CN101256230A - Continuous wave chaos phase-modulation radio fuse detection system and demodulation method - Google Patents

Abstract

The invention provides a continuous wave chaos phase modulation firebird detecting system, especially a continuous wave chaos phase modulation firebird detecting system implemented based on the generation of modulation signal of FPGA and the quick digital correlative demodulation arithmetic of signal after modulating. The system comprises chaos code generator, retarder, radio frequency oscillator, directional coupler, phase modulator, circulator, aerial, mixer, automatic gain control amplifier, correlator and signal detecting part. The invention has important application value in aspect of realizing fuze anti-interference. The system not only can make the fuze with very perfect distance, speed resolution and distance measurement, distance measurement accuracy, but also with better anti-capturing performance due to diversity and initial value sensitivity of generating method of chaos signal.

Description

Continuous wave chaos phase-modulation radio fuse detection system and demodulation method thereof

Technical field

The present invention relates to a kind of radio fuse detection system, relate to especially in a kind of continuous wave chaos phase-modulation radio fuse detection system based on the generation of the modulation signal of FPGA and the fast digital correlation demodulation algorithm of modulation back signal and realizing.

Background technology

Along with the complexity day by day of modern battlefield electromagnetic environment, can the detection performance of electronic fuse and antijamming capability have directly determined the warhead that is equipped with electronic fuse give full play to its fighting efficiency.

The antijamming capability of electronic fuse and detection performance waveform modulated good and bad and fuse is undivided, and under the demand pull of battlefield surroundings, the waveform modulated mode of electronic fuse becomes increasingly complex.On development trend, electronic fuse tends to more and more that the service band width is wideer, frequency is higher, and signal form more and more at random.

Though at present the pseudorandom code fuze used of broad research also is to utilize m sequence with pseudo-random characteristics or Gold sequence as modulation signal, but this pseudo-random code correlation properties are not very desirable, available sequence quantity is few, Cipher Strength is low, and owing to the reason sequence period length of production method is not allowed to be easy to do oversizely.

Summary of the invention

The present invention proposes a kind of continuous wave chaos phase-modulation radio fuse detection system and demodulation method thereof, this system can utilize the desirable correlation properties of chaotic signal, makes fuse have very desirable distance, speed resoluting force and range finding, rate accuracy.And, because the diversity and the initial value susceptibility of chaotic signal producing method make sort signal have better anti-interception capability.

Technical scheme of the present invention

A kind of continuous wave chaos phase-modulation radio fuse detection system of the present invention, comprise: chaos sign indicating number generator, chronotron, radio-frequency oscillator, directional coupler, phase converter, circulator, antenna, frequency mixer, automatic gain control amplifier, correlator and signal detecting part is characterized in that: the input that is transferred to phase converter after the chaotic signal that chaos sign indicating number generator produces drives through phase converter; The output of phase converter links to each other with circulator; Link to each other with the input of auto-gain circuit after the output signal process frequency mixer mixing of circulator; Auto-gain circuit links to each other with the input of correlator through analog to digital converter (A/D) sampling back; Another input of correlator is transferred to signal deteching circuit after delaying time through chronotron; Signal deteching circuit obtains the output of total system after by execution level; System can utilize the desirable correlation properties of chaotic signal, makes fuse have very desirable distance, speed resoluting force and range finding, rate accuracy; And, because the diversity and the initial value susceptibility of chaotic signal producing method make sort signal have better anti-interception capability.

The master chip of signal deteching circuit of the present invention can be the Sparton2 of an Xilinx company Series FPGA chip, also can be master clock frequency can reach 25ns greater than 40MHz, symbol width other fpga chip.

The chaotic signal demodulation method of continuous wave chaos phase-modulation radio fuse detection system of the present invention comprises the following steps:

(1) determine the sample frequency fc of phase modulation Doppler signal and storing in the correlator, fc should satisfy fc＜1/Tc, and wherein Tc is the time that FPGA does one time related operation spent;

(2) determine related operation data length N and storing in the correlator, $N\&le;\frac{{\mathrm{\&Delta;}}_{\mathrm{<figure-callout\; id="4"\; label="max\; C"\; filenames="A20071017783900122.png"\; state="\{\{state\}\}">max</figure-callout>}}C}{4\mathrm{\&pi;}{V}_r{f}_0{T}_P},$ Wherein, Δ _MaxThe Doppler signal variable quantity, c velocity of electromagnetic waves, v _rThe vertical terminal-velocity in the relative ground of fuse, f ₀Carrier frequency, T _PChaos pulse symbol width, $N\&GreaterEqual;\frac{1}{{4\mathrm{\&sigma;}}^2},$ Wherein, σ is chaos sequence autocorrelation function side lobe levels and cross-correlation function value to zero standard deviation;

(3) determine threshold value according to actual test target family curve, and store in the correlator;

(4) read sample frequency fc, related operation data length N and threshold value, and according to sample frequency fc read latch chaos sequence numerical value and phase modulation Doppler signal AD sampling numerical value, unison counter begins counting;

Definite method of determining of calculated rate fc is: on the basis of Nyquist's theorem, frequency is high more, restoring signal more better, if the Doppler signal frequency is fd, fc＞2fd is arranged, the time that one time related operation spent should be less than Doppler signal sampling interval time, and establishing the time that FPGA does one time related operation spent is Tc, then fc＜1/Tc.

When (5) related data computing length reaches N, time-delay chaos sequence numerical value and phase modulation Doppler signal AD sampling numerical value are carried out relevant treatment, i.e. the autocorrelation function of chaos sequence and Doppler signal product; Definite method of related operation data length N is: the length of a used chaos sequence of related operation is in the pairing time, and the amplitude of Doppler signal is answered approximate constant, and for satisfying this condition, the number percent of N and changes in amplitude closes and is: $N\&le;\frac{\mathrm{\&Delta;EC}}{4\mathrm{\&pi;}{V}_r{f}_0{T}_P};$ For guaranteeing the correlated performance of chaos sequence, chaos sequence length can not be too little; Chaos sequence autocorrelation function side lobe levels and cross-correlation function value to the zero standard deviation sigma and the pass of chaos sequence length N are: $\mathrm{\&sigma;}=\frac{1}{2\sqrt{N}},$ Behind given σ, data length N must satisfy: $N\&GreaterEqual;\frac{1}{{4\mathrm{\&sigma;}}^2}.$

(6) phase modulation Doppler signal amplitude detection is if range value reaches threshold value output detonator signal, if range value does not reach threshold value, counter O reset.

Beneficial effect of the present invention:

1, the FPGA technology has been used in the generation of chaos sign indicating number, can be adjusted modulation signal at an easy rate.

2, because the demodulation of phase modulation Doppler signal uses is FPGA, make that the parameter adjustment of algorithm is very convenient, thereby can control the real-time of demodulation accuracy and algorithm easily.

3, because the demodulation of the generation of modulation signal and phase-modulated signal and input have adopted the digital technology based on FPGA, can reduce the fuse volume.

Description of drawings

The schematic diagram of Fig. 1-continuous wave chaos phase-modulation radio fuse detection system;

The chaos time sequence pulse of Fig. 2-produce based on FPGA;

Fig. 3-fast digital phase modulation Doppler signal correlation demodulation algorithm flow chart;

Fig. 4-emulation input waveform (phase modulation Doppler signal);

Doppler signal sample value after Fig. 5-demodulation.

Embodiment

Embodiment

Below in conjunction with accompanying drawing the present invention is further detailed.

As shown in Figure 1, continuous wave chaos phase-modulation radio fuse detection system comprises chaos sign indicating number generator, chronotron, radio-frequency oscillator, directional coupler, phase converter, circulator, antenna, frequency mixer, automatic gain control amplifier, correlator and signal detecting part.Chaos sign indicating number generator, correlator and signal detecting part are the fpga chip circuit, and chaos sign indicating number generator produces chaos ripple signal.

Be used for that the chaotic signal of modulation signal is actual to be chaos time sequence, can accurately control the width of the chaos time sequence of generation by changing the crystal oscillator frequency that uses, and the rising edge of waveform and negative edge are very steep, have only about 1ns based on the FPGA technology.Fig. 2 is the chaotic signal demodulation method of continuous wave chaos phase-modulation radio fuse detection system, comprises the following steps:

1, determine the sample frequency fc of phase modulation Doppler signal and storing in the correlator, fc should satisfy fc＜1/Tc, and wherein Tc is the time that FPGA does one time related operation spent;

2, determine related operation data length N and storing in the correlator, $N\&le;\frac{{\mathrm{\&Delta;}}_{\mathrm{<figure-callout\; id="4"\; label="max\; C"\; filenames="A20071017783900122.png"\; state="\{\{state\}\}">max</figure-callout>}}C}{4\mathrm{\&pi;}{V}_r{f}_0{T}_P},$ Δ _MaxThe Doppler signal variable quantity, c velocity of electromagnetic waves, v _rThe vertical terminal-velocity in the relative ground of fuse, f ₀Carrier frequency, T _PChaos pulse symbol width, $N\&GreaterEqual;\frac{1}{{4\mathrm{\&sigma;}}^2},$ Wherein, σ is chaos sequence autocorrelation function side lobe levels and cross-correlation function value to zero standard deviation;

3, determine threshold value according to actual test target characteristic, and store in the correlator;

4, read sample frequency fc, related operation data length N and threshold value, and according to sample frequency fc read latch chaos sequence numerical value and phase modulation Doppler signal AD sampling numerical value, unison counter begins counting;

When 5, related data computing length reaches N, time-delay chaos sequence numerical value and phase modulation Doppler signal AD sampling numerical value are carried out relevant treatment, i.e. the autocorrelation function of chaos sequence and Doppler signal product;

6, amplitude detection is judged, promptly judges whether to carry out amplitude detection according to phase modulation Doppler signal sampling number;

7, phase modulation Doppler signal amplitude detection is if range value reaches threshold value output detonator signal, if range value does not reach threshold value, counter O reset;

Definite method of determining of calculated rate fc is: on the basis of Nyquist's theorem, frequency is high more, restoring signal more better, and establishing the Doppler signal frequency is fd, fc＞2fd is arranged, and the time that one time related operation spent should be less than Doppler signal sampling interval time; If the FPGA work time that one time related operation spent is Tc, then fc＜1/Tc.Definite method of related operation data length N is: the length of a used chaos sequence of related operation is in the pairing time, and the amplitude of Doppler signal is answered approximate constant, and for satisfying this condition, the number percent of N and changes in amplitude closes and is: $N\&le;\frac{\mathrm{\&Delta;EC}}{4\mathrm{\&pi;}{V}_r{f}_0{T}_P};$ For guaranteeing the correlated performance of chaos sequence, chaos sequence length can not be too little; Chaos sequence autocorrelation function side lobe levels and cross-correlation function value to the zero standard deviation sigma and the pass of chaos sequence length N are: $\mathrm{\&sigma;}=\frac{1}{2\sqrt{N}}.$ Behind given σ, data length N must satisfy: $N\&GreaterEqual;\frac{1}{{4\mathrm{\&sigma;}}^2}.$

System adopts the input file of phase modulation Doppler signal as emulation, and this signal waveforms is seen Fig. 3.See accompanying drawing 4 by the Doppler signal sample value after this algorithm demodulation, see accompanying drawing 5 with the figure that matlab draws, comparison diagram 3 and Fig. 5 as seen, the phase modulation Doppler signal is by correct perfect restitution.

After chaos sequence produces, form circuit by phase-modulated pulse and generate phase-modulated pulse, phase-modulated pulse carries out 0/ π phase modulation to the rf oscillation signal from directional coupler in phase converter after, the phase place of phase converter output signal is 0 degree or 180 degree with respect to input signal, and this phase-modulated signal is launched by antenna through circulator.Transmit behind target reflection to receive and (establish echoed signal with respect to being the time delay that transmits τ by antenna _r), enter frequency mixer through circulator, carry out mixing with local oscillation signal from directional coupler, obtain by the Doppler signal of chaos sequence phase modulation (PM).This signal carries out sending into correlator after the permanent width of cloth is handled through automatic gain amplifying circuit, and from the output of chaos sign indicating number generator, and (being established time-delay and being τ by suitable time-delay ₀, τ ₀Size and the predetermined distance dependent that detonates of fuse) chaos sequence in correlator, carry out relevant treatment.Correlator output signal is the autocorrelation function of chaos sequence and the product of Doppler signal, because the autocorrelation function of chaos sequence is similar to δ (τ) function, so when the echoed signal delay time T _rWith the chaos sequence delay time T ₀(last corresponding to the predetermined distance of detonating) equate, when that is to say echo from the target of the predetermined distance of detonating, the Doppler signal of phase modulation (PM) is by demodulation, correlator output Doppler signal, and this moment the amplitude maximum.Work as τ _rAnd τ ₀When slightly difference being arranged, because the auto-correlation function value of chaos sequence descends, the amplitude of the Doppler signal of correlator output reduces.Work as τ _rAnd τ ₀Difference when surpassing symbol width of phase-modulated pulse because the auto-correlation function value vanishing of chaos sequence, this moment correlator also vanishing of output, no Doppler signal is exported.Have or not Doppler signal output to judge to correlator, both can reach the purpose of spacing, can also obtain to play the relative velocity between order in addition in the Doppler signal that demodulates.

For persons skilled in the art, any conspicuous change that it is done all constitutes to infringement of patent right of the present invention, with corresponding legal responsibilities without departing from the premise in the spirit of the present invention.

Claims (3)

1, a kind of continuous wave chaos phase-modulation radio fuse detection system and demodulation method thereof, comprise: chaos sign indicating number generator, chronotron, radio-frequency oscillator, directional coupler, phase converter, circulator, antenna, frequency mixer, automatic gain control amplifier, correlator and signal detecting part is characterized in that: the input that is transferred to phase converter after the chaotic signal that chaos sign indicating number generator produces drives through phase converter; The output of phase converter links to each other with circulator; Link to each other with the input of auto-gain circuit after the output signal process frequency mixer mixing of circulator; Auto-gain circuit links to each other with the input of correlator through analog to digital converter (A/D) sampling back; Another input of correlator is transferred to signal deteching circuit after delaying time through chronotron; Signal deteching circuit obtains the output of total system after by execution level; System can utilize the desirable correlation properties of chaotic signal, makes fuse have very desirable distance, speed resoluting force and range finding, rate accuracy; And, because the diversity and the initial value susceptibility of chaotic signal producing method make sort signal have better anti-interception capability.

2, continuous wave chaos phase-modulation radio fuse detection system as claimed in claim 1, it is characterized in that: the master chip of signal deteching circuit can be the Sparton2 of an Xilinx company Series FPGA chip, also can be master clock frequency can reach 25ns greater than 40MHz, symbol width other fpga chip.

3, the demodulation method of continuous wave chaos phase-modulation radio fuse detection system as claimed in claim 1 is characterized in that comprising the following steps:

(1) determine the sample frequency fc of phase modulation Doppler signal and storing in the correlator, fc should satisfy fc＜1/Tc, and wherein Tc is the time that FPGA does one time related operation spent;

(2) determine related operation data length N and storing in the correlator, $N\&le;\frac{{\mathrm{\&Delta;}}_{\max }C}{4\mathrm{\&pi;}{V}_r{f}_0{T}_P},$ Wherein, Δ _MaxThe Doppler signal variable quantity, c velocity of electromagnetic waves, v _rThe vertical terminal-velocity in the relative ground of fuse, f ₀Carrier frequency, T _PChaos pulse symbol width, $N\&GreaterEqual;\frac{1}{{4\mathrm{\&sigma;}}^2},$ Wherein, σ is chaos sequence autocorrelation function side lobe levels and cross-correlation function value to zero standard deviation;

(3) determine threshold value according to actual test target family curve, and store in the correlator;

(4) read sample frequency fc, related operation data length N and threshold value, and according to sample frequency fc read latch chaos sequence numerical value and phase modulation Doppler signal AD sampling numerical value, unison counter begins counting;

Definite method of determining of calculated rate fc is: on the basis of Nyquist's theorem, frequency is high more, restoring signal more better, if the Doppler signal frequency is fd, fc＞2fd is arranged, the time that one time related operation spent should be less than Doppler signal sampling interval time, and establishing the time that FPGA does one time related operation spent is Tc, then fc＜1/Tc;

When (5) related data computing length reaches N, time-delay chaos sequence numerical value and phase modulation Doppler signal AD sampling numerical value are carried out relevant treatment, i.e. the autocorrelation function of chaos sequence and Doppler signal product; Definite method of related operation data length N is: the length of a used chaos sequence of related operation is in the pairing time, and the amplitude of Doppler signal is answered approximate constant, and for satisfying this condition, the number percent of N and changes in amplitude closes and is: $N\&le;\frac{\mathrm{\&Delta;EC}}{4\mathrm{\&pi;}{V}_r{f}_0{T}_P};$ For guaranteeing the correlated performance of chaos sequence, chaos sequence length can not be too little; Chaos sequence autocorrelation function side lobe levels and cross-correlation function value to the zero standard deviation sigma and the pass of chaos sequence length N are: $\mathrm{\&sigma;}=\frac{1}{2\sqrt{N}},$ Behind given σ, data length N must satisfy: $N\&GreaterEqual;\frac{1}{{4\mathrm{\&sigma;}}^2};$

(6) phase modulation Doppler signal amplitude detection is if range value reaches threshold value output detonator signal, if range value does not reach threshold value, counter O reset.

Images