CN105158737B - A kind of frequency-stepped signal time-frequency detection method - Google Patents
A kind of frequency-stepped signal time-frequency detection method Download PDFInfo
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- CN105158737B CN105158737B CN201510587124.9A CN201510587124A CN105158737B CN 105158737 B CN105158737 B CN 105158737B CN 201510587124 A CN201510587124 A CN 201510587124A CN 105158737 B CN105158737 B CN 105158737B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/021—Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
Abstract
The invention provides a kind of frequency-stepped signal time-frequency detection method, comprise the following steps：Auto-correlation processing is carried out to frequency-stepped signal x (t), recurrence interval estimate T between arteries and veins is obtainedr；Radon STFT conversion is carried out to frequency-stepped signal x (t), local linear FM signal is obtainedInitial frequency estimation f0With chirp rate estimate k；Local linear FM signalFrequency-stepped signal x (t) is multiplied, and obtains thick demodulated signal xde(t)；To thick demodulated signal xde(t) it is filtered acquisition signal xfilter(t)；To signal xfilter(t) reduced, obtained new signal xnew(t)；With TrFor window, to new signal xnew(t) the time-frequency detection that Short Time Fourier Transform obtains frequency-stepped signal is carried out；The present invention can detect frequency-stepped signal under low signal-to-noise ratio, and the accuracy detected is higher.
Description
Technical field
The present invention relates to field of signal processing, and in particular to a kind of frequency-stepped signal time-frequency detection method.
Background technology
Frequency-stepped signal is a kind of typical Low probability intercept signal, is had a wide range of applications in field of radar, in letter
It is in uniform stepping Energy distribution in number frequency band range；And linear FM signal is in the straight line of certain slope in the range of signal band
Energy distribution, therefore, linear FM signal can realize the approximate match with frequency-stepped signal to a certain extent；Especially for
Frequency interval is smaller, the longer frequency-stepped signal of pulse train, and from the point of view of time-frequency domain, linear FM signal can be matched more
It is good；It therefore, it can carry out frequency-stepped signal with linear FM signal just demodulation, the energy compression of frequency-stepped signal existed
In one less frequency band；How can be from compared with detecting that it is important that frequency-stepped signal has under low signal-to-noise ratio under non-cooperation
Meaning；Under low signal-to-noise ratio frequency-stepped signal can be detected there is presently no a kind of detection method under non-cooperation.
The content of the invention
The present invention provides frequency-stepped signal time-frequency detection method under a kind of non-condition for cooperation.
A kind of frequency-stepped signal time-frequency detection method, comprises the following steps：
Auto-correlation processing is carried out to frequency-stepped signal x (t), recurrence interval estimate T between arteries and veins is obtainedr；
Radon-STFT conversion is carried out to frequency-stepped signal x (t), local linear FM signal is obtained's
Initial frequency estimation f0With chirp rate estimate k；
Local linear FM signalIt is multiplied with frequency-stepped signal x (t), obtains thick demodulated signal xde(t)；
To thick demodulated signal xde(t) it is filtered acquisition signal xfilter(t)；
To signal xfilter(t) reduced, obtained new signal xnew(t)；
With TrFor window, to new signal xnew(t) the time-frequency inspection that Short Time Fourier Transform obtains frequency-stepped signal is carried out
Survey.
Preferably, the auto-correlation processing is according to the interval between the main peak and secondary peak of auto-correlation function, obtain between arteries and veins
Recurrence interval estimate Tr。
Preferably, the peak that the Radon-STFT conversion is converted according to Radon-STFT obtains original frequency and estimated
Evaluation f0With chirp rate estimate k.
Preferably, the filter bandwidht that the filtering is used is no more than kTr。
Preferably, the computational methods of the reduction are as follows：
The beneficial effects of the invention are as follows：
The present invention can detect frequency-stepped signal under low signal-to-noise ratio, and the accuracy detected is higher.
Brief description of the drawings
Fig. 1 is flow chart of the present invention.
Embodiment
The present invention will be further described with specific embodiment below in conjunction with the accompanying drawings.
A kind of frequency-stepped signal time-frequency detection method, comprises the following steps：
Auto-correlation processing is carried out to frequency-stepped signal x (t), recurrence interval estimate T between arteries and veins is obtainedr；
Radon-STFT conversion is carried out to frequency-stepped signal x (t), local linear FM signal is obtained's
Initial frequency estimation f0With chirp rate estimate k；
Local linear FM signalIt is multiplied with frequency-stepped signal x (t), obtains thick demodulated signal xde(t)；
To thick demodulated signal xde(t) it is filtered acquisition signal xfilter(t)；
To signal xfilter(t) reduced, obtained new signal xnew(t)；
With TrFor window, to new signal xnew(t) the time-frequency inspection that Short Time Fourier Transform obtains frequency-stepped signal is carried out
Survey.
The time-domain expression of frequency-stepped signal is：
In formula：TrFor recurrence interval estimate between arteries and veins, TpFor pulse width, fAFor carrier frequency initial frequency estimate, Δ f is
The stepping-in amount of carrier frequency, rect (t) is rectangular function, and N is u in the total length of frequency stepped pulse trains sequence, formulai(t) it is pulse bag
Network function；
Auto-correlation processing is carried out to frequency-stepped signal：
χ (τ)=∫ x (t) x* (t- τ) dt
By searching for the interval between the main peak of auto-correlation function and secondary peak, pulse recurrence interval estimate T is obtainedr；
It can be handled by other auto-correlation processing methods.
Radon-STFT conversion is done to frequency-stepped signal, if the STFT time-frequency representations for receiving signal are STFTx(t, ω),
Then the Radon-STFT of signal is transformed to：
By searching for the peak of Radon-STFT conversion, local linear FM signal is obtainedIt is initial
Frequency estimation f0With chirp rate estimate k.
Linear FM signalIt is multiplied with frequency-stepped signal x (t), obtains and the stepping frequency modulation received is believed
Number thick demodulation xde(t),
Bandwidth is carried out to thick demodulated signal and is no more than kTrFiltering, filter out-of-band noise, to lift signal to noise ratio, filtered
Signal x after ripplefilter(t)。
Filtered signal is reduced, new signal x is obtainednew(t)：
With TrSTFT (Short Time Fourier Transform) conversion is done to the signal after reduction for window length, time-frequency detection STFT is obtainedXnew
(t,ω)。
Presently preferred embodiments of the present invention is the foregoing is only, is not intended to limit the invention, all essences in the present invention
Any modification, equivalent and improvement made within refreshing and principle etc., should be included within the scope of the present invention.
Claims (5)
1. a kind of frequency-stepped signal time-frequency detection method, it is characterised in that comprise the following steps：
Auto-correlation processing is carried out to frequency-stepped signal x (t), recurrence interval estimate T between arteries and veins is obtainedr；
Radon-STFT conversion is carried out to frequency-stepped signal x (t), local linear FM signal is obtainedIt is initial
Frequency estimation f0With chirp rate estimate k；
Local linear FM signalIt is multiplied with frequency-stepped signal x (t), obtains thick demodulated signal xde(t)；
To thick demodulated signal xde(t) it is filtered acquisition signal xfilter(t)；
To signal xfilter(t) reduced, obtained new signal xnew(t)；
With TrFor window, to new signal xnew(t) the time-frequency detection that Short Time Fourier Transform obtains frequency-stepped signal is carried out.
2. a kind of frequency-stepped signal time-frequency detection method according to claim 1, it is characterised in that at the auto-correlation
The interval between the main peak and secondary peak according to auto-correlation function is managed, recurrence interval estimate T between arteries and veins is obtainedr。
3. a kind of frequency-stepped signal time-frequency detection method according to claim 1, it is characterised in that the Radon-
STFT conversion converts peak according to Radon-STFT and obtains local linear FM signalOriginal frequency estimate
Evaluation f0With chirp rate estimate k.
4. a kind of frequency-stepped signal time-frequency detection method according to claim 1, it is characterised in that the filtering is used
Filter bandwidht be no more than kTr。
5. a kind of frequency-stepped signal time-frequency detection method according to claim 1, it is characterised in that the meter of the reduction
Calculation method is as follows：
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Effective date of registration: 20190528 Address after: 610000 9-storey 928, No. 56 Tianhui Middle Street, Chengdu High-tech Zone, Sichuan Province Patentee after: Chengdu bang bang technology Co., Ltd. Address before: 610225 24 section 1 Xuefu Road, Southwest Airport Economic Development Zone, Chengdu, Sichuan Patentee before: Chengdu information engineering university |