index of the next frame header. b This is the position index of the previous frame header.

5. The shortwave 2FSK signal symbol synchronization method according to claim 1, characterized in that, The actual symbol rate is: Nn_symbolRate=n_length / (floor(n+length / (a*b))*b) Where Nn_symbolRate is the actual symbol rate, n_length is the length of each frame, floor indicates rounding down, n is the position index of the frame header, a is the theoretical actual symbol rate, and b is the length of the feature sequence.

6. The shortwave 2FSK signal symbol synchronization method according to claim 5, characterized in that, The theoretical actual symbol rate a is 20, and the length b of the feature sequence is 8 bits "11111000".

7. A shortwave 2FSK signal symbol synchronization system, characterized in that, The method for implementing shortwave 2FSK signal symbol synchronization as described in claim 1 includes: Burst detection module: used to detect the signal energy of shortwave 2FSK signals to determine whether a signal burst exists; Synchronization Index Module: Used to perform synchronization signal burst initiation indexing in response to the presence of a signal burst; Accumulation Calculation Module: After synchronizing the burst start index of the signal, it performs accumulation calculation on the initial part of the signal data in a single step manner to determine the burst start position; Cross-correlation calculation module: used to perform cross-correlation calculation on bursts from the burst start position using feature sequences to determine the position index of the frame header; Frame length calculation module: used to calculate the length of each frame based on the position index of the frame header; Real-rate calculation module: used to calculate the actual symbol rate based on the length of each frame and the theoretical symbol rate; Symbol synchronization module: Used for symbol synchronization based on the actual symbol rate.

8. A shortwave 2FSK signal symbol synchronization device, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1 to 6.

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