Signal depth detection method and device for low interception waveform, equipment and medium

Abstract

The invention discloses a signal depth detection method, a signal depth detection device, signal depth detection equipment and a medium for a low interception waveform, and relates to the technical field of signal identification. According to the method, the covert communication signal can be effectively detected without using signal energy and periodic characteristics, so that the use of the signal energy and the periodic characteristics of the frequency domain is avoided, and the covert communication signal of variable parameter spread frequency hopping can be effectively detected under the condition of low signal-to-noise ratio.

Description

Technical Field

[0001] This application relates to the field of signal recognition technology, specifically to a method, apparatus, device, and medium for signal depth detection of low intercept waveforms. Background Technology

[0002] In modern military communication scenarios, to prevent information eavesdropping and decryption, covert communication is often achieved using methods such as spread spectrum. Successful detection of covert communication signals is beneficial for striking enemy military nodes and deciphering enemy tactical intelligence. Covert communication signals are characterized by low energy, making energy detection methods extremely ineffective. Traditional covert communication signals primarily rely on spread spectrum technology, which can typically be detected using the cyclostationary characteristics of spread spectrum signals. However, with the development of covert communication technology, more and more covert communication signals are using techniques such as variable parameter spread spectrum and frequency hopping, making their energy resemble noise and thus lacking periodicity in the frequency domain. This renders traditional spread spectrum signal detection methods such as cyclic spectrum and cepstral spectrum ineffective, increasing the difficulty of detecting enemy communication signals and hindering the demodulation of enemy covert signals and the acquisition of enemy communication content.

[0003] Traditional signal detection methods, such as energy detection, rely on the signal-to-noise ratio (SNR) of the received signal for their detection performance. However, after spreading the signal, the SNR drops sharply, rendering energy detection ineffective for detecting covert communication signals. Similarly, methods that are relatively effective for detecting traditional spread spectrum signals, such as cyclostationary feature detection, utilize the signal's periodicity. However, covert communication signals can be processed using variable-parameter spread spectrum frequency hopping techniques, making the periodicity less pronounced or even nonexistent. Therefore, in such cases, cyclostationary feature detection also fails for detecting covert communication signals. Summary of the Invention

[0004] The purpose of this application is to provide a method, apparatus, device and medium for signal depth detection of low intercept waveforms, which solves the problem of failure in detecting covert communication signals with variable parameter spread frequency hopping.

[0005] This application is achieved through the following technical solution:

[0006] The first aspect of this application provides a signal depth detection method for low intercept waveforms, comprising:

[0007] The received signal with a low intercept waveform is acquired, and the power spectrum of the received signal is calculated twice consecutively to obtain the secondary power spectrum corresponding to the received signal.

[0008] Based on the secondary power spectrum corresponding to the received signal, a set of time delay values ​​is obtained, and the peak value and average value are obtained according to the set of time delay values;

[0009] Based on the peak value and the average value, a signal detection statistic is constructed, and the depth detection result of the received signal is obtained based on the signal detection statistic; wherein, the depth detection result includes whether the received signal is a covert communication signal or not.

[0010] In one possible design approach, the received signal undergoes two consecutive power spectrum calculations to obtain the secondary power spectrum corresponding to the received signal, including:

[0011] The received signal is subjected to a power spectrum calculation using Fourier transform to obtain an intermediate power spectrum. Then, the intermediate power spectrum is subjected to a power calculation using Fourier transform again to obtain the secondary power spectrum corresponding to the received signal.

[0012] In one possible design approach, based on the secondary power spectrum corresponding to the received signal, a set of time delay values ​​is obtained, including: obtaining the values ​​corresponding to the positive and negative time delays of the secondary power spectrum corresponding to the received signal, and forming a set to obtain the time delay value set.

[0013] In one possible design approach, obtaining the peak value and average value based on the set of delay values ​​includes: taking the maximum value in the set of delay values ​​as the peak value, and dividing the sum of all values ​​in the set of delay values ​​by the number of values ​​to obtain the average value.

[0014] In one possible design approach, constructing a signal detection statistic based on the peak value and the average value includes: dividing the peak value by the average value to obtain the signal detection statistic.

[0015] In one possible design approach, obtaining the depth detection result of the received signal based on the signal detection statistics includes:

[0016] Determine whether the signal detection statistic is greater than or equal to the decision threshold. If it is, determine that the received signal is a covert communication signal and obtain the depth detection result. Otherwise, determine that the received signal is not a covert communication signal and obtain the depth detection result.

[0017] In one possible design approach, the decision threshold is set as follows: ;in, Indicates the judgment threshold. This means taking the first row from Ratio. The column values, Ratio, represent the set of signal detection statistics when there is only noise, and Monte Carlo represents the values ​​that need to be generated when calculating the threshold. Secondary noise data This indicates a preset false alarm probability. Based on the same inventive concept, a second aspect of this application provides a signal depth detection device for low intercept waveforms, comprising: a signal preprocessing module, a signal feature acquisition module, and a signal depth detection module;

[0018] The signal preprocessing module is used to acquire the received signal as a low intercept waveform and perform two consecutive power spectrum calculations on the received signal to obtain the secondary power spectrum corresponding to the received signal.

[0019] The signal feature acquisition module is used to obtain a set of time delay values ​​based on the secondary power spectrum corresponding to the received signal, and to obtain the peak value and average value based on the set of time delay values.

[0020] The signal depth detection module is used to construct a signal detection statistic based on the peak value and the average value, and to obtain the depth detection result of the received signal based on the signal detection statistic; wherein, the depth detection result includes whether the received signal is a covert communication signal or whether the received signal is not a covert communication signal.

[0021] Based on the same inventive concept, a third aspect of this application provides a signal depth detection device for low intercept waveforms, including a processor and a memory;

[0022] The memory stores computer-executed instructions;

[0023] The processor executes computer execution instructions stored in the memory, causing the processor to perform a signal depth detection method for low intercept waveforms as described in any of the first aspects.

[0024] Based on the same inventive concept, a fourth aspect of this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the signal depth detection method for low intercept waveforms as described in any one aspect of the first aspect.

[0025] Compared with the prior art, this application has the following advantages and beneficial effects:

[0026] This application provides a signal depth detection method, apparatus, device, and medium for low intercept waveforms. The method uses the peak-to-average power ratio of the signal's secondary power spectrum as a detection statistic, which can effectively detect covert communication signals without utilizing signal energy and periodic characteristics. This avoids the use of signal energy and frequency domain periodic characteristics, and can effectively detect covert communication signals with variable parameter spread frequency hopping under low signal-to-noise ratio conditions. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the exemplary embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0028] Figure 1 A flowchart of a signal depth detection method for low intercept waveforms provided in this application embodiment;

[0029] Figure 2 An example diagram illustrating a signal depth detection method for low intercept waveforms provided in this application embodiment;

[0030] Figure 3 Example diagram of obtaining the decision threshold provided in the embodiments of this application;

[0031] Figure 4 A schematic diagram of a signal depth detection device for low intercept waveforms provided in this application embodiment;

[0032] Figure 5 A schematic diagram of a signal depth detection device for low intercept waveforms provided in this application embodiment;

[0033] The attached diagram shows the markings and corresponding component names:

[0034] 401 - Signal preprocessing module, 402 - Signal feature acquisition module, 403 - Signal depth detection module, 501 - Memory, 502 - Processor, 503 - Bus. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.

[0036] like Figure 1 As shown, this application provides a signal depth detection method for low intercept waveforms, including:

[0037] S101. Obtain the received signal with a low intercept waveform, and perform two consecutive power spectrum calculations on the received signal to obtain the secondary power spectrum corresponding to the received signal.

[0038] In one possible design approach, the power spectrum of the received signal is calculated twice consecutively to obtain the secondary power spectrum corresponding to the received signal. This includes: performing a power spectrum calculation on the received signal using Fourier transform to obtain an intermediate power spectrum, and then performing a power calculation on the intermediate power spectrum using Fourier transform again to obtain the secondary power spectrum corresponding to the received signal.

[0039] S102. Based on the secondary power spectrum corresponding to the received signal, obtain a set of time delay values, and obtain the peak value and average value according to the set of time delay values.

[0040] In one possible design approach, based on the secondary power spectrum corresponding to the received signal, a set of time delay values ​​is obtained, including: obtaining the values ​​corresponding to the positive and negative time delays of the secondary power spectrum corresponding to the received signal, and forming a set to obtain the time delay value set.

[0041] When calculating the peak-to-average value, only the positive or negative delay of the signal is taken for calculation. The positive and negative delays are symmetrically distributed. Therefore, the value of the positive or negative delay can be used to reflect the characteristics of the signal. In this application, the amount of calculation can be reduced without losing the characteristics of the signal's secondary spectrum.

[0042] In one possible design approach, obtaining the peak value and average value based on the set of delay values ​​includes: taking the maximum value in the set of delay values ​​as the peak value, and dividing the sum of all values ​​in the set of delay values ​​by the number of values ​​to obtain the average value.

[0043] S103. Based on the peak value and average value, construct a signal detection statistic, and obtain the depth detection result of the received signal based on the signal detection statistic. The depth detection result includes whether the received signal is a covert communication signal or not.

[0044] In one possible design approach, constructing a signal detection statistic based on the peak value and the average value includes: dividing the peak value by the average value to obtain the signal detection statistic.

[0045] In one possible design, obtaining the depth detection result of the received signal based on the signal detection statistics includes: determining whether the signal detection statistics are greater than or equal to a decision threshold; if so, determining that the received signal is a covert communication signal and obtaining the depth detection result; otherwise, determining that the received signal is not a covert communication signal and obtaining the depth detection result.

[0046] In one possible design approach, the decision threshold is set as follows: ;in, Indicates the judgment threshold. This means taking the first row from Ratio. The column values, Ratio, represent the set of signal detection statistics when there is only noise, and Monte Carlo represents the values ​​that need to be generated when calculating the threshold. Secondary noise data This represents the preset false alarm probability. This application combines the quadratic spectrum with the positive time delay peak-to-mean ratio of the quadratic spectrum. The quadratic spectrum of the signal is calculated, and then the positive time delay peak-to-mean ratio of the quadratic spectrum is used to construct a detection statistic. This detection statistic is independent of signal energy and the periodicity of the signal. The detection statistics constructed using the method of this application for variable parameter spread frequency hopping signals and pure noise show significant differences. Therefore, comparing the detection statistic with a preset threshold value can effectively detect covert communication signals such as variable parameter spread frequency hopping signals.

[0047] like Figure 2 As shown, based on the above-described signal depth detection method for low intercept waveforms, this application provides an implementation example that may include:

[0048] First, the secondary spectrum of the received signal is calculated. Then, a detection statistic is constructed using the ratio of its peak value to its mean value during positive time delay. Finally, the detection statistic is compared with a decision threshold, and a decision is made: if the detection statistic is greater than the decision threshold, a covert communication signal exists in the communication system; if the detection statistic is less than the decision threshold, a covert communication signal does not exist in the communication system. The flowchart is as follows: Figure 1 As shown, specifically:

[0049] Step 1: Calculate the received signal using Fourier transform primary power spectrum for:

[0050]

[0051] in, The signal received by the user this time, , It is the length of the received signal. This indicates that a Fourier transform is performed on the data.

[0052] Step 2: Perform a second power spectrum calculation on the primary power spectrum obtained in Step 1. The result is the secondary power spectrum. for:

[0053]

[0054] Step 3: Obtain the secondary power spectrum The set consists of all values ​​of positive or negative delay. and calculate the set peak and average for:

[0055]

[0056]

[0057] in, This represents the number of values ​​in set G. This represents the maximum value in set G.

[0058] Step 4: Construct the detection statistic using the peak value and mean value obtained in Step 3:

[0059]

[0060] Step 5: Calculate the detection statistic obtained in Step 4. With the judgment threshold Compare. If exists. This indicates that the secondary user detected the presence of a covert communication signal; if If the signal is not concealed, then it is determined that there is no concealed communication signal.

[0061] like Figure 3 As shown, the threshold value The value is an empirical value obtained through multiple simulations: the generated signal is the same length as the received signal. The noise data is used as a signal to generate the second noise data through steps 1, 2, 3, and 4. Statistical data of each detection until proceeding This step is repeated. The set... Sort the values ​​in the array from smallest to largest, then retrieve the values. As a threshold for judgment. The values ​​within are sorted from smallest to largest because the threshold here is an empirical value. The threshold needs to be set according to the false alarm probability. If the false alarm probability is higher, then the corresponding threshold value should be smaller. The value taken should be the value that appears earlier in the sorted Ratio set.

[0062] The method proposed in this application combines the secondary power spectrum with the peak-to-mean-index ratio (PMR), enabling accurate detection of covert communication signals even under low signal-to-noise ratio (SNR) conditions, which is significant for capturing enemy signals. With advancements in spread spectrum technology, the cyclostationary characteristics of many spread spectrum methods are becoming less pronounced, leading to a rapid decline in the detection performance of some traditional methods such as correlation spectrum and cepstral methods. However, the detection method proposed in this application can, to some extent, avoid exploiting cyclostationary characteristics, thus improving the detection capability of covert communication signals. Furthermore, the detection method proposed in this application demonstrates strong detection capabilities for covert communication signals such as variable-parameter spread frequency hopping signals, indicating its wide applicability.

[0063] The detection method proposed in this application is used to detect multiple sets of variable parameter spread frequency hopping signals with a signal-to-noise ratio of -20dB. This signal set contains a total of 50 signal sets, including 25 sets of variable parameter signals and 25 sets of complex Gaussian noise. The specific signal categories of the signal set to be detected are as follows: As shown in the figure. Where "1" indicates that the signal group is a variable parameter spread frequency hopping signal, and "0" indicates that the signal group is complex Gaussian noise.

[0064] surface Classification of signal types in the group of signals to be detected

[0065]

[0066] During detection, the detection method proposed in this application is used to detect the variable parameter spread frequency hopping signal under different false alarm probabilities. This is the detection result obtained when the false alarm probability is 0.1. This is the detection result obtained when the false alarm probability is 0. From and As can be seen, when the false alarm probability is 0.1, the detection scheme proposed in this application only makes a mistake in detecting two of the signals, while when the false alarm probability is 0, the detection scheme proposed in this application is completely correct in detecting the variable parameter spread frequency hopping signal. and The obtained detection results verify the effectiveness of the detection method proposed in this application for detecting variable parameter signals.

[0067] surface When the false alarm probability is 0.1, the detection result of the method proposed in this application is...

[0068]

[0069] surface When the false alarm probability is 0, the detection result of the method proposed in this application is...

[0070]

[0071] like Figure 4 As shown, this application provides a signal depth detection device for low intercept waveforms, including: a signal preprocessing module 401, a signal feature acquisition module 402, and a signal depth detection module 403;

[0072] The signal preprocessing module 401 is used to acquire a received signal with a low intercept waveform and perform two consecutive power spectrum calculations on the received signal to obtain the secondary power spectrum corresponding to the received signal.

[0073] The signal feature acquisition module 402 is used to obtain a set of time delay values ​​based on the secondary power spectrum corresponding to the received signal, and to obtain the peak value and average value based on the set of time delay values.

[0074] The signal depth detection module 403 is used to construct a signal detection statistic based on the peak value and the average value, and to obtain the depth detection result of the received signal based on the signal detection statistic; wherein, the depth detection result includes whether the received signal is a covert communication signal or whether the received signal is not a covert communication signal.

[0075] The signal depth detection device based on low intercept waveforms provided in this application embodiment can perform the above-described method and technical solution. Its principle and beneficial effects are similar, and will not be described again here.

[0076] like Figure 5 As shown, based on the same inventive concept, this application embodiment also provides a signal depth detection device based on low intercept waveforms, including a processor 502 and a memory 501; the memory 501 and the processor 502 are interconnected via a bus 503.

[0077] The memory 501 stores computer-executed instructions;

[0078] The processor 502 executes computer execution instructions stored in the memory 501, causing the processor 502 to perform a signal depth detection method based on low intercept waveforms as described in any embodiment of this application.

[0079] For specific examples, memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in-first-out (FIFO) memory, and / or first-in-last-out (FILO) memory, etc.; specifically, processor may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor may be implemented using at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), PLA (Programmable Logic Array). Furthermore, the processor may include a main processor and coprocessors. The main processor, also known as the CPU (Central Processing Unit), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state.

[0080] This application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the signal depth detection method based on low-interception waveforms described in any of the above embodiments.

[0081] This application embodiment may also provide a computer program product, including a computer program that, when executed by a processor, implements the signal depth detection method based on low intercept waveforms described in any of the above embodiments.

[0082] All or part of the steps in the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a readable memory. When the program is executed, it performs the steps of the above method embodiments; and the aforementioned memory (storage medium) includes: read-only memory (ROM), RAM, flash memory, hard disk, solid-state drive, magnetic tape, floppy disk, optical disk, and any combination thereof.

[0083] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It should 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 processing unit 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 processing unit of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0084] 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.

[0085] 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.

[0086] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0087] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A signal depth detection method for low intercept waveforms, characterized in that, include: The received signal with a low intercept waveform is acquired, and the power spectrum of the received signal is calculated twice consecutively to obtain the secondary power spectrum corresponding to the received signal. Based on the secondary power spectrum corresponding to the received signal, a set of time delay values ​​is obtained, and the peak value and average value are obtained according to the set of time delay values; Based on the peak value and the average value, a signal detection statistic is constructed, and the depth detection result of the received signal is obtained based on the signal detection statistic; wherein, the depth detection result includes whether the received signal is a covert communication signal or not.

2. The signal depth detection method for low intercept waveforms according to claim 1, characterized in that, The received signal is subjected to two consecutive power spectrum calculations to obtain the secondary power spectrum corresponding to the received signal, including: The received signal is subjected to a power spectrum calculation using Fourier transform to obtain an intermediate power spectrum. Then, the intermediate power spectrum is subjected to a power calculation using Fourier transform again to obtain the secondary power spectrum corresponding to the received signal.

3. The signal depth detection method for low intercept waveforms according to claim 1, characterized in that, Based on the secondary power spectrum corresponding to the received signal, a set of time delay values ​​is obtained, including: obtaining the values ​​corresponding to the positive and negative time delays of the secondary power spectrum corresponding to the received signal, and forming a set to obtain the time delay value set.

4. The signal depth detection method for low intercept waveforms according to claim 1, characterized in that, Obtaining the peak value and average value based on the set of delay values ​​includes: taking the maximum value in the set of delay values ​​as the peak value, and dividing the sum of all values ​​in the set of delay values ​​by the number of values ​​to obtain the average value.

5. The signal depth detection method for low intercept waveforms according to claim 1, characterized in that, Based on the peak value and the average value, a signal detection statistic is constructed, including dividing the peak value by the average value to obtain the signal detection statistic.

6. The signal depth detection method for low intercept waveforms according to any one of claims 1-5, characterized in that, The depth detection result of the received signal is obtained based on the signal detection statistics, including: Determine whether the signal detection statistic is greater than or equal to the decision threshold. If it is, determine that the received signal is a covert communication signal and obtain the depth detection result. Otherwise, determine that the received signal is not a covert communication signal and obtain the depth detection result.

7. The signal depth detection method for low intercept waveforms according to claim 6, characterized in that, The decision threshold is set as follows: ;in, Indicates the judgment threshold. This means taking the first row from Ratio. The column values, Ratio, represent the set of signal detection statistics when there is only noise, and Monte Carlo represents the values ​​that need to be generated when calculating the threshold. Secondary noise data This represents the preset false alarm probability.

8. A signal depth detection device for low intercept waveforms, characterized in that, include: Signal preprocessing module, signal feature acquisition module, and signal depth detection module; The signal preprocessing module is used to acquire the received signal as a low intercept waveform and perform two consecutive power spectrum calculations on the received signal to obtain the secondary power spectrum corresponding to the received signal. The signal feature acquisition module is used to obtain a set of time delay values ​​based on the secondary power spectrum corresponding to the received signal, and to obtain the peak value and average value based on the set of time delay values. The signal depth detection module is used to construct a signal detection statistic based on the peak value and the average value, and to obtain the depth detection result of the received signal based on the signal detection statistic; wherein, the depth detection result includes whether the received signal is a covert communication signal or whether the received signal is not a covert communication signal.

9. A signal depth detection device for low intercept waveforms, characterized in that, Including processor and memory; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the signal depth detection method for low intercept waveforms as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the signal depth detection method for low intercept waveforms as described in any one of claims 1 to 7.

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