Radio frequency interference joint detection method and system of satellite-borne radiometer

Abstract

The invention relates to the technical field of satellite-borne radio frequency signal processing, and discloses a radio frequency interference joint detection method and system for a satellite-borne radiometer, and the method comprises the steps: receiving horizontal polarization and vertical polarization analog signals through the satellite-borne radiometer, respectively inputting the analog signals into independent ADC channels, converting the analog signals into digital signals, and carrying out the preprocessing of the two digital signals; performing digital channelization processing on the pre-processed signal by adopting a multi-term filter bank which is divided at equal intervals, and dividing the pre-processed signal into a plurality of sub-band signals; for each sub-band signal, first-order to fourth-order central moments of the horizontal polarization signal and the vertical polarization signal are respectively calculated within preset integral time, and then a kurtosis value is calculated through second-order and fourth-order central moments; the detection threshold is set to meet the detection index, the radio frequency interference is detected and identified on each sub-band based on the set detection threshold and the kurtosis value obtained through calculation, the kurtosis detection and the polarization detection are sequentially combined to output a radio frequency interference identification signal, and the detection sensitivity and performance are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite-borne radio frequency signal processing, and in particular to a radio frequency interference joint detection method and system for a satellite-borne radiometer. Background Art

[0002] With the continuous development of my country's space industry, spaceborne microwave radiometers have assumed important roles in numerous fields, including weather forecasting, sea surface temperature and salinity measurement, and surface observation. In recent years, microwave radiometers have made significant progress in both military and commercial applications. They receive weak microwave radiation signals (brightness temperature) emitted by target objects and infer physical parameters of the Earth's surface or atmosphere. Due to the diversity and complexity of these missions, microwave radiometers are continuously evolving towards smaller size, lower power consumption, and higher resolution. However, due to their high sensitivity, microwave radiometers are susceptible to interference from electromagnetic frequencies in space, such as radar interference, communication interference, and electromagnetic waves emitted by artificial electronic and electromagnetic devices. Even minor radio frequency interference can cause significant errors in measurement results. Strong interference signals can cause radiometers to malfunction. Therefore, RFI detection and suppression technologies are becoming increasingly important in spaceborne microwave radiometers.

[0003] Existing RF interference detection methods are primarily categorized into four main categories: time-domain analysis, frequency-domain analysis, statistical feature detection, and polarization feature detection. However, all of these methods suffer from significant drawbacks. For example, time-domain / frequency-domain threshold detection methods are poorly adaptable to natural scenes with a wide dynamic range of brightness temperatures. Bandwidth interference manifests as a low-amplitude continuous spectrum in the frequency domain, making it difficult to identify using amplitude thresholds. Statistical feature detection alone suffers from blind spots: periodic pulses with a duty cycle approaching 50% (such as radar synchronization signals) still have a kurtosis close to 3, resulting in detection failure. Furthermore, statistical moment estimation errors are large within short integration times. Furthermore, polarization detection alone suffers from limited sensitivity, requiring extremely long integration times to distinguish weak interference. Furthermore, due to the limited computing power of onboard processors, traditional joint algorithms (such as time-frequency-polarization tandem) require >80% of FPGA resources, crowding out other critical functions. Therefore, a detection method is urgently needed that significantly improves interference detection efficiency without excessive resource consumption. Summary of the Invention

[0004] The purpose of the present invention is to address the shortcomings of the above-mentioned prior art and to provide a method and system for joint detection of radio frequency interference of a space-borne radiometer. Through the "digital channelization + kurtosis-polarization joint detection" architecture, blind spot complementarity and efficient calculation are achieved on the basis of reducing resource usage.

[0005] In one aspect, a method for joint detection of radio frequency interference of a spaceborne radiometer is provided, comprising the following steps: S1: Receives horizontally polarized and vertically polarized analog signals through a satellite-borne radiometer, inputs them into independent ADC channels, converts them into digital signals, and pre-processes the two digital signals; S2: performing digital channelization processing on the pre-processed signal by using a multi-filter bank divided at equal intervals to divide the signal into a plurality of sub-band signals; S3: For each subband signal, calculate the first to fourth order central moments of the horizontally polarized and vertically polarized signals within a preset integration time, and then calculate the kurtosis value from the second and fourth order central moments; S4: Set a detection threshold to meet the detection index. On each subband, detect and identify the radio frequency interference based on the set detection threshold and the calculated kurtosis value. Combine kurtosis detection and polarization detection in sequence to output the radio frequency interference identification signal.

[0006] Furthermore, in step S1, preprocessing the two digital signals includes: S11: Perform digital down-conversion (DDC) on the horizontally polarized and vertically polarized digital signals, filter out the high-frequency components after mixing, retain the baseband signal, and reduce the sampling rate; S12: Inputting the signal after the digital down-conversion DDC into the digital polyphase filter for multi-rate signal processing to improve the spectrum resolution and suppress out-of-band noise; Ensure that the horizontal polarization and vertical polarization signals are strictly synchronized in time and phase to avoid subsequent polarization detection errors.

[0007] Furthermore, in step S2, the division into a plurality of sub-band signals specifically includes: S21: Decompose the prototype filter into several parallel sub-filters, each sub-filter corresponds to a sub-band; S22: Divide the pre-processed horizontally polarized and vertically polarized full-band signals into blocks according to the number of sub-bands and input the blocks into sub-filters. Each sub-filter processes a corresponding input block to generate a sub-band signal.

[0008] Furthermore, in step S3, calculating the first-order to fourth-order central moments of the horizontally polarized and vertically polarized signals further includes: S31: By calculating the mean of the horizontal polarization signal and the vertical polarization signal and , get the first-order central moment, the calculation formula is as follows: in, represents a discrete sequence of horizontally polarized subband signals, represents a discrete sequence of vertically polarized subband signals, is the number of sampling points within the integration time, is the discrete time index; S32: Calculate the second to fourth order central moments , is the order, The order central moment is the difference between the signal and the mean The average value of the power is calculated as follows: Among them, the second-order central moment is used to calculate the variance of the horizontally polarized signal and the vertically polarized signal, the third-order central moment is used to calculate the skewness correlation, which is used to describe the asymmetry of the distribution, and the fourth-order central moment is used to calculate the kurtosis correlation, which is used to describe the sharpness of the distribution. S33: Calculate the kurtosis of horizontally polarized signals and vertically polarized signals based on the first to fourth order central moments and , the calculation formula is as follows: .

[0009] Furthermore, in step S4, the kurtosis detection is first performed, specifically including: S41: Dynamically adjust threshold offset through algorithm simulation And determine the standard reference kurtosis value , set the kurtosis detection threshold range to to ; S42: On each sub-band, the calculated kurtosis values of the horizontal polarization signal and the vertical polarization signal are calculated. and Compare with the kurtosis detection threshold range to determine whether there is radio frequency interference: like or , it is believed that there is radio frequency interference in the horizontally polarized sub-band signal; like or , it is believed that there is radio frequency interference in the vertically polarized sub-band signal; S43: If it is determined through the kurtosis detection that no interference exists, the polarization detection is performed.

[0010] Preferably, the polarization detection further comprises: S44: Cross-correlate the horizontally polarized signal and the vertically polarized signal on each sub-band. The cross-correlation formula is as follows: in, and Represents horizontal polarization and vertical polarization respectively. sub-band signals, represents the cross-correlation result, characterizing the similarity of the two polarization signals; S45: Extract the imaginary part according to the cross-correlation result to obtain the fourth Stokes parameter , the calculation formula is as follows: in, Represents the complex conjugate of the vertically polarized signal, the fourth Stokes parameter of the natural radiation source The value approaches 0, and human interference will cause the fourth Stokes parameter Significantly increased; S46: Preset polarization detection threshold according to actual scenario , the fourth Stokes parameter is obtained With the polarization detection threshold For comparison: like , it is considered that there is radio frequency interference; Otherwise, it is assumed that no RF interference exists.

[0011] In another aspect, a radio frequency interference joint detection system for a spaceborne radiometer is provided, comprising: The signal preprocessing module is used to receive horizontally polarized and vertically polarized analog signals from the satellite-borne radiometer, input them into independent ADC channels to convert them into digital signals, and preprocess the two digital signals; A channelization processing module, configured to perform digital channelization processing on the pre-processed signal by using a plurality of filter banks divided at equal intervals to divide the signal into a plurality of sub-band signals; A statistical numerical calculation module is used to calculate the first to fourth order central moments of the horizontally polarized and vertically polarized signals for each sub-band signal within a preset integration time, and then calculate the kurtosis value from the second and fourth order central moments; The joint detection module is used to set the detection threshold to meet the detection index. On each sub-band, it detects and identifies the radio frequency interference based on the set monitoring threshold and the calculated kurtosis value, and sequentially combines kurtosis detection and polarization detection to output the radio frequency interference identification signal.

[0012] At the same time, a computer-readable storage medium is provided, on which a computer program is stored, characterized in that the program includes a boot program and an application program, and when executed by a processor, implements the radio frequency interference joint detection method of the satellite-borne radiometer described in any of the above items.

[0013] In addition, an electronic device is provided, comprising: one or more processors; a storage device for storing one or more programs, which, when executed by the one or more processors, enables the one or more processors to implement the joint detection method for radio frequency interference of a satellite-borne radiometer as described in any one of the above items.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention decomposes the full frequency band into sub-bands through a polyphase filter bank, thereby reducing computational complexity and hardware resource usage. The present invention solves the problem of failure of traditional methods to detect broadband continuous interference and polarization blind zone interference by combining kurtosis detection and polarization detection, thus greatly expanding the coverage of interference type detection. The present invention adjusts the kurtosis detection threshold and polarization detection threshold in real time based on the sub-band statistical characteristics to adapt to the complex and changeable onboard electromagnetic environment (such as sudden interference from solar flares and frequency switching of ground radars), without relying on preset fixed thresholds on the ground. The present invention reduces the complexity of subsequent processing and improves the detection resolution and detection performance of the radiometer for broadband signals through digital signal preprocessing, including digital down-conversion and digital multi-layer filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 This is a flow chart of a method for joint detection of radio frequency interference of a spaceborne radiometer according to the present invention; Figure 2 This is a time domain schematic diagram of a channelized subband according to the present invention; Figure 3 A schematic diagram of a channelized sub-band frequency domain according to the present invention; Figure 4 A schematic diagram of a channelized sub-band kurtosis value of the present invention; Figure 5 This is a schematic diagram of the fourth Stokes parameter of a channelized sub-band according to the present invention; Figure 6 This is a schematic diagram of a sub-band joint detection mark of the present invention; Figure 7 A schematic diagram of the relationship between detection probability and signal-to-noise ratio of a single polarization method of the present invention; Figure 8 This is a schematic diagram of the relationship between detection probability and signal-to-noise ratio in a joint detection method of the present invention; Figure 9 This is a structural block diagram of a radio frequency interference joint detection system for a satellite-borne radiometer according to the present invention. DETAILED DESCRIPTION

[0016] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0017] The present invention proposes a combined radio frequency interference detection method suitable for satellite-borne microwave radiometers, which improves detection sensitivity while making up for the blind spots of a single detection method. In addition, the method of the present invention is simple and operable, and is easy to implement in engineering.

[0018] The specific implementation of the present invention is described below with reference to the accompanying drawings and embodiments.

[0019] Example 1 See also Figure 1 , a technical solution for a joint detection method of radio frequency interference of a spaceborne radiometer provided in this embodiment, includes the following steps: S1: Receives horizontally polarized and vertically polarized analog signals through a satellite-borne radiometer, inputs them into independent ADC channels, converts them into digital signals, and pre-processes the two digital signals; S2: performing digital channelization processing on the pre-processed signal by using a multi-filter bank divided at equal intervals to divide the signal into a plurality of sub-band signals; S3: For each subband signal, calculate the first to fourth order central moments of the horizontally polarized and vertically polarized signals within a preset integration time, and then calculate the kurtosis value from the second and fourth order central moments; S4: Set a detection threshold to meet the detection index. On each subband, detect and identify the radio frequency interference based on the set detection threshold and the calculated kurtosis value. Combine kurtosis detection and polarization detection in sequence to output the radio frequency interference identification signal.

[0020] We first receive horizontally polarized and vertically polarized analog signals from a satellite-borne radiometer, input them into independent ADC channels, convert them into digital signals, and preprocess the two digital signals. The preprocessing includes the following: S11: Perform digital down-conversion (DDC) on the horizontally polarized and vertically polarized digital signals, filter out the high-frequency components after mixing, retain the baseband signal, and reduce the sampling rate; S12: Inputting the signal after the digital down-conversion DDC into the digital polyphase filter for multi-rate signal processing to improve the spectrum resolution and suppress out-of-band noise; Ensure that the horizontal polarization and vertical polarization signals are strictly synchronized in time and phase to avoid subsequent polarization detection errors.

[0021] Specifically, linear frequency modulation (LFM) is a spread spectrum modulation technique. LFM signals are also known as chirps because their spectral bandwidth typically falls within the audible range, resembling birdsong. This technique is widely used in radar, sonar, and other fields and is a common radar signal. Its narrowband spectrum is similar to the interference often encountered by radiometers, so LFM signals can be used to simulate a typical RFI signal.

[0022] The time domain expression of the LFM signal can be written as: in, is the center frequency of the signal, is the signal bandwidth, is the pulse width of the signal.

[0023] Using an LFM signal as an RF interference signal, the joint detection process for channelized subbands was simulated. For a 1.2 GHz full-band receiver, the signal-to-noise ratio was preset to 10 dB using a 3 GHz sampling frequency. RF interference 1 had a center frequency of 260 MHz, a bandwidth of 10 MHz, and a pulse width of 0.2 s. RF interference 2 had a center frequency of 800 MHz, a bandwidth of 30 MHz, and a pulse width of 0.1 s.

[0024] A fully polarimetric microwave radiometer is a radiometer that can characterize the polarization characteristics of a target. Its key feature is its ability to measure four Stokes parameters—I, Q, U, and V—to obtain polarization information. U and V, or the third and fourth Stokes parameters, describe the linear and circular polarization components, respectively. Since man-made radiation sources are typically linearly or circularly polarized, while natural electromagnetic radiation sources have relatively low values, in areas free of RFI contamination, the brightness temperature of the fully polarimetric channel of a synthetic aperture microwave radiometer is two orders of magnitude lower than that of the orthogonal channel, indicating very low third and fourth Stokes parameters. However, in low-frequency microwave bands (such as the L-band), the third and fourth Stokes parameters, at naturally occurring levels, are highly sensitive to man-made RFI sources. Man-made radiation sources are likely to cause significant contamination of these parameters, leading to abnormal increases, indicating a possible source of radio frequency interference.

[0025] Any plane wave can be decomposed into two orthogonal components: horizontal and vertical polarizations. and , the vector expression of its synthetic field is expressed as: The vector expressions of the two components are: After improvement on this basis, the Stokes parameter equation can be expressed as: in, represents the wavelength, represents the Boltzmann constant, Indicates bandwidth, Indicates medium impedance (air).

[0026] Then, a multi-filter bank divided into equal intervals is used to perform digital channelization processing on the pre-processed signal to divide it into a number of sub-band signals, including: S21: Decompose the prototype filter into several parallel sub-filters, each sub-filter corresponds to a sub-band; S22: Divide the pre-processed horizontally polarized and vertically polarized full-band signals into blocks according to the number of sub-bands and input the blocks into sub-filters. Each sub-filter processes a corresponding input block to generate a sub-band signal.

[0027] Furthermore, statistical numerical calculations are performed to calculate the first to fourth order central moments of the horizontally polarized and vertically polarized signals for each subband signal within a preset integration time, and then the kurtosis value is calculated from the second and fourth order central moments. Specifically, this includes: S31: By calculating the mean of the horizontal polarization signal and the vertical polarization signal and , get the first-order central moment, the calculation formula is as follows: in, represents a discrete sequence of horizontally polarized subband signals, represents a discrete sequence of vertically polarized subband signals, is the number of sampling points within the integration time, is the discrete time index; S32: Calculate the second to fourth order central moments , is the order, The order central moment is the difference between the signal and the mean The average value of the power is calculated as follows: Among them, the second-order central moment is used to calculate the variance of the horizontally polarized signal and the vertically polarized signal, the third-order central moment is used to calculate the skewness correlation, which is used to describe the asymmetry of the distribution, and the fourth-order central moment is used to calculate the kurtosis correlation, which is used to describe the sharpness of the distribution. S33: Calculate the kurtosis of horizontally polarized signals and vertically polarized signals based on the first to fourth order central moments and , the calculation formula is as follows: .

[0028] In the first part of the test, the kurtosis test is first performed, which specifically includes: S41: Dynamically adjust threshold offset through algorithm simulation And determine the standard reference kurtosis value , set the kurtosis detection threshold range to to ; S42: On each sub-band, the calculated kurtosis values of the horizontal polarization signal and the vertical polarization signal are calculated. and Compare with the kurtosis detection threshold range to determine whether there is radio frequency interference: like or , it is believed that there is radio frequency interference in the horizontally polarized sub-band signal; like or , it is believed that there is radio frequency interference in the vertically polarized sub-band signal; S43: If it is determined through the kurtosis detection that no interference exists, the polarization detection is performed.

[0029] The polarization detection further includes: S44: Cross-correlate the horizontally polarized signal and the vertically polarized signal on each sub-band. The cross-correlation formula is as follows: in, and Represents horizontal polarization and vertical polarization respectively. sub-band signals, represents the cross-correlation result, characterizing the similarity of the two polarization signals; S45: Extract the imaginary part according to the cross-correlation result to obtain the fourth Stokes parameter , the calculation formula is as follows: in, Represents the complex conjugate of the vertically polarized signal, the fourth Stokes parameter of the natural radiation source The value approaches 0, and human interference will cause the fourth Stokes parameter Significantly increased; S46: Preset polarization detection threshold according to actual scenario , the fourth Stokes parameter is obtained With the polarization detection threshold For comparison: like , it is considered that there is radio frequency interference; Otherwise, it is assumed that there is no RF interference.

[0030] Specifically, for the signal received by the radiometer, if Indicates horizontal polarization signal, Represents a vertically polarized signal. Since all signals in nature conform to Gaussian distribution, the correlation between any two signals should be 0. To express the correlation between the two signals of horizontal polarization and vertical polarization at any time, we have: Therefore, the third and fourth Stokes parameters U and V are the results of time averaging the relevant output results, taking the real part and imaginary part respectively and multiplying them by some coefficients.

[0031] In this embodiment, interference is added only to the real part of the H polarization. The real part signal of the H polarization can be filtered by multiple filters. Figure 2 and Figure 3 The time and frequency domain plots of the channelized subbands show the presence of RFI signals in channels 3 and 10.

[0032] When RFI is present, the signals received by the radiometer primarily come from natural thermal radiation and thermal noise generated by the hardware system. The probability density function of these signals follows a Gaussian distribution with a mean of 0. The core idea of the kurtosis detection algorithm is to calculate the ratio of the fourth-order center distance of a random variable to the square of the second-order center distance to determine the presence of RFI. The expression for the nth-order center distance of a random variable v is: Where subscript n represents the order of the central moment of the variable. The expression of kurtosis is: In this embodiment, the Gaussian probability density function without RFI is substituted into the kurtosis expression to obtain R=3. However, when RFI interference occurs, the kurtosis value will deviate from 3. Taking the common pulsed sinusoidal interference (LFM signal is also a type of pulsed sinusoidal signal) as an example, we simulate the kurtosis value under different SNR and duty cycle according to the formula. Figure 4 ,From the simulation, it can be seen that when the duty cycle d is less than 0.5, the kurtosis value is greater than 3;,when the duty cycle is greater than 0.5, the kurtosis value is less than 3;,when the duty cycle is equal to 0.5, the kurtosis detection value is equal to 3,,and the single kurtosis detection algorithm fails.

[0033] The kurtosis value of the H-polarization real part subband can be obtained by averaging 128 data points. Figure 3 As shown, the fourth Stokes parameter obtained by time averaging 128 data points after correlation between subbands is as follows Figure 5 As shown in FIG, it can be found that the kurtosis of channel 3 and channel 10 is obviously less than 3, and the fourth Stokes parameter has an abnormally large value. These results indicate the existence of RFI.

[0034] Combining the joint detection algorithm process proposed above in this embodiment, we can draw a detection mark diagram for this simulation as follows: Figure 6 As shown, 1 indicates the presence of interference and 0 indicates the absence of interference.

[0035] Figure 7 is the relationship between detection probability and signal-to-noise ratio for single polarization detection, and Figure 8 The following graph shows the relationship between joint detection probability and signal-to-noise ratio (SNR). The comparison in the figure shows that the joint detection method overcomes the inapplicability of polarization detection at low SNRs. The detection threshold SNR of the joint detection method is 5dB higher than that of single-polarization detection. The SNR required to achieve a 90% detection probability with joint detection is approximately 4dB, while the SNR required for single-polarization detection is approximately 17dB. Furthermore, the joint detection method effectively compensates for the blind spots of the single-kurtosis detection method.

[0036] On the other hand, this embodiment also provides a radio frequency interference joint detection system for a spaceborne radiometer, such as Figure 9 Shown, including: The signal preprocessing module is used to receive horizontally polarized and vertically polarized analog signals from the satellite-borne radiometer, input them into independent ADC channels to convert them into digital signals, and preprocess the two digital signals; A channelization processing module, configured to perform digital channelization processing on the pre-processed signal by using a multi-filter group divided at equal intervals to divide the signal into a plurality of sub-band signals; A statistical numerical calculation module is used to calculate the first to fourth order central moments of the horizontally polarized and vertically polarized signals for each sub-band signal within a preset integration time, and then calculate the kurtosis value from the second and fourth order central moments; The joint detection module is used to set the detection threshold to meet the detection index. On each sub-band, it detects and identifies the radio frequency interference based on the set monitoring threshold and the calculated kurtosis value, and sequentially combines kurtosis detection and polarization detection to output the radio frequency interference identification signal.

[0037] It should be noted that the steps in the joint detection method of radio frequency interference of the satellite-borne radiometer provided in this embodiment can be implemented using the corresponding modules, devices, units, etc. in the joint detection system of radio frequency interference of the satellite-borne radiometer. Those skilled in the art can refer to the technical solution of the system to implement the step flow of the method, that is, the embodiments in the system can be understood as preferred examples for implementing the method, which will not be elaborated here.

[0038] In addition to implementing the system and its various devices provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same functions of the system and its various devices provided by the present invention in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. by logically programming the method steps. Therefore, the system and its various devices provided by the present invention can be considered a hardware component, and the devices included therein for implementing the various functions can also be considered as structures within the hardware component; the devices for implementing the various functions can also be considered as both software modules implementing the method and structures within the hardware component.

[0039] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that improvements and modifications that do not depart from the principles of the present invention, which are apparent to those skilled in the art, should also be considered within the scope of protection of the present invention.

[0040] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for joint detection of radio frequency interference of a spaceborne radiometer, characterized in that: The steps include: S1: Receives horizontally polarized and vertically polarized analog signals through a satellite-borne radiometer, inputs them into independent ADC channels, converts them into digital signals, and pre-processes the two digital signals; S2: performing digital channelization processing on the pre-processed signal by using a multi-filter bank divided at equal intervals to divide the signal into a plurality of sub-band signals; S3: For each subband signal, calculate the first to fourth order central moments of the horizontally polarized and vertically polarized signals within a preset integration time, and then calculate the kurtosis value from the second and fourth order central moments; S4: Set a detection threshold to meet the detection index. On each subband, detect and identify the radio frequency interference based on the set detection threshold and the calculated kurtosis value. Combine kurtosis detection and polarization detection in sequence to output the radio frequency interference identification signal.

2. The method for joint detection of radio frequency interference of a spaceborne radiometer according to claim 1, characterized in that: In step S1, preprocessing the two digital signals further includes: S11: Perform digital down-conversion (DDC) on the horizontally polarized and vertically polarized digital signals, filter out the high-frequency components after mixing, retain the baseband signal, and reduce the sampling rate; S12: Inputting the signal after the digital down-conversion DDC into the digital polyphase filter for multi-rate signal processing to improve the spectrum resolution and suppress out-of-band noise; Ensure that the horizontal polarization and vertical polarization signals are strictly synchronized in time and phase to avoid subsequent polarization detection errors.

3. The method for joint detection of radio frequency interference of a spaceborne radiometer according to claim 1, characterized in that: In step S2, the division into a number of sub-band signals specifically includes: S21: Decompose the prototype filter into several parallel sub-filters, each sub-filter corresponds to a sub-band; S22: Divide the pre-processed horizontally polarized and vertically polarized full-band signals into blocks according to the number of sub-bands and input the blocks into sub-filters. Each sub-filter processes a corresponding input block to generate a sub-band signal.

4. The method for joint detection of radio frequency interference of a spaceborne radiometer according to claim 1, characterized in that: In step S3, calculating the first-order to fourth-order central moments of the horizontally polarized and vertically polarized signals further includes: S31: By calculating the mean of the horizontal polarization signal and the vertical polarization signal and , get the first-order central moment, the calculation formula is as follows: in, represents a discrete sequence of horizontally polarized subband signals, represents a discrete sequence of vertically polarized subband signals, is the number of sampling points within the integration time, is the discrete time index; S32: Calculate the second to fourth order central moments , is the order, The order central moment is the difference between the signal and the mean The average value of the power is calculated as follows: Among them, the second-order central moment is used to calculate the variance of the horizontally polarized signal and the vertically polarized signal, the third-order central moment is used to calculate the skewness correlation, which is used to describe the asymmetry of the distribution, and the fourth-order central moment is used to calculate the kurtosis correlation, which is used to describe the sharpness of the distribution. S33: Calculate the kurtosis of horizontally polarized signals and vertically polarized signals based on the first to fourth order central moments and , the calculation formula is as follows: 。 5. The method for joint detection of radio frequency interference of a spaceborne radiometer according to claim 4, characterized in that: In step S4, the kurtosis detection is first performed, which specifically includes: S41: Dynamically adjust threshold offset through algorithm simulation And determine the standard reference kurtosis value , set the kurtosis detection threshold range to to ; S42: On each sub-band, the calculated kurtosis values of the horizontal polarization signal and the vertical polarization signal are calculated. and Compare with the kurtosis detection threshold range to determine whether there is radio frequency interference: like or , it is believed that there is radio frequency interference in the horizontally polarized sub-band signal; like or , it is believed that there is radio frequency interference in the vertically polarized sub-band signal; S43: If it is determined through the kurtosis detection that no interference exists, the polarization detection is performed.

6. The method for joint detection of radio frequency interference of a spaceborne radiometer according to claim 5, characterized in that: The polarization detection further comprises: S44: Cross-correlate the horizontally polarized signal and the vertically polarized signal on each sub-band. The cross-correlation formula is as follows: in, and Represents horizontal polarization and vertical polarization respectively. sub-band signals, represents the cross-correlation result, characterizing the similarity of the two polarization signals; S45: Extract the imaginary part according to the cross-correlation result to obtain the fourth Stokes parameter , the calculation formula is as follows: in, Represents the complex conjugate of the vertically polarized signal, the fourth Stokes parameter of the natural radiation source The value approaches 0, and human interference will cause the fourth Stokes parameter Significantly increased; S46: Preset polarization detection threshold according to actual scenario , the fourth Stokes parameter is obtained With the polarization detection threshold For comparison: like , it is considered that there is radio frequency interference; Otherwise, it is assumed that no RF interference exists.

7. A radio frequency interference joint detection system for a spaceborne radiometer, characterized in that: include: The signal preprocessing module is used to receive horizontally polarized and vertically polarized analog signals from the satellite-borne radiometer, input them into independent ADC channels to convert them into digital signals, and preprocess the two digital signals; A channelization processing module, configured to perform digital channelization processing on the pre-processed signal by using a plurality of filter banks divided at equal intervals to divide the signal into a plurality of sub-band signals; A statistical numerical calculation module is used to calculate the first to fourth order central moments of the horizontally polarized and vertically polarized signals for each sub-band signal within a preset integration time, and then calculate the kurtosis value from the second and fourth order central moments; The joint detection module is used to set the detection threshold to meet the detection index. On each sub-band, it detects and identifies the radio frequency interference based on the set monitoring threshold and the calculated kurtosis value, and sequentially combines kurtosis detection and polarization detection to output the radio frequency interference identification signal.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program includes a boot program and an application program, and when executed by a processor, implements the radio frequency interference joint detection method of a spaceborne radiometer according to any one of claims 1 to 6.

9. An electronic device, characterized in that: include: one or more processors; A storage device for storing one or more programs, which, when executed by the one or more processors, enables the one or more processors to implement the radio frequency interference joint detection method of the space-borne radiometer according to any one of claims 1 to 6.

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