Method, device, storage medium and equipment for generating two-dimensional modulation interference signal

Abstract

The present invention discloses a method, device, storage medium and equipment for generating a two-dimensional modulated interference signal, and belongs to the field of radar countermeasure technology. The method includes a jammer performing reconnaissance reception on a target SAR signal and converting it into a digital SAR signal; generating a phase coding modulation signal and a range frequency shift modulation signal according to the required interference type and signal parameters; generating an azimuth sine function secondary modulation signal and an azimuth frequency shift modulation signal according to the required interference type and signal parameters; completing range modulation and azimuth modulation based on the generated various modulation signals and digital SAR signals to obtain a digital interference signal; converting the digital interference signal into an analog interference signal and forwarding it to the target SAR system. The present invention combines range phase coding modulation, azimuth secondary sine function modulation and two-dimensional frequency shift modulation, and can flexibly generate six different types of two-dimensional interference effects, while being able to accurately control the center position of the interference result.

Description

Technical Field

[0001] The present invention belongs to the field of radar countermeasure technology, and in particular relates to a method, device, storage medium and equipment for generating a two-dimensional modulated interference signal. Background Art

[0002] As an active microwave detection device, spaceborne synthetic aperture radar (SAR) can perform all-day, all-weather and high-resolution imaging of ground targets, and is therefore widely used in terrain mapping, resource exploration, and other aspects. Therefore, it is of great theoretical significance and engineering value to study the devices and methods for interfering with SAR systems to weaken the detection capability of target SAR systems. Existing SAR interference devices and methods achieve interference effects by generating false targets or scenes, and can be divided into two categories according to the energy source of the interference signal: active interference methods and passive interference methods.

[0003] Compared with intermittent sampling and forwarding interference, the phase coding modulation method can effectively avoid signal energy loss and improve interference performance, and is therefore widely used in SAR active interference methods. Some scholars use periodic phase coding sequences to perform intra-pulse modulation on target SAR signals, which can produce distance-directed point array interference effects. However, this image modulation method can only produce one-dimensional image interference effects, and the interference style is single; some scholars also perform intra-pulse grouping amplitude and phase joint modulation on SAR signals, as well as inter-pulse grouping amplitude and phase joint modulation, and then perform up-conversion processing to finally obtain the desired interference signal. However, this modulator can only produce one-dimensional point array or two-dimensional dot matrix interference effects, and cannot flexibly adapt to different application scenarios, and has certain limitations.

[0004] In summary, although the existing phase modulation active jamming method can achieve a two-dimensional jamming effect, it can only produce point array or dot matrix jamming effects, and cannot flexibly change the jamming style according to the change of the jamming scene. At the same time, it cannot flexibly adjust the center position of the jamming result, and has certain limitations. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method, device, storage medium and equipment for generating a two-dimensional modulated interference signal.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for generating a two-dimensional modulated interference signal, the method comprising:

[0008] Step 1: The jammer detects and receives the target SAR signal and performs down-conversion processing to obtain an analog SAR signal, samples the analog SAR signal to obtain a digital SAR signal, stores the digital SAR signal and calculates signal parameters;

[0009] Step 2: according to the required interference type and signal parameters, set the symbol time width of the periodic phase coding sequence or the non-periodic phase coding sequence to generate a phase coding modulation signal with a duty cycle of 0.5; generate a range frequency shift modulation signal according to the required range offset;

[0010] Step 3: According to the required interference type, select the first-order modulation index, the first-order modulation frequency, the second-order modulation index, and the second-order modulation frequency to generate an azimuth sine function secondary modulation signal; and generate an azimuth frequency shift modulation signal according to the required azimuth offset;

[0011] Step 4: multiply the generated phase coded modulation signal and the range frequency shift modulation signal with the digital SAR signal in the fast time domain to complete the range modulation; multiply the generated azimuth sine function secondary modulation signal and the azimuth frequency shift modulation signal with the range modulated digital SAR signal in the slow time domain to complete the azimuth modulation and obtain the digital interference signal;

[0012] Step 5: Convert the digital interference signal into an analog interference signal and forward it to the target SAR system pulse by pulse; the analog interference signal is down-converted and analog-to-digital converted by the target SAR system to obtain a baseband interference signal; the baseband interference signal is imaged and processed by the target SAR system to produce different types of interference effects.

[0013] On the other hand, the present invention provides a device for generating a two-dimensional modulated interference signal, comprising:

[0014] A digital SAR signal acquisition unit is used to use a jammer to perform reconnaissance and reception of a target SAR signal and perform down-conversion processing to obtain an analog SAR signal, sample the analog SAR signal to obtain a digital SAR signal, store the digital SAR signal and calculate signal parameters;

[0015] The first modulation signal generating unit is used to set the symbol time width of the periodic phase coding sequence or the non-periodic phase coding sequence according to the required interference type and signal parameters, and generate a phase coding modulation signal with a duty cycle of 0.5; and generate a range frequency shift modulation signal according to the required range offset;

[0016] The second modulation signal generating unit is used to select a first-order modulation index, a first-order modulation frequency, a second-order modulation index, and a second-order modulation frequency according to the required interference type, and generate an azimuth sine function secondary modulation signal; and generate an azimuth frequency shift modulation signal according to the required azimuth offset;

[0017] The modulation unit is used for step 4, multiplying the generated phase coding modulation signal and the range frequency shift modulation signal with the digital SAR signal in the fast time domain to complete the range modulation; multiplying the generated azimuth sine function secondary modulation signal and the azimuth frequency shift modulation signal with the range modulated digital SAR signal in the slow time domain to complete the azimuth modulation and obtain the digital interference signal;

[0018] The interference signal generating unit is used to convert the digital interference signal into an analog interference signal and forward it to the target SAR system pulse by pulse; the analog interference signal is down-converted and analog-to-digital converted by the target SAR system to obtain a baseband interference signal; the baseband interference signal is imaged and processed by the target SAR system to produce different types of interference effects.

[0019] In a third aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned method for generating a two-dimensional modulated interference signal.

[0020] In a fourth aspect, the present invention provides an electronic device, comprising: an antenna unit, a processor unit and a storage unit; the antenna unit is used to receive signals transmitted by a target SAR system and transmit interference signals; the storage unit is used to store one or more programs; wherein, when one or more programs are executed by one or more processors, the one or more processors implement the aforementioned method for generating a two-dimensional modulated interference signal.

[0021] The beneficial effects of the present invention are:

[0022] The present invention combines phase coding modulation in the distance direction, quadratic sinusoidal function modulation in the azimuth direction and two-dimensional frequency shift modulation, and can flexibly generate six different types of two-dimensional interference effects, while being able to accurately control the center position of the interference result. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of a method for generating a two-dimensional modulated interference signal of the present invention;

[0024] Figure 2 This is a typical SAR interference scene diagram;

[0025] Figure 3 It is the time domain waveform diagram of the periodic phase sequence;

[0026] Figure 4 It is a time domain waveform diagram of a non-periodic phase sequence;

[0027] Figure 5 This is the SAR image when the jammer is not working;

[0028] Figure 6A two-dimensional dot matrix interference effect diagram generated by the method for generating a two-dimensional modulated interference signal of the present invention;

[0029] Figure 7 This is an effect diagram of azimuthally discontinuous strips distributed at equal intervals in the distance direction generated by the method for generating a two-dimensional modulated interference signal of the present invention;

[0030] Figure 8 This is an effect diagram of continuous strips in azimuth with equal intervals in distance generated by the method for generating a two-dimensional modulated interference signal of the present invention;

[0031] Fig. 9 This is an effect diagram of continuous strips in the distance direction that are equally spaced in the azimuth direction and generated by the method for generating a two-dimensional modulated interference signal of the present invention;

[0032] Fig.10 This is an effect diagram of continuous wide strips in the distance direction that are equally spaced in the azimuth direction and generated by the method for generating a two-dimensional modulated interference signal of the present invention;

[0033] Fig.11 A two-dimensional surface target suppression interference effect diagram generated by the method for generating a two-dimensional modulated interference signal of the present invention;

[0034] Fig.12 This is an example diagram of the framework of the device for generating a two-dimensional modulated interference signal according to the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] The present invention provides a method, device, storage medium and equipment for generating a two-dimensional modulated interference signal, which combines two-dimensional frequency shift modulation, azimuth sinusoidal function secondary modulation and distance phase coding sequence modulation to flexibly achieve different types of interference effects and accurately control the center position of the interference result.

[0037] like Figure 1 As shown, on the one hand, the present invention discloses a method for generating a two-dimensional modulated interference signal, comprising the following steps:

[0038] Step 1: The jammer conducts reconnaissance and reception of the target SAR signal, then performs down-conversion processing on the received SAR signal to obtain an analog SAR signal, then uses an analog-to-digital converter to sample the analog SAR signal to obtain a digital SAR signal, then stores the digital SAR signal and measures the bandwidth, pulse width, frequency modulation slope, pulse repetition period and other parameters of the intercepted target SAR signal;

[0039] Step 2: According to the required interference type and signal parameters, select a periodic phase coding sequence or a non-periodic phase coding sequence to generate, and then set the period of the periodic phase coding sequence or the code element time width of the non-periodic phase coding sequence according to the signal parameters, and generate a phase coded modulation signal with a duty cycle of 0.5 according to the obtained parameters, and then set the distance frequency shift amount according to the required distance offset and generate a distance frequency shift modulation signal.

[0040] Step 3: According to the required interference type and signal parameters, select the first-order modulation index, first-order modulation frequency, second-order modulation index, and second-order modulation frequency to generate an azimuth sinusoidal function secondary modulation signal. Then, set the azimuth frequency shift amount according to the required azimuth offset and generate an azimuth frequency shift modulation signal.

[0041] Step 4: Multiply the generated phase-coded modulation signal and the range frequency-shift modulation signal with the digital SAR signal in the fast time domain to complete the range modulation, and multiply the generated azimuth sinusoidal function secondary modulation signal and the azimuth frequency-shift modulation signal with the range-modulated digital SAR signal in the slow time domain to complete the azimuth modulation and obtain the digital interference signal.

[0042] Step 5: Use a digital-to-analog converter to convert the digital interference signal into an analog interference signal, then up-convert the analog interference signal according to the carrier frequency of the digital SAR signal and forward it pulse by pulse to the target SAR system. The analog interference signal is processed by down-conversion and analog-to-digital conversion of the target SAR system to obtain a baseband interference signal; the baseband interference signal can produce different types of interference effects after imaging processing by the target SAR system.

[0043] Typical SAR interference scenarios include: Figure 2 As shown, the flight speed of the side-view airborne SAR platform is set to , the flight altitude is , jammer Located at the center of the SAR system imaging swath and with coordinates , taking the SAR flight direction as Axis, vertical upward direction Axis to establish coordinate system. Set jammer The shortest slant range to the SAR platform is , the instantaneous slope distance is , then we can calculate , .

[0044] The specific implementation process of step one is as follows:

[0045] The target SAR system transmits the signal, that is, the target SAR signal The expression is as follows:

[0046] (1)

[0047] in, is a rectangular window function, is the distance to time, is the pulse width, is the carrier frequency, is the frequency modulation slope of the linear frequency modulation signal, Is an imaginary unit.

[0048] The jammer intercepts the transmission signal of the target SAR system through the receiving antenna, and then down-converts the received transmission signal to obtain an analog SAR signal, and then uses an analog-to-digital converter to sample the analog SAR signal to obtain a digital SAR signal. The expression of the digital SAR signal is as follows:

[0049] (2)

[0050] in, Further, the digital SAR signal is stored and the bandwidth, pulse width, frequency modulation slope, pulse repetition period and other parameters of the digital SAR signal are measured.

[0051] From the analysis, it can be seen that when the jammer is not working, the baseband signal of the point target echo received by the SAR system is:

[0052] (3)

[0053] in, is the azimuth time, is the synthetic aperture time.

[0054] The specific implementation process of step 2 is as follows:

[0055] According to the measured signal parameters, set the phase sequence code element By changing the periodicity of the sequence code element, periodic phase sequence and non-periodic phase sequence can be generated respectively. By using the generated different types of phase sequences to modulate the received SAR signal, various interference effects can be achieved.

[0056] When the symbols appear alternately, the modulation sequence is a periodic phase coded sequence. Set the period of the phase sequence to , the duty cycle is 0.5, then its time domain waveform is as follows Figure 3 shown.

[0057] The phase sequence can be converted into the following form using Fourier series theory:

[0058] (4)

[0059] in, is the order of the harmonic component of the periodic phase modulation sequence, is a set of integers;

[0060] When the code elements appear randomly, the modulation sequence is a non-periodic phase sequence. Set the code element width of the phase sequence to The total number of code elements is And the number of code element 0 and code element π in the phase sequence is the same, then its time domain waveform is as follows Figure 4 shown.

[0061] After analysis, it can be seen that the time domain expression of the non-periodic phase modulation sequence can be converted into:

[0062] (5)

[0063] in, represents a symbol of a bipolar non-periodic phase coded sequence and , represents the unit impulse function.

[0064] At the same time, set the distance frequency shift according to the required distance offset And generate a distance frequency shift modulation signal, the expression of which is .

[0065] The specific implementation process of step three is as follows:

[0066] According to the measured signal parameters, the expression of the sine function secondary phase modulation signal is set as:

[0067] (6)

[0068] in, is the first-order modulation index, is the first-order modulation frequency, is the second-order modulation index, is the second-order modulation frequency. According to the series expansion, it can be expressed as:

[0069] (7)

[0070] in, is the harmonic component order corresponding to the first-order sinusoidal function modulation signal, is the first-order Bessel function corresponding to the first-order sine function modulation signal, is the harmonic component order corresponding to the second-order sinusoidal function modulation signal, It is the first-order Bessel function corresponding to the second-order sine function modulation signal.

[0071] Then the spectrum of the signal in equation (6) is:

[0072] (8)

[0073] in, It indicates the azimuth angular frequency. From formula (8), we can know that the spectrum of the sine function quadratic phase modulation signal contains infinite spectral components. The amplitude of each sideband component is proportional to the Bessel function of the corresponding order. The interval of the sideband components is determined by the angular frequency of the cosine phase modulation signal. The spectrum bandwidth of the phase modulation signal is estimated by the Casson formula:

[0074] (9)

[0075] in, is the bandwidth of the first-order sinusoidal modulation signal, The bandwidth of the signal is modulated by a second-order sine function. At the same time, the azimuth frequency shift is set according to the required azimuth offset. And generate azimuth frequency shift modulation signal, its expression is .

[0076] The specific implementation process of step 4 is as follows:

[0077] The jammer performs range frequency shift, azimuth frequency shift, range phase coding sequence modulation, and azimuth sinusoidal function secondary phase modulation on the received baseband SAR signal to obtain a digital jamming signal. When the range phase coding sequence is a periodic phase coding sequence, its expression is: As shown below:

[0078] (10)

[0079] When the range phase modulation sequence is a non-periodic phase coding sequence, the digital interference signal expression is As shown below:

[0080] (11)

[0081] The specific implementation process of step 5 is as follows:

[0082] The digital interference signal is converted into an analog interference signal using a digital-to-analog converter, and then the analog interference signal is up-converted according to the carrier frequency of the intercepted SAR signal and forwarded to the target SAR system pulse by pulse.

[0083] The target SAR system performs down-conversion and analog-to-digital conversion on the received analog interference signal to obtain a baseband interference signal. Furthermore, the target SAR system performs imaging processing on the baseband interference signal. The following analyzes the baseband interference signal imaging model under the modulation conditions of periodic phase coded sequence and non-periodic phase coded sequence respectively.

[0084] For periodic phase sequence modulation analysis:

[0085] According to the above analysis, the baseband interference signal expression is:

[0086] (12)

[0087] The imaging characteristics of the interference model are analyzed using the RD algorithm. First, the range-to-frequency domain matched filter is used. The interference signal is processed by pulse compression in the range direction, and then the frequency domain matched filter in the azimuth direction is used The interference signal is subjected to azimuth pulse compression processing, and the final imaging result is:

[0088] (13)

[0089] in, is the azimuth frequency modulation slope, .

[0090] According to the above results, the distance direction will produce a position offset after frequency shift modulation, and further after phase coding sequence modulation, multiple frequency shift modulations will be formed on the basis of the position offset, generating false targets of various orders. The distance of the false target to the center position for:

[0091] (14)

[0092] For the direction The false target is oriented towards the center. for:

[0093] (15)

[0094] For non-periodic phase sequence modulation analysis:

[0095] After analysis, it can be seen that the time domain expression of the non-periodic phase modulation sequence can be converted into:

[0096] (16)

[0097] in, represents a symbol of a bipolar non-periodic phase coded sequence and .

[0098] Therefore, the spectrum of the non-periodic rectangular modulated pulse can be converted into the following form:

[0099] (17)

[0100] in, is the distance frequency. According to the Fourier transform characteristic analysis, the continuous spectrum modulation term can continuously shift the spectrum of the incident signal to produce a stripe interference effect.

[0101] In addition, when , , at this time the main lobe width of the modulated signal spectrum is:

[0102] (18)

[0103] According to the above analysis, the baseband interference signal expression is:

[0104] (19)

[0105] The imaging characteristics of the interference model are analyzed using the RD algorithm. First, the range-to-frequency domain matched filter is used. The interference signal is processed by pulse compression in the range direction, and then the frequency domain matched filter in the azimuth direction is used The interference signal is subjected to azimuth pulse compression processing, and the final imaging result is:

[0106] (20)

[0107] in,

[0108] .

[0109] The continuous frequency shift modulation introduced by the non-periodic phase coding sequence is linearly superimposed during matched filtering, which will cause a continuous shift in the range position. Since the main lobe width of the modulation signal spectrum is , then the range main lobe width of the interference result can be expressed as:

[0110] (twenty one)

[0111] The distance of the interference result to the center of the main lobe is:

[0112] (twenty two)

[0113] Interference result direction The false target direction is towards the center position for:

[0114] (twenty three)

[0115] The theoretical model of the present invention is verified and analyzed in combination with the simulation results. The target SAR system is set to work in strip imaging mode, the working frequency band is X-band, the center frequency is 9.6GHz, the carrier speed is 154.2m / s, the signal bandwidth is 480MHz, the signal time width is 2.4μs, and the pulse repetition frequency is 533.3Hz. According to the simulation parameter calculation, it can be known that the SAR system range resolution The azimuth resolution is 0.2769m. It is 0.3461m.

[0116] The jammer is deployed at 0m in distance and 0m in azimuth, and the signal-to-interference ratio of the target SAR system receiver is set to -3dB. Figure 5 The SAR image is shown when the jammer is not working. The jammer imaging result is a point target located at the coordinate zero. By changing the modulation parameters, different types of jamming effects can be achieved.

[0117] Set the frequency shift in the range direction to 10MHz, the frequency shift in the azimuth direction to 3Hz, and the first-order modulation coefficient is 2, the first-order modulation frequency is 10rad, the second-order modulation coefficient is 0, the second-order modulation frequency The period of the rectangular pulse signal is 0.5 μs, and the duty cycle is 0.5. According to the theoretical model calculation and analysis, the interference result is a two-dimensional dot matrix. The simulation results are as follows: Figure 6 As shown, it is consistent with the theoretical analysis.

[0118] Set the frequency shift in the range direction to 10MHz, the frequency shift in the azimuth direction to 3Hz, and the first-order modulation coefficient is 3, the first-order modulation frequency is 15rad, the second-order modulation coefficient is 5, the second-order modulation frequency The period of the rectangular pulse signal is 0.72 rad, the period of the periodic rectangular pulse signal is 0.5 μs, and the duty cycle is 0.5. According to the theoretical model calculation and analysis, the interference result is an azimuthally discontinuous strip distributed at equal intervals in the distance direction. The simulation results are shown in Figure 7 As shown, it is consistent with the theoretical analysis.

[0119] Set the frequency shift in the range direction to 10MHz, the frequency shift in the azimuth direction to 3Hz, and the first-order modulation coefficient is 2, the first-order modulation frequency is 10rad, the second-order modulation coefficient is 10, the second-order modulation frequency is 0.8, the period of the periodic rectangular pulse signal is 0.5μs, and the duty cycle is 0.5. According to the theoretical model calculation and analysis, the interference result is a continuous strip in the azimuth direction with equal intervals in the distance direction. The simulation results are as follows Figure 8 As shown, it is consistent with the theoretical analysis.

[0120] Set the frequency shift in the range direction to -10MHz, the frequency shift in the azimuth direction to -3Hz, and the first-order modulation coefficient is 2, the first-order modulation frequency is 10rad, the second-order modulation coefficient is 0, the second-order modulation frequency is 0, the code element width of the non-periodic rectangular pulse signal is 0.05μs, and the duty cycle is 0.5. According to the theoretical model calculation, the interference result at this time is a continuous strip in the distance direction with equal intervals in the azimuth direction. The simulation results are as follows Fig. 9 As shown, it is consistent with the theoretical analysis.

[0121] Set the frequency shift in the range direction to -10MHz, the frequency shift in the azimuth direction to -3Hz, and the first-order modulation coefficient is 3, the first-order modulation frequency is 15rad, the second-order modulation coefficient is 5, the second-order modulation frequency is 0.72, the period of the periodic rectangular pulse signal is 0.05μs, and the duty cycle is 0.5. According to the theoretical model calculation, the interference result is a continuous wide strip in the distance direction with equal intervals in the azimuth direction. The simulation results are as follows: Fig.10 As shown, it is consistent with the theoretical analysis.

[0122] Set the frequency shift in the range direction to -10MHz, the frequency shift in the azimuth direction to -3Hz, and the first-order modulation coefficient is 2, the first-order modulation frequency is 10rad, the second-order modulation coefficient is 10, the second-order modulation frequency is 0.8, the period of the rectangular pulse signal is 0.05μs, and the duty cycle is 0.5. According to the theoretical model calculation, the interference result is a two-dimensional surface target suppression interference. The simulation results are as follows Fig.11 As shown, it is consistent with the theoretical analysis.

[0123] Therefore, the novel SAR jamming method proposed in the present invention can realize smart two-dimensional jamming of SAR images, ultimately producing six different types of jamming effects, and can precisely adjust the center position of the jamming result, and its effectiveness has been proven.

[0124] A two-dimensional modulated interference signal generating device of the present invention comprises a digital SAR signal acquisition unit, which is used to use a jammer to perform reconnaissance reception on a target SAR signal and perform down-conversion processing to obtain an analog SAR signal, sample the analog SAR signal to obtain a digital SAR signal, store the digital SAR signal and calculate signal parameters;

[0125] The first modulation signal generating unit is used to set the symbol time width of the periodic phase coding sequence or the non-periodic phase coding sequence according to the required interference type and signal parameters, and generate a phase coding modulation signal with a duty cycle of 0.5; and generate a range frequency shift modulation signal according to the required range offset;

[0126] The second modulation signal generating unit is used to select a first-order modulation index, a first-order modulation frequency, a second-order modulation index, and a second-order modulation frequency according to the required interference type, and generate an azimuth sine function secondary modulation signal; and generate an azimuth frequency shift modulation signal according to the required azimuth offset;

[0127] The modulation unit is used to multiply the generated phase coding modulation signal and the range frequency shift modulation signal with the digital SAR signal in the fast time domain to complete the range modulation; and multiply the generated azimuth sine function secondary modulation signal and the azimuth frequency shift modulation signal with the range modulated digital SAR signal in the slow time domain to complete the azimuth modulation and obtain the digital interference signal;

[0128] The interference signal generating unit is used to convert the digital interference signal into an analog interference signal and forward it to the target SAR system pulse by pulse. After down-conversion, analog-to-digital conversion and imaging processing by the target SAR system, the analog interference signal produces different types of interference effects.

[0129] Specifically, Fig.12 As shown, it includes: a signal detection module, which is used to detect and receive the target SAR system transmission signal; a down-conversion module, which is used to perform down-conversion processing on the received SAR signal; an analog-to-digital conversion module, which is used to sample and convert the intercepted target SAR transmission signal into a digital signal; a signal parameter measurement module, which is used to measure the pulse width, bandwidth, pulse repetition frequency and other signal parameters of the received signal; a phase coding modulation module, which is used to generate a periodic or non-periodic phase coding sequence and perform intra-pulse modulation on the digital signal; a range frequency shift modulation module, which is used to generate a range frequency shift modulation signal and perform intra-pulse modulation on the digital signal; a sine function secondary phase modulation modulation module, which is used to generate a sine function secondary phase modulation signal and perform inter-pulse modulation on the digital signal; an azimuth frequency shift modulation module, which is used to generate an azimuth frequency shift modulation signal and perform inter-pulse modulation on the digital signal; a digital-to-analog conversion module, which converts the obtained digital interference signal into an analog interference signal; an up-conversion module, which is used to perform up-conversion processing on the analog interference signal; and a transmitting module, which is used to transmit the interference signal pulse by pulse.

[0130] A storage medium of the present invention is a computer-readable storage medium capable of storing a computer program. When the program is called and executed by a processor, the device where the storage medium is located executes the method for generating a two-dimensional modulated interference signal disclosed in the present invention.

[0131] An electronic device of the present invention comprises an antenna unit, a processor unit and a storage unit; wherein the antenna unit comprises a pulse antenna and an array antenna, etc., and is mainly used to receive a target SAR system transmission signal and transmit an interference signal; the processor unit comprises a central processing unit, a digital signal processor, a field programmable gate array, etc., and is mainly used to call and execute various programs to realize functions such as down-conversion, analog-to-digital conversion, signal parameter measurement, phase-coded sequence modulation, sinusoidal function secondary phase modulation modulation, range frequency shift modulation, azimuth frequency shift modulation, digital-to-analog conversion, and up-conversion; the storage unit comprises a digital radio frequency memory, a mobile hard disk, a read-only memory, etc., and is mainly used to store signal data and programs; when the program in the storage unit is executed by the processor unit, the electronic device executes the method of the present invention.

[0132] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for generating a two-dimensional modulated interference signal, characterized in that: The method comprises: Step 1: The jammer detects and receives the target SAR signal and performs down-conversion processing to obtain an analog SAR signal, samples the analog SAR signal to obtain a digital SAR signal, stores the digital SAR signal and calculates signal parameters; Step 2: according to the required interference type and signal parameters, set the symbol time width of the periodic phase coding sequence or the non-periodic phase coding sequence to generate a phase coding modulation signal with a duty cycle of 0.5; generate a range frequency shift modulation signal according to the required range offset; Step 3: According to the required interference type and signal parameters, select the first-order modulation index, the first-order modulation frequency, the second-order modulation index, and the second-order modulation frequency to generate an azimuth sine function secondary modulation signal; and generate an azimuth frequency shift modulation signal according to the required azimuth offset; Step 4: multiply the generated phase coded modulation signal and the range frequency shift modulation signal with the digital SAR signal in the fast time domain to complete the range modulation; multiply the generated azimuth sine function secondary modulation signal and the azimuth frequency shift modulation signal with the range modulated digital SAR signal in the slow time domain to complete the azimuth modulation and obtain the digital interference signal; Step 5: Convert the digital interference signal into an analog interference signal and forward it to the target SAR system pulse by pulse; the analog interference signal is down-converted and analog-to-digital converted by the target SAR system to obtain a baseband interference signal; the baseband interference signal is imaged and processed by the target SAR system to produce different types of interference effects.

2. The method for generating a two-dimensional modulated interference signal according to claim 1, characterized in that: The step one comprises: Target SAR signal The expression is as follows: （1） in, is the pulse width, is the carrier frequency, is the frequency modulation slope of the linear frequency modulation signal, j is the imaginary unit; The jammer intercepts the target SAR signal transmitted by the target SAR system through the receiving antenna reconnaissance, and down-converts the received target SAR signal to obtain an analog SAR signal. The analog SAR signal is sampled by an analog-to-digital converter to obtain a digital SAR signal: （2） in, is the speed of light, For jammer The instantaneous slant range to the SAR platform, is the azimuth time; Store digital SAR signals and measure the bandwidth, pulse width, frequency modulation slope, and pulse repetition period of digital SAR signals.

3. The method for generating a two-dimensional modulated interference signal according to claim 2, characterized in that: The second step comprises: According to the signal parameters obtained by measuring the digital SAR signal, the phase sequence code element is set , when the symbols appear alternately, the modulation sequence is periodic The expression of the periodic phase coding sequence with a duty cycle of 0.5 is as follows: （4） in, is the harmonic component order of the periodic phase coded sequence, is a set of integers; When the symbols appear randomly, the modulation sequence is the symbol width The total number of code elements is And code element With code element The expression of the same number of non-periodic phase-coded sequences is as follows: （5） in, represents the symbol of the non-periodic phase coded sequence and , represents the unit impulse function; Set the distance frequency shift according to the required distance offset And generate a distance frequency shift modulation signal, the expression of which is .

4. The method for generating a two-dimensional modulated interference signal according to claim 3, characterized in that: The step three comprises: According to the signal parameters obtained by measuring the digital SAR signal, set the sine function secondary modulation signal The expression is: in, is the first-order modulation index, is the first-order modulation frequency, is the second-order modulation index, is the second-order modulation frequency; Set the azimuth frequency shift according to the required azimuth offset And generate azimuth frequency shift modulation signal, its expression is .

5. The method for generating a two-dimensional modulated interference signal according to claim 4, characterized in that: The fourth step includes: the jammer performs range frequency shift, azimuth frequency shift, range phase coding sequence modulation, and azimuth sinusoidal function secondary phase modulation on the received digital SAR signal to obtain a digital interference signal. When the range phase coding sequence is a periodic phase coding sequence, its expression is: As shown below: When the range phase coding sequence is a non-periodic phase coding sequence, the digital interference signal expression is As shown below: （11）。 6. The method for generating a two-dimensional modulated interference signal according to claim 5, characterized in that: The step five includes: using a digital-to-analog converter to convert the digital interference signal into an analog interference signal, up-converting the analog interference signal according to the carrier frequency of the digital SAR signal and forwarding it pulse by pulse to the target SAR system; the analog interference signal is down-converted and analog-to-digital converted by the target SAR system to obtain a baseband interference signal; the baseband interference signal can produce different types of interference effects after imaging processing.

7. The method for generating a two-dimensional modulated interference signal according to claim 6, characterized in that: By changing the periodicity of code elements to generate range-direction periodic phase-coded sequence modulation signals or non-periodic phase-coded sequence modulation signals, different types of range-direction phase-coded sequence modulation signals are combined with range-direction frequency-shift modulation signals, azimuth-direction sinusoidal function secondary modulation signals, and azimuth-direction frequency-shift modulation signals to produce different types of interference effects.

8. A device for generating a two-dimensional modulated interference signal, characterized in that: include: A digital SAR signal acquisition unit is used to use a jammer to perform reconnaissance and reception of a target SAR signal and perform down-conversion processing to obtain an analog SAR signal, sample the analog SAR signal to obtain a digital SAR signal, store the digital SAR signal and calculate signal parameters; The first modulation signal generating unit is used to set the symbol time width of the periodic phase coding sequence or the non-periodic phase coding sequence according to the required interference type and signal parameters, and generate a phase coding modulation signal with a duty cycle of 0.5; and generate a range frequency shift modulation signal according to the required range offset; The second modulation signal generating unit is used to select a first-order modulation index, a first-order modulation frequency, a second-order modulation index, and a second-order modulation frequency according to the required interference type, and generate an azimuth sine function secondary modulation signal; and generate an azimuth frequency shift modulation signal according to the required azimuth offset; The modulation unit is used to multiply the generated phase coding modulation signal and the range frequency shift modulation signal with the digital SAR signal in the fast time domain to complete the range modulation; and multiply the generated azimuth sine function secondary modulation signal and the azimuth frequency shift modulation signal with the range modulated digital SAR signal in the slow time domain to complete the azimuth modulation and obtain the digital interference signal; An interference signal generating unit, used for converting a digital interference signal into an analog interference signal and forwarding it pulse by pulse to a target SAR system; The analog interference signal is down-converted and analog-to-digital converted by the target SAR system to obtain a baseband interference signal; the baseband interference signal is imaged and processed by the target SAR system to produce different types of interference effects.

9. A computer-readable storage medium, characterized in that: Executable instructions are stored thereon, and when the instructions are executed by a processor, the processor can implement a method for generating a two-dimensional modulated interference signal as described in any one of claims 1-7.

10. An electronic device, characterized in that: include: Antenna unit, processor unit and storage unit; The antenna unit is used to receive the target SAR system transmission signal and transmit an interference signal; The storage unit is used to store one or more programs; When one or more programs are executed by one or more processors, the one or more processors implement a method for generating a two-dimensional modulated interference signal as described in any one of claims 1 to 7.

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