CN113311396A

CN113311396A - Interference and anti-interference digital simulation system based on millimeter wave fuse and construction method thereof

Info

Publication number: CN113311396A
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: 2021-08-27

Abstract

The invention discloses an interference and anti-interference digital simulation system based on a millimeter wave fuze and a construction method thereof, wherein the system is based on the millimeter wave fuze with carrier wave length of 3 mm and 8 mm, two kinds of interference of forwarding and frequency sweeping are added, and the functions of receiving and sending analog signals, processing fuze signals, verifying the effectiveness of interference signals and monitoring fuze states can be realized according to the set parameters of the intersection speed of bullets, the initial distance of the bullets, the falling angle of the bullets and the like; the system constructs a graphical user interface based on Matlab, parameters are assigned by global variables and are imported from the top layer, and the parameters can be changed, covered and output in the process; the functional modules of the graphical user interface are mutually independent, some functional modules can be added and deleted, a new fuze system and new interference and anti-interference selection can be added on the basis of the existing model, the fuze type of an adaptation system can be expanded, and a theoretical basis is provided for the field interference experiment of the conventional cannonball millimeter wave fuze.

Description

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

Technical Field

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

Background

Millimeter waves are favored in the application of proximity fuses due to the advantages of short wavelength, high distance precision, strong anti-interference capability and the like. The millimeter wave is slightly influenced by weather conditions, so that the advantages of strong capability of distinguishing a metal target from a background environment and the like are always regarded as the key points of development. The traditional microwave fuse has low ranging and speed measuring precision and low hit rate and damage effect. And the fuse body is large due to the long wavelength, and the influence of weather conditions on the fuse body is large. The anti-interference capability is weak, and the fuse is easily influenced by interference to cause early explosion or misfire.

In the aspect of tracking precision, a millimeter wave system is better than a general microwave system, and in the aspects of performance under severe meteorological conditions and airspace search, the millimeter wave system is better than an optical system. Due to the limited space in the fuse structure, there is a corresponding constraint on the volume of each part of the device. The short-range millimeter wave detector just enables the system to meet the requirements of small size, light weight, simple structure, good performance and low cost. Along with the continuous improvement of the modern air defense technology level, electronic countermeasure is more and more fierce, and is very urgent for exploring the battlefield adaptability of the millimeter wave proximity detonator, meeting the requirements of a complex battlefield and realizing the breakthrough and innovation of the related technology. From the perspective of protecting the own target, the method for implementing 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 fuse and a construction method thereof, which aim to simulate the problems of signal receiving and transmitting, antenna, signal processing, detonation judgment, anti-interference algorithm, verification of the effectiveness of interference signals, monitoring of the state of the fuse 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 a millimeter wave fuse comprises:

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

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

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 fuse; 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 the fuze parameters, and after the signal processing module obtains the relevant parameters, the cut-off frequency is stored in a working area and called in the filter and the next-stage GUI; the large signal locking controller is arranged at the front end of the signal processing module and monitors received signal power in real time, and if the signal power is detected to be larger than a threshold value, the fuze closes the signal processing module in the next millisecond;

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

Further, the millimeter wave wavelengths are set to 3 mm and 8 mm, and the fuze types include: the millimeter wave fuse has four systems of continuous wave Doppler, pulse Doppler, harmonic spacing and linear frequency modulation.

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

setting the setting range of the relative speed of the bullet meshes to be 50-1200 m/s;

the setting range of the bullet mesh simulation distance is 3000m-0 m.

Further, the anti-interference selection 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 the change of the digital wave and the amplitude;

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

1) the continuous wave Doppler millimeter wave fuse interference source is amplitude modulation forwarding interference and sine amplitude modulation frequency sweep interference;

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

3) the harmonic fixed-distance millimeter wave fuze interference source is interval forwarding interference and amplitude modulation frequency sweeping interference;

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

the interference source selection module comprises an interference machine parameter setting module which is used for setting interference power of an interference machine, antenna gain of the interference machine, a fuse directional diagram main-to-side ratio, an initial shot-to-shot distance and a shot-to-shot simulation distance.

Further, the GUI construction module is configured to:

simulating signal receiving and transmitting and signal processing of fuzes of different systems through a GUI (graphical user interface) under an MATLAB (matrix laboratory) platform, calling corresponding interference sources aiming at the fuzes of different systems, and adding selectable anti-interference options; the influence of the parameters on the fuse echo signal and the influence of anti-interference measures on the fuse starting condition are simulated by changing the fuse speed, the bullet initial distance and the signal strength parameters; and the fuze speed and distance information is extracted by utilizing time domain undersampling, CZT and adaptive filtering methods.

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

the method comprises the following steps: selecting millimeter wave wavelengths of 3 mm and 8 mm;

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

setting millimeter wave fuze parameters, including: initial shot eye distance, relative shot eye velocity, set detonation distance, drop angle, antenna gain and fuze sensitivity;

1) setting the setting range of the relative speed of the bullet meshes to be 50-1200 m/s;

2) setting the setting range of the bullet mesh simulation distance to be 3000m-0 m;

step two: constructing an anti-interference selection module for selecting anti-interference measures, comprising:

default options: large signal blocking, spectral analysis, and selectable options: and detecting the change of the number wave and the amplitude.

Step three: the method for constructing 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 fuse interference source is amplitude modulation forwarding interference and sine amplitude modulation frequency sweeping interference.

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

3) The harmonic fixed-distance millimeter wave fuze interference source is used for transmitting interference and amplitude modulation frequency sweep interference at intervals.

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

Constructing an interference machine parameter setting module for setting interference power of an interference machine, antenna gain of the interference machine, a fuse directional diagram main-to-side ratio, an initial shot-to-shot distance and a shot-to-shot simulation distance;

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

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

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

step five: and (3) GUI construction:

simulating signal receiving and sending and signal processing of fuzes of different systems through a GUI (graphical user interface) under an MATLAB platform, calling corresponding interference sources aiming at the fuzes of different systems, and adding selectable anti-interference options so as to explore the effectiveness of the interference signals under different anti-interference options and the monitoring problem of fuze states; the influence of the parameters on the fuse echo signal and the influence of anti-interference measures on the fuse starting condition are researched by changing the fuse speed, the initial distance of the projectile and the signal strength parameters; and the fuze speed and distance information is extracted by using a time domain undersampling, CZT and adaptive filtering method.

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

1) continuous wave doppler fuze:

the emission signals are:

u_t(t)＝U_t cos2πf₀t

in the formula of U_tTo transmit signal amplitude, f₀Is the signal frequency, its initial phase is zero;

after the transmitting signal is radiated to a target by the 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, system parameters, ground environment and ground height, and the expression is as follows:

in the formula of U_rAmplitude of echo signal received for fuze, λ is fuze wavelength, P_tFor transmitting power to fuze, D_tFor fuze transmitting antenna gain, R_∑For the distance of the fuze to the target,

as a function of the directivity of the transmitting antenna of the fuze, D_rIn order to fuze the gain of the receiving antenna,

is a fuseReceiving an antenna directivity function, wherein H is the height of a fuse from the ground, and N is a ground reflection coefficient;

the echo signal received by the fuze is:

in the formula (I), the compound is shown in the specification,

τ is the time delay of the echo signal relative to the transmitted signal;

let t₀The distance and the height of the fuse at the moment are H₀The vertical falling speed of the fuse is v_yThen τ can be expressed as:

substituting it into the formula above yields:

in the formula (f)_d＝f₀·2v_yThe/c is the Doppler frequency produced by relative movement of the projectile,

is the initial phase of the echo signal;

echo signal and local oscillator mixing, pass through Doppler band pass filter again, can obtain Doppler signal:

in the formula, k is a mixing coefficient;

analysis of the above formula, f_dDirectly reflecting speed information, amplitude kU_tC_rthe/2H directly reflects distance information; the amplitude of the Doppler signal also being a function of timeNumber, the doppler signal amplification rate can be defined:

from the above formula, it can be seen that the amplification rate can reflect the ground height H and the vertical falling speed v of the fuse at the same time_y；

2) In the harmonic comparison type frequency modulation fuse 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 of the transmitting signal and the echo signal is as follows;

suppose the center frequency of the transmitted signal is f₀Modulation period of T_mModulation frequency deviation of Δ F_m；

In a modulation period T_mThe difference frequency signal is divided into an irregular area and a regular area; t is less than T in short-range detection_mThe irregular area can be ignored, and only difference frequency signals in a regular interval need to be considered in an important mode; the difference frequency signal in the regular interval is rewritten into Fourier series as follows:

in the formula (I), the compound is shown in the specification,

for the amplitude of the difference frequency signal, U_tIs the system local oscillator amplitude, U_rIs the echo amplitude;

as can be seen from the above formulas, when the bullet is relatively still, the frequency spectrum of the difference frequency signal is a discrete spectrum, and each harmonic is dividedQuantity being modulation frequency f_mIntegral multiple of (a), even harmonic coefficient of a_e(n) odd harmonic coefficient is a_o(n) harmonic coefficient is offset by modulation frequency Δ F_mTime delay tau and modulation period T_mDetermining;

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

in the formula, R₀Is t₀Distance of the eyes, τ, at the moment₀Is t₀Time delay;

the difference frequency signal obtained by substituting the above expression into the regular interval is rewritten into a fourier series, and the following results are obtained:

in the formula (f)_d＝2vf₀The value/c is the Doppler frequency,

is the initial phase;

when there is relative motion of the projectile, the spectral lines at each harmonic disappear, instead of being within f of the original harmonic_dTwo spectral lines of (1); therefore, the movement speed of the fuse can be calculated;

3) the center frequency of the triangular wave frequency modulation fuse transmitting signal is f₀Modulation period of T_mModulation frequency deviation of Δ F_mThen, the instantaneous frequency relationship between the transmitted signal and the echo signal and the difference frequency signal frequency are as follows:

f_t(t) is the transmission frequency, f_r(T) is the echo frequency, one modulation period T_mFrequency f of internal and difference frequency signal_i(t) may be divided into regular and irregular regions; in the rule area f_i(t) can be considered constant, while f is in the irregular area_i(t) change in real time, therefore, focus is on discussing f within the rule region_i(t) relationship to distance R:

for ease of analysis, two assumptions are made:

(1) ignoring a modulation period T_mVariation of the internal delay τ, i.e. distance R being considered during the modulation period T_mInner is a fixed value;

(2) doppler frequency expression is f_d＝2v_rf₀/c；

Setting the system frequency modulation slope as:

when there is relative movement of the eyes, T is in one modulation period_m，f_i(t) can be divided into ascending sections f_i+And a descending zone f_i-Two sections discuss, according to the transmitting signal and echo signal, combining the time delay tau as the expression of 2R/c, f_i+、f_i-Are respectively:

adding the two equations to obtain the relationship between the distance and the difference frequency:

the above formula shows that the ranging system measures f separately_i+、f_i-Then, the two are averaged to eliminate the influence of Doppler frequency;

subtracting the two equations to obtain the relation between the Doppler frequency and the difference frequency:

recombined Doppler frequency expression f_d＝2v_rf₀And/c, obtaining an expression of the radial speed of the bullet:

theoretically, the system only needs to measure the difference frequency f of the ascending and descending regions_i+、f_i-The distance and the speed at the corresponding moment can be calculated through the above formulas;

4) when the pulse Doppler fuse system works, the transmitting frequency of the oscillator is f₀The sine wave signal is sent to a pulse modulator, and the pulse generator emits a pulse width tau_mWith a period of T_MPulse signal u of_p(t) coupling to generate pulse modulation signal, and amplifying to obtain emission signal u_t(t) transmitting by a transmitting antenna; the echo signal u of the target is received by the receiving antenna_r(t) corresponding attenuation and delay are generated; u. of_r(t) mixing with a local oscillator signal u in a mixer₀(t) mixing, where u₀(t) with a frequency f emitted by the oscillator₀The sine wave signals of (1) are completely coherent; down-mixing and once filtering to obtain a video signal u_d(t)，u_d(t) is a pulse train signal modulated by the doppler signal; u. of_d(t) after video amplification, sending the amplified video to a range gate gating circuit to obtain a range gate gating output signal u_out(t); the signal is processed by Doppler signals, and is judged by data processing and threshold, so that a fuse starting instruction is generated and a warhead is detonated;

pulse doppler fuze: the oscillator output signal is

In the formula of U_LMOutputting a signal amplitude for the oscillator; f. of₀Outputting a signal frequency for the oscillator;

is an initial phase;

the pulse generator generates a pulse train of

In the formula of U_PMIs the pulse amplitude;

is a rectangular function which is used to generate a rectangular function having a width of tau_mThe pulse of (2); t is_MIs a pulse repetition period; n is the number of accumulated pulses;

is a convolution operation symbol;

the pulse train signal modulates the oscillator signal to obtain a transmission signal

In the formula of U_TMIs the transmit signal amplitude.

The transmitted signal encounters a target to produce an echo signal, the target echo signal being

In the formula of U_RMIs the target echo signal amplitude; τ is the delay time of the signal generated during the round trip of the fuze to the target, i.e.

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

1) large signal blocking: when an echo receiving system of the fuse receives a signal, the digital signal is sent to a signal processing module for processing, if the receiving system receives a high-power interference signal, the power of the interference signal is greatly different from that of the echo signal received when the fuse works normally, the normal work of the fuse is influenced, and the starting output of the fuse is interfered. In order to overcome the influence of the high-power signal, the system adds a large-signal latching decision controller at the front end of a signal processing module; the controller monitors the received signal power 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) and (3) spectrum analysis: determining a Doppler frequency range through the relative speed range of the bullet and the center frequency of the fuse, and meeting the starting condition of the fuse when the speed measurement result is within a speed judgment threshold;

3) wave counting: when the fuze works and a signal receiving system is interfered by an impulse signal, the amplitude of the impulse signal can interfere the start of the fuze. Therefore, an output module is started in signal processing, wave number anti-interference measures are added, and if the fuze amplitude judgment threshold is met in more than three continuous periods, the starting output condition is met, so that the anti-interference purpose is achieved;

4) and (3) amplitude change detection: the method comprises the steps of detecting the amplitude change rate of a signal between two time points, and meeting the starting condition of a fuse when the amplitude change rate judgment threshold is reached;

by using the anti-interference means of large signal blocking, spectrum analysis, digital wave and amplitude change detection, the fuze jointly judges whether to start or not through the signal amplitude judgment threshold, the Doppler frequency judgment threshold and the 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 type of the fuze specifically as follows:

(1) sinusoidal amplitude modulation frequency sweep interference:

when the jammer interferes the fuse, the sweep frequency bandwidth must cover the working frequency band of the fuse, and the carrier frequency of the sweep frequency signal can swing at the same time in a certain frequency range according to a certain rule; frequency sweep start frequency of interference machineA rate of f_j0Frequency sweep termination frequency of f_jNThe sweep frequency step length is delta f, and the interference signal carrier frequency of the nth sweep frequency point is f_jnThe total number of frequency sweep points is N +1, then

f_jn＝f_j0+Δf,n＝0,1,...,N

Because the carrier frequency of the sweep frequency interference signal transmitted by the interference machine is discretely changed, the expression of the interference signal received by the fuze is a piecewise function, and the piecewise function can be written into a form of multiplication of an AND gate function; the frequency sweep interference signal received by the fuse can be expressed as

In the formula, A_jIs the interference signal carrier amplitude;

for the initial phase of the interference signal, it can be set without loss of generality

f (t) is interference modulation signal waveform, the sweep frequency type 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 as

Wherein A is_jMFor modulating signal amplitude, f_jMFor modulating the frequency, it is generally set to a Doppler frequency, f, which may occur during a bullet-and-bullet meeting_jM≈f_d，

For modulating the initial phase of the signal, again, without loss of generalityCan be provided with

At is the time the jammer dwells at each sweep point. The expression of the local oscillator signal of the continuous wave Doppler fuse is set as

In the formula, A_LIs the amplitude of the local oscillator signal of the fuze; omega_LIs the local oscillator frequency;

for the initial phase of the local oscillator signal, set

(2) Interval forwarding interference:

the forwarding type deception jamming refers to that an interference party detects and intercepts a signal transmitted by a fuse, stores the signal, performs corresponding processing and forwards the signal;

the difference frequency signal frequency is mainly dependent on the signal delay, so it is desirable to make f_ijGet into the passband of the fuze low pass filter, the interference delay tau_jeCertain conditions must be met; let the chirp fuse distance threshold be (R)_p1，R_p2) Considering the ambiguity problem of range finding, the interference delay needs to be satisfied

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 called a 'detonation delay interval', wherein tau_p1And τ_p2Can be expressed as

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

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

In the formula, R_jIndicating the distance, tau, of the jammer from the fuze_sThe time for the jammer to process the received signal is shown, delta tau represents the forwarding interval added by the jammer, and n represents the interval forwarding times;

τ₁can also be expressed as tau₁＝lT_M+τ_jWherein l is a positive integer, τ_j＜T_M(ii) a For the same integer l, τ_jIs changed by₁A change in (c); according to the periodicity of the triangular wave frequency modulation signal, the time delay is lT_M+τ_jAnd a delay of τ_jThe resulting difference frequency signals are identical, so τ₁Can also be represented as; thus, the frequency of the difference frequency signal generated by the interference depends mainly on τ_j(ii) a In the formula tau_sCan be regarded as a constant value, so that the interference delay tau_jIs dependent on the interference distance R_jAnd interval forwarding times n; wherein R is_jIs changed to generate a spoofed doppler frequency f_djAnd as n is continuously increased, the interference delay is also increased at intervals of delta tau, and when the increment n delta tau covers one modulation period T_MThe time can be recorded as a complete interference delay change period; in an interference delay change period, interference delay of one or more forwarding interferences is bound to fall in a detonation delay interval;

(3) variable delay repeating interference:

the relevant output mainly depends on signal delay, so that the interference delay of the pulse delay within the range of gating of the range gate is required to meet a certain condition; if the intercepted fuse transmitting signal is directly forwarded, the method is only equivalent to performing minimum time delay modulation on the transmitting signal, and the interference delay is difficult to be ensured to fall within the range gate gating range. Obviously, a single delay cannot meet the interference requirement, and a method of delay dynamic change can be adopted to improve the deception interference probability;

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

τ₁can also be expressed as tau₁＝lT_M+τ_jWherein l is a positive integer, τ_j＜T_M(ii) a For the same integer l, τ_jIs changed by₁A change in (c); according to the periodicity of the pulse signal, the delay is lT_M+τ_jAnd a delay of τ_jThe pulse positions are the same, so τ₁Can also be expressed as tau₁＝τ_j(ii) a Thus, the correlation output of the interference generation depends mainly on τ_j(ii) a In the above formula_sCan be regarded as a constant value, so that the interference delay tau_jIs dependent on the interference distance R_jThe number of interference delays n; wherein R is_jIs changed to generate a spoofed doppler frequency f_djAnd as n is continuously increased, the interference delay is also increased at intervals of delta tau, and when the increment n delta tau covers one modulation period T_MCan be marked as a complete interferenceAnd a delay change period, wherein in one interference delay change period, interference delay of one or more times of forwarding interference falls in the detonation delay interval.

Furthermore, the signal processing module uses the adaptive filter for multiple times, the millimeter wave fuse speed range is 50m/s-1200m/s, when the central frequency f0 is 100GHz, the Doppler signal frequency range is 33 kHz-800 kHz, and the pass band range of the band-pass filter is the fuse central frequency plus-minus Doppler frequency; the band pass filter bandwidth is 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, a self-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 changed independently to explore the influence of the parameter on the operation of the fuze system, and several parameters can be changed simultaneously to verify whether the working 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; the method simulates the receiving and sending of fuze signals of different systems and signal processing, can call corresponding interference sources aiming at the fuzes of different systems, and adds selectable anti-interference options so as to explore the problems of effectiveness of the interference signals under different anti-interference options, monitoring of fuze states and the like.

Drawings

Fig. 1 is a flowchart of an interference and anti-interference digital simulation system based on a millimeter wave fuse.

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

Fig. 3 is a diagram showing the relationship between the echo pulse, the range gate pulse and the range gate gated output pulse.

Figure 4 is a graph of the baseband doppler signal amplitude versus time t.

FIG. 5 is a schematic diagram of a time-varying retransmission-type interference timing diagram

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

FIG. 7 is a diagram illustrating the result of the autocorrelation of the target echo in a non-interference state

FIG. 8 is a schematic diagram of the start-up output signal in a non-interference state.

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

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

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

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

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

Fig. 14 shows a millimeter wave fuse digital simulation system, a fuse operation state and a result display interface.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

An interference and anti-interference digital simulation system based on a millimeter wave fuse comprises:

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 fuse type as a pulse Doppler millimeter wave fuse; a schematic block diagram of a pulse-to-continuous wave coherent detection pulse doppler fuze is shown in fig. 2.

Setting the output signal of the oscillator as

is the initial phase.

The pulse generator generates a pulse train of

In the formula of U_PMIs the pulse amplitude;

is a convolution operation symbol.

In the formula of U_TMIs the transmit signal amplitude.

When relative motion exists between the bullets, Doppler frequency offset is generated. Let v be the relative velocity of the missile and target, then when they are close to each other, there is R (t) ═ R₀-vt, wherein R₀Is the initial distance between the target and the fuse, so there is

While the Doppler frequency

u_r(t) can also be represented by

In the formula (I), the compound is shown in the specification,

and (4) the initial phase of the received target echo signal.

The echo signal is received and mixed with the local oscillation signal output by the oscillator, and the high frequency component is filtered and removed by one-time filtering (the 2 times carrier frequency, namely f is filtered and removed)_lp1＜2f₀) Obtaining a video pulse signal of

In the formula of U_DMAnd

respectively the video pulse signal amplitude and the initial phase.

Amplifying the video pulse signal and sending the amplified video pulse signal to a range gate gating circuit, and assuming the delay tau of the range gate_dSo that the range gate strobes an output signal of

In the formula, alpha is the amplification factor of the video amplifier; the width of the range gate is the same as the width of the emission pulse, and the delay time is tau relative to the emission pulse_dI.e. at a distance d ═ c τ from the door opening position_dAnd/2. Gating output signal u according to range gate_out(t) it can be seen that the signal is a pulse train signal modulated by a doppler signal. Unlike a transmit burst, which has a fixed pulse width and repetition period, this burst is the product of an echo burst and a range gate burst, both of which pulse width and repetition period are time-varying. Figure 3 visually illustrates the range gate gated output pulse width versus range gate and echo.

From fig. 3, we can find out intuitively that the pulse width of the range gate gating output pulse is Δ τ ═ τ_m+τ_dτ due to echo delayτ is varying so that the range gate gates the location of the output pulse (τ)_i+ τ)/2 also varies. Thus, the range gate strobe output signal may also be represented as

In the formula (I), the compound is shown in the specification,

for gating the output pulse, U, for range gates_outIs the range gate gated output signal amplitude. It is apparent from FIG. 3 and the above equation that the delay τ is set when the target echo pulse signal is delayed τ and the range gate_dWhen the pulse width is completely equal, the output pulse width of the range gate gating is widest and is equal to the original pulse width tau_mAnd when the distance door position is equal, the distance between the target and the fuze corresponds to the distance between the target and the fuze.

Fourier transform is performed on the range gate gating output signal to obtain the amplitude spectrum of the signal

In the formula, omega_M＝2π/T_MIs the pulse repetition angular frequency.

As can be seen from the above equation, the frequency spectrum of the range gate gated output signal is distributed in n Ω_M±Ω_dIs a Doppler signal, and has an amplitude

When n is 0, the spectrum leaves only the baseband signal, where the amplitude a is_dIs at a maximum value, i.e.

The above equation illustrates that the doppler signal amplitude is proportional to the pulse width Δ τ of the range gate gating output. It has been analyzed above that Δ τ varies with the distance between the shots, i.e., the amplitude of the doppler signal after gating through the range gate also varies with the distance between the shots.

The range gate output pulse width deltatau can be found by correlating the range gate pulse with the echo pulse,

based on the above equation, the variation of the Doppler signal amplitude A (or the gated output pulse width Δ τ of the range gate) with time (or the bullet-eye distance R) is plotted, as shown in FIG. 4

Step 2, adding a fuse anti-interference measure, wherein the following steps are selected: large signal blocking, spectral analysis, and wavelets.

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

the key variable influencing the relevant distance is the time delay between the receiving echo signal and the transmitting signal of the fuse, so that the completion of distance deception needs to start with interference time delay, and the time delay is caused to fall within a distance threshold by generating a false echo signal. The fuze speed measurement mainly depends on Doppler frequency, so that the speed deception can be completed by modulating the Doppler frequency of an interference signal.

The forwarding type deception jamming refers to that an interference party detects and intercepts a signal transmitted by a fuze, stores the signal, processes the signal correspondingly and forwards the signal. At this time, the interference signal received by the fuze is almost consistent with the target echo signal in basic parameters, and only certain differences exist in the aspects of phase, amplitude and the like.

The correlation output depends mainly on the signal delay, so that the interference delay must satisfy a certain condition when the pulse delay is expected to fall within the range of gating of the range gate. If the intercepted fuse transmitting signal is directly forwarded, the method is only equivalent to performing minimum time delay modulation on the transmitting signal, and the interference delay is difficult to be ensured to fall within the range gate gating range. Obviously, a single delay cannot meet the interference requirement, and a method of dynamically changing the delay can be adopted in order to improve the deception interference probability.

Based on the time sequence of the variable-delay forwarding type interference shown in fig. 5, after an interferer detects a pulse doppler signal transmitted by a fuze, assuming that an interferer already obtains a modulation period T of the interferer through parameter extraction, the length of NT is intercepted from the fuze signal to perform sampling storage, and then the stored signal is repeatedly forwarded for multiple times, wherein a fixed time step exists between every two times of forwarding.

In the formula, R_jIndicating the distance, tau, of the jammer from the fuze_sDenotes the time for the jammer to process the received signal, Δ τ denotes the jammer's additional retransmission interval, and n denotes the interval retransmission times.

τ₁Can also be expressed as tau₁＝lT_M+τ_jWherein l is a positive integer, τ_j＜T_M. For the same integer l, τ_jIs changed by₁A change in (c). According to the periodicity of the pulse signal, the delay is lT_M+τ_jAnd a delay of τ_jThe pulse positions are the same, so τ₁Can also be expressed as tau₁＝τ_j. Thus, the correlation output of the interference generation depends mainly on τ_j. In the above formula_sCan be regarded as a constant value, so that the interference delay tau_jIs dependent on the interference distance R_jAnd the number of interference delays n. Wherein R is_jIs changed to generate a spoofed doppler frequency f_djAnd as n is continuously increased, the interference delay is also increased at intervals of delta tau, and when the increment n delta tau covers one modulation period T_MThe time can be recorded as a complete interference delay change period, theoretically, in one interference delay change period, interference delay of one or more forwarding interferences must fall in the detonation delay interval.

For the interference of the pulse Doppler fuse used by the system, the jammer transmits interference signals with ten modulation periods each time, a fixed step time delta tau exists between every two transmissions, and the delta tau is taken as 16 ns. In order to enable the interference delay to cover one modulation period, 500 interference signals are required to be forwarded totally, the forwarding process is called a complete interference period, the time of one interference period is 0.04s, the missile is assumed to move at the speed of 800m/s, and the missile moves about 32m in one interference period.

Step 4, signal processing module

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

An adaptive filter: changes in the fuse parameters result in changes in the doppler frequency, the frequency of the harmonic components, and thus affect changes in the cut-off frequencies of the band-pass filter and the low-pass filter. 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. And after the signal processing module obtains the relevant parameters, the relevant parameters are stored in a working area and called in a filter and a next-level GUI.

Large signal blocking 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 closes the signal processing module in the next millisecond.

The signal processing module is used for a plurality of times in an adaptive filter, the speed range of the millimeter wave fuse is 50m/s-1200m/s, when the central frequency f0 is 100GHz, the frequency range of the Doppler signal is 33 kHz-800 kHz, and the pass band range of the band-pass filter is the central frequency of the fuse plus or minus the Doppler frequency.

The parameter setting basis of the self-adaptive band-pass filter is as follows: the harmonic component after mixing is n times of modulation frequency plus-minus Doppler frequency, and the bandwidth of the band-pass filter is ensured to be more than twice of the maximum Doppler frequency in order to ensure no Doppler signal loss. According to simulation, the maximum value of the fuse falling speed is 1200m/s, the corresponding Doppler frequency is 800kHz, if only one band-pass filter is used, the passband bandwidth meets the requirement of the corresponding maximum Doppler frequency, when the filter is used for filtering the fuse with lower speed, clutter cannot be filtered completely, the subsequent Doppler signal processing is influenced, and therefore the speed measurement precision is reduced.

The adaptive low-pass filter parameter setting basis is as follows: the low-pass filter is used for extracting difference frequency signals and harmonic envelopes. According to simulation, the maximum value of the fuse drop speed is 1200m/s, the corresponding Doppler frequency is 800kHz, if only one low-pass filter is used, the cut-off frequency meets the requirement of the corresponding maximum Doppler frequency, when the fuse with lower speed is filtered by the filter, clutter cannot be filtered completely, useful signals cannot be extracted, and the fuse work is influenced.

Therefore, the system adopts the self-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 corresponding parameters are stored in a working area and called in a filter or a next-level GUI.

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

Step 5, GUI construction

And (3) setting up a GUI graphical user interface under an MATLAB platform, wherein the system comprises 4 layers of interfaces from the top layer to the bottom layer, namely a fuze system selection interface, a fuze parameter setting interface, an interference machine parameter setting interface and a fuze parameter result display interface. The system adopts global variable assignment and is imported from the top layer, and parameters can be changed, covered and output in the midway.

Under an MATLAB platform, through a GUI graphical user interface, calling corresponding algorithms such as time domain undersampling, czt spectrum refining and other methods, and combining an adaptive filter, extracting key information such as fuze speed, distance, Doppler signals and the like, simulating fuze signal receiving, transmitting and signal processing of different systems, calling corresponding interference sources for fuzes of different systems, and adding selectable anti-interference options to explore the effectiveness of interference signals under different anti-interference options and the monitoring problem of fuze states. By changing the parameters of the fuze speed, the initial distance of the bullet eyes and the signal strength, the influence of the parameters on the fuze echo signals and the influence of anti-interference measures on the fuze starting condition are researched.

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 certain reference is provided for further research on millimeter wave fuze interference and interference resistance.

Examples

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

Parameters of the jammer:

the relative positions of the jammer and the target are as shown in fig. 6:

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

Heading (y-axis) relative distance: 150m

Heading (z-axis) relative distance: 0m

The number of single forwarding cycles is 10, the forwarding interval is 16ns, the interference power is 66dBm, the antenna gain of an interference machine is 10dB, the initial distance of a bullet is 150m, the simulation distance is 150m, and the main lobe and side lobe ratio of a fuse is 20dbc

In a non-interference state:

fig. 7 shows that the range gate gating and the doppler signal processing implement 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 a start output signal.

When variable delay forwarding interference is applied:

fig. 9 shows that the range gate gating and the doppler signal processing implement 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 a start output signal. The fuze start at 285m is successfully disturbed as shown in fig. 10. Therefore, the interference can quickly interfere the shot, and own equipment can be effectively protected.

A GUI graphical user interface is built under an MATLAB platform, the system comprises 4 layers of interfaces in total, and a fuze system selection interface, a fuze parameter setting interface, an interference machine parameter setting interface and fuze parameter result display interfaces are respectively shown in figures 11-14 from the top layer to the bottom layer.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The utility model provides an interference and anti-interference digital simulation system based on millimeter wave fuze which characterized in that includes:

2. The interference and interference rejection digital simulation system for millimeter wave fuzes of claim 1 wherein the millimeter wave wavelengths are set at 3 mm and 8 mm, the fuze types comprising: the millimeter wave fuse has four systems of continuous wave Doppler, pulse Doppler, harmonic spacing and linear frequency modulation.

3. The interference and anti-interference digital simulation system for the millimeter wave fuze of claim 1, wherein the millimeter wave fuze parameters comprise initial distance of the shot, relative speed of the shot, set detonation distance, landing angle, antenna gain, fuze sensitivity;

the setting range of the bullet mesh simulation distance is 3000m-0 m.

4. The system according to claim 1, wherein the immunity selection module is configured to select an immunity measure, the immunity measure comprising default options: large signal blocking, spectral analysis, and selectable options: detecting the change of the digital wave and the amplitude;

5. The interference and interference rejection digital simulation system for the millimeter wave fuze of claim 1, wherein the GUI construction module is configured to:

6. A method for constructing an interference and anti-interference digital simulation system based on a millimeter wave fuse is characterized by comprising the following steps:

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

step five: and (3) GUI construction:

7. The method for constructing the interference and anti-interference digital simulation system based on the millimeter wave fuze according to claim 6, wherein the millimeter wave fuze of four systems is specifically as follows:

1) continuous wave doppler fuze:

the emission signals are:

u_t(t)＝U_t cos2πf₀t

the direction function of the fuse receiving antenna is shown, H is the fuse distance ground height, and N is the ground reflection coefficient;

the echo signal received by the fuze is:

in the formula (I), the compound is shown in the specification,

τ is the time delay of the echo signal relative to the transmitted signal;

substituting it into the formula above yields:

is the initial phase of the echo signal;

in the formula, k is a mixing coefficient;

analysis of the above formula, f_dDirectly reflecting speed information, amplitude kU_tC_rthe/2H directly reflects distance information; the doppler signal amplitude is also a function of time and may define the doppler signal amplification rate:

in the formula (I), the compound is shown in the specification,

as can be seen from the above formulas, when the bullet is relatively stationary, the frequency spectrum of the difference frequency signal is a discrete spectrum, and each subharmonic component is the modulation frequency f_mIntegral multiple of (a), even harmonic coefficient of a_e(n) odd harmonic coefficient is a_o(n) harmonic coefficient is offset by modulation frequency Δ F_mTime delay tau and modulation period T_mDetermining;

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

in the formula (f)_d＝2vf₀The value/c is the Doppler frequency,

is the initial phase;

3) the center frequency of the triangular wave frequency modulation fuse transmitting signal is f₀Modulation period of T_mRegulating the flow ofFrequency deviation of Δ F_mThen, the instantaneous frequency relationship between the transmitted signal and the echo signal and the difference frequency signal frequency are as follows:

two assumptions are made:

(2) doppler frequency expression is f_d＝2v_rf₀/c；

Setting the system frequency modulation slope as:

4) when the pulse Doppler fuse system works, the transmitting frequency of the oscillator is f₀The sine wave signal is sent to a pulse modulator, and the pulse generator emits a pulse width tau_mWith a period of T_MPulse signal u of_p(t) coupling to generate pulse modulation signal, and amplifying to obtain emission signal u_t(t) transmitting by a transmitting antenna; the echo signal u of the target is received by the receiving antenna_r(t) corresponding attenuation and delay are generated; u. of_r(t) mixing with a local oscillator signal u in a mixer₀(t) mixing, where u₀(t) with a frequency f emitted by the oscillator₀The sine wave signals of (1) are completely coherent; down-mixing and once filtering to obtain a video signal u_d(t)，u_d(t) is a pulse train signal modulated by the doppler signal; u. of_d(t) after video amplification, sending the amplified video to a range gate gating circuit to obtain a range gate gating output signal u_out(t) (ii) a The signal is processed by Doppler signals, and is judged by data processing and threshold, so that a fuse starting instruction is generated and a warhead is detonated;

pulse doppler fuze: the oscillator output signal is

is an initial phase;

the pulse generator generates a pulse train of

In the formula of U_PMIs the pulse amplitude;

is a convolution operation symbol;

In the formula of U_TMIs the transmit signal amplitude.

8. The method for constructing the millimeter wave fuze-based interference and interference-resistant digital simulation system according to claim 6, wherein the interference-resistant measures are as follows:

1) large signal blocking: adding a large signal locking judgment controller 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 closes the signal processing module of the fuze in the next millisecond;

3) wave counting: 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 fuze jointly judges whether to start or not by a signal amplitude judgment threshold, a Doppler frequency judgment threshold and a signal amplitude change rate judgment threshold by using a plurality of anti-interference means such as large signal blocking, spectrum analysis and digital wave and amplitude change detection.

9. The method for constructing the millimeter wave fuze-based interference and anti-interference digital simulation system according to claim 6, wherein interference signals are added according to the fuze type, specifically as follows:

(1) sinusoidal amplitude modulation frequency sweep interference:

when the jammer interferes the fuse, the sweep frequency bandwidth must cover the working frequency band of the fuse, and the carrier frequency of the sweep frequency signal can swing at the same time in a certain frequency range according to a certain rule; let the frequency sweep start frequency of the jammer be f_j0Frequency sweep termination frequency of f_jNThe sweep frequency step length is delta f, and the interference signal carrier frequency of the nth sweep frequency point is f_jnThe total number of frequency sweep points is N +1, then

f_jn＝f_j0+Δf,n＝0,1,...,N

In the formula, A_jIs the interference signal carrier amplitude;

is the initial phase of the interference signal, f (t) is the waveform of the interference modulation signal;

(2) interval forwarding interference:

the forwarding type deception jamming refers to that an interference party detects and intercepts a signal transmitted by a fuse, stores the signal, performs corresponding processing and forwards the signal; at this time, the interference signal received by the fuze is almost consistent with the target echo signal in basic parameters, and only certain differences exist in the aspects of phase, amplitude and the like.

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

τ₁can also be expressed as tau₁＝lT_M+τ_jWherein l is a positive integer, τ_j＜T_M(ii) a For the same integer l, τ_jIs changed by₁A change in (c); according to the periodicity of the triangular wave frequency modulation signal, the time delay is lT_M+τ_jAnd a delay of τ_jThe resulting difference frequency signals are identical, so τ₁Can also be represented as; thus, the frequency of the difference frequency signal generated by the interference depends mainly on τ_j(ii) a In the formula tau_sCan be regarded as a constant value, so that the interference delay tau_jIs dependent on the interference distance R_jAnd interval forwarding times n; wherein R is_jIs changed to generate a spoofed doppler frequency f_djAnd with n does notThe interference delay is increased at intervals of delta tau, and when the increment n delta tau covers one modulation period T_MThe time can be recorded as a complete interference delay change period;

(3) variable delay repeating interference:

τ₁can also be expressed as tau₁＝lT_M+τ_jWherein l is a positive integer, τ_j＜T_M(ii) a For the same integer l, τ_jIs changed by₁A change in (c); according to the periodicity of the pulse signal, the delay is lT_M+τ_jAnd a delay of τ_jThe pulse positions are the same, so τ₁Can also be expressed as tau₁＝τ_j(ii) a Thus, the correlation output of the interference generation depends mainly on τ_j(ii) a In the above formula_sCan be regarded as a constant value, so that the interference delay tau_jIs dependent on the interference distance R_jThe number of interference delays n; wherein R is_jIs changed to generate a spoofed doppler frequency f_djAnd as n is continuously increased, the interference delay is also increased at intervals of delta tau, and when the increment n delta tau covers one modulation period T_MThe time can be recorded as a complete interference delay variation period.

10. The method according to claim 6, wherein the adaptive filter is applied to the signal processing module for multiple times, the millimeter wave fuse has a speed ranging from 50m/s to 1200m/s, the doppler signal has a frequency ranging from 33kHz to 800kHz when the center frequency f0 is 100GHz, and the passband of the bandpass filter is the fuse center frequency plus-minus doppler frequency; the band pass filter bandwidth is greater than twice the maximum doppler frequency.