CN113534068A - Non-linear frequency modulation signal modulation interference method and system - Google Patents
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Abstract
The application provides a non-linear frequency modulation signal modulation interference method and a system, wherein the method comprises the following steps: s101, measuring parameter information of the SAR emission signal intercepted by the jammer to obtain SAR signal characteristics; step S102, generating a nonlinear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle; step S103, the nonlinear frequency modulation signal is modulated in a segmented mode, and cosine amplitude weighting is carried out on the nonlinear frequency modulation signal after the segmented modulation, so that an SAR interference signal is generated. Therefore, the SAR interference signal with the low sidelobe locality suppression effect can be obtained, and the leakage of interference energy to sidelobes is effectively reduced.
Description
Technical Field
The present application relates to the field of signal processing technologies, and in particular, to a method and a system for modulating interference with a non-linear frequency modulation signal.
Background
Synthetic Aperture Radar (SAR for short) is an advanced active microwave imaging device, has the working capability of being all-day-long, all-weather, long-distance and high in penetrability, and can perform two-dimensional high-resolution imaging on a target area. Therefore, the synthetic aperture radar has wide application in both military and civil fields, and has extremely important application value particularly in the military field. With the continuous development of military technology, the SAR plays an increasingly important role in modern electronic warfare. Various satellite-borne or airborne SAR systems become important equipment for acquiring information gradually, and with the continuous development and application of synthetic aperture radar systems in other countries in the world, the development in the aspect of the synthetic aperture radar system also faces increasingly serious challenges, and targets are protected from being detected by enemy SAR equipment, so that the SAR systems become important research points in the current electronic countermeasure field.
How to suppress and disturb the imaging reconnaissance of the SAR device and realize effective protection of high-value targets and grounds has become one of the hot difficulties in the research in the field of current electronic countermeasure. There are many methods of synthetic aperture radar interference, which can be classified into active interference and passive interference according to the source of energy. The active interference can be classified into active suppression interference and active spoofing interference. The active suppression interference requires a large transmission power; active spoofing interference requires more accurate measurement of relevant parameter information such as carrier frequency, modulation frequency, pulse width, bandwidth and the like of an SAR emission signal.
Therefore, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art.
Disclosure of Invention
It is an object of the present invention to provide a method for modulating interference by a non-linear fm signal, so as to solve or alleviate the above-mentioned problems in the prior art.
In order to achieve the above purpose, the present application provides the following technical solutions:
the application provides a non-linear frequency modulation signal modulation interference method, which comprises the following steps: s101, measuring parameter information of the intercepted SAR emission signal to acquire SAR signal characteristics; step S102, generating a nonlinear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle; step S103, the nonlinear frequency modulation signal is modulated in a segmented mode, and cosine amplitude weighting is carried out on the nonlinear frequency modulation signal after the segmented modulation, so that an SAR interference signal is generated.
Preferably, step S101 specifically includes: storing the intercepted parameter information of the SAR emission signal based on a digital radio frequency technology, and acquiring the SAR signal characteristics by a pulse description word measurement technology; wherein the SAR signal characteristics include: carrier frequency, beam width, antenna aperture size and bandwidth, pulse width of the baseband signal.
Preferably, step S102 specifically includes: based on a stationary phase principle, according to the SAR signal characteristics, according to a formula:
generating the non-linear frequency modulation signal;
wherein s is2(T) denotes the non-chirp signal, T denotes the pulse duration of the baseband SAR signal, T denotes the fast time of the baseband SAR signal, f denotes the instantaneous frequency of the baseband SAR signal, j denotes the imaginary part of the complex number, τ denotes the integration variable, τ e [0, T ∈]。
Preferably, step S103 includes: segmenting the non-linear frequency modulation signal on a time domain through a preset segmented modulation interference function, and modulating a phase value in each segment of the non-linear frequency modulation signal; wherein, the phase value is any value in the interval of [0,2 pi ]; and based on a time domain weighting function, carrying out cosine amplitude weighting on the nonlinear frequency modulation signal after the segmented modulation so as to generate the SAR interference signal.
Preferably, the piecewise modulation interference function is:
wherein P (t) represents a preset segmented modulation interference function, and n representsThe number of the sections of the nonlinear frequency modulation signal in the time domain is larger than or equal to 1 and not larger than the number of sampling points of the baseband SAR signal, n is a positive integer, t represents the fast time of the baseband SAR signal, ai、ai+1Respectively representing the start and end of the ith segment of the non-chirp signal, epsilon represents a unit step function,
and modulating the phase value on each signal segment after the non-linear frequency modulation signal is segmented.
Preferably, the cosine amplitude weighting is performed on the non-linear frequency modulation signal after the segmented modulation based on the time domain weighting function, specifically: based on a time domain weighting function, taking the central point of each section of nonlinear frequency modulation signal as the central point of the time domain weighting function, and carrying out sectional weighting on the nonlinear frequency modulation signal, wherein the central point of each section of the nonlinear frequency modulation signal is the central position of the corresponding section of the nonlinear frequency modulation signal.
Preferably, the time domain weighting function is a cosine weighting function, and the cosine weighting function is:
wherein w (t) represents a cosine weighting function; t denotes the fast time of the baseband SAR signal, a is a weighting factor, a ∈ [0.5, 1 ].
The embodiment of the present application further provides a non-linear frequency modulation signal modulation interference system, including: the characteristic acquisition unit is configured to measure the intercepted parameter information of the SAR emission signal and acquire the SAR signal characteristic; the nonlinear frequency modulation signal unit is configured to generate a nonlinear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle; and the signal processing unit is configured to perform segmented modulation on the nonlinear frequency modulation signal and perform cosine amplitude weighting on the nonlinear frequency modulation signal subjected to segmented modulation so as to generate an SAR interference signal.
Compared with the closest prior art, the technical scheme of the embodiment of the application has the following beneficial effects:
in the technical scheme provided by the embodiment of the application, the interference machine intercepts parameter information of an SAR emission signal to measure, obtains SAR signal characteristics, and generates a non-linear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle; carrying out segmented modulation on the nonlinear frequency modulation signal, and carrying out cosine amplitude weighting on the nonlinear frequency modulation signal subjected to segmented modulation so as to generate an SAR interference signal; after the cosine amplitude weighted nonlinear frequency modulation signal is transmitted, a target object (such as an enemy plane and the like) generates a corresponding SAR interference signal after pulse compression, so that the target object is interfered. Therefore, the SAR interference signal with the low sidelobe locality suppression effect can be obtained, and the leakage of interference energy to sidelobes is effectively reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application. Wherein:
fig. 1 is a schematic flow chart of a method for modulating interference by a non-chirp signal according to some embodiments of the present application;
fig. 2 is a schematic diagram of a non-chirp modulated jamming system according to some embodiments of the present application;
fig. 3 is a schematic illustration of a non-chirp signal generated based on a hamming window function provided in accordance with some embodiments of the present application;
fig. 4 is a schematic diagram of phase modulating a chirp signal in 10 segments according to some embodiments of the present application;
fig. 5 is a schematic diagram of phase modulating a chirp signal in 20 segments according to some embodiments of the present application;
fig. 6 is a schematic diagram of phase modulating a chirp signal in 30 segments according to some embodiments of the present application;
fig. 7 is a schematic diagram of phase modulating a non-chirp signal in 10 segments according to some embodiments of the present application;
fig. 8 is a schematic diagram of phase modulating a non-chirp signal in 20 segments according to some embodiments of the present application;
Fig. 9 is a schematic diagram of phase modulating a non-chirp signal in 30 segments according to some embodiments of the present application;
fig. 10 is a schematic diagram of cosine amplitude weighting after 10-segment modulation of a chirp signal according to some embodiments of the present application;
fig. 11 is a diagram illustrating cosine amplitude weighting after 20-segment modulation of a chirp signal according to some embodiments of the present application;
fig. 12 is a diagram of cosine amplitude weighting after 30-segment modulation of a chirp signal according to some embodiments of the present application;
fig. 13 is a schematic diagram of cosine amplitude weighting after 10-segment modulation of a non-chirp signal according to some embodiments of the present application;
fig. 14 is a diagram illustrating cosine amplitude weighting after 20-segment modulation of a non-chirp signal according to some embodiments of the present application;
fig. 15 is a schematic diagram of cosine amplitude weighting after 30-segment modulation of a non-chirp signal according to some embodiments of the present application;
fig. 16 is a schematic diagram of a SAR interference signal generated by multiphase segmented modulation with a weighting coefficient of 0.54 provided according to some embodiments of the present application;
Fig. 17 is a schematic diagram of a SAR interference signal generated by multiphase segmented modulation with a weighting coefficient of 0.75 provided according to some embodiments of the present application.
Detailed Description
The present application will be described in detail below with reference to the embodiments with reference to the attached drawings. The various examples are provided by way of explanation of the application and are not limiting of the application. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present application without departing from the scope or spirit of the application. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. It is therefore intended that the present application cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Exemplary method
Fig. 1 is a schematic flow chart of a method for modulating interference by a non-chirp signal according to some embodiments of the present application; as shown in fig. 1, the method for modulating interference by using a non-chirp signal includes:
s101, measuring parameter information of the intercepted SAR emission signal to acquire SAR signal characteristics;
in the embodiment of the application, the SAR emission signal is intercepted by the jammer, and the parameter information of the SAR emission signal comprises: radar flight speed, pulse width, radar carrier frequency, bandwidth, pulse arrival time.
The method for measuring the SAR emission signal intercepted by the jammer comprises the following steps of: based on the digital radio frequency technology, the parameter information of the SAR emission signal intercepted by the jammer is stored, and the SAR signal characteristics are acquired in time by adopting a detection device of a pulse description word measurement technology. Namely, the jammer firstly intercepts SAR signals transmitted to a protection area by an enemy SAR, stores the signals by a digital radio frequency technology, and then acquires relevant parameter indexes such as speed, bandwidth, carrier frequency, beam width, antenna aperture size and the like of the baseband SAR signals in time by a detection device adopting a pulse description word measurement technology.
In the embodiment of the present application, the analytic expression of the baseband SAR signal is shown in formula (1), where formula (1) is as follows:
wherein s is1(T) denotes the baseband SAR signal, T denotes the pulse duration of the baseband SAR signal, T denotes the fast time of the baseband SAR signal, rect denotes a rectangular window function, k denotes the intercepted baseband signal of the SAR emission signalAnd adjusting the frequency.
Step S102, generating a nonlinear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle;
specifically, based on the stationary phase principle, a non-chirp signal is generated according to formula (2) according to the SAR signal characteristics. Equation (2) is as follows:
Wherein s is2(T) denotes the non-chirp signal, T denotes the pulse duration of the baseband SAR signal, T denotes the fast time of the baseband SAR signal, θ (T) denotes the phase of the signal modulation of the baseband SAR signal, f denotes the instantaneous frequency of the baseband SAR signal, j denotes the imaginary part of the complex number, τ is an integral variable, τ is 0, T]。
In the embodiment of the present application, as can be seen from equation (2), the differential relationship between the instantaneous frequency f and the modulation phase of the baseband SAR signal is shown in equation (3), where equation (3) is as follows:
where the instantaneous frequency f is a function of time t and theta represents the phase of the signal modulation.
The instantaneous tuning frequency v is the derivative of the instantaneous frequency f, as shown in equation (4), equation (4) is as follows:
according to the stationary phase principle, the power spectral density of a signal is related to the inverse of the frequency modulation rate. The stationary phase principle relates the power spectral density at each frequency to the line tone frequency, thereby allowing the use of a predetermined shape of the signal power spectral density function to generate the desired signal waveform. Thereby providing a radar matched filter output with lower sidelobe and mainlobe broadening. The amplitude form of the power spectrum is shown in formula (5), and formula (5) is as follows:
in the embodiment of the present application, a window function p (f) (taylor window, hanning window, hamming window, etc.) is used as a basis for generating the non-chirp signal.
Defining t ═ q (f) as a function of the instantaneous frequency f, we can see from equation (5):
the equation for the pulse duration T of the baseband SAR signal is shown in equation (6), and equation (6) is as follows:
where B is the pulse bandwidth of the SAR transmission signal, C represents a constant, and the expression of C is shown in equation (7). Equation (7) is as follows:
the resulting chirp signal can be shaped to meet the pulse duration and bandwidth requirements, and q (f) is expressed as equation (8), where equation (8) is as follows:
obviously, the instantaneous frequency f (t) is a function of Q (f).
In the present embodiment, it is generally difficult to solve the inverse function using an analytical expression of the weighting function, so we use polynomial fitting to do numerical solution, according to equation (9),
f(t)＝Q-1(f)……………………………(9)
and generating instantaneous frequency f (t), substituting the instantaneous frequency f (t) into a formula (2), and generating a nonlinear frequency modulation signal according to the intercepted SAR emission signal.
Step S103, carrying out segmented modulation on the nonlinear frequency modulation signal, and carrying out cosine amplitude weighting on the nonlinear frequency modulation signal subjected to segmented modulation;
specifically, based on a preset piecewise modulation interference function, segmenting the nonlinear frequency modulation signal in a time domain, and modulating a phase value in each segment of the nonlinear frequency modulation signal; wherein, the phase value is any value in the interval of [0, 2 pi ];
In the embodiment of the present application, when the nonlinear frequency modulation signal is segmented in the time domain by using the preset segmentation function, the length of the segment of the nonlinear frequency modulation signal is arbitrary, and may be equally divided, or may be unequally divided. Piecewise function p of each segment after nonlinear frequency modulation signal segmentationiThe expression of (t) is as follows:
pi(t)＝ε(t-ai)-ε(t-ai+1)
the combined piecewise function of each piecewise function is shown in equation (10), where equation (10) is as follows:
wherein p isi(t) represents the piecewise function of each segment of the non-chirp signal after segmentation, P1(t) represents a piecewise function formed by combining each piecewise function in the nonlinear frequency modulation signal, n represents the number of the sections of the nonlinear frequency modulation signal in the time domain, n is more than or equal to 1 and not more than the number of sampling points of the baseband SAR signal, n is a positive integer, t represents the fast time of the baseband SAR signal, ai、ai+1Respectively representing the start and end of the ith segment of the non-chirp signal and epsilon representing the unit step function.
In the embodiment of the application, according to the segmented modulation interference function:
adding a phase value to each segment of the non-linear frequency-modulated signal
And realizing the modulation of the segmented nonlinear frequency modulation signal, wherein P (t) represents a segmented modulation interference function.
In the embodiment of the present application, after adding a phase value to each section of the non-chirp signal in different sections, the expression of the non-chirp signal after the section modulation is shown as formula (11), where formula (11) is as follows:
wherein the content of the first and second substances,
and modulating the phase value on each signal segment after the non-linear frequency modulation signal segment.
In the embodiment of the present application, cosine amplitude weighting is performed on the non-linear frequency modulation signal after the segmented modulation based on a time domain weighting function, specifically, based on the time domain weighting function, a center point of each segment of the non-linear frequency modulation signal is used as a center point of the time domain weighting function to perform segmented weighting on the non-linear frequency modulation signal, where the center point of each segment of the non-linear frequency modulation signal is a center position of the corresponding segment of the non-linear frequency modulation signal.
In the embodiment of the present application, the time-domain weighting function is a cosine weighting function, the cosine weighting function is shown in formula (12), and formula (12) is as follows:
wherein w (t) represents a cosine weighting function; t denotes the fast time of the baseband SAR signal, a is a weighting factor, a ∈ [0.5, 1 ].
In the embodiment of the application, window functions such as a taylor window, a hanning window, a hamming window and the like can be selected to generate the nonlinear frequency modulation signal, and cosine amplitude weighting of different degrees is performed on the generated nonlinear frequency modulation signal by controlling the value of the weighting coefficient a. When the nonlinear frequency modulation signal is generated according to the Hamming window, a is 0.5; when the non-linear frequency modulation signal is generated according to the Hanning window, a is 0.54.
In the embodiment of the application, different weighting coefficients can be selected to weight the non-linear frequency modulation signals after the segmented modulation to different degrees, and each segment of the non-linear frequency modulation signals S subjected to cosine amplitude weightingwThe expression of (t) is shown in equation (13), and equation (13) is as follows:
and adding carrier frequency to the cosine amplitude weighted nonlinear frequency modulation signal to generate an SAR interference signal. Specifically, the cosine amplitude weighted nonlinear frequency modulation signal is pulse compressed to generate an SAR interference signal. The function analytic expression of the SAR interference signal generated after compression is shown as formula (14),
in the formula (I), the compound is shown in the specification,
representing the convolution operation, h (t) represents the transfer function of the matched filter, and the function analysis expression of h (t) is shown in formula (15), wherein the formula (15) is as follows:
the matched filter is used for pulse compression of the nonlinear frequency modulation signal. Here, it should be noted that the cosine amplitude weighted non-linear frequency modulationSignal Sw(t) after transmission, the cosine amplitude weighted non-chirp signal S is filtered by a matched filter of the target object (e.g., enemy, etc.)w(t) after pulse compression, generating corresponding SAR interference signals, generating interference effects with local suppression effects, and achieving different interference effects by controlling different parameters, thereby realizing effective interference on target objects.
In the embodiment of the application, the jammer intercepts parameter information of an SAR emission signal to measure, obtains the SAR signal characteristics, and generates a non-linear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle; and carrying out segmented modulation on the nonlinear frequency modulation signal, and carrying out cosine amplitude weighting on the nonlinear frequency modulation signal subjected to segmented modulation so as to generate the SAR interference signal. Therefore, compared with the linear frequency modulation signal, the power spectrum density of the non-linear frequency modulation signal shaping signal is utilized, the output of the radar matching filter with lower side lobe and wider main lobe can be provided, so that more interference energy is concentrated in the main lobe, the lower side lobe is provided, the interference range is wider, the SAR interference signal with the lower side lobe local suppression effect is obtained, the leakage of the interference energy to the side lobe is effectively reduced, and the ideal interference effect is achieved.
Exemplary System
Fig. 2 is a schematic diagram of a non-chirp modulated jamming system according to some embodiments of the present application; as shown in fig. 2, the chirp-modulated jamming system includes: the device comprises a characteristic acquisition unit, a nonlinear frequency modulation signal unit, a signal processing unit and an interference signal unit. The characteristic acquisition unit is configured to measure parameter information of the intercepted SAR emission signal and acquire SAR signal characteristics; the nonlinear frequency modulation signal unit is configured to generate a nonlinear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle; the signal processing unit is configured to perform segmented modulation on the nonlinear frequency modulation signal and perform cosine amplitude weighting on the nonlinear frequency modulation signal subjected to segmented modulation so as to generate an SAR interference signal.
In some optional embodiments, the characteristic obtaining unit is further configured to store the intercepted and obtained parameter information of the SAR transmission signal based on a digital radio frequency technology, and obtain the characteristic of the SAR signal through a pulse description word measurement technology; wherein the SAR signal characteristics include: carrier frequency, beam width, antenna aperture size and bandwidth, pulse width of the baseband signal.
In some optional embodiments, the non-chirp unit is further configured to, based on the stationary phase principle, according to the SAR signal characteristic, according to the formula:
generating a non-linear frequency modulation signal;
wherein s is2Representing the non-chirp signal, T representing the pulse duration of the baseband SAR signal, T representing the fast time of the baseband SAR signal, f representing the instantaneous frequency of the baseband SAR signal, j representing the imaginary part of the complex number, τ being an integral variable, τ being [0, T ∈ []。
In some optional embodiments, the signal processing unit comprises: a segment modulation subunit and a weighting subunit. The segmented modulation subunit is configured to segment the non-linear frequency modulation signal in a time domain through a step function, and modulate a phase value in each segment of the non-linear frequency modulation signal; wherein, the phase value is any value in the interval of [0,2 pi ]; the weighting subunit is configured to perform cosine amplitude weighting on the segmented modulated nonlinear frequency modulation signal based on a time domain weighting function to generate an SAR interference signal.
In some optional embodiments, the weighting subunit is further configured to perform segment weighting on the non-chirp signal based on a time-domain weighting function, with a central point of each segment of the non-chirp signal as a central point of the time-domain weighting function, where the central point of each segment of the non-chirp signal is a central position of the corresponding segment of the non-chirp signal.
The non-linear frequency modulation signal modulation interference system provided by the embodiment of the application can realize the steps, the flow and the beneficial effects of any one of the above non-linear frequency modulation signal modulation interference method embodiments, which are not repeated herein.
Exemplary applications
In fig. 4 to 15, the chirp signal and the non-chirp signal are both the result of the same segment length with a weight coefficient of 0.5. As can be seen from fig. 4-9, fig. 7, 8, and 9 compare with fig. 4, 5, and 6, respectively, it can be seen that as the number of segments increases, the interference main lobes of the non-chirp signal and the chirp signal increase, the corresponding amplitudes decrease, and the non-chirp signal has a wider main lobe compared with the chirp signal.
As can be seen from fig. 10-15, fig. 13, 14, and 15 compare with fig. 10, 11, and 12, respectively, it can be seen that the cosine amplitude weighted non-chirp signal has a wider main lobe, lower side lobes, and better energy concentration in the main lobe than the chirp signal; and the effect is optimal at a number of segments of 30, resulting in a noise-like suppressive interference effect only in the main lobe.
Fig. 16 and 17 show images formed by modulating the non-chirp signal in 30 steps with weighting coefficients of 0.54 and 0.75, respectively. As can be seen from fig. 4 to 17, by controlling the number of segments, the weighting coefficient, and the segment length, the interference energy range can be accurately and effectively controlled, and the influence of the side lobe is substantially eliminated.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (8)
1. A method for modulating interference with a non-chirp signal, comprising:
s101, measuring parameter information of the intercepted SAR emission signal to acquire SAR signal characteristics;
step S102, generating a nonlinear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle;
step S103, the nonlinear frequency modulation signal is modulated in a segmented mode, and cosine amplitude weighting is carried out on the nonlinear frequency modulation signal after the segmented modulation, so that an SAR interference signal is generated.
2. The method according to claim 1, wherein step S101 specifically comprises:
storing the intercepted parameter information of the SAR emission signal based on a digital radio frequency technology, and acquiring the SAR signal characteristics by a pulse description word measurement technology; wherein the SAR signal characteristics include: carrier frequency, beam width, antenna aperture size and bandwidth, pulse width of the baseband signal.
3. The method according to claim 1, wherein step S102 specifically comprises:
based on a stationary phase principle, according to the SAR signal characteristics, according to a formula:
generating the non-linear frequency modulation signal;
wherein s is2(T) represents the non-chirp signal, T represents the pulse duration of the baseband SAR signal, T represents the fast time of the baseband SAR signal, T ∈ [0, T]F denotes the instantaneous frequency of the baseband SAR signal, j denotes the imaginary part of the complex number, τ is the integral variable, τ is [0, t ]]。
4. The method according to any of claims 1-3, wherein step S103 comprises:
segmenting the non-linear frequency modulation signal on a time domain through a preset segmented modulation interference function, and modulating a phase value in each segment of the non-linear frequency modulation signal; wherein, the phase value is any value in the interval of [0,2 pi ];
And based on a time domain weighting function, carrying out cosine amplitude weighting on the nonlinear frequency modulation signal after the segmented modulation so as to generate the SAR interference signal.
5. The method of claim 4, wherein the piecewise modulation interference function is:
wherein, P (t) represents a preset segmented modulation interference function, n represents the segmented number of the nonlinear frequency modulation signal in the time domain, n is more than or equal to 1 and not more than the sampling point number of the baseband SAR signal, n is a positive integer, t represents the fast time of the baseband SAR signal, ai、ai+1Respectively representing the start and end of the ith segment of the non-chirp signal, epsilon represents a unit step function,
and modulating the phase value on each signal segment after the non-linear frequency modulation signal is segmented.
6. The method for modulating interference on a non-linear frequency modulation signal according to claim 4, wherein the cosine amplitude weighting is performed on the non-linear frequency modulation signal after the segmented modulation based on a time domain weighting function, specifically: based on a time domain weighting function, taking the central point of each section of nonlinear frequency modulation signal as the central point of the time domain weighting function, and carrying out sectional weighting on the nonlinear frequency modulation signal, wherein the central point of each section of the nonlinear frequency modulation signal is the central position of the corresponding section of the nonlinear frequency modulation signal.
7. The method of claim 6, wherein the time-domain weighting function is a cosine weighting function, the cosine weighting function being:
wherein w (t) represents a cosine weighting function; t represents the fast time, a is the weighting factor, a ∈ [0.5, 1 ].
8. A system for chirp-modulated jamming, comprising:
the characteristic acquisition unit is configured to measure the intercepted parameter information of the SAR emission signal and acquire the SAR signal characteristic;
the nonlinear frequency modulation signal unit is configured to generate a nonlinear frequency modulation signal according to the SAR signal characteristics based on a stationary phase principle;
and the signal processing unit is configured to perform segmented modulation on the nonlinear frequency modulation signal and perform cosine amplitude weighting on the nonlinear frequency modulation signal subjected to segmented modulation so as to generate an SAR interference signal.
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| CN114076945A (en) * | 2022-01-19 | 2022-02-22 | 中国科学院空天信息创新研究院 | Method for establishing ionized layer dispersion effect analytic model of NLFM signal |
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| CN114076945A (en) * | 2022-01-19 | 2022-02-22 | 中国科学院空天信息创新研究院 | Method for establishing ionized layer dispersion effect analytic model of NLFM signal |
| CN114089292A (en) * | 2022-01-19 | 2022-02-25 | 北京宏锐星通科技有限公司 | Radar jamming device |
| CN114089291A (en) * | 2022-01-19 | 2022-02-25 | 北京宏锐星通科技有限公司 | Device for interfering synthetic aperture radar |
| CN117435871A (en) * | 2023-11-07 | 2024-01-23 | 深圳市赛盛技术有限公司 | Method, system and medium for reducing electromagnetic interference of equipment based on magnetic field analysis |
| CN117949903A (en) * | 2024-03-26 | 2024-04-30 | 中国科学院空天信息创新研究院 | Method and device for generating random time wide bandwidth nonlinear frequency modulation signal in real time |
| CN117949903B (en) * | 2024-03-26 | 2024-05-28 | 中国科学院空天信息创新研究院 | Method and device for generating random time wide bandwidth nonlinear frequency modulation signal in real time |
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