Modulation identification method and device of wireless signal and blind demodulation system of wireless signal

Abstract

The application belongs to the technical field of signal processing, and provides a modulation identification method and device of a wireless signal and a wireless signal blind demodulation system. The method comprises the following steps: extracting a target feature from the wireless signal, the target feature being at least one of a time domain feature, a frequency domain feature and a time-frequency domain feature; obtaining a signal type of the wireless signal based on the target feature, and determining at least one candidate modulation mode according to the signal type; for each candidate modulation mode, performing blind demodulation on the wireless signal by using the candidate modulation mode and calculating an error vector magnitude (EVM) to obtain multiple EVM values; and screening a target EVM value from the multiple EVM values by using a synchronization point optimization strategy to obtain a target modulation mode, so as to realize demodulation of the wireless signal. The method disclosed in the application enhances the recognition robustness and accuracy under a low signal-to-noise ratio condition by fusing the multi-dimensional features of the wireless signal and combining the error vector magnitude auxiliary judgment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of signal processing, in particular to a modulation recognition method and device of wireless signal and a blind demodulation system of wireless signal. BACKGROUND

[0002] With the rapid development of modern communication technology, wireless communication systems are widely used in military, civilian and industrial control and other fields; since the modulation mode directly determines the transmission characteristics of the signal, the accurate identification and blind demodulation of the unknown signal modulation mode have become an important research topic in the fields of wireless signal monitoring, spectrum supervision and non-cooperative communication.

[0003] In practical applications, the modulation mode of wireless signal includes linear modulation mode (such as AM, FM), nonlinear modulation mode (such as PSK, QAM) and composite modulation mode (such as MSK+AM, 2FSK+FM) and the like, and with the development of high-order modulation technology, the spectrum utilization rate of the signal is significantly improved, but at the same time, it also brings higher challenges to the identification and demodulation of the modulation mode under low signal-to-noise ratio, complex interference and unknown environment.

[0004] In the related art, the wireless signal is mainly modulated by linear modulation mode, and the blind demodulation capability for composite modulation signals containing multiple modulation components is limited, resulting in reduced signal blind demodulation recognition accuracy in complex channels or low signal-to-noise ratio environments, which cannot meet the diversified needs of complex signal processing in the modern wireless communication field. SUMMARY

[0005] The present application provides a modulation recognition method and device of wireless signal and a blind demodulation system of wireless signal to solve the defect that the blind demodulation capability for composite modulation signals containing multiple modulation components is limited in the prior art, resulting in low signal blind demodulation recognition accuracy in complex channels or low signal-to-noise ratio environments, and improves the signal blind demodulation recognition accuracy and robustness.

[0006] The present application provides a modulation recognition method of wireless signal, comprising:

[0007] extracting a target feature from the wireless signal, the target feature being at least one of a time domain feature, a frequency domain feature and a time-frequency domain feature;

[0008] obtaining a signal type of the wireless signal based on the target feature, and determining at least one candidate modulation mode according to the signal type;

[0009] for each candidate modulation mode, blind demodulating the wireless signal using the candidate modulation mode and calculating an error vector magnitude (EVM) to obtain a plurality of EVM values;

[0010] The target EVM value is selected from the plurality of EVM values by using a synchronization point optimization strategy, and a target modulation mode is obtained to realize demodulation of the wireless signal.

[0011] According to the application, a wireless signal modulation identification method is provided, the target feature is a time domain feature, a frequency domain feature and a time-frequency domain feature; the time domain feature includes a flatness of a signal envelope of the wireless signal; the frequency domain feature includes a peak number of a power spectrum of the wireless signal and a spectrum flatness; and the time-frequency domain feature includes a flatness of an instantaneous frequency of the wireless signal.

[0012] The signal type of the wireless signal is obtained based on the target feature, and includes:

[0013] In a case where the peak number of the power spectrum of different powers of the wireless signal is 1, and the spectrum flatness of different powers is greater than a first threshold value, it is determined that the signal type of the wireless signal includes a constant envelope signal.

[0014] In a case where the flatness of the signal envelope of the wireless signal is greater than a second threshold value, and the flatness of the instantaneous frequency is greater than a third threshold value, it is determined that the signal type of the wireless signal includes an amplitude modulation signal.

[0015] In a case where the peak number of the power spectrum of the first power of the wireless signal is 0, the spectrum flatness of the first power is less than or equal to the first threshold value, the peak number of the power spectrum of the fourth power is 1, the spectrum flatness of the fourth power is greater than the first threshold value, the flatness of the instantaneous frequency is less than or equal to a fourth threshold value, and the flatness of the signal envelope is less than a fifth threshold value, it is determined that the signal type of the wireless signal includes a quadrature offset quadrature phase shift keying 4OQPSK signal.

[0016] According to the application, a wireless signal modulation identification method is provided, the target feature is a time domain feature and a frequency domain feature; the time domain feature includes a modulation depth of a signal envelope of the wireless signal; and the frequency domain feature includes a peak number of a power spectrum of the wireless signal and a spectrum flatness.

[0017] The signal type of the wireless signal is obtained based on the target feature, and includes:

[0018] In a case where the peak number of the power spectrum of the first power of the wireless signal is 2, and the spectrum flatness satisfies a sixth threshold value, it is determined that the signal type of the wireless signal includes a binary frequency shift keying 2FSK signal and an amplitude modulation AM signal.

[0019] In a case where the number of peaks of the 2nd power spectrum of the wireless signal is 2 and the flatness of the 2nd frequency spectrum satisfies the sixth threshold value, it is determined that the signal type of the wireless signal includes a binary minimum shift keying 2MSK signal and an AM signal;

[0020] In a case where the modulation depth is greater than a seventh threshold value, the signal type of the wireless signal includes an AM signal; in a case where the modulation depth is less than or equal to the seventh threshold value, the signal type of the wireless signal includes a continuous wave CW signal;

[0021] In a case where the number of peaks of the 1st power spectrum of the wireless signal is 2 and the flatness of the 1st frequency spectrum satisfies the sixth threshold value, it is determined that the signal type of the wireless signal includes a 2FSK signal.

[0022] According to the present application, a modulation recognition method of a wireless signal is provided, the target feature is a frequency domain feature and a time-frequency domain feature; wherein the frequency domain feature includes the number of peaks of the power spectrum of the wireless signal and the flatness of the frequency spectrum; the time-frequency domain feature includes the flatness of the instantaneous frequency of the wireless signal;

[0023] The signal type of the wireless signal is acquired based on the target feature, and the method further includes:

[0024] In a case where the number of peaks of the 1st power spectrum of the wireless signal is 0, the flatness of the 1st frequency spectrum is less than or equal to a first threshold value, the number of peaks of the 2nd power spectrum of the wireless signal is 2, and the flatness of the 2nd frequency spectrum satisfies an eighth threshold value, it is determined that the signal type of the wireless signal includes a 2MSK or a binary Gaussian minimum shift keying 2GMSK signal.

[0025] In a case where the number of peaks of the 1st power spectrum of the wireless signal is 0, the flatness of the 1st frequency spectrum is less than or equal to a first threshold value, the number of peaks of the 2nd power spectrum of the wireless signal is 1 or 3, the flatness of the 2nd frequency spectrum is greater than the first threshold value, and the flatness of the instantaneous frequency is greater than a third threshold value, it is determined that the signal type of the wireless signal includes a binary phase shift keying 2PSK signal.

[0026] According to the present application, a modulation recognition method of a wireless signal is provided, the target feature is a frequency domain feature; wherein the frequency domain feature includes the number of peaks of the power spectrum of the wireless signal and the flatness of the frequency spectrum;

[0027] The signal type of the wireless signal is acquired based on the target feature, and the method further includes:

[0028] In a case where the number of peaks of the power spectrum of the 1st power of the wireless signal is 0, the number of peaks of the 4th power spectrum is 1 or 3, and the number of peaks of the 2nd power spectrum is 1, it is determined that the signal type of the wireless signal includes an 8 Quadrature Amplitude Modulation (8QAM) signal;

[0029] In a case where the number of peaks of the power spectrum of the 1st power of the wireless signal is 0, the number of peaks of the 4th power spectrum is 1 or 3, and the number of peaks of the 2nd power spectrum is not 1, it is determined that the signal type of the wireless signal includes a 4 Phase Shift Keying (4PSK) or 8QAM signal;

[0030] In a case where the number of peaks of the power spectrum of the 1st power of the wireless signal and the number of peaks of the power spectrum of the 2nd power are 0, and the number of peaks of the power spectrum of the 4th power is 1 or 3, it is determined that the signal type of the wireless signal includes a 16 / 32 / 64QAM signal;

[0031] In a case where the number of peaks of the power spectrum of the 1st power, the 2nd power, the 4th power and the 8th power of the wireless signal are 0, and the number of peaks of the power spectrum of the 16th power is 1, it is determined that the signal type of the wireless signal includes a 16 Amplitude Phase Shift Keying (16APSK) signal;

[0032] In a case where the number of peaks of the power spectrum of the 1st power of the wireless signal is 0, the degree of flatness of the 1st power spectrum is less than or equal to a first threshold value, the number of peaks of the 4th power spectrum is 1, the degree of flatness of the 4th power spectrum is greater than the first threshold value, and the number of peaks of the 2nd power spectrum is 2, the degree of flatness of the 2nd power spectrum is less than or equal to a ninth threshold value, it is determined that the signal type of the wireless signal includes a 4 Offset Quadrature Phase Shift Keying (4OQPSK) signal.

[0033] According to the present application, a modulation recognition method of a wireless signal is provided, wherein the target feature further includes a time domain feature; and the time domain feature includes a degree of flatness of a signal envelope of the wireless signal.

[0034] The obtaining of the signal type of the wireless signal based on the target feature further includes:

[0035] In a case where the degree of flatness of the signal envelope is less than or equal to a tenth threshold value, and the wireless signal can be demodulated by a Frequency Modulation (FM) signal, it is determined that the signal type of the wireless signal includes a 2 Frequency Shift Keying (FSK) or Minimum Shift Keying (MSK) modulated signal.

[0036] In a case where the degree of flatness of the signal envelope is less than or equal to the tenth threshold value, the wireless signal cannot be demodulated by an FM signal, and a ratio of a sampling rate of the wireless signal to a code rate is not an integer, it is determined that the signal type of the wireless signal includes an FM signal.

[0037] According to the method for identifying modulation of a wireless signal provided by the application, the target feature is a frequency domain feature and a time-frequency domain feature; wherein the frequency domain feature comprises a peak number of a power spectrum of the wireless signal and a spectrum flatness degree; and the time-frequency domain feature comprises an instantaneous frequency flatness degree of the wireless signal.

[0038] The method further comprises:

[0039] In a case where the peak number of the power spectrum of the first order is 0, the peak number of the power spectrum of the second order is 0, the peak number of the power spectrum of the fourth order is 2 or 4, the spectrum flatness degree of the first order satisfies a sixth threshold value, and the instantaneous frequency flatness degree is greater than an eleventh threshold value, it is determined that the signal type of the wireless signal comprises a π / 4 QPSK signal.

[0040] In a case where the peak number of the power spectrum of the first order is 0, the peak number of the power spectrum of the second order is 1, the peak number of the power spectrum of the fourth order is 1 or 2, the spectrum flatness degree of the first order is less than a ninth threshold value, the spectrum flatness degrees of the second order and the fourth order are greater than a first threshold value, and the instantaneous frequency flatness degree is greater than the eleventh threshold value, it is determined that the signal type of the wireless signal comprises a 4π differential quadrature phase shift keying 4π / DQPSK signal.

[0041] In a case where the peak number of the power spectrum of the first order, the peak number of the power spectrum of the second order and the peak number of the power spectrum of the fourth order are 0, and the instantaneous frequency flatness degree is greater than the eleventh threshold value, it is determined that the signal type of the wireless signal comprises an 8PSK signal.

[0042] The application further provides a device for identifying modulation of a wireless signal, comprising:

[0043] a feature extraction module configured to extract a target feature from the wireless signal, wherein the target feature is at least one of a time domain feature, a frequency domain feature and a time-frequency domain feature;

[0044] a modulation identification module configured to acquire a signal type of the wireless signal based on the target feature, and determine at least one candidate modulation mode according to the signal type;

[0045] a calculation module configured to, for each candidate modulation mode, perform blind demodulation on the wireless signal by using the candidate modulation mode and calculate an error vector magnitude (EVM) to obtain a plurality of EVM values;

[0046] a screening module configured to screen a target EVM value from the plurality of EVM values by using a synchronization point optimization strategy to obtain a target modulation mode, so as to realize demodulation of the wireless signal.

[0047] The application further provides a wireless signal blind demodulation system, comprising:

[0048] a signal receiving module, used for the wireless signal;

[0049] a modulation identification device of the wireless signal;

[0050] a demodulation module, used for demodulating the wireless signal according to the target modulation mode output by the modulation identification device of the wireless signal to obtain a demodulation result; wherein the demodulation result comprises at least one of a demodulated symbol stream, a modulation mode index and an EVM value.

[0051] The application further provides an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the modulation identification method of the wireless signal according to any one of the above-mentioned methods when executing the computer program.

[0052] The application further provides a non-transitory computer readable storage medium having a computer program stored thereon, wherein the computer program is executable by a processor to implement the modulation identification method of the wireless signal according to any one of the above-mentioned methods.

[0053] The application further provides a computer program product comprising a computer program, wherein the computer program is executable by a processor to implement the modulation identification method of the wireless signal according to any one of the above-mentioned methods.

[0054] The modulation identification method of the wireless signal, the device and the wireless signal blind demodulation system provided by the application can extract a target feature from the wireless signal to obtain the signal type of the wireless signal, determine the candidate modulation mode according to the signal type, perform blind demodulation on the wireless signal by using the candidate modulation mode and calculate the error vector magnitude EVM, finally screen out the target EVM value from the multiple EVM values by using the synchronization point optimization strategy to obtain the target modulation mode, so as to realize the demodulation of the wireless signal, and the identification robustness and accuracy under the condition of low signal-to-noise ratio are enhanced by fusing the multi-dimensional features of the wireless signal and combining the error vector magnitude auxiliary judgment. BRIEF DESCRIPTION OF DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0056] Figure 1 is one of the flowcharts of the modulation identification method of the wireless signal provided by the present application.

[0057] Figure 2 is the second flowchart of the wireless signal modulation identification method provided by the present application.

[0058] Figure 3 is the structural schematic diagram of the wireless signal modulation identification device provided by the present application.

[0059] Figure 4 is the structural schematic diagram of the wireless signal blind demodulation system provided by the present application.

[0060] Figure 5 is the structural schematic diagram of the electronic device provided by the present application. DETAILED DESCRIPTION

[0061] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0062] The wireless signal modulation identification method, device and wireless signal blind demodulation system of the present application will be described below. Figures 1-4

[0063] Figure 1 is the first flowchart of the wireless signal modulation identification method provided by the present application, as shown in the figure, the method comprises the following steps. Figure 1

[0064] Step 110, extracting a target feature from the wireless signal, the target feature being at least one of a time domain feature, a frequency domain feature and a time-frequency domain feature.

[0065] In this step, the time domain feature includes the change of amplitude and phase, such as high-order cumulant, statistical feature of instantaneous amplitude, etc.

[0066] In some embodiments, the time domain feature specifically includes the flatness of the envelope of the wireless signal, which is used for preliminary screening of the modulation mode; the envelope flatness of the input signal IQ data is calculated by the following formula:

[0067] ;

[0068] wherein, ​​​The modulus value of the IQ data is taken, and evlpR is a characteristic parameter of the smoothness of the signal envelope, which is the ratio of the mean value of the envelope square to the square of the envelope mean value, and the minimum value of evlpR is 1; the smaller the value of R is, the smoother the signal envelope distribution fluctuation is, and the more likely it is a non-amplitude modulation signal; the greater the value of evlpR is, the steeper the signal envelope distribution fluctuation is, and the more likely it is an amplitude modulation signal; The mean value of the envelope square, The square of the envelope mean value.

[0069] In this embodiment, the frequency domain features include the peak number and the smoothness of the power spectrum of different orders of the signal, which are used to further narrow the range of possible modulation modes;

[0070] Specifically, the corresponding frequency domain features are calculated by the following steps:

[0071] After the signal is raised to the power of p=1, 2, 4, and 8, the linear power spectrum is calculated by FFT, and then normalized based on the maximum value, and the peak number of the normalized power spectrum is calculated, which corresponds to parameters PeakNum(1), PeakNum(2), PeakNum(3), and PeakNum(4) respectively.

[0072] In this embodiment, the time-frequency domain features include the normalized smoothness of the instantaneous frequency, which is used to determine the composite modulation signal and the complex modulation mode.

[0073] Specifically, the corresponding time-frequency domain features are calculated by the following steps:

[0074] The instantaneous frequency corresponding to the IQ data is calculated The original solution of the instantaneous frequency involves two times of difference (posterior minus anterior) operation in the unwrapping and differentiation process, which can be simplified to one operation when applied to engineering:

[0075] ;

[0076] Wherein, ; then , and

[0077] ;

[0078] The above is the instantaneous frequency, which is normalized by dividing by 0.5 times the sampling rate and then taking the modulus value to obtain:

[0079] ;

[0080] Finally, substitute into the smoothness calculation method above to obtain the smoothness of the instantaneous frequency, denoted as .

[0081] In this embodiment, before extracting the target features, the wireless signal can be preprocessed, including but not limited to signal denoising (such as wavelet threshold denoising), normalization processing, and outlier rejection.

[0082] Step 120, based on the target features, the signal type of the wireless signal is obtained, and at least one candidate modulation mode is determined according to the signal type.

[0083] In this step, the signal type can be determined according to one or more types of target features extracted from the wireless signal.

[0084] In this embodiment, the signal type determined according to the above target features may include one, and the corresponding modulation method can be directly selected for demodulation, but if the signal type may include two or more, the wireless signal needs to be demodulated one by one in combination with multiple candidate modulation modes, so as to select the modulation mode with the best demodulation effect as the target modulation mode.

[0085] In this embodiment, the mapping of the signal type to the possible modulation mode includes:

[0086] (1) FSK signal, the possible modulation mode includes: 2-FSK, 4-FSK, MSK (minimum shift keying), GMSK (Gaussian minimum shift keying);

[0087] (2) PSK signal, the possible modulation mode includes: BPSK, QPSK, 8PSK, π / 4-QPSK, π / 4-DQPSK, 4OQPSK, 16APSK;

[0088] (3) QAM signal, the possible modulation mode includes: 16QAM, 32QAM, 64QAM.

[0089] Step 130, for each candidate modulation mode, the wireless signal is blindly demodulated by using the candidate modulation mode, and the error vector magnitude EVM is calculated, to obtain multiple EVM values.

[0090] In this step, for the selected candidate modulation mode, blind demodulation is tried one by one, and the corresponding EVM value is calculated.

[0091] In this embodiment, after identifying the type of the input wireless signal, multiple candidate modulation modes can be obtained; the demodulation parameters are set according to the input signal type, including the symbol rate, the sampling rate, and the initial frequency offset, etc. If the symbol rate and the frequency offset are unknown, the symbol rate estimation and the frequency offset estimation need to be performed according to the modulation mode.

[0092] In this embodiment, the signal demodulation step includes:

[0093] (1) Frequency offset compensation: The frequency offset of the signal is initially estimated by frequency domain analysis method, and the frequency domain data of the signal is compensated.

[0094] (2) Symbol synchronization: The symbol rate is obtained by estimating the symbol rate using the symbol characteristics of a specific modulation method, and the optimal synchronization point is obtained by blind synchronization and EVM calculation.

[0095] (3) Constellation diagram recovery: Based on the modulation method, the demodulation result is mapped to a standard constellation diagram shape, such as the grid pattern of QAM or the phase circle of PSK.

[0096] (4) Error calculation: Match the constellation diagram of the received signal with the ideal constellation diagram and calculate the error vector magnitude (EVM) value; try demodulation for each candidate modulation method and record the EVM value of each modulation method.

[0097] Specifically, the above EVM value can be calculated using the following formula:

[0098] ;

[0099] in, For the first The error vector of each symbol (the complex difference between the demodulated symbol and the ideal constellation point). N The number of error vectors. The average power is given by an ideal sign.

[0100] Step 140: Use a synchronization point optimization strategy to select the target EVM value from multiple EVM values ​​to obtain the target modulation mode, so as to demodulate the wireless signal.

[0101] In this step, the EVM value is used as the evaluation standard for demodulation performance. The lower the EVM, the closer the demodulation result is to the ideal constellation. For example, an EVM threshold is set for successful demodulation. Modulation methods below the threshold are judged as successful demodulation, and the successfully demodulated modulation method and its parameters (such as symbol rate, frequency offset, phase offset, etc.) are output.

[0102] In this embodiment, the demodulation result obtained according to the target modulation method includes parameters such as the demodulated symbol stream, modulation method index, and EVM value, which are used to provide input for subsequent signal processing.

[0103] Specifically, the process of blind synchronization and demodulation of continuous wireless signals includes:

[0104] (1) Resample the signal to a multiple of the symbol rate (sps), where the sps value is the interpolation factor, to ensure that there are integer samples within one symbol. The recommended sps value is 8 or 16.

[0105] (2) By traversing each possible starting synchronization point (from 1 to sps), for each synchronization point, extract the sample value of each symbol, calculate the EVM using the sample value;

[0106] (3) Average value normalization is performed on the sample value, and then the ideal constellation is taken as a reference to calculate the EVM;

[0107] (4) In actual operation, the synchronization point corresponding to the smallest EVM can be selected as the synchronization point of the signal, and the optimal extraction value of the signal starting from this synchronization point can be extracted as the data for subsequent processing.

[0108] The modulation recognition method of the wireless signal provided by the embodiment of the application extracts target features from the wireless signal to obtain the signal type of the wireless signal, determines the candidate modulation mode according to the signal type, performs blind modulation on the wireless signal using the candidate modulation mode and calculates the error vector magnitude EVM, finally selects the target EVM value from multiple EVM values using the synchronization point optimization strategy to obtain the target modulation mode, so as to realize the demodulation of the wireless signal. Through the fusion of the multi-dimensional features of the wireless signal and the error vector magnitude auxiliary judgment, the recognition robustness and accuracy under the condition of low signal-to-noise ratio are enhanced.

[0109] In some embodiments, the target features are time domain features, frequency domain features and time-frequency domain features; wherein the time domain features include the flatness of the signal envelope of the wireless signal; the frequency domain features include the peak value number and the spectral flatness of the power spectrum of the wireless signal; and the time-frequency domain features include the instantaneous frequency flatness of the wireless signal; and the signal type of the wireless signal is obtained based on the target features, including:

[0110] In the case that the peak value number of the power spectrum of different powers of the wireless signal is 1, and the spectral flatness of different powers is greater than a first threshold value, the signal type of the wireless signal is determined to include a constant envelope signal.

[0111] In this embodiment, the first threshold value is in the range of 0.2-0.5, for example, the first threshold value is 0.3.

[0112] In this embodiment, if condition 1: the peak value number of the 1st power, 2nd power and 4th power of the signal is 1 (vPeakNum is 1), condition 2: the spectral flatness of the 1st power, 2nd power and 4th power of the signal is greater than 0.3 (vKur>0.3), and either condition is not met, then it is determined whether the wireless signal is an AM signal or a CW signal.

[0113] In the case that the flatness of the signal envelope of the wireless signal is greater than a second threshold value, and the instantaneous frequency flatness is greater than a third threshold value, the signal type of the wireless signal is determined to include an amplitude modulation signal.

[0114] In this embodiment, the second threshold value belongs to the range of 1-1.8, for example, the first threshold value is 1.27; the third threshold value belongs to the range of 1.5-2, for example, the first threshold value is 1.8.

[0115] In this embodiment, the above-mentioned amplitude modulation signal includes a 2ASK signal or a 4ASK signal.

[0116] In the case that the number of peaks of the power spectrum of the 1st power of the wireless signal is 0, the flatness of the 1st power spectrum is less than or equal to the first threshold value, the number of peaks of the 4th power spectrum is 1, the flatness of the 4th power spectrum is greater than the first threshold value, the flatness of the instantaneous frequency is less than or equal to the fourth threshold value, and the flatness of the signal envelope is less than the fifth threshold value, it is confirmed that the signal type of the wireless signal includes a 4OQPSK signal.

[0117] In this embodiment, the fourth threshold value belongs to the range of 0.3-0.8, for example, the third threshold value is 0.5; the fifth threshold value belongs to the range of 0.2-0.5, for example, the fifth threshold value is 0.35.

[0118] In this embodiment, the wireless signal is determined whether it includes a 4OQPSK signal by the following determination conditions:

[0119] Condition 1: the 1st power spectrum of the signal has no peak (vPeakNum(1) = 0), and the number of peaks of the 4th power spectrum is 1 (vPeakNum(3) = 1), the flatness of the 1st power spectrum vKur(1) is less than or equal to 0.3, and the flatness of the 4th power spectrum vKur(3) is greater than 0.3.

[0120] Condition 2: the number of peaks of the 2nd power spectrum of the signal is 2 (vPeakNum(2) == 2) and the flatness vKur(2) is less than or equal to 0.15;

[0121] Or, the flatness of the instantaneous frequency ftAbsKur0 is less than or equal to 0.5 and the flatness of the envelope evlpKur0 is less than 0.35.

[0122] If both the condition 1 and the condition 2 are met, it is determined that the current wireless signal is likely to be a 4OQPSK signal, and the current wireless signal is demodulated by using the corresponding candidate modulation mode, and if the demodulation is successful, the subsequent steps are not performed.

[0123] The modulation recognition method of the wireless signal provided by the embodiment of the present application realizes the step-by-step screening and fast demodulation of the constant envelope signal, the amplitude modulation signal and the 4OQPSK signal by extracting the time domain features, the frequency domain features and the time-frequency domain features from the wireless signal, and improves the real-time performance of the signal blind demodulation process.

[0124] In some embodiments, the target features are time domain features and frequency domain features; wherein the time domain features include a modulation depth of a signal envelope of the wireless signal; and the frequency domain features include a peak number and a spectral flatness of a power spectrum of the wireless signal.

[0125] In this embodiment, in the process of identifying whether the wireless signal contains an amplitude modulation (AM) signal, the following processes can be performed to obtain corresponding time domain features and frequency domain features:

[0126] 1. Perform spectral analysis, extract the signal spectrum using FFT, find the position of the main frequency component estFcIdx corresponding to the wireless signal; then call the fine frequency estimation module to obtain a more accurate frequency offset estFc.

[0127] 2. Calculate the modulation depth, extract the signal envelope, and calculate the modulation depth (modDepth) as a characteristic parameter of the AM signal.

[0128] 3. Perform second-order spectrum characteristic analysis, perform second-order processing on the envelope of the signal, and calculate the flatness and peak number of the second-order spectrum, and the results are stored in vKurAM and vPeakNumAM.

[0129] Based on the target features, the signal type of the wireless signal can also include:

[0130] Condition 1: In the case where the peak number of the first-order power spectrum of the wireless signal is 2, and the spectral flatness satisfies the sixth threshold value, it is confirmed that the signal type of the wireless signal includes a binary frequency shift keying (2FSK) signal and an amplitude modulation (AM) signal.

[0131] Condition 2: In the case where the peak number of the second-order power spectrum of the wireless signal is 2, and the spectral flatness of the second-order satisfies the sixth threshold value, it is confirmed that the signal type of the wireless signal includes a binary minimum shift keying (2MSK) signal and an AM signal.

[0132] In the case where the peak number of the first-order power spectrum of the wireless signal is 2, and the spectral flatness of the first-order satisfies the sixth threshold value, it is confirmed that the signal type of the wireless signal includes a 2FSK signal.

[0133] In addition, whether the wireless signal is an AM signal can be determined by the calculated modulation depth; specifically: in the case where the modulation depth is greater than a seventh threshold value, the signal type of the wireless signal includes an AM signal; in the case where the modulation depth is less than or equal to the seventh threshold value, the signal type of the wireless signal includes a continuous wave (CW) signal.

[0134] In this embodiment, the sixth threshold value belongs to the range of 0.05-0.5, for example, the sixth threshold value is 0.1-0.35; the seventh threshold value belongs to the range of 0.05-0.3, for example, the seventh threshold value is 0.1.

[0135] The modulation recognition method for the wireless signal provided by the embodiment of the application realizes step-by-step screening and fast demodulation of single type modulation modes (2FSK, AM, CW) and mixed modulation modes (2FSK+AM, 2MSK+AM) by extracting time domain features and frequency domain features from the wireless signal, and further improves the real-time performance of the signal blind demodulation process.

[0136] In some embodiments, the target features are frequency domain features and time-frequency domain features; wherein the frequency domain features include a peak value number of a power spectrum of the wireless signal and a spectrum flatness degree; and the time-frequency domain features include an instantaneous frequency flatness degree of the wireless signal.

[0137] The signal type of the wireless signal based on the target features further includes:

[0138] (1) in the case that the peak value number of the power spectrum of the first order of the wireless signal is 0, the spectrum flatness degree of the first order is less than or equal to the first threshold value, the peak value number of the power spectrum of the second order is 2, and the spectrum flatness degree of the second order satisfies the eighth threshold value, it is confirmed that the signal type of the wireless signal includes 2MSK or 2GMSK signal, and the determination of the signal with quadratic spectrum characteristics is realized.

[0139] (2) in the case that the peak value number of the power spectrum of the first order of the wireless signal is 0, the spectrum flatness degree of the first order is less than or equal to the first threshold value, the peak value number of the power spectrum of the second order is 1 or 3, the spectrum flatness degree of the second order is greater than the first threshold value, and the instantaneous frequency flatness degree is greater than the third threshold value, it is confirmed that the signal type of the wireless signal includes 2PSK signal, and the determination of the signal with quadratic spectrum unimodal / multimodal signal is realized.

[0140] In this embodiment, the eighth threshold value belongs to the range of 0.1-0.5, for example, the sixth threshold value is 0.15-0.3.

[0141] The modulation recognition method for the wireless signal provided by the embodiment of the application realizes step-by-step screening and fast demodulation of 2MSK, 2GMSK and 2PSK signals by extracting frequency domain features and time-frequency domain features from the wireless signal, and further improves the real-time performance of the signal blind demodulation process.

[0142] In some embodiments, the target features are frequency domain features; wherein the frequency domain features include a peak value number of a power spectrum of the wireless signal and a spectrum flatness degree.

[0143] The signal type of the wireless signal based on the target feature further includes:

[0144] (1) in the case that the number of peaks of the power spectrum of the 1st power of the wireless signal is 0, the number of peaks of the power spectrum of the 4th power is 1 or 3, and the number of peaks of the power spectrum of the 2nd power is 1, it is confirmed that the signal type of the wireless signal includes an 8-quadrature amplitude modulation (8QAM) signal.

[0145] (2) in the case that the number of peaks of the power spectrum of the 1st power of the wireless signal is 0, the number of peaks of the power spectrum of the 4th power is 1 or 3, and the number of peaks of the power spectrum of the 2nd power is not 1, it is confirmed that the signal type of the wireless signal includes a 4-phase shift keying (4PSK) or 8QAM signal.

[0146] (3) in the case that the number of peaks of the power spectrum of the 1st power and the number of peaks of the power spectrum of the 2nd power of the wireless signal are 0, and the number of peaks of the power spectrum of the 4th power is 1 or 3, it is confirmed that the signal type of the wireless signal includes a 16 / 32 / 64QAM signal;

[0147] (4) in the case that the number of peaks of the power spectrum of the 1st power, the 2nd power, the 4th power and the 8th power of the wireless signal is 0, and the number of peaks of the power spectrum of the 16th power is 1, it is confirmed that the signal type of the wireless signal includes a 16-amplitude phase shift keying (16APSK) signal.

[0148] The above four types of identification methods are all achieved by the number of peaks of the power spectrum in the frequency domain feature to identify the 4PSK, 8 / 16 / 32 / 64QAM and 16APSK signals.

[0149] In the case that the number of peaks of the power spectrum of the 1st power of the wireless signal is 0, the degree of flatness of the 1st power spectrum is less than or equal to a first threshold value, the number of peaks of the power spectrum of the 4th power is 1, the degree of flatness of the 4th power spectrum is greater than the first threshold value, and the number of peaks of the power spectrum of the 2nd power is 2, the degree of flatness of the 2nd power spectrum is less than or equal to a ninth threshold value, it is confirmed that the signal type of the wireless signal includes a 4-offset quadrature phase shift keying (4OQPSK) signal; the method is achieved by the number of peaks of the power spectrum and the degree of flatness of the spectrum in the frequency domain feature to identify the 4OQPSK signal.

[0150] In this embodiment, the ninth threshold value is within the range of 0.1-0.3, for example, the sixth threshold value is 0.15.

[0151] The modulation identification method of the wireless signal provided by the embodiment of the application realizes the step-by-step screening and fast demodulation of the 4PSK, 8 / 16 / 32 / 64QAM, 16APSK and 4OQPSK signals by extracting the frequency domain feature from the wireless signal, and further improves the real-time performance of the signal blind demodulation process.

[0152] In some embodiments, the target feature further comprises a time domain feature; the time domain feature comprises a smoothness of a signal envelope of the wireless signal.

[0153] In this embodiment, the refinement of the FM signal is achieved by the following steps:

[0154] If the smoothness of the envelope of the signal evlpR is less than or equal to the tenth threshold, the processing flow of the FM composite modulation signal is entered.

[0155] Specifically, the signal type of the wireless signal based on the target feature further comprises:

[0156] (1) In the case that the smoothness of the signal envelope is less than or equal to the tenth threshold, and the wireless signal can be demodulated by the FM signal, it is determined that the signal type of the wireless signal comprises a 2FSK or MSK modulated signal.

[0157] (2) In the case that the smoothness of the signal envelope is less than or equal to the tenth threshold, and the wireless signal cannot be demodulated by the FM signal, and the ratio of the sampling rate of the wireless signal to the code rate is not an integer, it is determined that the signal type of the wireless signal comprises an FM signal.

[0158] In this embodiment, the tenth threshold is within the range of 0.8-1.2, for example, the tenth threshold is 1.13.

[0159] The modulation recognition method of the wireless signal provided by the embodiment of the application realizes the step-by-step screening and fast demodulation of the 2FSK, MSK and FM signals by extracting the time domain feature from the wireless signal, and further improves the real-time performance of the signal blind demodulation process.

[0160] Further, the target feature is a frequency domain feature and a time-frequency domain feature; the frequency domain feature comprises a peak number of a power spectrum of the wireless signal and a spectral smoothness; the time-frequency domain feature comprises a smoothness of an instantaneous frequency of the wireless signal.

[0161] The signal type of the wireless signal based on the target feature further comprises:

[0162] Condition 1: the peak number of the power spectrum of the first order of the wireless signal and the peak number of the power spectrum of the second order are 0, and the peak number of the power spectrum of the fourth order is 2 or 4;

[0163] Condition 2: the spectral smoothness of the first order satisfies the sixth threshold, and the smoothness of the instantaneous frequency is greater than the eleventh threshold.

[0164] If both the condition 1 and the condition 2 are satisfied, it is determined that the signal is possibly a π / 4 QPSK signal, and a corresponding candidate modulation mode is selected for demodulating the wireless signal, and if the demodulation is successful, the subsequent steps are not performed.

[0165] Condition 1: the number of peaks of the power spectrum of the 1st power of the wireless signal is 0, the number of peaks of the power spectrum of the 2nd power is 1, and the number of peaks of the power spectrum of the 4th power is 1 or 2;

[0166] Condition 2: the spectral flatness of the 1st power is less than the ninth threshold value, the spectral flatness of the 2nd power and the spectral flatness of the 4th power are greater than the first threshold value, and the instantaneous frequency flatness is greater than the eleventh threshold value.

[0167] If both Condition 1 and Condition 2 are met, it is determined that the signal is likely to be a 4π differential quadrature phase shift keying (4π / DQPSK) signal, and a corresponding candidate modulation mode is selected for demodulation of the wireless signal. If the demodulation is successful, subsequent steps are not performed.

[0168] In the case where the number of peaks of the power spectrum of the 1st power, the number of peaks of the power spectrum of the 2nd power, and the number of peaks of the power spectrum of the 4th power of the wireless signal are 0, and the instantaneous frequency flatness is greater than the eleventh threshold value, it is determined that the signal type of the wireless signal includes an 8PSK signal.

[0169] In this embodiment, it is also possible to determine whether the wireless signal contains a 2 / 4 / 8FSK signal according to the instantaneous frequency flatness in the time-frequency domain feature.

[0170] Specifically, if the instantaneous frequency flatness (ftNormAbsR) is less than 1.13, it is determined that the wireless signal contains a 2FSK, 4FSK, and 8FSK signal, and a corresponding candidate modulation mode is selected for demodulation of the wireless signal. If the demodulation is successful, subsequent steps are not performed. Otherwise, it is determined that the input signal cannot be identified and demodulated.

[0171] In this embodiment, the eleventh threshold value is in the range of 0.3-0.6, for example, the eleventh threshold value is 0.45.

[0172] The modulation identification method for wireless signals provided by the embodiment of the present application realizes step-by-step screening and fast demodulation of π / 4QPSK, 4π / DQPSK, 8PSK, and 2 / 4 / 8FSK signals by extracting time domain features and time-frequency domain features from the wireless signal, and further improves the real-time performance of the signal blind demodulation process.

[0173] Figure 2 is a flowchart of the modulation identification method for wireless signals provided by the present application, and Figure 2In the illustrated embodiment, a modulation recognition method of a wireless signal is also implemented through the following steps: Step 1, time domain feature, frequency domain feature and time-frequency domain feature calculation of the signal; Step 2, preliminary judgment of constant envelope signals; Step 3, detailed processing of AM signals; Step 4, judgment of MSK and FSK signals; Step 5, AM and CW judgment; Step 6, subsequent judgment of constant envelope signals; Step 7, judgment of quadratic spectrum characteristic signals; Step 8, judgment of quadratic spectrum unimodal / multimodal signals; Step 9, judgment of quartic spectrum characteristic signals; Step 10, judgment of 4OQPSK signals; Step 11, judgment of π / 4QPSK signals; Step 12, judgment of 4π / DQPSK signals; Step 13, judgment of 8PSK signals; Step 14, judgment of 16 / 32 / 64QAM; Step 15, judgment of 16APSK; Step 16, detailed processing of FM signals; and Step 17, judgment of FSK.

[0174] In summary, in combination with the above-described embodiments of the present application, the following advantages are provided:

[0175] (1) The recognition and blind demodulation of linear modulation modes including AM, FM, PSK, QAM, high-order modulation modes (such as 64QAM, 16APSK) and composite modulation modes (such as 2FSK+FM, MSK+AM) are covered, and the application range of modulation modes is significantly expanded through multi-dimensional feature analysis and judgment;

[0176] (2) Time domain features (such as envelope smoothness), frequency domain features (such as the number of peak values and flatness of quadratic spectrum), and time-frequency domain features (such as the smoothness of instantaneous frequency) are comprehensively extracted to form a multi-dimensional feature fusion judgment system, thereby improving the robustness and accuracy in complex signals and low signal-to-noise ratio environments;

[0177] (3) An identification method for composite modulation signals is proposed, for example, the characteristics of quadratic spectrum flatness and peak value number are used to accurately distinguish 2FSK+FM, MSK+AM and other composite signals, thereby improving the processing capability for complex modulation modes and solving the short board of the prior art;

[0178] (4) A hierarchical judgment and step-by-step optimization blind demodulation strategy is adopted, through preliminary screening, candidate demodulation attempt, EVM comparison and other steps, the best demodulation mode is quickly converged, the real-time processing performance is optimized, and the real-time application demand in dynamic channels is met.

[0179] The modulation recognition device of a wireless signal provided by the present application is described below, and the modulation recognition device of a wireless signal described below can be correspondingly referred to the modulation recognition method of a wireless signal described above.

[0180] Figure 3is a structural schematic diagram of a wireless signal modulation identification device provided by the present application, as shown in Figure 3 The wireless signal modulation identification device 300 comprises a feature extraction module 310, a modulation identification module 320, a calculation module 330 and a screening module 340.

[0181] The feature extraction module 310 is used for extracting target features from the wireless signal, and the target features are at least one of time domain features, frequency domain features and time-frequency domain features.

[0182] The modulation identification module 320 is used for obtaining the signal type of the wireless signal based on the target features, and determining at least one candidate modulation mode according to the signal type.

[0183] The calculation module 330 is used for performing blind modulation on the wireless signal by using the candidate modulation mode and calculating the error vector magnitude (EVM) for each candidate modulation mode, so as to obtain a plurality of EVM values.

[0184] The screening module 340 is used for screening a target EVM value from the plurality of EVM values by using a synchronization point optimization strategy, so as to obtain a target modulation mode, thereby realizing the demodulation of the wireless signal.

[0185] The wireless signal modulation identification device provided by the present application is used for extracting target features from the wireless signal to obtain the signal type of the wireless signal, determining the candidate modulation mode according to the signal type, performing blind modulation on the wireless signal by using the candidate modulation mode and calculating the error vector magnitude (EVM), and finally screening the target EVM value from the plurality of EVM values by using the synchronization point optimization strategy, so as to obtain the target modulation mode, thereby realizing the demodulation of the wireless signal. The wireless signal modulation identification device provided by the present application enhances the recognition robustness and accuracy under the condition of low signal-to-noise ratio by fusing the multi-dimensional features of the wireless signal and combining the error vector magnitude auxiliary decision.

[0186] The wireless signal modulation identification device provided by the present application is described below, and the wireless signal modulation identification device described below can be correspondingly referred to the wireless signal modulation identification method described above.

[0187] Figure 4 is a structural schematic diagram of a wireless signal blind demodulation system provided by the present application, as shown in Figure 4 The wireless signal blind demodulation system comprises a signal receiving module 410, a wireless signal modulation identification device 300 and a demodulation module 420.

[0188] The signal receiving module 410 is used for wireless signal.

[0189] In this embodiment, the signal receiving module 410 can receive wireless signal data inputted by wireless signal, and can also receive a candidate list of specific modulation modes; the candidate list is determined by steps 110-120 described above, and can also be set according to expert experience or user demand.

[0190] In this embodiment, the modulation recognition device 300 of the wireless signal comprises:

[0191] The feature extraction module is configured to extract target features from the wireless signal, the target features being at least one of time domain features, frequency domain features and time-frequency domain features.

[0192] The modulation recognition module is configured to obtain a signal type of the wireless signal based on the target features, and determine at least one candidate modulation mode according to the signal type.

[0193] The calculation module is configured to, for each candidate modulation mode, perform blind demodulation on the wireless signal by using the candidate modulation mode and calculate an error vector magnitude (EVM) to obtain a plurality of EVM values.

[0194] The screening module is configured to screen a target EVM value from the plurality of EVM values by using a synchronization point optimization strategy to obtain a target modulation mode, so as to realize demodulation of the wireless signal.

[0195] In this embodiment, the feature extraction module, the modulation recognition module, the calculation module and the screening module correspond to the same implementation manners of the corresponding functions of steps 110-140 described above, and thus will not be described herein.

[0196] The demodulation module 420 is configured to demodulate the wireless signal according to the target modulation mode outputted by the modulation recognition device of the wireless signal to obtain a demodulation result; wherein the demodulation result comprises at least one of a demodulated symbol stream, a modulation mode index and an EVM value.

[0197] In an embodiment, the demodulation module 420 sets demodulation parameters including a symbol rate, a sampling rate and an initial frequency offset according to the input signal type; if the symbol rate and the frequency offset are unknown, symbol rate estimation and frequency offset estimation need to be performed according to the modulation mode; wherein the signal demodulation step comprises: (1) frequency offset compensation, (2) symbol synchronization, (3) constellation recovery and (4) error calculation.

[0198] In this embodiment, the demodulation module 420 sets an EVM threshold of demodulation success, and the modulation mode below the threshold is determined as demodulation success, and the demodulation successful modulation mode and its parameters (such as symbol rate, frequency offset, phase offset, etc.) are outputted.

[0199] The wireless signal blind demodulation system provided in this invention sets up a wireless signal receiving module, extracts target features from the wireless signal using a wireless signal modulation identification device to obtain the signal type of the wireless signal, determines candidate modulation methods based on the signal type, performs blind demodulation on the wireless signal using the candidate modulation methods, calculates the error vector amplitude (EVM), and finally uses a synchronization point optimization strategy to filter out the target EVM value from multiple EVM values ​​to obtain the target modulation method. Finally, the demodulation module demodulates the wireless signal according to the target modulation method output by the wireless signal modulation identification device to obtain the demodulation result. A multi-stage decision process is designed for the blind demodulation of wireless signals to filter modulation methods, avoiding blind demodulation with a large traversal range and many iterations, reducing the number of times the blind demodulation module is called, and improving the efficiency and accuracy of blind demodulation of wireless signals.

[0200] Figure 5 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 5 As shown, the electronic device may include a processor 510, a communications interface 520, a memory 530, and a communication bus 540, wherein the processor 510, communications interface 520, and memory 530 communicate with each other via the communication bus 540. The processor 510 can call logical instructions in the memory 530 to execute a modulation identification method for wireless signals. This method includes: extracting target features from the wireless signal, wherein the target features are at least one of time-domain features, frequency-domain features, and time-frequency-domain features; obtaining the signal type of the wireless signal based on the target features, and determining at least one candidate modulation scheme according to the signal type; for each candidate modulation scheme, blindly modulating the wireless signal using the candidate modulation scheme and calculating the error vector amplitude (EVM) to obtain multiple EVM values; and using a synchronization point optimization strategy to select a target EVM value from the multiple EVM values ​​to obtain the target modulation scheme, thereby achieving demodulation of the wireless signal.

[0201] In addition, the logic instructions in the memory 530 described above can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions for making a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0202] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program can be executed by a processor to enable a computer to execute the modulation identification method of the wireless signal provided by the above-mentioned methods. The method comprises: extracting a target feature from the wireless signal, the target feature being at least one of a time domain feature, a frequency domain feature and a time-frequency domain feature; obtaining a signal type of the wireless signal based on the target feature, and determining at least one candidate modulation mode according to the signal type; for each candidate modulation mode, performing blind modulation on the wireless signal using the candidate modulation mode and calculating an error vector magnitude (EVM) to obtain a plurality of EVM values; and filtering a target EVM value from the plurality of EVM values using a synchronization point optimization strategy to obtain a target modulation mode, so as to realize demodulation of the wireless signal.

[0203] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program can be executed by a processor to enable a computer to execute the modulation identification method of the wireless signal provided by the above-mentioned methods. The method comprises: extracting a target feature from the wireless signal, the target feature being at least one of a time domain feature, a frequency domain feature and a time-frequency domain feature; obtaining a signal type of the wireless signal based on the target feature, and determining at least one candidate modulation mode according to the signal type; for each candidate modulation mode, performing blind modulation on the wireless signal using the candidate modulation mode and calculating an error vector magnitude (EVM) to obtain a plurality of EVM values; and filtering a target EVM value from the plurality of EVM values using a synchronization point optimization strategy to obtain a target modulation mode, so as to realize demodulation of the wireless signal.

[0204] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed to multiple network units. Part or all of the modules can be selected to achieve the purposes of the embodiments according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0205] Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software and the necessary general hardware platform, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0206] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of modulation identification of a wireless signal, characterized in that, The method comprises: extracting a target feature from a wireless signal; the wireless signal comprises a composite modulation signal of two or more signal types; acquiring a signal type of the wireless signal based on the target feature, and determining at least one candidate modulation mode according to the signal type; for each candidate modulation mode, performing blind demodulation on the wireless signal by using a demodulation algorithm corresponding to the candidate modulation mode, and calculating an error vector magnitude (EVM) to obtain a plurality of EVM values; using a synchronization point optimization strategy to screen a target EVM value from the plurality of EVM values, and obtaining a target modulation mode to realize demodulation of the wireless signal; the synchronization point optimization strategy selects a synchronization point corresponding to the smallest EVM as a synchronization point of the signal, and extracts an optimal extraction value of the signal from the synchronization point; the target feature is a time domain feature, a frequency domain feature, and a time-frequency domain feature; the time-frequency domain feature comprises a degree of smoothness of an instantaneous frequency of the wireless signal; the time-frequency domain feature is used for determination of a composite modulation signal and a complex modulation mode; the signal type comprises FSK, PSK, ASK, QAM, QPSK, APSK, MSK, FM, AM, and CW.

2. The method of claim 1, wherein the time domain feature comprises a degree of smoothness of a signal envelope of the wireless signal; the frequency domain feature comprises a number of peak values and a degree of smoothness of a power spectrum of the wireless signal; the acquiring of the signal type of the wireless signal based on the target feature comprises: in a case where the number of peak values of the power spectrum of different powers of the wireless signal is 1, and the degrees of smoothness of the frequency spectrum of different powers are all greater than a first threshold value, it is determined that the signal type of the wireless signal comprises a constant envelope signal; in a case where the degree of smoothness of the signal envelope of the wireless signal is greater than a second threshold value, and the degree of smoothness of the instantaneous frequency is greater than a third threshold value, it is determined that the signal type of the wireless signal comprises an amplitude modulation signal; in a case where the number of peak values of the power spectrum of the first power of the wireless signal is 0, the degree of smoothness of the frequency spectrum of the first power is less than or equal to the first threshold value, the number of peak values of the frequency spectrum of the fourth power is 1, the degree of smoothness of the frequency spectrum of the fourth power is greater than the first threshold value, the degree of smoothness of the instantaneous frequency is less than or equal to a fourth threshold value, and the degree of smoothness of the signal envelope is less than a fifth threshold value, it is determined that the signal type of the wireless signal comprises a quaternary offset quadrature phase shift keying (4OQPSK) signal.

3. The method of claim 1, wherein the target feature is a time domain feature and a frequency domain feature; the time domain feature comprises a modulation depth of a signal envelope of the wireless signal; the frequency domain feature comprises a number of peak values and a degree of smoothness of a power spectrum of the wireless signal; the acquiring of the signal type of the wireless signal based on the target feature further comprises: in a case where the number of peak values of the power spectrum of the first power of the wireless signal is 2, and the degree of smoothness of the frequency spectrum satisfies a sixth threshold value, it is determined that the signal type of the wireless signal comprises a binary frequency shift keying (2FSK) signal and an amplitude modulation (AM) signal; In a case where the number of peaks of the 2nd power spectrum of the wireless signal is 2 and the 2nd power spectrum flatness degree satisfies the sixth threshold value, it is determined that the signal type of the wireless signal includes a binary minimum shift keying 2MSK signal and an AM signal; In a case where the modulation depth is greater than a seventh threshold value, the signal type of the wireless signal includes an AM signal; in a case where the modulation depth is less than or equal to the seventh threshold value, the signal type of the wireless signal includes a continuous wave CW signal; In a case where the number of peaks of the 1st power spectrum of the wireless signal is 2 and the 1st power spectrum flatness degree satisfies the sixth threshold value, it is determined that the signal type of the wireless signal includes a 2FSK signal.

4. The method of claim 1, wherein The target feature is a frequency domain feature and a time-frequency domain feature; wherein the frequency domain feature includes a number of peaks of a power spectrum of the wireless signal and a spectrum flatness degree; the time-frequency domain feature includes an instantaneous frequency flatness degree of the wireless signal; The method further includes: In a case where the number of peaks of the 1st power spectrum of the wireless signal is 0, the 1st power spectrum flatness degree is less than or equal to a first threshold value, the number of peaks of the 2nd power spectrum of the wireless signal is 2, and the 2nd power spectrum flatness degree satisfies an eighth threshold value, it is determined that the signal type of the wireless signal includes a 2MSK or a binary Gaussian minimum shift keying 2GMSK signal; In a case where the number of peaks of the 1st power spectrum of the wireless signal is 0, the 1st power spectrum flatness degree is less than or equal to a first threshold value, the number of peaks of the 2nd power spectrum of the wireless signal is 1 or 3, the 2nd power spectrum flatness degree is greater than the first threshold value, and an instantaneous frequency flatness degree is greater than a third threshold value, it is determined that the signal type of the wireless signal includes a binary phase shift keying 2PSK signal.

5. The method of claim 1, wherein, The target feature is a frequency domain feature; wherein the frequency domain feature includes a number of peaks of a power spectrum of the wireless signal and a spectrum flatness degree; The method further includes: In a case where the number of peaks of the 1st power spectrum of the wireless signal is 0, the number of peaks of the 4th power spectrum is 1 or 3, and the number of peaks of the 2nd power spectrum is 1, it is determined that the signal type of the wireless signal includes an octal quadrature amplitude modulation 8QAM signal; In a case where the number of peaks of the 1st power spectrum of the wireless signal is 0, the number of peaks of the 4th power spectrum is 1 or 3, and the number of peaks of the 2nd power spectrum is not 1, it is determined that the signal type of the wireless signal includes a quadrature phase shift keying 4PSK or an 8QAM signal; In a case where the number of peaks of the 1st power spectrum of the wireless signal and the number of peaks of the 2nd power spectrum of the wireless signal are 0, and the number of peaks of the 4th power spectrum of the wireless signal is 1 or 3, it is determined that the signal type of the wireless signal includes a 16 / 32 / 64QAM signal; In a case where the number of peaks of power spectrum of 1st power, 2nd power, 4th power and 8th power of the wireless signal is 0, and the number of peaks of power spectrum of 16th power is 1, it is determined that the signal type of the wireless signal comprises a 16-ary amplitude phase shift keying (16APSK) signal; In a case where the number of peaks of power spectrum of 1st power of the wireless signal is 0, the smoothness of 1st power spectrum is less than or equal to a first threshold, the number of peaks of 4th power spectrum is 1, the smoothness of 4th power spectrum is greater than the first threshold, and the number of peaks of 2nd power spectrum is 2, the smoothness of 2nd power spectrum is less than or equal to a ninth threshold, it is determined that the signal type of the wireless signal comprises a 4-ary offset quadrature phase shift keying (4OQPSK) signal.

6. The method of claim 5, wherein The target feature further comprises a time domain feature, and the time domain feature comprises a smoothness of a signal envelope of the wireless signal; The determining the signal type of the wireless signal based on the target feature further comprises: In a case where the smoothness of the signal envelope is less than or equal to a tenth threshold, and the wireless signal can be demodulated by a frequency modulation (FM) signal, it is determined that the signal type of the wireless signal comprises a 2-frequency shift keying (2FSK) or a minimum shift keying (MSK) modulated signal; In a case where the smoothness of the signal envelope is less than or equal to the tenth threshold, the wireless signal cannot be demodulated by the FM signal, and a ratio of a sampling rate to a code rate of the wireless signal is not an integer, it is determined that the signal type of the wireless signal comprises an FM signal.

7. The method of claim 1, wherein The target feature comprises a frequency domain feature and a time-frequency domain feature, wherein the frequency domain feature comprises a number of peaks of power spectrum and a smoothness of spectrum of the wireless signal, and the time-frequency domain feature comprises a smoothness of instantaneous frequency of the wireless signal; The determining the signal type of the wireless signal based on the target feature further comprises: In a case where the number of peaks of power spectrum of 1st power and the number of peaks of power spectrum of 2nd power of the wireless signal are 0, the number of peaks of power spectrum of 4th power is 2 or 4, the smoothness of 1st power spectrum satisfies a sixth threshold, and the smoothness of instantaneous frequency is greater than an eleventh threshold, it is determined that the signal type of the wireless signal comprises a π / 4-quadrature phase shift keying (π / 4QPSK) signal; In a case where the number of peaks of power spectrum of 1st power of the wireless signal is 0, the number of peaks of power spectrum of 2nd power is 1, the number of peaks of power spectrum of 4th power is 1 or 2, the smoothness of 1st power spectrum is less than a ninth threshold, the smoothness of 2nd power spectrum and the smoothness of 4th power spectrum are greater than the first threshold, and the smoothness of instantaneous frequency is greater than the eleventh threshold, it is determined that the signal type of the wireless signal comprises a 4π-differential quadrature phase shift keying (4π / DQPSK) signal; In a case where the number of peaks of power spectrum of 1st power, the number of peaks of power spectrum of 2nd power and the number of peaks of power spectrum of 4th power of the wireless signal are 0, and the smoothness of instantaneous frequency is greater than the eleventh threshold, it is determined that the signal type of the wireless signal comprises an 8-ary phase shift keying (8PSK) signal.

8. An apparatus for modulation identification of a radio signal, applying the modulation identification method of a radio signal as claimed in claim 1, characterized in that, The method comprises: a feature extraction module configured to extract a target feature from a wireless signal, the target feature being at least one of a time domain feature, a frequency domain feature and a time-frequency domain feature; The modulation identification module is configured to acquire a signal type of the wireless signal based on the target feature, and determine at least one candidate modulation mode according to the signal type; The calculation module is configured to, for each candidate modulation mode, perform blind demodulation on the wireless signal by using a demodulation algorithm corresponding to the candidate modulation mode, and calculate an error vector magnitude (EVM) to obtain a plurality of EVM values; The screening module is configured to screen a target EVM value from the plurality of EVM values by using a synchronization point optimization strategy, and obtain a target modulation mode to realize demodulation of the wireless signal.

9. A blind demodulation system for wireless signals, characterized by The wireless signal modulation identification device comprises: a signal receiving module configured to receive the wireless signal; The wireless signal modulation identification device according to claim 8; The demodulation module is configured to demodulate the wireless signal according to a demodulation algorithm corresponding to the target modulation mode output by the wireless signal modulation identification device to obtain a demodulation result, wherein the demodulation result comprises at least one of a demodulated symbol stream, a modulation mode index, and an EVM value.

10. An electronic device comprising a memory, a processor, and a computer program stored on the memory and running on the processor, characterized in that, The processor executes the computer program to realize the wireless signal modulation identification method according to any one of claims 1 to 7.

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