Short-wave 2FSK signal symbol synchronization system and method

Abstract

The invention discloses a short-wave 2FSK signal symbol synchronization system and method in the technical field of signal burst detection, and the method comprises the steps: carrying out the signal energy detection of a short-wave 2FSK signal, and judging whether a signal burst exists or not; in response to existence of the signal burst, performing synchronization signal burst initial indexing; after a signal burst start index is synchronized, cumulative sum calculation is carried out on signal start part data in a single stepping mode, and a burst start position is determined; performing cross-correlation calculation on the burst through the feature sequence from the initial position of the burst, and determining a position index of a frame header; calculating the length of each frame based on the position index of the frame header; calculating an actual symbol rate based on the length of each frame in combination with a theoretical symbol rate; and carrying out symbol synchronization through the actual symbol rate. According to the method, the synchronization accuracy is improved, synchronization is carried out by calculating the accurate symbol rate, and subsequent code word judgment is facilitated.

Description

Technical Field

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

[0002] There are many factors that affect reception in shortwave signals, such as noise and multipath. Generally, the early and late gate method is used to synchronize shortwave signals. When synchronizing with a 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 of the signal is easily affected by various factors such as noise and propagation distance, and the deviation between the actual symbol rate and the theoretical value occurs. In particular, if the synchronization point of the first symbol adjustment is deviated, subsequent adjustments will be wrong. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a shortwave 2FSK signal symbol synchronization system and method. The present invention performs synchronization by calculating an accurate symbol rate to facilitate subsequent codeword decision.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

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

[0007] Through signal energy detection of shortwave 2FSK signal, determine whether there is signal burst;

[0008] In response to the presence of a signal burst, performing a synchronization signal burst start index;

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

[0010] Perform cross-correlation calculation on the burst through the characteristic sequence from the burst start position to determine the position index of the frame head;

[0011] Calculate the length of each frame based on the position index of the frame header;

[0012] The actual symbol rate is calculated based on the length of each frame combined with the theoretical symbol rate;

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

[0014] Further, the burst start position is the start index under the maximum value of the step-accumulative sum calculation result, and the step-accumulative sum 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] Where A(n) represents the nth data at the beginning of the signal, and A(SUM)_n represents the step-by-step cumulative calculation result of the nth data.

[0020] Furthermore, the characteristic 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:

[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] Wherein, B(n1)~B(n8) are frame header data and are sequentially taken from the signal burst, 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] Where n_length is the length of each frame, n a is the position index of the next frame header, n b The 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] Among them, Nn_symbolRate is the actual symbol rate, n_length is the length of each frame, floor means 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 characteristic sequence is 8 bits "11111000".

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

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

[0033] Synchronous index module: used for performing a synchronization signal burst start index in response to the presence of a signal burst;

[0034] Cumulative calculation module: after synchronizing the burst start index of the signal, it performs cumulative calculation on the starting part of the signal in a single step manner to determine the burst start position;

[0035] Cross-correlation calculation module: used to perform cross-correlation calculation on the burst from the burst start position through the characteristic sequence 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] Actual rate calculation module: used to calculate the actual symbol rate based on the length of each frame combined with the theoretical symbol rate;

[0038] Symbol synchronization module: used to perform symbol synchronization using the actual symbol rate.

[0039] In a third aspect, 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 used to operate according to the instructions to execute the steps of any of the methods described above.

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

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. The present invention performs synchronization on the signal burst start index, then determines the position index of the frame head through cumulative calculation and cross-correlation calculation, determines the length of each frame, and then calculates the actual symbol rate and performs symbol synchronization, thereby avoiding the deviation of the synchronization point when the symbol adjustment is performed for the first time, thereby improving the synchronization accuracy, calculating the accurate symbol rate for synchronization, and facilitating the subsequent codeword judgment;

[0045] 2. The present invention is aimed at specific signal types. The characteristic sequence exists in the specific signal. Symbol synchronization is performed through the characteristic sequence. The symbol starting position calculated from the beginning is the most accurate, which avoids the situation where errors occur in the first synchronization. Therefore, the accuracy and efficiency of symbol synchronization for specific types of signals in this scheme are higher, and the extracted signal information is more and more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0047] Figure 1 A schematic flow chart of a shortwave 2FSK signal symbol synchronization method provided in Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0049] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0050] Embodiment 1:

[0051] 2FSK (Frequency Shift Keying) is a binary digital frequency modulation (binary frequency shift keying), which uses the frequency of the carrier to transmit digital information, that is, the frequency of the carrier is controlled by the transmitted digital information. The 2FSK signal is a modulated waveform in which the symbol "0" corresponds to the carrier frequency f1, and the symbol "1" corresponds to the carrier frequency f2 (another carrier frequency different from f1), and the change between f1 and f2 is instantaneous. When transmitting the "0" signal, a carrier with a frequency of f1 is sent; when transmitting the "1" signal, a carrier with a frequency of f2 is sent. It can be seen that FSK uses carriers of different frequencies to transmit digital messages. After research, it was found that there is a deviation between the theoretical and actual symbol rates of short-wave 2FSK signals, and symbol synchronization is required in the judgment process.

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

[0053] First, the shortwave 2FSK signal is subjected to signal energy detection to obtain a signal burst, which is a signal containing information (non-noise part). Then the start index of the signal burst is synchronized, which is time synchronization here, that is, confirming the symbol decision start index (position). The symbol start point is obtained by accumulating and calculating the peak value of the signal start part data in a single step mode (the start part data is the data of the first half of the signal burst). The start index under the maximum value of the accumulation result is the start point of the signal symbol position. The formula is as follows:

[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] Wherein, A(n) represents the nth data at the beginning of the signal, A(SUM)_n represents the step-accumulated calculation result of the nth data, and 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, that is, the burst starting position.

[0059] Secondly, the burst is cross-correlated from the burst start position through the characteristic sequence. The characteristic sequence here refers to the frame header data of the signal, specifically "F8" in hexadecimal and "11111000" in binary. The characteristic sequence is known. Multiple frame header data exist in the burst. The cross-correlation calculation represents the sum of products. When the data is the same, the result of the sum of products is the largest, that is, multiple peaks are obtained. 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 frame header data, and are taken from the signal burst in sequence. B(SUM)_n represents the cross-correlation calculation result. The step is 1 to traverse the entire signal burst once to calculate all B(SUM)_n. There will be multiple B(SUM)_n with 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 by the position of each frame header. The formula is as follows:

[0063] n_length = n a -n b

[0064] Where n_length is the length of each frame, n a is the position index of the next frame header, n b It is the position index of the previous frame header. The length of each frame is obtained by subtracting the value of the next n from the previous n in B(SUM)_n.

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

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

[0067] Among them, Nn_symbolRate is the actual symbol rate, n_length is the length of each frame, floor means rounding down, n is the position index of the frame header, and 8 is the length of the characteristic sequence, 8 bits "11111000".

[0068] After obtaining the actual symbol rate, symbol synchronization is performed using the actual symbol rate. The symbol rate is the number of sampling points occupied by one symbol. For example, one bit of a signal that is not affected by noise occupies 20 sampling points. The number of sampling points occupied by one bit of the actual signal is not an integer of 20. The bit "01" decision is performed according to the actual symbol rate, and symbol synchronization is performed to make the demodulation decision result more accurate.

[0069] Since it is aimed at a specific signal type, the characteristic sequence exists in the specific signal. The symbol synchronization is performed through the characteristic sequence. The symbol starting position calculated from the beginning is the most accurate, which avoids the situation that the gate will make an error when it is synchronized for the first time sooner or later. Therefore, the accuracy and efficiency of symbol synchronization for specific types of signals in this scheme are higher. If symbol synchronization is not performed, the demodulation judgment "01" will be wrong, the result will be worse, and further lead to decoding errors, that is, the information obtained is incomplete and erroneous. Therefore, the signal information extracted through symbol synchronization is more and more accurate.

[0070] Embodiment 2:

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

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

[0073] Synchronous index module: used for performing a synchronization signal burst start index in response to the presence of a signal burst;

[0074] Cumulative calculation module: after synchronizing the burst start index of the signal, it performs cumulative calculation on the starting part of the signal in a single step manner to determine the burst start position;

[0075] Cross-correlation calculation module: used to perform cross-correlation calculation on the burst from the burst start position through the characteristic sequence 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] Actual rate calculation module: used to calculate the actual symbol rate based on the length of each frame combined with the theoretical symbol rate;

[0078] Symbol synchronization module: used to perform symbol synchronization using the actual symbol rate.

[0079] Embodiment three:

[0080] The embodiment of the present invention further provides a shortwave 2FSK signal symbol synchronization device, which can implement a shortwave 2FSK signal symbol synchronization method described in the first embodiment, including a processor and a storage medium;

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

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

[0083] Through signal energy detection of shortwave 2FSK signal, determine whether there is signal burst;

[0084] In response to the presence of a signal burst, performing a synchronization signal burst start index;

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

[0086] Perform cross-correlation calculation on the burst through the characteristic sequence from the burst start position to determine the position index of the frame head;

[0087] Calculate the length of each frame based on the position index of the frame header;

[0088] The actual symbol rate is calculated based on the length of each frame combined with the theoretical symbol rate;

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

[0090] Embodiment 4:

[0091] The embodiment of the present invention further provides a computer-readable storage medium, which can implement the shortwave 2FSK signal symbol synchronization method described in the first embodiment, and stores a computer program thereon, which implements the steps of the following method when the program is executed by a processor:

[0092] Through signal energy detection of shortwave 2FSK signal, determine whether there is signal burst;

[0093] In response to the presence of a signal burst, performing a synchronization signal burst start index;

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

[0095] Perform cross-correlation calculation on the burst through the characteristic sequence from the burst start position to determine the position index of the frame head;

[0096] Calculate the length of each frame based on the position index of the frame header;

[0097] The actual symbol rate is calculated based on the length of each frame combined with the theoretical symbol rate;

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

[0099] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0100] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented 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] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems) and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the process in the flowchart. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0102] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0103] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions 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 rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does 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: Through signal energy detection of shortwave 2FSK signal, determine whether there is signal burst; In response to the presence of a signal burst, performing a synchronization signal burst start index; After the burst start index of the synchronization signal is obtained, the data of the start part of the signal is accumulated and calculated in a single step manner to determine the burst start position; Perform cross-correlation calculation on the burst through the characteristic sequence from the burst start position to determine the position index of the frame head; Calculate the length of each frame based on the position index of the frame header; The actual symbol rate is calculated based on the length of each frame combined with 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 burst start position is the start index of the maximum value of the step-accumulation calculation result, and the step-accumulation 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) Where A(n) represents the nth data at the beginning of the signal, and A(SUM)_n represents the step-by-step cumulative calculation result of the nth data.

3. The shortwave 2FSK signal symbol synchronization method according to claim 1, characterized in that: The characteristic 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 product summation. When the frame header data are the same, the result of the product summation is the largest, that is, multiple peaks are obtained, and the index of each peak is the position index of the frame header.

4. The shortwave 2FSK signal symbol synchronization method according to claim 1, characterized in that: The cross-correlation calculation formula 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 Wherein, B(n1)~B(n8) are frame header data and are sequentially taken from the signal burst, and B(SUM)_n represents the cross-correlation calculation result.

5. 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 Where n_length is the length of each frame, n a is the position index of the next frame header, n b The index of the previous frame header.

6. 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) Among them, Nn_symbolRate is the actual symbol rate, n_length is the length of each frame, floor means 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.

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

8. A shortwave 2FSK signal symbol synchronization system, characterized in that: include: Burst detection module: used to detect the signal energy of the shortwave 2FSK signal to determine whether there is a signal burst; Synchronous index module: used for performing a synchronization signal burst start index in response to the presence of a signal burst; Cumulative calculation module: after synchronizing the burst start index of the signal, it performs cumulative calculation on the starting part of the signal in a single step manner to determine the burst start position; Cross-correlation calculation module: used to perform cross-correlation calculation on the burst from the burst start position through the characteristic sequence 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; Actual rate calculation module: used to calculate the actual symbol rate based on the length of each frame combined with the theoretical symbol rate; Symbol synchronization module: used to perform symbol synchronization using the actual symbol rate.

9. A shortwave 2FSK signal symbol synchronization device, characterized in that: including processor and storage medium; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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