High-speed broadband frequency hopping detection method based on double-window-ratio adaptive threshold

Abstract

The invention discloses a high-speed broadband frequency hopping detection method based on a double-window-ratio adaptive threshold, and the method comprises the following steps: S1, calculating the size of a single data cache block and the FFT length according to the hopping speed range and the sampling rate of broadband data; s2, receiving broadband data in real time according to the size of the data cache block; and S3, receiving a single data cache block, and carrying out frequency hopping signal detection. According to the method, the adaptive double-window-ratio threshold technology is utilized, and the detection probability of the burst signal under the low signal-to-noise ratio is improved. According to the method, time domain broadband data are used as input, the method can adapt to frequency hopping signal detection of low / medium / high hopping speeds, and meanwhile, through carrier detection and refined search in a single burst, distinguishing of multiple network station conflict hop points can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of frequency hopping detection, in particular to a high-speed broadband frequency hopping detection method based on a dual-window ratio adaptive threshold. Background Art

[0002] In communication systems, frequency hopping technology is often used in communication links to improve anti-interference and anti-interception capabilities.

[0003] Generally speaking, a frequency hopping signal with a rate of more than 1000 hops / second is called high-speed frequency hopping, 100 to 1000 hops / second is called medium-speed frequency hopping, and less than 100 hops / second is called low-speed frequency hopping. With the advancement of electronic countermeasure technology, high-power directional suppression can effectively interfere with frequency hopping communication links. Therefore, modern tactical radios usually increase the working bandwidth and adaptively select other frequency hopping frequencies when some frequency bands are interfered, so as to ensure the normal operation of the communication link.

[0004] With the rapid development of frequency hopping communication technology, non-cooperative reception of frequency hopping communication faces severe challenges, which are mainly manifested in two aspects: first, the frequency hopping rate is high, and frequency hopping signals above 5000 hops / second have been applied to tactical radio communications; second, the frequency hopping bandwidth is wide, and there are more and more frequency hopping signals greater than 200MHz.

[0005] The detection technologies for frequency hopping non-cooperative reception mainly include adaptive multi-channel detection technology and edge detection technology based on morphological image processing.

[0006] The prior art has the following defects: (1) Based on adaptive multi-channel detection technology, channel resources must be dynamically planned and allocated, and the algorithm complexity is high. In addition, the burst detection threshold mostly uses a dual-window ratio algorithm, and the threshold of the dual-window ratio detection must be set manually. When the interference noise is large, the burst missed detection rate is high, and the frequency hopping detection parameter estimation is inaccurate. (2) The detection technology based on morphological image processing requires specifying the size of the structural element. When the frequency hopping parameters are unknown, it has poor universality and large computational complexity. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a high-speed broadband frequency hopping detection method based on a dual-window ratio adaptive threshold, comprising the following steps: S1. Calculating the size of a single data cache block and the FFT length according to the hopping rate range and the sampling rate of broadband data; S2. Receive broadband data in real time according to the size of the data cache block; S3. Receive a single data cache block and perform frequency hopping signal detection.

[0008] Furthermore, the relevant detection performed in step S3 specifically includes: burst detection, spectrum calculation, single-hop extraction, and network station sorting.

[0009] Furthermore, the S3 step specifically includes the following sub-steps: S31. For broadband data, a double-window ratio burst detection method is used to detect burst signals; S32. Single data is cached quickly, spectrum data is calculated according to the FFT length, and a time spectrum diagram is formed; S33. The start and end indexes of the spectrum frame are calculated, and single-hop parameters are extracted; S34. The K clustering method is used to perform frequency hopping station sorting and frequency hopping parameter estimation based on duration, bandwidth, and power.

[0010] Furthermore, the dual-window ratio burst detection method in the step S31 specifically includes the following steps: S311. Taking a single data cache block as a unit, calculate the dual-window energy ratio, marked as vector R; S312. Construct a statistical histogram of vector R, and generate a statistical histogram curve; S313. Calculate the local variance value, and determine the detection threshold of the dual-window energy ratio; S314. Traverse all dual-window energy ratios, and compare and judge with the absolute value of the detection threshold.

[0011] Furthermore, the step S314 is specifically as follows: if the absolute value is higher than the detection threshold, it is considered that the burst start is detected; if the absolute value is lower than the negative value of the detection threshold, it is considered that the burst end is detected.

[0012] Furthermore, the step S33 specifically includes the following sub-steps: S331. Calculate the spectrum frame index occupied by a single burst based on the burst start and end times, FFT length and overlap length; S332. Detect the number of signals in the burst and the carrier frequency and bandwidth; S333. Use threshold detection to detect the signal in the burst; S334. Perform a refined search for the start and end positions of the burst; wherein, the detection threshold used in the threshold detection in step S333 is obtained by smoothing filtering of the maximum value holding data.

[0013] Furthermore, the step S334 performs a refined search for the start and end positions of the burst as follows: starting from the index of the spectrum frame occupied by the signal, searching frame by frame to the left, if all frequency points within the signal bandwidth are lower than the detection threshold, it is considered that the signal starting point should be indented to the right; then searching frame by frame to the right, if more than 1 / 2 of the frequency points within the signal bandwidth are higher than the detection threshold, this position is considered to be the signal starting point.

[0014] The present invention provides a high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold, which has the following beneficial effects: The present invention uses adaptive double window ratio threshold technology to improve the detection probability of burst signals under low signal-to-noise ratio. With time domain broadband data as input, it can adapt to the detection of frequency hopping signals with low / medium / high hopping rates. At the same time, through carrier detection and refined search within a single burst, it can realize the resolution of multi-network station conflict hopping points. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0016] Figure 1 A flow chart of the method provided by the present invention; Figure 2 The double window ratio statistical histogram provided by the present invention; Figure 3 The double window ratio statistical local variance curve provided by the present invention; Figure 4 This is a dual-window ratio adaptive threshold calculation effect diagram provided by the present invention; Figure 5 This is a diagram showing the effect of the dual-window ratio burst detection with adaptive threshold provided by the present invention. DETAILED DESCRIPTION

[0017] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0018] The following is a detailed description of the implementation method of the present invention in conjunction with the accompanying drawings. Only some embodiments are described, not all embodiments. For the purpose of clarity, representations and descriptions that are not related to the present invention are omitted in the drawings and descriptions.

[0019] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below. Obviously, the implementation cases described are part of the embodiments of the present invention, not all of the embodiments, and cannot be understood as limiting the scope of the implementation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0020] like Figure 1 As shown, the present invention provides a high-speed broadband frequency hopping detection method based on a dual-window ratio adaptive threshold, comprising the following steps: S1. Calculating the size of a single data cache block and the FFT length according to the hopping rate range and the sampling rate of broadband data; S2. Receive broadband data in real time according to the size of the data cache block; S3. Receive a single data cache block and perform frequency hopping signal detection.

[0021] The frequency hopping signal detection in step S3 specifically includes: burst detection, spectrum calculation, single hop extraction, and network station sorting.

[0022] Step S3 specifically includes the following sub-steps: S31. For broadband data, a double-window ratio burst detection method is used to detect burst signals; S32. Single data is cached quickly, spectrum data is calculated according to the FFT length, and a time spectrum diagram is formed; S33. The start and end indexes of the spectrum frame are calculated, and single-hop parameters are extracted; S34. The K clustering method is used to perform frequency hopping station sorting and frequency hopping parameter estimation based on duration, bandwidth, and power.

[0023] The double-window ratio burst detection method in step S31 specifically includes the following steps: S311. Taking a single data cache block as a unit, calculate the double-window energy ratio, marked as vector R; S312. Calculate the statistical histogram of vector R, convert the value of each Bin of the statistical histogram into a dB value, and obtain the statistical histogram curve, such as Figure 2 , Figure 3 As shown; S313. Count the local variance values ​​and determine the detection threshold of the double-window energy ratio; S314. Traverse all double-window energy ratios and compare and judge with the absolute value of the detection threshold.

[0024] Step S314 is specifically as follows: if the absolute value is higher than the detection threshold, it is considered that the burst start is detected; if the absolute value is lower than the negative value of the detection threshold, it is considered that the burst end is detected.

[0025] like Figure 4 , Figure 5 As shown, step S33 specifically includes the following sub-steps: S331. Calculate the spectrum frame index occupied by a single burst based on the burst start and end time, FFT length and overlap length; S332. Detect the number of signals in the burst and the carrier frequency and bandwidth; S333. Use threshold detection to detect the signal in the burst; S334. Perform a refined search for the start and end positions of the burst.

[0026] The detection threshold used in the threshold detection in step S333 is obtained by smoothing filtering of the maximum value holding data.

[0027] In step S334, the burst start and end positions are searched in detail as follows: starting from the spectrum frame occupied by the signal, search frame by frame to the left. If all frequency points within the signal bandwidth are lower than the detection threshold, it is considered that the signal starting point should be indented to the right; then search frame by frame to the right. If more than 1 / 2 of the frequency points within the signal bandwidth are higher than the detection threshold, this position is considered to be the signal starting point.

[0028] Embodiment: A high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold includes broadband data caching and broadband frequency hopping detection. Broadband data caching refers to receiving time domain broadband data in real time according to the size of a single data cache block; the size of the data cache block is calculated and output after the broadband frequency hopping detection is initialized.

[0029] The broadband frequency hopping detection is initialized, and the FFT length and the size of a single data buffer block are automatically calculated based on the hopping rate range and broadband data sampling rate. The calculation basis is: the minimum burst occupies 3 spectrum frames, and the single-hop signal bandwidth is greater than or equal to 3 frequency points.

[0030] Broadband frequency hopping detection includes four sub-modules: burst detection, spectrum calculation, single hop extraction, and network station sorting.

[0031] Burst detection is to perform burst detection on a single data cache block. The specific operation steps are: (1) Calculate the dual-window energy ratio, where the window length is 10% of the minimum burst data length of the frequency hopping signal; (2) According to steps S312 and S313, the detection threshold of the dual-window energy ratio is calculated; (3) According to step S314, the burst start and end positions are extracted; According to the method of step S314, when the signal-to-noise ratio is low, the situation where the burst signal missed detection rate is high due to the artificial setting of the double window ratio threshold can be avoided. This method has a stronger adaptability to the detection environment and a higher burst detection rate.

[0032] After the burst detection is completed, the spectrum data is calculated according to the initialized FFT length to form a time spectrum diagram; For each burst signal, according to step S33, signal detection and refined search are performed.

[0033] In step S332, all spectrum frames corresponding to a single burst are used to hold the maximum value. The maximum value data is filtered by a sliding average method as a detection threshold; the detection threshold is a curve, not a fixed threshold value.

[0034] If the signal is higher than the detection threshold by more than NdB, it is considered to be a valid signal. If multiple valid signals are detected, it is considered to be a frequency conflict between different network stations and all are retained. According to the empirical value N, when 5dB is taken, the probability of signal false detection is the lowest.

[0035] In order to improve the efficiency of refined search, the calculation process of holding the maximum value of all spectrum frames of a single burst can be performed according to the following steps: (1) All spectrum frames corresponding to a single burst are divided into three parts, and each part is individually maintained at the maximum value; (2) Perform maximum value holding again on the three maximum value holding spectrum frame data to obtain the final maximum value holding data; (3) Smoothing and filtering the final maximum value holding data to obtain the detection threshold; (4) If the maximum value of the first portion on the left does not exceed the detection threshold, the signal starts from the second portion; (5) If the maximum value of the first portion on the right does not exceed the detection threshold, the signal ends at the second portion; Then, as described in S334, the start and end frequency frame indexes of the signal are searched frame by frame to obtain the bandwidth, carrier frequency, start time, and duration of the signal.

[0036] In order to improve the estimation accuracy of the frequency hopping network station parameters, after the single-hop detection parameters of multiple data cache blocks are obtained, step S34 is followed to complete the frequency hopping network station sorting and parameter estimation.

[0037] The present invention uses adaptive double window ratio threshold technology to improve the detection probability of burst signals under low signal-to-noise ratio. With time domain broadband data as input, it can adapt to the detection of frequency hopping signals with low / medium / high hopping rates. At the same time, through carrier detection and refined search within a single burst, it can realize the resolution of multi-network station conflict hopping points.

[0038] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold, characterized in that: The following steps are involved: S1. Calculate the size of a single data buffer block and the FFT length according to the hopping rate range and the sampling rate of the broadband data; S2. Receive broadband data in real time according to the size of the data cache block; S3. Receive a single data buffer block and perform frequency hopping signal detection.

2. The high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold according to claim 1 is characterized in that: The frequency hopping signal detection in step S3 specifically includes: burst detection, spectrum calculation, single hop extraction, and network station sorting.

3. The high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold according to claim 2 is characterized in that: The S3 step specifically includes the following sub-steps: S31. For broadband data, a dual-window burst detection method is used for burst signal detection; S32. Cache single data quickly, calculate spectrum data according to FFT length, and form a time spectrum diagram; S33. Calculate the start and end indexes of the spectrum frame and extract single-hop parameters; S34. K clustering method is used to classify frequency hopping stations and estimate frequency hopping parameters based on duration, bandwidth and power.

4. The high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold according to claim 3 is characterized in that: The double-window ratio burst detection method in step S31 specifically comprises the following steps: S311. Calculate the dual-window energy ratio based on a single data cache block, marked as vector R; S312. Construct a statistical histogram of the vector R and generate a statistical histogram curve; S313. Calculate the local variance value and determine the detection threshold of the dual-window energy ratio; S314. Traverse all dual-window energy ratios and compare them with the absolute value of the detection threshold.

5. The high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold according to claim 4 is characterized in that: The step S314 is specifically as follows: if the absolute value is higher than the detection threshold, it is considered that the burst start is detected; if the absolute value is lower than the negative value of the detection threshold, it is considered that the burst end is detected.

6. The high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold according to claim 3 is characterized in that: The step S33 specifically includes the following sub-steps: S331. Calculate the spectrum frame index occupied by a single burst based on the burst start and end times, FFT length, and overlap length; S332. Detect the number of signals, carrier frequency and bandwidth within the burst; S333. Use threshold detection to detect the signal within the burst; S334. Perform a refined search for the start and end positions of the burst; The detection threshold used in the threshold detection in step S333 is obtained by smoothing filtering of the maximum value holding data.

7. The high-speed broadband frequency hopping detection method based on dual-window ratio adaptive threshold according to claim 6 is characterized in that: The detailed search for the start and end positions of the burst in step S334 is as follows: starting from the index of the spectrum frame occupied by the signal, searching frame by frame to the left, if all frequency points within the signal bandwidth are lower than the detection threshold, it is considered that the signal starting point should be indented to the right; then searching frame by frame to the right, if more than 1 / 2 of the frequency points within the signal bandwidth are higher than the detection threshold, this position is considered to be the signal starting point.

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