CN113311396B

CN113311396B - Interference and anti-interference digital simulation system based on millimeter wave fuze and construction method thereof

Info

Publication number: CN113311396B
Application number: CN202110543939.2A
Authority: CN
Inventors: 陈思; 朱捷伟; 袁月; 陈魁宇; 张淑宁; 赵惠昌
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2024-10-18
Anticipated expiration: 2041-05-19
Also published as: CN113311396A

Abstract

The invention discloses an interference and anti-interference digital simulation system based on millimeter wave fuzes and a construction method thereof, wherein the system is based on millimeter wave fuzes with carrier wave wavelength of 3mm and 8mm, two kinds of interference of forwarding and frequency sweeping are added, and analog signal receiving and sending, fuze signal processing, verification of interference signal effectiveness and fuze state monitoring functions can be realized according to parameters such as set shot intersection speed, shot initial distance, shot falling angle and the like; the system constructs a graphic user interface based on Matlab, and parameters are assigned by global variables and imported by a top layer, and can be changed, covered and output in the middle; the functional modules of the graphic user interface are mutually independent, a part of functional modules can be added and deleted, a new fuze system, new interference and anti-interference selection and fuze type of an expansion adaptation system can be added on the basis of the existing model, and a theoretical basis is provided for the conventional shell millimeter wave fuze in-situ interference experiment.

Description

Interference and anti-interference digital simulation system based on millimeter wave fuze and construction method thereof

Technical Field

The invention relates to millimeter wave fuze signal processing technology, in particular to an interference and anti-interference digital simulation system based on millimeter wave fuzes and a construction method thereof.

Background

Millimeter waves are favored in proximity fuse applications because of the advantages of short wavelength, high distance accuracy, strong anti-interference capability, and the like. Millimeter waves have been regarded as the focus of development because of their small influence from meteorological conditions and their strong ability to distinguish metallic objects from background environments. The traditional microwave fuze has low distance and speed measurement precision, low hit rate and low damage effect. And the fuse body is larger due to long wavelength, and is greatly influenced by the weather conditions. The anti-jamming capability is weak, and the fuse premature burst or the fire is easy to be influenced by the jamming.

In the aspect of tracking precision, the millimeter wave system is better than a general microwave system, and in the aspects of performance under severe weather conditions and airspace search, the millimeter wave system is more superior than an optical system. Due to the limited space in the fuse structure, there is a corresponding restriction on the volume of the devices of each part. The short-range millimeter wave detector can just make the system meet the requirements of small volume, light weight, simple structure, good performance and low cost. With the continuous improvement of the modern air defense technology level, electronic countermeasure is more and more intense, and the improvement of the electronic countermeasure is urgent to realize the breakthrough and innovation of the related technology for exploring the battlefield adaptability of the Bo-meter wave proximity fuze and meeting the requirements of complex battlefield. From the perspective of protecting own targets, the implementation of interference on the fuze is the last protective barrier, so that the interference and anti-interference research of the millimeter wave fuze has very important significance.

Disclosure of Invention

The invention aims to provide an interference and anti-interference digital simulation system based on a millimeter wave fuze and a construction method thereof, which are used for simulating the problems of signal receiving and transmitting, antenna, signal processing, detonation judgment, verification of anti-interference algorithm and interference signal effectiveness, monitoring of fuze state and the like.

The technical solution for realizing the purpose of the invention is as follows: an interference and anti-interference digital simulation system based on millimeter wave fuzes, comprising:

the fuze selection module is used for setting millimeter wave wavelength and selecting fuze types;

The parameter setting module is used for setting parameters of the millimeter wave fuze;

The anti-interference selection module is used for selecting anti-interference measures;

The interference source selection module is used for adding interference signals according to the fuze type;

The signal processing module is used for simulating the system work of the fuze; the signal processing module comprises an adaptive filter and a large signal locking controller, the cut-off frequency of the adaptive filter is automatically set according to fuze parameters, and after the signal processing module obtains relevant parameters, the relevant parameters are stored in a working area and are called in the filter and a next-stage GUI; the large signal locking controller is arranged at the front end of the signal processing module, monitors the received signal power in real time, and if the detected signal power is greater than a threshold value, the fuze closes the signal processing module in the next millisecond;

The GUI construction module is used for displaying the receiving and sending of the fuze signals of different systems, the processing results of the fuze system signals and the processing results of the fuze system signals after adding the interference signals and the anti-interference measures through a GUI graphical user interface.

Further, the millimeter wave wavelength is set to 3 mm and 8mm, and the fuze type includes: millimeter wave fuze of four systems of continuous wave Doppler, pulse Doppler, harmonic spacing and linear frequency modulation.

Further, the millimeter wave fuze parameters comprise initial shot distance, relative shot speed, set detonation distance, falling angle, antenna gain and fuze sensitivity;

The setting range of the bullet mesh relative speed is 50m/s-1200m/s;

the bullet mesh simulation distance is set to be 3000m-0m.

Further, the anti-interference selecting module is configured to select an anti-interference measure, where the anti-interference measure includes a default option: large signal blocking, spectral analysis, and selectable options: detecting digital wave and amplitude variation;

the interference source selection module is used for adding interference signals according to the fuze type, and comprises the following steps:

1) The continuous wave Doppler millimeter wave fuze interference source is amplification modulation forwarding interference and sine amplitude modulation sweep frequency interference;

2) The pulse Doppler millimeter wave fuze interference source is variable delay forwarding interference and amplitude modulation sweep frequency interference;

3) The harmonic spacing millimeter wave fuze interference source is interval forwarding interference and amplitude modulation sweep frequency interference;

4) The linear frequency modulation millimeter wave fuze interference source is interval forwarding interference and amplitude modulation sweep frequency interference;

The interference source selection module comprises an interference machine parameter setting module and is used for setting interference machine interference power, interference machine antenna gain, fuze direction diagram main-auxiliary ratio, bullet mesh initial distance and bullet mesh simulation distance.

Further, the GUI construction module is configured to:

Simulating the receiving and transmitting of fuze signals of different systems and signal processing through a GUI graphical user interface under an MATLAB platform, calling corresponding interference sources aiming at fuzes of different systems, and adding selectable anti-interference options; simulating the influence of parameters of the speed, the initial distance of the bullet and the signal strength of the fuze on the starting condition of the fuze by echo signals and anti-interference measures of the fuze; and extracting fuze speed and distance information by using methods of time domain undersampling, CZT and self-adaptive filtering waves.

The invention also provides a method for constructing the interference and anti-interference digital simulation system based on the millimeter wave fuze, which is characterized by comprising the following steps:

step one: the wavelength of millimeter wave is selected to be 3mm and 8 mm;

Alternative fuze types include: millimeter wave fuze of four systems of continuous wave Doppler, pulse Doppler, harmonic spacing and linear frequency modulation;

setting millimeter wave fuze parameters, including: the initial distance of the bullet, the relative speed of the bullet, the set detonation distance, the falling angle, the antenna gain and the fuze sensitivity;

1) The setting range of the bullet mesh relative speed is 50m/s-1200m/s;

2) The setting range of the bullet mesh simulation distance is 3000m-0m;

step two: an anti-interference selection module is constructed and used for selecting anti-interference measures, and the anti-interference selection module comprises:

default options: large signal blocking, spectral analysis, and selectable options: and detecting digital wave and amplitude variation.

Step three: an interference source selection module is constructed and used for adding interference signals according to the fuze type, and the interference source selection module comprises:

1) The continuous wave Doppler millimeter wave fuze interference source is amplification modulation forwarding interference and sine amplitude modulation sweep frequency interference.

2) The pulse Doppler millimeter wave fuze interference source is variable delay forwarding interference and amplitude modulation sweep frequency interference.

3) The harmonic spacing millimeter wave fuze interference source is interval forwarding interference and amplitude modulation sweep frequency interference.

4) The linear frequency modulation millimeter wave fuze interference source is interval forwarding interference and amplitude modulation sweep frequency interference.

An jammer parameter setting module is constructed and used for setting jammer interference power, jammer antenna gain, fuze pattern main-auxiliary ratio, bullet initial distance and bullet simulation distance;

step four: constructing a signal processing module, the module comprising:

An adaptive filter: the cut-off frequency of the self-adaptive filter is automatically set according to the fuze parameters, and after the signal processing module obtains the related parameters, the related parameters are stored in a working area and are called in the filter and the next-stage GUI;

Large signal latch controller: adding a large signal locking controller at the front end of the signal processing module; the large signal lock monitors the power of the received signal in real time, and if the large power signal is detected, the fuze closes the signal processing module in the next millisecond;

Step five: GUI construction:

Simulating receiving and transmitting of fuze signals of different systems and signal processing through a GUI graphical user interface under an MATLAB platform, calling corresponding interference sources aiming at fuzes of different systems, and adding selectable anti-interference options to explore the effectiveness of the interference signals under different anti-interference options and the monitoring problem of fuze states; the influence of parameters of the speed, the initial distance of the bullet and the signal intensity on the starting condition of the fuze is explored by changing the parameters of the speed, the initial distance of the bullet and the signal intensity of the fuze; and extracting fuze speed and distance information by using a method of time domain undersampling, CZT and self-adaptive filtering waves.

Further, millimeter wave fuses of the four systems are specifically as follows:

1) Continuous wave doppler fuze:

The transmitted signal is:

u_t(t)＝U_t cos2πf₀t

Wherein U _t is the amplitude of the transmitted signal, f ₀ is the frequency of the signal, and the initial phase is zero;

After the transmitting signal is radiated to a target through an antenna, an echo signal is generated and then reflected back to the system; the amplitude of the echo signal of the ground radio fuse depends on the transmitting power, the system parameters, the ground environment and the ground altitude, and the expression is as follows:

Wherein U _r is the amplitude of the echo signal received by the fuze, lambda is the wavelength of the fuze, P _t is the transmitting power of the fuze, D _t is the gain of the transmitting antenna of the fuze, R _∑ is the distance from the fuze to the target, As a function of the directivity of the fuze transmit antenna, D _r is the gain of the fuze receive antenna,The method is characterized in that the method is used for receiving a directional function of an antenna by a fuze, H is the height of the fuze from the ground, and N is the ground reflection coefficient;

The echo signal received by the fuze is:

In the method, in the process of the invention, Τ is the delay of the echo signal relative to the transmit signal;

Let t ₀ be H ₀, let v _y be the vertical falling speed of the fuse, τ can be expressed as:

substituting it into the above formula yields:

Wherein f _d＝f₀·2v_y/c is Doppler frequency generated by the relative movement of the bullet, An initial phase of the echo signal;

the echo signal is mixed with the local oscillator, and then the Doppler signal can be obtained through a Doppler band-pass filter:

wherein k is a mixing coefficient;

Analyzing the above, wherein f _d directly reflects the speed information, and the amplitude kU _tC_r/2H directly reflects the distance information; the doppler signal amplitude is also a function of time, and the doppler signal amplification rate can be defined:

From the above, it can be seen that the rate of amplification can reflect both the ground height H and the fuze vertical falling velocity v _y;

2) In the harmonic wave comparison type frequency modulation fuze system, a difference frequency signal is obtained by mixing an echo signal and a local oscillator, the form of the difference frequency signal is determined by the delay tau of the echo signal relative to a transmitting signal, and the instantaneous frequency relation between the transmitting signal and the echo signal is as follows;

Assuming that the center frequency of a transmitting signal is F ₀, the modulation period is T _m, and the modulation frequency deviation is delta F _m;

In a modulation period T _m, the difference frequency signal is divided into an irregular area and a regular area; when in short-range detection, tau is less than T _m, an irregular area can be ignored, and only difference frequency signals in the regular area need to be considered; the difference frequency signal of the regular interval is rewritten into a fourier series of:

In the method, in the process of the invention, The difference frequency signal amplitude is the system local oscillation amplitude, U _t is the echo amplitude, and U _r is the system local oscillation amplitude;

As can be seen from the above description, when the bullet is relatively stationary, the spectrum of the difference frequency signal is a discrete spectrum, each harmonic component is an integer multiple of the modulation frequency F _m, the even harmonic coefficient is a _e (n), the odd harmonic coefficient is a _o (n), and the harmonic coefficient is determined by the modulation frequency offset Δf _m, the delay τ and the modulation period T _m;

the delay τ can be expressed as follows when considering the relative motion:

Wherein R ₀ is the bullet distance at time t ₀, and τ ₀ is the time delay at time t ₀;

the difference frequency signal substituted into the regular interval is rewritten into the Fourier series, and the method can be obtained:

Where f _d＝2vf₀/c is the Doppler frequency, Is the initial phase;

Compared with the relative static condition, when the bullet meshes have relative motion, the spectral lines at each subharmonic disappear, and two spectral lines which are +/- _d different from the original harmonic are replaced; the fuze movement speed can be calculated;

3) The center frequency of the triangular wave frequency modulation fuze transmitting signal is F ₀, the modulation period is T _m, the modulation frequency deviation is delta F _m, and the instantaneous frequency relation between the transmitting signal and the echo signal and the frequency of the difference signal are as follows:

f _t (T) is the transmitting frequency, f _r (T) is the echo frequency, and the difference frequency signal frequency f _i (T) can be divided into a regular area and an irregular area in one modulation period T _m; f _i (t) can be considered constant within the regular region, while f _i (t) varies in real time within the irregular region, thus focusing on the discussion of the relationship of f _i (t) to distance R within the regular region:

To facilitate analysis, two assumptions are made:

(1) Ignoring the change in delay tau during a modulation period T _m, i.e. considering the distance R as a fixed value during the modulation period T _m;

(2) The Doppler frequency expression is f _d＝2v_rf₀/c;

The system frequency-regulating slope is as follows:

When there is relative motion of the bullet, the T _m,f_i (T) in one modulation period can be divided into two sections of discussion of a rising area f _i+ and a falling area f _i-, according to the transmission signal and the echo signal, the expressions of combining the delay τ=2r/c and the expressions of f _i+、f_i- are respectively:

The two formulas are added to obtain the relation between the distance and the difference frequency:

The above formula shows that the ranging system measures f _i+、f_i- respectively, then averages the two, and can eliminate the influence of Doppler frequency;

the two formulas are subtracted to obtain the relation between Doppler frequency and difference frequency:

And combining the Doppler frequency expression f _d＝2v_rf₀/c to obtain an expression of the radial velocity of the bullet meshes:

Theoretically, the system only measures the difference frequency f _i+、f_i- of the ascending and descending areas, and the distance and the speed of the corresponding moment can be calculated through the above formulas;

4) When the pulse Doppler fuze system works, the oscillator transmits a sine wave signal with the frequency of f ₀ to the pulse modulator, the sine wave signal is coupled with a pulse signal u _p (T) with the pulse width of tau _m and the period of T _M transmitted by the pulse generator to generate a pulse modulation signal, and then the pulse modulation signal is amplified by power to obtain a transmission signal u _t (T) which is transmitted by the transmitting antenna; the target echo signal is received by the receiving antenna, and the echo signal u _r (t) generates corresponding attenuation and delay; u _r (t) is mixed in a mixer with the local oscillation signal u ₀ (t), where u ₀ (t) is fully coherent with the sine wave signal emitted by the oscillator at frequency f ₀; the video signal u _d(t),u_d (t) is a pulse train signal modulated by Doppler signals after the down mixing and the primary filtering; u _d (t) is amplified by video and then is sent into a distance gate gating circuit to obtain a distance gate gating output signal u _out (t); the signal is processed by Doppler signal, and through data processing and threshold discrimination, a fuze starting instruction is generated and the warhead is detonated;

pulse Doppler fuze: the oscillator output signal is

Wherein U _LM is the oscillator output signal amplitude; f ₀ is the oscillator output signal frequency; Is the initial phase;

The pulse generator generates a pulse train of

Wherein U _PM is pulse amplitude; Is a rectangular function with which a pulse of width τ _m is generated; t _M is the pulse repetition period; n is the accumulated pulse number; Is a convolution operation symbol;

modulating the oscillator signal by the pulse train signal to obtain a transmitting signal as

Where U _TM is the transmit signal amplitude.

Generating an echo signal after the transmitting signal meets the target, wherein the target echo signal is

Wherein U _RM is the target echo signal amplitude; τ is the delay time of the signal during the fuze-to-target round trip, i.e

Further, the anti-interference measures are specifically as follows:

1) Large signal blocking: when the echo receiving system of the fuze receives the signal, the digital signal is sent to the signal processing module for processing, if the receiving system receives a high-power interference signal at the moment, the power of the high-power interference signal is greatly different from that of the echo signal received when the fuze works normally, the normal work of the fuze can be influenced, and the starting output of the fuze is interfered. In order to overcome the influence of the high-power signal, the system adds a high-signal locking judgment controller at the front end of the signal processing module; the controller monitors the power of the received signal in real time, and if the controller detects a high-power signal, the fuze closes the signal processing module of the fuze in the next millisecond;

2) Spectral analysis: determining a Doppler frequency range through the bullet relative speed range and the fuze center frequency, and meeting fuze starting conditions when the speed measurement result is within a speed judgment threshold;

3) Counting the waves: when the fuze works, the signal receiving system is interfered by the impulse signal, and the amplitude of the impulse signal can interfere the fuze to start. The method comprises the steps that a wave number anti-interference measure is added to a signal processing starting output module, and if the fuze amplitude judgment threshold is met in more than three continuous periods, starting output conditions are met, so that the anti-interference purpose is achieved;

4) Amplitude change detection: the method is to detect the signal amplitude change rate between two time points, and when the amplitude change rate judgment threshold is reached, the fuze starting condition is met;

The method utilizes the anti-interference means of large signal locking, spectrum analysis, digital wave and amplitude change detection, and the fuze judges whether to start or not through the combination of a signal amplitude judgment threshold, a Doppler frequency judgment threshold and a signal amplitude change rate judgment threshold, so that the situation that the fuze starts when a single condition is met is avoided, and the anti-interference measures are effective.

Further, adding an interference signal according to the fuze type, specifically as follows:

(1) Sinusoidal amplitude modulated sweep frequency interference:

When the jammer jams the fuze, the frequency sweep bandwidth must cover the working frequency band of the fuze, and the carrier frequency of the frequency sweep signal swings together according to a certain rule in a certain frequency range; setting the initial frequency of the frequency sweep of the jammer as f _j0, the end frequency of the frequency sweep as f _jN, the frequency sweep step length as delta f, the carrier frequency of the jammer signal at the nth frequency sweep point as f _jn and the total frequency sweep point as n+1

f_jn＝f_j0+Δf,n＝0,1,...,N

Because the carrier frequency of the sweep frequency interference signal emitted by the jammer is discretely changed, the expression of the interference signal received by the fuze is a piecewise function which can be written into a form of multiplication with an AND gate function; the swept interference signal received by the fuze can be expressed as

Wherein A _j is the carrier amplitude of the interference signal; To interfere with the initial phase of the signal, the method can be set F (t) is an interference modulation signal waveform, the sweep-frequency interference modulation signal waveform has various forms, such as sine wave, triangular wave, square wave and the like, the software takes sine wave amplitude modulation sweep-frequency interference signal as an example to carry out interference mechanism analysis, and the sine wave modulation signal can be expressed asWhere a _jM is the amplitude of the modulated signal, f _jM is the modulation frequency, generally set to the doppler frequency that may occur during bullet-mesh intersection, i.e. f _jM≈f_d,For modulating the initial phase of the signal, also, for not losing generality, can be provided withΔt is the time the jammer resides at each sweep point. Let the expression of the local oscillation signal of the continuous wave Doppler fuze be

Wherein A _L is the amplitude of a fuse local oscillation signal; omega _L is the local oscillation frequency; For the initial phase of local oscillation signal, set

(2) Interval forwarding interference:

The forward deception jamming means that an interfering party detects and intercepts a signal transmitted by a fuze, stores the signal and forwards the signal after corresponding processing;

The frequency of the difference frequency signal mainly depends on the signal delay, so that f _ij needs to enter the passband of the fuse low-pass filter, and the interference delay tau _je needs to meet certain conditions; setting the linear frequency modulation fuze distance threshold as (R _p1,R_p2), considering the distance-measuring fuzzy problem, the interference delay needs to satisfy

τ_je∈(nT_M-τ_p1,nT_M-τ_p2)U(nT_M+τ_p1,nT_M+τ_p2)

The interval in the formula is referred to as the "detonation delay interval", where τ _p1 and τ _p2 can be expressed as

If the intercepted fuze transmitting signal is directly forwarded, the minimum time delay modulation is only equivalent to the transmitting signal, and the interference time delay is difficult to be ensured to fall in the two intervals; obviously, the single delay can not meet the interference requirement, and the method of dynamically changing the delay can be adopted to improve the deception interference probability;

when the fuze receives the interference signal, the delay between the interference signal and the local oscillation signal can be expressed as

Wherein R _j represents the distance between the jammer and the fuze, τ _s represents the time for the jammer to process the received signal, deltaτ represents the additional forwarding interval of the jammer, and n represents the interval forwarding times;

τ ₁ can also be represented as τ ₁＝lT_M+τ_j, where l is a positive integer, τ _j＜T_M; for the same integer l, the change in τ _j is the change in τ ₁; according to the periodicity of the triangular wave frequency modulation signal, the difference frequency signal obtained by the time delay of lT _M+τ_j and the time delay of tau _j is the same, so tau ₁ can be expressed as; therefore, the frequency of the difference signal generated by interference is mainly determined by τ _j; where τ _s can be considered a constant value, so that the variation of the interference delay τ _j depends on the variation of the interference distance R _j and the number of interval forwarding n; wherein, the change of R _j generates the deception Doppler frequency f _dj, and as n increases, the interference delay increases at intervals of Deltaτ, and when the increment nDeltaτ covers one modulation period T _M, the interference delay can be recorded as a complete interference delay change period; in an interference delay change period, the interference delay with one or several times of forwarding interference is necessarily in the detonation delay interval;

(3) Variable delay forwarding type interference:

The correlation output mainly depends on signal delay, so that the interference delay when the wanted pulse delay falls in the range of the range gate must meet certain conditions; if the intercepted fuze transmitting signal is directly forwarded, the minimum time delay modulation is only equivalent to the transmitting signal, and the interference time delay is difficult to be ensured to fall in the range of the range gate gating. Obviously, the single delay can not meet the interference requirement, and the method of dynamically changing the delay can be adopted to improve the deception interference probability;

After an interfering party based on variable delay forwarding type interference detects a pulse Doppler signal transmitted by a fuze, assuming that an interfering machine has obtained a modulation period T through parameter extraction, sampling and storing the length of NT intercepted by the fuze signal, and then repeatedly forwarding a stored signal for a plurality of times, wherein a fixed time step exists between every two times of forwarding;

τ ₁ can also be represented as τ ₁＝lT_M+τ_j, where l is a positive integer, τ _j＜T_M; for the same integer l, the change in τ _j is the change in τ ₁; depending on the periodicity of the pulse signal, the pulse position is the same for a delay lT _M+τ_j and a delay τ _j, so τ ₁ can also be denoted as τ ₁＝τ_j; thus, the correlation output resulting from the interference depends primarily on τ _j; where τ _s can be considered a constant value, so that the variation of the interference delay τ _j depends on the variation of the interference distance R _j and the number of interference delays n; the change of R _j generates the spoofed doppler frequency f _dj, and as n increases, the interference delay increases at intervals of Δτ, and when the increment nΔτ covers one modulation period T _M, the interference delay can be recorded as a complete interference delay change period, and in one interference delay change period, there must be one or several interference delays for forwarding interference to fall in the initiation delay interval.

Further, the self-adaptive filter is applied to the signal processing module for a plurality of times, the millimeter wave fuze speed range is 50 m/s-1200 m/s, when the central frequency f0=100 GHz, the Doppler signal frequency range is 33 kHz-800 kHz, and at the moment, the passband range of the band-pass filter is the fuze central frequency plus-minus Doppler frequency; the bandpass filter has a bandwidth greater than twice the maximum doppler frequency.

Compared with the prior art, the invention has the beneficial effects that: (1) The millimeter wave fuze digital simulation system provides a new anti-interference measure, increases the anti-interference performance of the fuze, and provides a new variable delay forwarding interference, and when the anti-interference measure is added, the influence of the interference on the working state of the fuze is explored; (2) In the signal processing process, an adaptive filter is adopted to achieve a more accurate and ideal filtering effect; (3) When the GUI interface is operated, various parameters of the fuze can be changed, and anti-interference measures and interference sources can be selected according to requirements; one parameter can be independently changed to explore the influence of the parameter on the operation of the fuze system, and several parameters can be simultaneously changed to verify whether the operation state of the fuze is normal or not; (4) The system can extract key information such as fuze speed, distance, doppler signals and the like; and simulating the receiving and transmitting of fuze signals of different systems, processing the signals, calling corresponding interference sources aiming at fuzes of different systems, adding selectable anti-interference options, and exploring the effectiveness of the interference signals under different anti-interference options, monitoring the state of the fuzes and the like.

Drawings

FIG. 1 is a flow chart of a millimeter wave fuze-based interference and anti-interference digital simulation system.

Fig. 2 is a schematic block diagram of a pulse-to-continuous wave coherent detection heterodyne pulse doppler fuse.

FIG. 3 is a schematic diagram of the relationship of echo pulse, range gate pulse and range gate output pulse.

Fig. 4 is a graph of the amplitude of the baseband doppler signal over time t.

Fig. 5 is a schematic diagram of a variable delay-and-forward interference timing sequence

FIG. 6 is a schematic diagram of relative target orientation of an jammer

FIG. 7 is a schematic diagram showing the result of auto-correlation of target echo in the interference-free state

FIG. 8 is a schematic diagram of the start-up output signal in the no-disturbance state.

Fig. 9 is a schematic diagram of the result of target echo autocorrelation under variable delay forwarding interference.

FIG. 10 is a schematic diagram of the start-up output signal under a variable delay forwarding disturbance.

Fig. 11 is a main interface of the millimeter wave fuze digital simulation system, and a millimeter wave fuze system selection module.

Fig. 12 is a millimeter wave fuze digital simulation system, fuze parameter setting interface.

Fig. 13 is a millimeter wave fuze digital simulation system, jammer parameter setting interface.

Fig. 14 is a millimeter wave fuze digital simulation system, fuze operating state and result display interface.

Detailed Description

The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.

An interference and anti-interference digital simulation system based on millimeter wave fuzes, comprising:

The construction process of the system is described below with reference to fig. 1:

Step 1, selecting millimeter wave wavelengths of 3 mm and 8 mm; determining the type of the fuze as a pulse Doppler millimeter wave fuze; the schematic block diagram of the pulse-to-continuous wave coherent detection pulse Doppler fuze is shown in figure 2.

Let the oscillator output signal be

Wherein U _LM is the oscillator output signal amplitude; f ₀ is the oscillator output signal frequency; Is the initial phase.

The pulse generator generates a pulse train of

Wherein U _PM is pulse amplitude; Is a rectangular function with which a pulse of width τ _m is generated; t _M is the pulse repetition period; n is the accumulated pulse number; Is a convolution operation symbol.

Where U _TM is the transmit signal amplitude.

When there is relative motion between the bullets, doppler frequency offset is generated. Let the relative movement speed of the missile and the target be v, then when the two are close to each other, there is R (t) =R ₀ -vt, where R ₀ is the initial distance between the target and the fuze, so there is

And Doppler frequencyU _r (t) can also be expressed as

In the method, in the process of the invention,Is the initial phase of the received target echo signal.

After receiving the echo signal, mixing the echo signal with a local oscillation signal output by an oscillator, and performing primary filtering to remove a high-frequency component (2 times of carrier frequency is f _lp1＜2f₀ is removed), thereby obtaining a video pulse signal as

Wherein U _DM andThe video pulse signal amplitude and the initial phase are respectively.

The video pulse signal is amplified and then sent to a range gate gating circuit, and the range gate gating output signal is given by the assumption of the range gate delay tau _d

Wherein alpha is the amplification factor of the video amplifier; the range gate width is the same as the transmit pulse width and is delayed by τ _d relative to the transmit pulse, i.e., the range gate is open at a position of d=cτ _d/2. It is readily apparent from the range gate output signal u _out (t) that this signal is a pulse train signal modulated by the doppler signal. Unlike a transmit burst having a fixed pulse width and repetition period, which is the product of an echo burst and a range gate burst, its pulse width and repetition period are both time-varying. Fig. 3 shows intuitively the relationship of the range gate gating output pulse width to the range gate and the echo.

From fig. 3, we can intuitively find that the pulse width of the range gate output pulse is Δτ=τ _m+τ_d - τ, and the position (τ _i +τ)/2 of the range gate output pulse is also changed since the echo delay τ is changed. Thus, the range gate strobe output signal can also be expressed as

In the method, in the process of the invention,For a range gate output pulse, U _out is the range gate output signal amplitude. Obviously, according to fig. 3 and the above equation, when the target echo pulse signal delay τ and the range gate set delay τ _d are completely equal, the range gate output pulse width is the widest and equal to the original pulse width τ _m, and the range gate position corresponds to the distance between the target and the fuze.

Fourier transform is carried out on the range gate gating output signal to obtain the amplitude spectrum of the signal as

Where Ω _M＝2π/T_M is the pulse repetition angle frequency.

As can be seen from the above, the spectrum of the range gate output signal is a double sideband signal distributed in nΩ _M±Ω_d, i.e. Doppler signal, and the amplitudeWhen n=0, the spectrum only remains with the baseband signal, and the amplitude a _d is at a maximum, i.e

The above equation illustrates that the Doppler signal amplitude is proportional to the pulse width Δτ of the range gate strobe output. It has been analyzed above that Δτ varies with the gaze distance, that is, the doppler signal amplitude after gating by the range gate also varies with the gaze distance.

The range gate strobe output pulse width delta tau can be obtained by correlating the range gate pulse with the echo pulse,

From the above, the Doppler signal amplitude A (or range gate output pulse width Deltaτ) is related to the change in time (or eye distance R) as shown in FIG. 4

Step 2, adding fuze anti-interference measures, wherein: large signal lock-out, spectral analysis, and digital wave.

Step 3, an interference source selection module selects variable delay forwarding interference:

The key variable affecting the relative distance is the delay between the fuze receiving echo signal and the transmitting signal, so that the completion of distance spoofing requires starting from the interfering delay, by generating false echo signals such that the delay falls within the distance threshold. The fuze speed measurement mainly depends on Doppler frequency, so that speed spoofing can be achieved by modulating Doppler frequency of an interference signal.

The forward deception jamming refers to that an interfering party detects and intercepts a signal transmitted by a fuze, stores the signal and forwards the signal after corresponding processing. At this time, the interference signal received by the fuze is almost consistent with the target echo signal in basic parameters, and only has certain differences in phase, amplitude and the like.

The correlation output is mainly dependent on the signal delay, so that the interference delay, which is intended to fall within the range of the range gate, must meet certain conditions. If the intercepted fuze transmitting signal is directly forwarded, the minimum time delay modulation is only equivalent to the transmitting signal, and the interference time delay is difficult to be ensured to fall in the range of the range gate gating. Obviously, the single delay can not meet the interference requirement, and the method of dynamically changing the delay can be adopted to improve the deception jamming probability.

Based on the variable delay forwarding type interference time sequence shown in fig. 5, after the interference party detects the pulse Doppler signal transmitted by the fuze, assuming that the interference machine has obtained a modulation period T through parameter extraction, the length of NT intercepted by the fuze signal is sampled and stored, then the stored signal is repeatedly forwarded for a plurality of times, and a fixed time step exists between each two times of forwarding.

Where R _j represents the distance between the jammer and the fuze, τ _s represents the time when the jammer processes the received signal, Δτ represents the additional forwarding interval of the jammer, and n represents the number of interval forwarding times.

Τ ₁ can also be denoted as τ ₁＝lT_M+τ_j, where l is a positive integer, τ _j＜T_M. For the same integer/, the change in τ _j is the change in τ ₁. Depending on the periodicity of the pulse signal, the pulse position is the same for a delay lT _M+τ_j and a delay τ _j, so τ ₁ can also be denoted as τ ₁＝τ_j. Thus, the correlation output produced by the interference depends primarily on τ _j. In the above equation τ _s can be regarded as a constant value, so that the variation of the interference delay τ _j depends on the variation of the interference distance R _j and the number of interference delays n. The change of R _j generates the spoofed doppler frequency f _dj, and as n increases, the interference delay increases at intervals of Δτ, and when the increment nΔτ covers one modulation period T _M, the interference delay can be recorded as a complete interference delay change period, theoretically, in one interference delay change period, there must be one or several interference delays forwarding interference within the initiation delay interval.

For the pulse Doppler fuze used by the system to interfere, the jammer transmits interference signals of ten modulation periods each time, and a fixed stepping time delta tau exists between every two transmissions, and the delta tau is taken as 16ns. In order to make the interference delay cover a modulation period, which is called a complete interference period, a total of 500 times of interference signals need to be forwarded, the interference period time is 0.04s, and the missile is assumed to move at 800m/s, and the missile moves for about 32m in one interference period.

Step4, a signal processing module

The range gate gating and Doppler signal processing realize the autocorrelation operation of the target echo, and when the echo signal is related to the range gate signal, the output Doppler signal amplitude is the largest. And then the baseband Doppler signal can be extracted through subsequent filtering and amplifying treatment.

An adaptive filter: the change of the parameters of the fuze can lead to the change of Doppler frequency and harmonic component frequency, thereby affecting the cut-off frequency of the band-pass filter and the low-pass filter to change. Therefore, the system provides the self-adaptive filter, the cut-off frequency of the filter is automatically set according to the fuse parameters, and manual calculation and modification are not needed. After the signal processing module obtains the relevant parameters, the relevant parameters are stored in a working area and are called in a filter and a next-stage GUI.

Large signal latch controller: and a large signal locking controller is added at the front end of the signal processing module. The controller monitors the received signal power in real time, and if the controller detects a high-power signal, the fuze shuts down the signal processing module in the next millisecond.

When the signal processing module is applied to the self-adaptive filter for a plurality of times, the speed range of the millimeter wave fuze is 50 m/s-1200 m/s, and when the central frequency f0=100 GHz, the Doppler signal frequency range is 33 kHz-800 kHz, and at the moment, the passband range of the band-pass filter is the fuze central frequency plus or minus Doppler frequency.

The parameter setting of the self-adaptive band-pass filter is as follows: the harmonic component after mixing is n times of the modulation frequency plus or minus Doppler frequency, so that Doppler signals are free from loss, and the bandwidth of the band-pass filter is ensured to be more than twice of the maximum Doppler frequency. According to simulation, the maximum falling speed of the fuze is 1200m/s, the corresponding Doppler frequency is 800kHz, if only one band-pass filter is used, and the band-pass bandwidth meets the requirement of the corresponding maximum Doppler frequency, when the fuze with lower speed is filtered by the filter, clutter cannot be filtered cleanly, the subsequent Doppler signal processing is affected, and therefore the speed measurement precision is reduced.

The parameter setting of the adaptive low-pass filter is as follows: the low pass filter is used for extracting the difference frequency signal and the harmonic envelope. According to simulation, the maximum falling speed of the fuze is 1200m/s, the corresponding Doppler frequency is 800kHz, and if only one low-pass filter is used, and the cut-off frequency meets the requirement of the corresponding maximum Doppler frequency, when the filter is used for filtering the fuze with lower speed, clutter cannot be filtered out, and useful signals cannot be extracted, so that the fuze work is affected.

Therefore, the system adopts an adaptive filter, and the cut-off frequency of the filter is determined according to the fuse setting parameters. After the signal processing module calculates the corresponding parameters, the parameters are stored in the working area and are called in the filter or the next-stage GUI.

When the echo receiving system of the fuze receives the signal, the digital signal is sent to the signal processing module for processing, if the receiving system receives a high-power interference signal at the moment, the power of the high-power interference signal is greatly different from that of the echo signal received when the fuze works normally, the normal work of the fuze can be influenced, and the starting output of the fuze is interfered. In order to overcome the influence of the high-power signal, the system is provided with a high-signal locking decision controller at the front end of the signal processing module. The controller monitors the power of the received signal in real time, and if the controller detects a high-power signal, the fuze closes the signal processing module of the fuze in the next millisecond.

Step5, GUI construction

And building a GUI graphical user interface under the MATLAB platform, wherein the system comprises 4 layers of interfaces, namely a fuze system selection interface, a fuze parameter setting interface, an jammer parameter setting interface and a fuze various parameter result display interface from top to bottom. The system adopts global variable assignment, is imported by the top layer, and parameters can be changed, covered and output in the middle.

And calling a corresponding algorithm such as methods of time domain undersampling, czt spectrum refinement and the like under a MATLAB platform through a GUI graphical user interface, combining an adaptive filter, extracting key information such as fuze speed, distance, doppler signals and the like, simulating fuze signal receiving and transmitting and signal processing of different systems, calling corresponding interference sources aiming at fuzes of different systems, adding selectable anti-interference options, and exploring the effectiveness of the interference signals under different anti-interference options and the monitoring problem of the fuze state. The influence of parameters on the fuze echo signal and anti-interference measures on the fuze starting condition is explored through the change of the fuze speed, the initial distance of the bullet and the signal intensity parameters.

The response characteristic of the fuze to the interference can be simply and vividly analyzed by setting the input parameters on the simulation platform, and good interactivity is provided, so that a certain reference is provided for further research of millimeter wave fuze interference and anti-interference.

Examples

In order to verify the effectiveness of the scheme of the invention, the following simulation experiment is carried out, and parameters of the fuzes are set: setting a pulse Doppler fuze carrier frequency 100G; pulse period repetition period 8us, duty cycle 0.005; the relative speed of the bullet hole is 700m/s, the detonation distance is 12m, the transmitting power is 26dBm, and the antenna gain is 5dB; fuze sensitivity-70 dBm.

Parameters of jammer:

The relative position of the jammer and the target is as shown in fig. 6:

relative distance along heading (x-axis): 0m

Heading (y-axis) relative distance: 150m

Tangential heading (z-axis) relative distance: 0m

The single forwarding cycle number is 10, the forwarding interval is 16ns, the interference power is 66dBm, the antenna gain of the jammer is 10dB, the initial shot-to-eye distance is 150m, the simulation distance is 150m, and the main and side lobe ratio of the fuze is 20dbc

In the interference-free state:

Fig. 7 shows the range gate gating and doppler signal processing, which implements the autocorrelation operation on the target echo, and when the echo signal is correlated with the range gate signal, the output doppler signal has the largest amplitude. Fig. 8 is an enable output signal.

When variable delay forwarding interference is applied:

fig. 9 shows the range gate gating and doppler signal processing, which implements the autocorrelation operation on the target echo, and when the echo signal is correlated with the range gate signal, the output doppler signal has the largest amplitude. Fig. 10 is an enable output signal. The fuze start-up is successfully disturbed at 285m as shown in fig. 10. Therefore, the interference can rapidly interfere the projectile and can effectively protect own equipment.

And constructing a GUI graphical user interface under the MATLAB platform, wherein the system comprises 4 layers of interfaces, namely a fuze system selection interface, a fuze parameter setting interface, an jammer parameter setting interface and a fuze various parameter result display interface from top to bottom, which are shown in figures 11-14.

The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims

1. An interference and anti-interference digital simulation system based on millimeter wave fuzes is characterized by comprising:

the fuze selection module is used for setting millimeter wave wavelength and selecting fuze types; the millimeter wave wavelength is set to 3mm and 8mm, and the fuze type includes: millimeter wave fuze of four systems of continuous wave Doppler, pulse Doppler, harmonic spacing and linear frequency modulation;

The anti-interference selection module is used for selecting anti-interference measures, wherein the anti-interference measures comprise default options: large signal blocking, spectral analysis, and selectable options: detecting digital wave and amplitude variation;

The interference source selection module comprises an interference machine parameter setting module, a control module and a control module, wherein the interference machine parameter setting module is used for setting interference machine interference power, interference machine antenna gain, fuze direction diagram main-auxiliary ratio, bullet mesh initial distance and bullet mesh simulation distance;

The GUI construction module is used for displaying the receiving and sending of the fuze signals of different systems, the processing results of the fuze system signals, the adding of the interference signals and the processing results of the fuze system signals after the anti-interference measures through a GUI graphical user interface;

The GUI construction module is used for:

2. The system of claim 1, wherein the millimeter wave fuze parameters include initial shot distance, relative shot speed, set detonation distance, drop angle, antenna gain, fuze sensitivity;

The setting range of the bullet mesh relative speed is 50m/s-1200m/s;

the bullet mesh simulation distance is set to be 3000m-0m.

3. The method for constructing the interference and anti-interference digital simulation system based on the millimeter wave fuze is characterized by comprising the following steps of:

step one: the wavelength of millimeter wave is selected to be 3mm and 8 mm;

1) The setting range of the bullet mesh relative speed is 50m/s-1200m/s;

2) The setting range of the bullet mesh simulation distance is 3000m-0m;

Default options: large signal blocking, spectral analysis, and selectable options: detecting digital wave and amplitude variation;

the interference signal is added according to the type of fuze, the method comprises the following steps:

(1) Sinusoidal amplitude modulated sweep frequency interference:

f_jn＝f_j0+Δf,n＝0,1,...,N

Wherein A _j is the carrier amplitude of the interference signal; F (t) is the waveform of the interference modulation signal, which is the initial phase of the interference signal;

(2) Interval forwarding interference:

the forward deception jamming means that an interfering party detects and intercepts a signal transmitted by a fuze, stores the signal and forwards the signal after corresponding processing; at the moment, the interference signal received by the fuze is almost consistent with the target echo signal in basic parameters, and only certain differences are made in the aspects of phase, amplitude and the like;

The frequency of the difference frequency signal mainly depends on the signal delay, so that f _ij enters the passband of the fuse low-pass filter, and the interference delay tau _je must meet certain conditions; setting the linear frequency modulation fuze distance threshold as (R _p1,R_p2), considering the distance-measuring fuzzy problem, the interference delay needs to satisfy

τ_je∈(nT_M-τ_p1,nT_M-τ_p2)U(nT_M+τ_p1,nT_M+τ_p2)

τ ₁ can also be represented as τ ₁＝lT_M+τ_j, where l is a positive integer, τ _j＜T_M; for the same integer l, the change in τ _j is the change in τ ₁; according to the periodicity of the triangular wave frequency modulation signal, the difference frequency signal obtained by the time delay of lT _M+τ_j and the time delay of tau _j is the same, so tau ₁ can be expressed as tau ₁＝τ_j; therefore, the frequency of the difference signal generated by interference is mainly determined by τ _j; where τ _s can be considered a constant value, so that the variation of the interference delay τ _j depends on the variation of the interference distance R _j and the number of interval forwarding n; wherein, the change of R _j generates the deception Doppler frequency f _dj, and as n increases, the interference delay increases at intervals of Deltaτ, and when the increment nDeltaτ covers one modulation period T _M, the interference delay can be recorded as a complete interference delay change period;

(3) Variable delay forwarding type interference:

τ ₁ can also be represented as τ ₁＝lT_M+τ_j, where l is a positive integer, τ _j＜T_M; for the same integer l, the change in τ _j is the change in τ ₁; depending on the periodicity of the pulse signal, the pulse position is the same for a delay lT _M+τ_j and a delay τ _j, so τ ₁ can also be denoted as τ ₁＝τ_j; thus, the correlation output resulting from the interference depends primarily on τ _j; where τ _s can be considered a constant value, so that the variation of the interference delay τ _j depends on the variation of the interference distance R _j and the number of interference delays n; wherein, the change of R _j generates the deception Doppler frequency f _dj, and as n increases, the interference delay increases at intervals of Deltaτ, and when the increment nDeltaτ covers one modulation period T _M, the interference delay can be recorded as a complete interference delay change period;

step four: constructing a signal processing module, the module comprising:

Step five: GUI construction:

4. The method for constructing the interference and anti-interference digital simulation system based on the millimeter wave fuzes according to claim 3, wherein the millimeter wave fuzes of four systems are specifically as follows:

1) Continuous wave doppler fuze:

The transmitted signal is:

u_t(t)＝U_tcos2πf₀t

Wherein U _r is the amplitude of the echo signal received by the fuze, lambda is the wavelength of the fuze, P _t is the transmitting power of the fuze, D _t is the gain of the transmitting antenna of the fuze, R _Σ is the distance from the fuze to the target, As a function of the directivity of the fuze transmit antenna, D _r is the gain of the fuze receive antenna,The method is characterized in that the method is used for receiving a directional function of an antenna by a fuze, H is the height of the fuze from the ground, and N is the ground reflection coefficient;

The echo signal received by the fuze is:

substituting it into the above formula yields:

wherein k is a mixing coefficient;

the delay τ can be expressed as follows when considering the relative motion:

Where f _d＝2vf₀/c is the Doppler frequency, Is the initial phase;

Two assumptions are made:

(2) The Doppler frequency expression is f _d＝2v_rf₀/c;

The system frequency-regulating slope is as follows:

pulse Doppler fuze: the oscillator output signal is

The pulse generator generates a pulse train of

Wherein U _TM is the amplitude of the transmitted signal;

5. The method for constructing the millimeter wave fuze-based interference and anti-interference digital simulation system according to claim 3, wherein the anti-interference measures are as follows:

1) Large signal blocking: a large signal locking judgment controller is added at the front end of the signal processing module; the controller monitors the power of the received signal in real time, and if the controller detects a high-power signal, the fuze closes the signal processing module of the fuze in the next millisecond;

3) Counting the waves: adding wave number anti-interference measures, and if the fuze amplitude judgment threshold is met in more than three continuous periods, meeting the starting output condition;

The method comprises the steps of utilizing a large signal locking means, a frequency spectrum analysis means, a digital wave means and an amplitude variation detection means to judge whether the fuze is started or not through the combination of a signal amplitude judgment threshold, a Doppler frequency judgment threshold and a signal amplitude variation rate judgment threshold.

6. The method for constructing the interference and anti-interference digital simulation system based on the millimeter wave fuze, which is disclosed in claim 3, wherein the self-adaptive filter is applied to the signal processing module for a plurality of times, when the millimeter wave fuze speed range is 50 m/s-1200 m/s and the center frequency f0=100 GHz, the Doppler signal frequency range is 33 kHz-800 kHz, and the passband range of the band-pass filter is the fuze center frequency plus or minus Doppler frequency; the bandpass filter has a bandwidth greater than twice the maximum doppler frequency.