Frequency hopping signal detection method and device, computing equipment and storage medium

Abstract

The invention discloses a frequency hopping signal detection method and a frequency hopping signal detection device, which are applied to the field of wireless communication and are used for solving the problem that a frequency hopping signal is difficult to detect in programmable logic equipment in the prior art. The method comprises the steps of obtaining a to-be-detected signal, performing Fourier transform on the to-be-detected signal to obtain a frequency spectrum of the to-be-detected signal, calculating a reference amplitude of each frequency point according to a frequency point amplitude of each frequency point in the frequency spectrum, and then determining a detection threshold of each frequency point according to the reference amplitude of each frequency point and a threshold factor. Wherein the threshold factor is selected from a preset threshold factor range. And then, determining the frequency point with the frequency point amplitude greater than the detection threshold as a frequency hopping signal. According to the scheme, the detection threshold of each frequency point is quickly calculated through the frequency point amplitude of each frequency point in the frequency spectrum, and the threshold factor is directly selected from the preset threshold factor range in the process of calculating the detection threshold, so that the detection of the frequency hopping signal can be realized by consuming less calculation resources, and the scheme can be applied to programmable logic equipment.

Description

Technical Field

[0001] The present invention relates to the field of wireless communications, and in particular to a frequency hopping signal detection method, device, computing equipment and storage medium. Background Art

[0002] Frequency hopping communication refers to a communication method in which the carrier frequency of the transmission signal between the sender and the receiver changes discretely according to a predetermined rule. It is widely used in the field of military communications as an anti-interference communication method. Frequency hopping signal detection is a key link in frequency hopping signal reconnaissance and interference, and its detection performance directly affects the subsequent frequency hopping parameter estimation, frequency hopping pattern splicing, network station sorting and other links. The common frequency hopping signal detection method is the spectrum matrix local variance method. This method combines short-time Fourier transform, time-frequency cancellation and variance characteristics to detect frequency hopping signals, and can still obtain a high recognition rate under low signal-to-noise ratio conditions. However, this method needs to calculate the decision threshold λ through Monte Carlo simulation, which is relatively complex and consumes a lot of computing resources.

[0003] At present, since Field Programmable Gate Array (FPGA) performs signal processing tasks at the hardware level and has the characteristics of high parallel processing, it can achieve very low processing delay, which is conducive to the rapid detection and identification of frequency hopping signals. Therefore, it is hoped to perform frequency hopping signal detection based on FPGA. However, the calculation methods for detecting frequency hopping signals at this stage are relatively complex and occupy more computing resources. Since FPGA is not suitable for complex calculations, it is currently difficult to perform frequency hopping signal detection on FPGA. Summary of the invention

[0004] The present invention provides a frequency hopping signal detection method, device, computing equipment and storage medium, which calculate the detection threshold of each frequency point according to the frequency amplitude of each frequency point in the spectrum, and in the process of calculating the detection threshold, directly select the threshold factor from the preset threshold factor range, so that the present invention can realize the detection of frequency hopping signals with less computing resources, thereby solving the problem that the prior art is difficult to detect frequency hopping signals in programmable logic devices (such as FPGA).

[0005] In a first aspect, the present invention provides a method for detecting a frequency hopping signal, the method comprising: acquiring a signal to be detected; performing Fourier transform on the signal to be detected to obtain a spectrum of the signal to be detected; calculating a reference amplitude of each frequency point according to the frequency amplitude of each frequency point in the spectrum; determining a detection threshold of each frequency point according to the reference amplitude of each frequency point and a threshold factor; wherein the threshold factor is selected from a preset threshold factor range; and determining a frequency point whose frequency amplitude is greater than the detection threshold as a frequency hopping signal.

[0006] In the above scheme, the detection threshold of each frequency point is quickly calculated by the frequency amplitude of each frequency point in the spectrum, and in the process of calculating the detection threshold, the threshold factor is directly selected from the preset threshold factor range. The calculation logic is relatively simple, thereby avoiding the need to consume a large amount of computing resources due to the complexity of the calculation formula of the threshold factor. The present invention consumes less computing resources to realize the detection of frequency hopping signals. Therefore, this scheme is not only applicable to devices suitable for complex calculations (such as CPU), but also applicable to programmable logic devices, and has a wide range of applications.

[0007] Optionally, the reference amplitude of each frequency point is calculated, including: for any frequency point i in the spectrum, by means of a preset sliding window, determining the comprehensive amplitude of the frequency point i in the corresponding sliding window and the reference frequency point amplitude; according to the reference amplitude of each frequency point and the threshold factor, determining the detection threshold of each frequency point, including: for any frequency point i in the spectrum, using the threshold factor as a weight factor of the comprehensive amplitude of the frequency point i, and determining the detection threshold of the frequency point i in combination with the amplitude of the reference frequency point.

[0008] In the above scheme, the detection threshold of the frequency point is calculated according to the comprehensive amplitude in the sliding window and the reference frequency point amplitude, so that the calculated detection threshold is more accurate, which is conducive to the subsequent identification of the frequency hopping signal from the clutter according to the detection threshold.

[0009] Optionally, the preset sliding window corresponding to any frequency point i refers to a window of a set frequency point length with frequency point i as the central unit; the left and right sub-areas in the window include a protection unit and a reference unit respectively; the left and right sub-areas are divided based on the central unit of the window; the protection unit in any sub-area is located between the central unit and the reference unit; determining the comprehensive amplitude and reference frequency point amplitude of frequency point i in the corresponding sliding window, including: for each sub-area, according to the frequency point amplitudes of each frequency point in the sub-area, determining the comprehensive amplitude of frequency point i in the sub-area and the reference frequency point amplitude in the sub-area; for any frequency point i in the spectrum, using the threshold factor as a weight factor of the comprehensive amplitude of frequency point i, and determining the detection threshold of frequency point i in combination with the reference frequency point amplitude, including: for each sub-area, using the threshold factor as a weight factor of the comprehensive amplitude of frequency point i in the sub-area, and determining the reference threshold of the sub-area in combination with the reference frequency point amplitude of frequency point i in the sub-area; determining the smaller reference threshold of the reference thresholds in the left and right sub-areas as the detection threshold of frequency point i.

[0010] In the above scheme, the preset sliding window is divided into two left and right sub-areas, and the reference thresholds in the left and right sub-areas are calculated respectively, and the smaller reference threshold is determined as the detection threshold of frequency point i. In this way, the selected detection threshold is more accurate, which effectively improves the detection accuracy of subsequent frequency hopping signals.

[0011] Optionally, based on the frequency amplitude of each frequency point in the sub-region, the comprehensive amplitude of frequency point i in the sub-region and the reference frequency amplitude in the sub-region are determined, including: determining the average of the frequency amplitudes of each frequency point in the sub-region as the comprehensive amplitude of frequency point i in the sub-region; determining the Kth frequency amplitude in the sub-region as the reference frequency amplitude of frequency point i in the sub-region; determining the reference threshold of the sub-region, including: multiplying the comprehensive amplitude of frequency point i in the sub-region by a threshold factor to obtain a multiplication result; adding the multiplication result and the reference frequency amplitude of frequency point i in the sub-region to obtain the reference threshold of the sub-region.

[0012] This scheme gives a preset threshold factor range. Any value selected as the threshold factor within this range will also result in a better detection threshold. In addition, the mean of the frequency amplitude can better represent the amplitude of each frequency point in the sliding window. Therefore, this scheme calculates the reference threshold by combining the mean of the frequency amplitude of each frequency point in the sub-area, so that the selected detection threshold is more accurate, effectively improving the detection accuracy of the frequency hopping signal.

[0013] Optionally, when the bandwidth of the signal to be detected is known, the frequency point length N corresponding to the protection unit is project The calculation formula is: Among them, FFT is the preset Fourier transform points, BW signal is the bandwidth of the signal to be detected, F s is the signal sampling rate; when the bandwidth of the signal to be detected is unknown, the frequency point length N corresponding to the protection unit project The calculation formula is: N project ≤N*10%; where N is the set frequency point length of the window.

[0014] In this scheme, the frequency point length corresponding to the protection unit should not be too short, otherwise the signal energy of frequency point i will leak into the background clutter, affecting the accuracy of background clutter power calculation; at the same time, the frequency point length corresponding to the protection unit should not be too long, otherwise more reference units will be included in the protection unit, resulting in a reduction in reference unit samples, which also affects the accuracy of background clutter power calculation. Therefore, by using the above calculation formula to determine the frequency point length corresponding to the protection unit, the appropriate frequency point length corresponding to the protection unit can be determined in the case of known or unknown bandwidth of the signal to be detected, so that the calculated detection threshold is more representative, effectively improving the detection accuracy of the frequency hopping signal.

[0015] Optionally, Fourier transforming the signal to be detected to obtain the spectrum of the signal to be detected includes: windowing the signal to be detected based on a window function to obtain a windowed signal to be detected; and Fourier transforming the windowed signal to be detected to obtain the spectrum of the signal to be detected.

[0016] In the above scheme, by windowing the signal to be detected, it is equivalent to intercepting a section of the signal to be detected. The length of the signal to be detected after windowing is shorter, which is convenient for subsequent Fourier transformation. Further, through Fourier transformation, it can only be obtained which frequency hopping signals are included in the signal to be detected as a whole, but the time when each frequency hopping signal appears is unknown. By first windowing the signal to be detected and then Fourier transforming the signal to be detected after windowing, a spectrum with time information can be obtained, and the time period of the frequency hopping signal can be determined from the spectrum later.

[0017] Optionally, after acquiring the signal to be detected and before performing Fourier transform on the signal to be detected, the method further includes: sampling the signal to be detected to obtain a digital signal; down-converting and filtering the digital signal to obtain a baseband signal, and determining the baseband signal as the signal to be detected.

[0018] In the above scheme, by sampling, down-converting and filtering the signal to be detected, the distinguishability of the signal can be effectively improved on the basis of reducing the complexity of the signal, and it is also helpful to suppress the noise in the signal and improve the signal-to-noise ratio.

[0019] Optionally, when the threshold factor is selected from a preset threshold factor range, the value of the threshold factor is positively correlated with the signal-to-noise ratio of the signal to be detected.

[0020] In the above scheme, when the signal-to-noise ratio is high, a larger threshold factor can be selected so that the detection threshold can cover all noise; when the signal-to-noise ratio is low, if a larger threshold factor is selected, the detection threshold may cover the frequency hopping signal, resulting in missed alarms, so a smaller threshold factor can be selected.

[0021] Optionally, the preset threshold factor range is [0, 4].

[0022] Selecting the threshold factor within the range of [0, 4] ensures that the value of the selected threshold factor is neither too large nor too small, which is conducive to selecting a suitable threshold factor, further making the selected detection threshold more accurate, and can effectively improve the detection accuracy of subsequent frequency hopping signals.

[0023] In a second aspect, the present invention provides a frequency hopping signal detection system, which is applied to a field programmable gate array FPGA, wherein the FPGA includes a signal processing module, a threshold calculation module, a delay module, and a signal detection module; the signal processing module is used to obtain a signal to be detected, perform Fourier transform on the signal to be detected, obtain a spectrum of the signal to be detected, and simultaneously input the spectrum into the threshold calculation module and the delay module; the threshold calculation module is used to calculate a reference amplitude of each frequency point in the spectrum, and determine a detection threshold of each frequency point according to the reference amplitude of each frequency point and a threshold factor; wherein the threshold factor is selected from a preset threshold factor range; the delay module is used to output the spectrum after a first time; wherein the first time is equal to the time required for the threshold calculation module to calculate and output the detection threshold; the signal detection module is used to compare the frequency amplitude of each frequency point in the spectrum output by the delay module with the detection threshold output by the threshold calculation module, and determine the frequency point whose frequency amplitude is greater than the detection threshold as a frequency hopping signal.

[0024] Optionally, the threshold calculation module is specifically used to: for any frequency point i in the spectrum, determine the comprehensive amplitude of frequency point i in the corresponding sliding window and the reference frequency point amplitude by means of a preset sliding window; for any frequency point i in the spectrum, use the threshold factor as a weight factor of the comprehensive amplitude of frequency point i, and determine the detection threshold of frequency point i in combination with the amplitude of the reference frequency point.

[0025] Optionally, the preset sliding window corresponding to any frequency point i refers to a window of a set frequency point length with frequency point i as the central unit; the left and right sub-areas in the window respectively include a protection unit and a reference unit; the left and right sub-areas are divided based on the central unit of the window; the protection unit in any sub-area is located between the central unit and the reference unit; the threshold calculation module is specifically used to: for each sub-area, determine the comprehensive amplitude of frequency point i in the sub-area and the reference frequency point amplitude in the sub-area according to the frequency amplitude of each frequency point in the sub-area; for each sub-area, use the threshold factor as the weight factor of the comprehensive amplitude of frequency point i in the sub-area, and combine the reference frequency point amplitude of frequency point i in the sub-area to determine the reference threshold of the sub-area; determine the smaller reference threshold of the reference thresholds in the left and right sub-areas as the detection threshold of frequency point i.

[0026] Optionally, the threshold calculation module is specifically used to: determine the average of the frequency amplitudes of each frequency point in the sub-region as the comprehensive amplitude of the frequency point i in the sub-region; determine the Kth frequency amplitude in the sub-region as the reference frequency amplitude of the frequency point i in the sub-region; multiply the comprehensive amplitude of the frequency point i in the sub-region by the threshold factor to obtain a multiplication result; add the multiplication result and the reference frequency amplitude of the frequency point i in the sub-region to obtain a reference threshold of the sub-region.

[0027] Optionally, when the bandwidth of the signal to be detected is known, the frequency point length N corresponding to the protection unit is project The calculation formula is: Among them, FFT is the preset Fourier transform points, BW signal is the bandwidth of the signal to be detected, F s is the signal sampling rate; when the bandwidth of the signal to be detected is unknown, the frequency point length N corresponding to the protection unit project The calculation formula is: N project ≤N*10%; where N is the set frequency point length of the window.

[0028] Optionally, the signal processing module is further used to: perform windowing processing on the signal to be detected based on a window function to obtain a windowed signal to be detected; and perform Fourier transform on the windowed signal to be detected to obtain a frequency spectrum of the signal to be detected.

[0029] Optionally, the signal processing module is further used to: sample the signal to be detected to obtain a digital signal; down-convert and filter the digital signal to obtain a baseband signal, and determine the baseband signal as the signal to be detected.

[0030] Optionally, when the threshold factor is selected from the preset threshold factor range, the value of the threshold factor is positively correlated with the signal-to-noise of the signal to be detected.

[0031] Optionally, the preset threshold factor range is [0, 4].

[0032] In a third aspect, the present invention provides a frequency hopping signal detection device, comprising: an acquisition unit, used to acquire a signal to be detected; a processing unit, used to perform Fourier transform on the signal to be detected to obtain a spectrum of the signal to be detected; calculating a reference amplitude of each frequency point according to the frequency amplitude of each frequency point in the spectrum; determining a detection threshold of each frequency point according to the reference amplitude of each frequency point and a threshold factor; wherein the threshold factor is selected from a preset threshold factor range; and determining a frequency point whose frequency amplitude is greater than the detection threshold as a frequency hopping signal.

[0033] In a fourth aspect, the present invention provides a computing device comprising at least one processor and at least one memory, wherein the memory stores a computer program, and when the program is executed by the processor, the processor executes the frequency hopping signal detection method described in any one of the first aspects above.

[0034] In a fifth aspect, the present invention further provides a computer-readable storage medium, wherein the storage medium stores a program, and when the program is run on a computer, the computer implements any of the frequency hopping signal detection methods described in the first aspect.

[0035] For the beneficial effects of the second to fifth aspects mentioned above, please refer to the technical effects that can be achieved by the corresponding design in the first aspect mentioned above, and no further details will be given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0037] Figure 1 A schematic diagram of an application scenario provided by an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of a flow chart of a frequency hopping signal detection method provided by an embodiment of the present invention;

[0039] Figure 3 A schematic flow chart of a method for preprocessing a signal to be detected provided by an embodiment of the present invention;

[0040] Figure 4 A schematic flow chart of a method for performing Fourier transform on a signal to be detected provided by an embodiment of the present invention;

[0041] Figure 5 A schematic diagram of a structure of a preset sliding window provided by an embodiment of the present invention;

[0042] Figure 6 A schematic diagram of a possible method for determining a frequency hopping signal provided by an embodiment of the present invention;

[0043] Figure 7 A frequency hopping signal detection system provided by an embodiment of the present invention;

[0044] Figure 8 A structural diagram of a frequency hopping signal detection device provided by an embodiment of the present invention;

[0045] Fig. 9A schematic diagram of the structure of a computing device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be noted that in the description of the present invention, "multiple" is understood as "at least two". "And / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone. A and B are connected, which can represent two situations: A and B are directly connected and A and B are connected through C. In addition, in the description of the present invention, words such as "first" and "second" are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order.

[0048] Hereinafter, some terms in the embodiments of the present invention are explained. It should be noted that these explanations are for the convenience of understanding by those skilled in the art and do not constitute a limitation on the protection scope claimed by the present invention.

[0049] like Figure 1As shown, it is a schematic diagram of an application scenario provided by an embodiment of the present invention, and the application scenario includes an antenna 101 and a frequency hopping signal detection device 102. Among them, the antenna 101 is used to receive the radio frequency signal and convert it into an intermediate frequency signal and transmit it to the frequency hopping signal detection device 102. The type of antenna includes but is not limited to a directional antenna, an omnidirectional antenna, a microstrip antenna, etc. The frequency hopping signal detection device 102 is used to receive the intermediate frequency signal transmitted by the antenna 101, and use it as a signal to be detected to detect whether the signal to be detected is a frequency hopping signal. The embodiment of the present invention does not specifically limit the type of the frequency hopping signal detection device 102. For example, the frequency hopping signal detection device 102 can refer to a device suitable for complex calculations or a programmable logic device. Among them, common devices suitable for complex calculations include central processing units (CPU), graphics processing units (GPU), etc. Common programmable logic devices include field programmable gate arrays (FPGA), complex programmable logic devices (CPLD), etc. Among them, FPGA can perform signal processing tasks at the hardware level, so it can achieve very low processing delay, which is conducive to quickly detecting and identifying frequency hopping signals. In addition, FPGA is programmable hardware, has a large number of programmable logic units and hardware resources, and can implement tasks in parallel. Specifically, the frequency hopping signal detection device 102 can be one or any combination of CPU, GPU, FPGA, CPLD, etc.

[0050] Based on the above Figure 1 The application scenario shown, Figure 2 A flow chart of a frequency hopping signal detection method provided by an embodiment of the present invention, which is applicable to the above Figure 1 The frequency hopping signal detection device 102 shown. The method comprises the following steps:

[0051] Step 201: The frequency hopping signal detection device 102 obtains a signal to be detected.

[0052] In a possible implementation, the signal to be detected is an intermediate frequency signal converted from a radio frequency signal, which is usually in a higher frequency range, which is not conducive to subsequent processing of the signal. Therefore, after obtaining the signal to be detected, the frequency hopping signal detection device 102 will first pre-process the signal to be detected, and then perform Fourier transform on the pre-processed signal to be detected.

[0053] like Figure 3 FIG. 1 is a flow chart of a method for preprocessing a signal to be detected provided by an embodiment of the present invention, the method comprising the following steps:

[0054] Step 301: The frequency hopping signal detection device 102 samples the signal to be detected to obtain a digital signal.

[0055] Specifically, the frequency hopping signal detection device 102 samples the intermediate frequency signal to be detected according to the sampling theorem to obtain a digital signal. Sampling refers to the process of taking the instantaneous value of a continuous time signal point by point at a certain time interval △t to obtain a discrete time digital signal. In the embodiment of the present invention, the signal sampling rate is F s .

[0056] In step 302, the frequency hopping signal detection device 102 performs down-conversion processing and filtering processing on the digital signal to obtain a baseband signal, and determines the baseband signal as the signal to be detected.

[0057] Specifically, down conversion refers to changing the frequency of a digital signal to convert it to a lower frequency. Filtering is used to remove unnecessary frequency components and suppress noise.

[0058] Through the above steps 301 to 302, by sampling, down-converting and filtering the signal to be detected, the signal distinguishability can be effectively improved on the basis of reducing the signal complexity, and it is also helpful to suppress the noise in the signal and improve the signal-to-noise ratio.

[0059] Step 202: The frequency hopping signal detection device 102 performs Fourier transform on the signal to be detected to obtain the frequency spectrum of the signal to be detected.

[0060] Specifically, Fourier transform (FT) is a linear integral transform used to transform a signal from the time domain to the frequency domain. By performing Fourier transform on the signal to be detected, the signal to be detected in the frequency domain can be obtained, that is, the spectrum of the signal to be detected. The spectrum shows the intensity or power of the signal to be detected at different frequencies. Specifically, the horizontal axis of the spectrum represents the frequency, usually in Hertz (Hz), and each point on the horizontal axis represents a specific frequency. The vertical axis of the spectrum represents the amplitude of the signal to be detected, which is used to show the signal strength of the signal to be detected at different frequencies. The amplitude can refer to the intensity, power or amplitude of the signal, etc., and the embodiment of the present invention does not specifically limit this.

[0061] In the embodiment of the present invention, the spectrum of the signal to be detected is a discrete spectrum diagram, which is composed of a series of discrete frequency points, each of which corresponds to a frequency component, that is, each frequency point is the number of a fixed frequency. It can be judged whether there is a frequency hopping signal in the signal to be detected according to the frequency amplitude of the frequency point.

[0062] In the embodiment of the present invention, the spectrum of the signal to be detected has M frequency points in total, and the spectrum of the signal to be detected is recorded as SP(m), where m∈[0,M-1].

[0063] By performing Fourier transform on the spectrum, it is possible to determine which frequency hopping signals are contained in the overall signal to be detected. However, it is impossible to determine the time when each frequency hopping signal appears. In order to solve the above problem, Figure 4 A schematic flow chart of a method for performing Fourier transform on a signal to be detected is shown by way of example.

[0064] like Figure 4 As shown, the method comprises the following steps:

[0065] Step 401: Based on the window function, the frequency hopping signal detection device 102 performs windowing processing on the signal to be detected to obtain a windowed signal to be detected.

[0066] Specifically, a window function refers to a weighted function of a unit weight, and a window function may also be referred to as a time window. Common time windows include rectangular windows, Hanning windows, and flat-top windows. By using a window function to perform windowing on the detection signal, the signal within the time window can be intercepted. In other words, performing windowing on the signal to be detected is equivalent to intercepting a section of the signal from the signal to be detected. By setting the number of points of the window function, a signal segment of the corresponding number of points can be intercepted from the signal to be detected. For example, if the number of points of the window function is set to 1000, a signal segment with a sampling point number of 1000 can be intercepted from the signal to be detected. In an embodiment of the present invention, the number of points of the window function is the same as the number of points of the subsequent Fourier transform.

[0067] By windowing the signal to be detected, the signal to be detected can be divided into small time windows, and the signal in each time window is called the windowed signal to be detected. The windowed signal to be detected carries time information. For example, assuming that each signal segment represents a 0.1us signal, the first windowed signal to be detected refers to the 0.1us signal segment, and the fifth windowed signal to be detected refers to the 0.5us signal segment.

[0068] Step 402: The frequency hopping signal detection device 102 performs Fourier transform on the windowed signal to be detected to obtain a frequency spectrum of the signal to be detected.

[0069] Optionally, the windowed signal to be detected may be converted into a spectrum using a fast Fourier transform. The number of points of the Fourier transform may be set by actual personnel according to business scenarios or technical experience, and the embodiment of the present invention does not specifically limit this.

[0070] In the embodiment of the present invention, since the signal to be detected after windowing refers to a section of the signal to be detected, the frequency spectrum obtained by Fourier transforming the signal to be detected after windowing is the frequency spectrum corresponding to the section of the signal. Since the signal to be detected after windowing carries time information, after Fourier transforming each signal to be detected after windowing, the frequency information in the time period can be obtained, so the frequency spectrum information of the signal to be detected that varies with time can be obtained. When subsequently determining the frequency hopping signal from the frequency spectrum, the time period where the frequency hopping signal is located can be determined according to the frequency spectrum where the frequency hopping signal is located.

[0071] In the embodiment of the present invention, the number of frequency points in the spectrum of the signal to be detected is equal to the number of points of Fourier transform. For example, assuming that the number of points of Fourier transform is 8192, the number of frequency points in the spectrum of the signal to be detected is equal to 8192.

[0072] Step 203: The frequency hopping signal detection device 102 calculates a reference amplitude of each frequency point according to the frequency amplitude of each frequency point in the spectrum.

[0073] Optionally, the reference amplitude of each frequency point can be determined by detecting the sliding window. Figure 5 As shown, it is a schematic diagram of the structure of a preset sliding window provided by an embodiment of the present invention. Among them, the preset sliding window corresponding to any frequency point i refers to a window of a set frequency point length with frequency point i as the center unit. Taking the center unit of the window as the division basis, the window includes two left and right sub-areas, and the left and right sub-areas respectively include a protection unit and a reference unit, and the protection unit in any sub-area is located between the center unit and the reference unit.

[0074] In the embodiment of the present invention, the set frequency point length of the window is N, that is, the sliding window includes N frequency points. Wherein, N is an odd number. The value of N can be determined by the data of the frequency points in the spectrum. Specifically, the calculation formula for setting the frequency point length N is:

[0075] N=M*(3%~4%)……(1)

[0076] Where M is the number of frequencies in the spectrum.

[0077] Optionally, the frequency point length N corresponding to the protection unit project for:

[0078] When the bandwidth of the signal to be detected is known, the frequency point length N corresponding to the protection unit project The calculation formula is:

[0079]

[0080] Among them, FFT is the preset Fourier transform points, BW signal is the bandwidth of the signal to be detected, F s is the signal sampling rate.

[0081] In the case of unknown signal bandwidth to be detected, the frequency point length N corresponding to the protection unit project The calculation formula is:

[0082] N project ≤N*10%……(3)

[0083] Wherein, N is the set frequency point length of the window.

[0084] In an embodiment of the present invention, the method for calculating the reference amplitude of each frequency point by a preset sliding window is as follows: for any frequency point i in the spectrum, the comprehensive amplitude of the frequency point i in the corresponding sliding window and the reference frequency point amplitude are determined by a preset sliding window.

[0085] Specifically, the central unit of the preset sliding window is aligned with the frequency point i in the spectrum, the protection unit and the reference unit in the sliding window correspond to the frequency points around the frequency point i respectively, and the comprehensive amplitude and the reference frequency amplitude of the frequency point i in the corresponding sliding window are determined by calculating the comprehensive amplitude and the reference frequency amplitude of the frequency point corresponding to the reference unit.

[0086] In a possible implementation, the comprehensive amplitude refers to the average of the frequency amplitudes of all frequencies, and the reference frequency amplitude refers to the Kth largest amplitude. In other words, the comprehensive amplitude refers to the average of the frequency amplitudes of all frequencies corresponding to the reference unit, and the reference frequency amplitude refers to taking the Kth largest amplitude of the frequency amplitudes of all frequencies corresponding to the reference unit as the reference frequency amplitude. K can be selected based on the bandwidth characteristics of the frequency hopping signal. If the bandwidth of the frequency hopping signal is large, the K value can be appropriately selected to be larger; if the bandwidth of the frequency hopping signal is small, the K value can be appropriately selected to be smaller. Generally, when the bandwidth of the frequency hopping signal is unknown, K=4 can be used.

[0087] Further optionally, determining the comprehensive amplitude and reference frequency amplitude of frequency point i in the corresponding sliding window includes: for each sub-region, determining the comprehensive amplitude of frequency point i in the sub-region and the reference frequency amplitude in the sub-region according to the frequency amplitudes of each frequency point in the sub-region.

[0088] Specifically, the comprehensive amplitude and the reference frequency amplitude of all frequency points corresponding to the left reference unit in the left sub-region are calculated to determine the comprehensive amplitude of frequency point i in the left sub-region and the reference frequency amplitude in the sub-region; and the comprehensive amplitude and the reference frequency amplitude of all frequency points corresponding to the left reference unit in the right sub-region are calculated to determine the comprehensive amplitude of frequency point i in the right sub-region and the reference frequency amplitude in the sub-region.

[0089] Step 204: The frequency hopping signal detection device 102 determines the detection threshold of each frequency point according to the reference amplitude of each frequency point and the threshold factor.

[0090] The threshold factor is selected from a preset threshold factor range. In a possible implementation, the preset threshold factor range is [0, 4]. In the present embodiment, the threshold factor is directly selected from the preset threshold factor range, and its calculation logic is relatively simple, thereby avoiding the need to consume a large amount of computing resources due to the complexity of the calculation formula of the threshold factor, so that the present invention consumes less computing resources to realize the detection of frequency hopping signals.

[0091] Optionally, when the threshold factor is selected from the preset threshold factor range, the value of the threshold factor is positively correlated with the signal-to-noise ratio of the signal to be detected. Specifically, when the signal-to-noise ratio of the signal to be detected is larger, the threshold factor is larger; when the signal-to-noise ratio of the signal to be detected is smaller, the threshold factor is smaller.

[0092] In the above scheme, when the signal-to-noise ratio is high, a larger threshold factor can be selected so that the detection threshold can cover all noise; when the signal-to-noise ratio is low, if a larger threshold factor is selected, the detection threshold may cover the frequency hopping signal, resulting in missed alarms, so a smaller threshold factor can be selected.

[0093] Optionally, for any frequency point i in the spectrum, the threshold factor is used as a weight factor of the comprehensive amplitude of the frequency point i, and the detection threshold of the frequency point i is determined in combination with the amplitude of the reference frequency point.

[0094] Further optionally, for any frequency point i in the spectrum, the threshold factor can be used as a weight factor of the comprehensive amplitude of the frequency point i, and the detection threshold of the frequency point i can be determined in combination with the reference frequency point amplitude. The method includes the following process a1 and process a2:

[0095] Process a1: For each sub-region, the threshold factor is used as a weight factor of the comprehensive amplitude of the frequency point i in the sub-region, and the reference threshold of the sub-region is determined in combination with the reference frequency point amplitude of the frequency point i in the sub-region.

[0096] Optionally, when the comprehensive amplitude refers to the average of the frequency amplitudes of each frequency point, and the reference frequency amplitude refers to the Kth frequency amplitude, the method for determining the comprehensive amplitude and the reference frequency amplitude of the frequency point i in the sub-region includes:

[0097] The average of the frequency amplitudes of each frequency point in the sub-region is determined as the comprehensive amplitude of the frequency point i in the sub-region. The Kth amplitude in the sub-region is determined as the reference frequency amplitude of the frequency point i in the sub-region.

[0098] In this case, the calculation formula of the reference threshold of the sub-area is: reference threshold = threshold factor × comprehensive amplitude + reference frequency amplitude.

[0099] In other words, the method for determining the reference threshold of the sub-area is: multiply the comprehensive amplitude of frequency point i in the sub-area by the threshold factor to obtain the multiplication result; add the multiplication result to the reference frequency point amplitude of frequency point i in the sub-area to obtain the reference threshold of the sub-area.

[0100] Process a2: The smaller reference threshold of the reference thresholds in the left and right sub-regions is determined as the detection threshold of the frequency point i. For example, if the reference threshold in the left sub-region is smaller than the reference threshold in the right sub-region, the reference threshold in the left sub-region is determined as the detection threshold of the frequency point i.

[0101] Step 205: The frequency hopping signal detection device 102 determines the frequency point whose reference amplitude is greater than the detection threshold as a frequency hopping signal.

[0102] Through the above steps 201 to 205, more accurate frequency hopping signal detection can be performed with less computing resources consumed.

[0103] like Figure 6 As shown, it is a possible schematic diagram of determining a frequency hopping signal provided by an embodiment of the present invention. The frequency hopping signal detection device 102 simulates the frequency hopping signal detection, wherein the signal sampling rate is set to 192MHz, the center frequency of the intermediate frequency signal is 140MHz, the low-pass filter Fpass=30MHz, Fstop=33MHz, the stopband suppression is 80dB, the number of FFT operation points is 8192, the protection unit size is 16, the reference unit size is 256, the threshold factor α is 3 / 2, and K=4.

[0104] according to Figure 6 It can be concluded that the frequency hopping signal detection device 102 detects three frequency hopping signals, and the frequency of signal 1 is 130 MHz (at Figure 6 The corresponding frequency point position on the mid-frequency spectrum is 3670), and the frequency of signal 2 is 145MHz (in Figure 6 The corresponding frequency point position on the mid-frequency spectrum is 4310), and the frequency of signal 3 is 146MHz (in Figure 6 The corresponding frequency point position on the mid-spectrum is 4353). Threshold calculation is performed on a spectrum data, and the result is as follows Figure 6 As shown, it can be seen that within the frequency range that needs to be detected, the amplitudes of signal 1, signal 2, and signal 3 are greater than their corresponding threshold values, and the amplitudes of noise signals at other frequency points are all less than their corresponding threshold values.

[0105] It should be noted that in the above step 202, after the spectrum of the signal to be detected is obtained, when calculating the detection threshold of each frequency point, only the detection threshold of the frequency points in the core area of ​​the spectrum may be calculated.

[0106] Specifically, assuming that the frequency point range of the signal to be detected on the spectrum is M1 to M2, [M1, M1+(N1-1) / 2] and [M2-(N1-1) / 2, M2] are regarded as non-core areas in the spectrum, and [M1+(N1-1) / 2, M2-(N1-1) / 2] is regarded as the core area in the spectrum. In this scheme, the detection threshold TH(n) of the frequency points in the core area is obtained, and the detection threshold TH(n) of the frequency points in the non-core area is taken as 1.

[0107] The final detection threshold of the entire spectrum data is:

[0108]

[0109] like Figure 7 As shown, a frequency hopping signal detection system provided by an embodiment of the present invention is applied to FPGA, wherein the FPGA includes a signal processing module, a threshold calculation module, a delay module, and a signal detection module. Each module is introduced below.

[0110] The signal processing module is used to obtain the signal to be detected, perform Fourier transform on the signal to be detected, obtain the spectrum of the signal to be detected, and input the spectrum into the threshold calculation module and the delay module at the same time.

[0111] The threshold calculation module is used to calculate the reference amplitude of each frequency point in the spectrum, and determine the detection threshold of each frequency point according to the reference amplitude of each frequency point and the threshold factor; wherein the threshold factor is selected from the preset threshold factor range.

[0112] The delay module is used to output the spectrum after a first time has passed; wherein the first time is equal to the time required for the threshold calculation module to calculate and output the detection threshold.

[0113] The signal detection module is used to compare the frequency amplitude of each frequency point in the spectrum output by the delay module with the detection threshold output by the threshold calculation module, and determine the frequency point with a frequency amplitude greater than the detection threshold as a frequency hopping signal.

[0114] In the embodiment of the present invention, FPGA performs signal processing tasks at the hardware level, so very low processing delay can be achieved, which is conducive to rapid detection and identification of frequency hopping signals. In addition, FPGA is programmable hardware with a large number of programmable logic units and hardware resources, so different frequency hopping signal detection algorithms and requirements can be implemented by reprogramming, and frequency hopping signal detection tasks can be implemented in parallel.

[0115] Based on the same inventive concept as above, the present invention also provides a frequency hopping signal detection device, which can execute the method in the above invention embodiment. The structure of the frequency hopping signal detection device provided by the present invention can be seen in Figure 8The frequency hopping signal detection device 800 includes an acquisition unit 801 and a processing unit 802. The acquisition unit 801 is used to acquire the signal to be detected; the processing unit 802 is used to perform Fourier transform on the signal to be detected to obtain the spectrum of the signal to be detected; the reference amplitude of each frequency point in the spectrum is calculated; the detection threshold of each frequency point is determined according to the reference amplitude of each frequency point and the threshold factor; the threshold factor is selected from the preset threshold factor range; the frequency point whose frequency amplitude is greater than the detection threshold is determined as a frequency hopping signal.

[0116] For a more detailed description of the acquisition unit 801 and the processing unit 802, please refer to Figure 2 The relevant descriptions in the method embodiment shown are directly obtained and will not be repeated here.

[0117] Based on the same technical concept, the present invention also provides a computing device, such as Fig. 9 As shown, the computing device 900 includes at least one processor 901 and a memory 902 connected to the at least one processor. The present invention does not limit the specific connection medium between the processor 901 and the memory 902. Fig. 9 For example, the processor 901 and the memory 902 are connected via a bus. The bus can be divided into an address bus, a data bus, a control bus, etc.

[0118] In the present invention, the memory 902 stores instructions that can be executed by at least one processor 901. By executing the instructions stored in the memory 902, the at least one processor 901 can perform the steps included in the aforementioned frequency hopping signal detection method.

[0119] Among them, the processor 901 is the control center of the computing device, and can use various interfaces and lines to connect various parts of the computing device, and realize frequency hopping signal detection by running or executing instructions stored in the memory 902 and calling data stored in the memory 902. Optionally, the processor 901 may include one or more processing units, and the processor 901 may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface, and application programs, and the modem processor mainly processes the issuance of instructions. It can be understood that the above-mentioned modem processor may not be integrated into the processor 901. In some embodiments, the processor 901 and the memory 902 may be implemented on the same chip, and in some embodiments, they may also be implemented separately on independent chips.

[0120] The processor 901 may be a general-purpose processor, such as a central processing unit (CPU), a digital signal processor, an application specific integrated circuit (ASIC), a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute the methods, steps, and logic block diagrams disclosed in the present invention. A general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the method disclosed in the embodiment of the frequency hopping signal detection method may be directly embodied as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.

[0121] The memory 902 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The memory 902 may include at least one type of storage medium, such as flash memory, hard disk, multimedia card, card-type memory, random access memory (RAM), static random access memory (SRAM), programmable read only memory (PROM), read only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic memory, disk, optical disk, etc. The memory 902 is any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 902 in the present invention can also be a circuit or any other device that can realize a storage function, used to store program instructions and / or data.

[0122] Based on the same technical concept, the present invention also provides a computer-readable storage medium storing a computer program executable by a computing device. When the program runs on the computing device, the computing device executes the steps of the above-mentioned frequency hopping signal detection method.

[0123] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0124] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes 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 processes in the flowchart and / or block diagram. 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.

[0125] 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 including 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.

[0126] 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.

[0127] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A frequency hopping signal detection method, characterized in that: The method comprises: Obtain the signal to be detected; Performing Fourier transform on the signal to be detected to obtain a frequency spectrum of the signal to be detected; Calculating a reference amplitude of each frequency point according to the frequency amplitude of each frequency point in the spectrum; Determining the detection threshold of each frequency point according to the reference amplitude of each frequency point and the threshold factor; wherein the threshold factor is selected from a preset threshold factor range; The frequency point whose amplitude is greater than the detection threshold is determined as the frequency hopping signal.

2. The method according to claim 1, characterized in that The calculating of the reference amplitude of each frequency point includes: For any frequency point i in the spectrum, determine the comprehensive amplitude of the frequency point i in the corresponding sliding window and the reference frequency point amplitude by means of a preset sliding window; The determining the detection threshold of each frequency point according to the reference amplitude of each frequency point and the threshold factor includes: For any frequency point i in the spectrum, the threshold factor is used as a weight factor of the comprehensive amplitude of the frequency point i, and the detection threshold of the frequency point i is determined in combination with the amplitude of the reference frequency point.

3. The method according to claim 2, characterized in that The preset sliding window corresponding to any frequency point i refers to a window of a set frequency point length with frequency point i as the central unit; the left and right sub-areas in the window respectively include a protection unit and a reference unit; the left and right sub-areas are divided based on the central unit of the window; the protection unit in any sub-area is located between the central unit and the reference unit; The step of determining the comprehensive amplitude of the frequency point i in the corresponding sliding window and the reference frequency point amplitude comprises: For each sub-region, according to the frequency amplitudes of each frequency point in the sub-region, determine the comprehensive amplitude of the frequency point i in the sub-region and the reference frequency amplitude in the sub-region; For any frequency point i in the spectrum, using the threshold factor as a weight factor of the comprehensive amplitude of the frequency point i, and determining the detection threshold of the frequency point i in combination with the reference frequency point amplitude, comprises: For each sub-region, the threshold factor is used as a weight factor of the comprehensive amplitude of the frequency point i in the sub-region, and the reference threshold of the sub-region is determined in combination with the reference frequency point amplitude of the frequency point i in the sub-region; The smaller reference threshold among the reference thresholds in the left and right sub-areas is determined as the detection threshold of the frequency point i.

4. The method according to claim 3, characterized in that The step of determining the comprehensive amplitude of the frequency point i in the sub-region and the reference frequency point amplitude in the sub-region according to the frequency point amplitudes of each frequency point in the sub-region comprises: Determine the average of the frequency amplitudes of each frequency point in the sub-region as the comprehensive amplitude of the frequency point i in the sub-region; Determine the Kth amplitude in the sub-region as the reference frequency amplitude of the frequency point i in the sub-region; The determining of the reference threshold of the sub-area includes: The comprehensive amplitude of the frequency point i in the sub-region is multiplied by the threshold factor to obtain a multiplication result; the multiplication result is added to the reference frequency point amplitude of the frequency point i in the sub-region to obtain a reference threshold of the sub-region.

5. The method according to any one of claims 1 to 4, characterized in that: The performing Fourier transform on the signal to be detected to obtain the frequency spectrum of the signal to be detected includes: Based on the window function, the signal to be detected is subjected to windowing processing to obtain a windowed signal to be detected; Performing Fourier transform on the windowed signal to be detected to obtain a frequency spectrum of the signal to be detected.

6. The method according to claim 1, characterized in that After acquiring the signal to be detected and before performing Fourier transform on the signal to be detected, the method further includes: Sampling the signal to be detected to obtain a digital signal; The digital signal is down-converted and filtered to obtain a baseband signal, and the baseband signal is determined as the signal to be detected.

7. The method according to any one of claims 1 to 4, characterized in that: When the threshold factor is selected from the preset threshold factor range, the value of the threshold factor is positively correlated with the signal-to-noise ratio of the signal to be detected.

8. The method according to claim 1, characterized in that The preset threshold factor range is [0, 4].

9. A frequency hopping signal detection system, characterized in that: Applied to a field programmable gate array FPGA, the FPGA includes a signal processing module, a threshold calculation module, a delay module, and a signal detection module; The signal processing module is used to obtain the signal to be detected, perform Fourier transform on the signal to be detected, obtain the spectrum of the signal to be detected, and input the spectrum into the threshold calculation module and the delay module at the same time; The threshold calculation module is used to calculate the reference amplitude of each frequency point in the spectrum, and determine the detection threshold of each frequency point according to the reference amplitude of each frequency point and the threshold factor; wherein the threshold factor is selected from a preset threshold factor range; The delay module is used to output the spectrum after a first time; wherein the first time is equal to the time required by the threshold calculation module to calculate and output the detection threshold; The signal detection module is used to compare the frequency amplitude of each frequency point in the spectrum output by the delay module with the detection threshold output by the threshold calculation module, and determine the frequency point with a frequency amplitude greater than the detection threshold as a frequency hopping signal.

10. A frequency hopping signal detection device, characterized in that: include: An acquisition unit, used for acquiring a signal to be detected; A processing unit, used for performing Fourier transform on the signal to be detected to obtain a frequency spectrum of the signal to be detected; Calculating a reference amplitude of each frequency point according to the frequency amplitude of each frequency point in the spectrum; determining a detection threshold of each frequency point according to the reference amplitude of each frequency point and a threshold factor; wherein the threshold factor is selected from a preset threshold factor range; The frequency point whose amplitude is greater than the detection threshold is determined as the frequency hopping signal.

11. A computing device, characterized in that: The method comprises at least one processor and at least one memory, wherein the memory stores a computer program, and when the program is executed by the processor, the processor executes the method according to any one of claims 1 to 8.

12. A computer-readable storage medium, characterized in that: The storage medium stores a program, and when the program is run on a computer, the computer is enabled to implement the method according to any one of claims 1 to 8.

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