CN104655929B - A kind of digital time-frequency measuring method of time-domain signal and corresponding target identification method - Google Patents
A kind of digital time-frequency measuring method of time-domain signal and corresponding target identification method Download PDFInfo
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Abstract
The present invention provides a kind of digital time-frequency measuring method of time-domain signal, including：1) according to the sample rate v setting time length of window Δ T of measured signal, the spectral range of time and frequency measurement is determined, the spectral range is between 1/ Δ T to v/2；2) measured signal is intercepted with time window；3) discrete frequency sequence is set in identified spectral range, for each frequency, it is equal to current frequency with frequency values, and constant phase difference is 90 degree of two sinusoidal signals as reference signal, correlation computations are carried out to currently pending signal burst respectively, mould and argument are calculated using two correlation calculation results as real and imaginary parts, obtains the range value and phase value of current point in time, current frequency；4) step 2) is repeated to 3), and corresponding range value and phase value are combined until obtaining measured signal each time point and frequency.The present invention can accurately measure phase time-frequency spectrum while accurately amplitude time-frequency spectrum is measured, and anti-noise ability is strong, fast response time, and time sense is high.
Description
Technical field
The present invention relates to electronics and time and frequency measurement technical field, and specifically, the present invention relates to a kind of number of time-domain signal
Word time and frequency measurement method.
Background technology
Frequency spectrograph is a kind of typical spectrum measuring device, and it is widely used in electrotechnical, electronic, physical chemistry, biomedicine
With each field such as national defense safety.With application level and require step up, requirement of the people to frequency spectrograph function is also more next
It is higher.Such as the application in terms of ultrasonic diagnosis, electrocardiogram and pulse radar, frequency spectrograph do not need only to have excellent frequency spectrum point
Ability is distinguished, should also possess excellent time resolution.
The popular frequency spectrograph in domestic and international market is the frequency spectrograph based on Fourier transformation at present, and for amplitude spectrum, it possesses
Good frequency spectrum resolution capability and time resolution, can handle to a certain extent complexity transient response signal and its
The differentiation of derivative signal.However, Fourier transformation has the window truncation effect of time domain, it needs to utilize limited time window
Interior signal carrys out signal of the approximate representation without limit, and this causes phase measurement obvious deviation to be present with amplitude measurement.It is i.e. existing
Based on the frequency spectrograph of Fourier transformation while the amplitude spectrum of signal is accurately measured, its simultaneously measured phase spectrum is present
Larger deviation even mistake.And phase spectrum can reflect the big measure feature of measured signal, if can not synchronously measure exactly
Amplitude spectrum and phase spectrum, just it is difficult in intactly signal Analysis (the especially signal and its derivative signal of complicated transient response)
Entrained information.
To overcome drawbacks described above, Chinese patent application CN 101308175A propose one kind on the basis of Fourier transformation
Improvement project, the program introduces some parameters during Fourier transformation and its phase spectrum is modified, so as to one
Determine to reduce phase deviation in degree.But the time-domain window that this scheme can not fundamentally change in Fourier's change blocks
Effect, and this scheme is possible to bring extra deviation because being artificially introduced parameter, therefore the degree of accuracy of its phase spectrum is still
Shortcomings, have much room for improvement.
Therefore, currently there is an urgent need to a kind of solution for the amplitude spectrum and phase spectrum that can synchronously measure time-domain signal exactly
Scheme.
The content of the invention
The task of the present invention is to provide a kind of solution for the amplitude spectrum and phase spectrum that can synchronously measure time-domain signal exactly
Certainly scheme.
For achieving the above object, the invention provides a kind of digital time-frequency measuring method, comprise the following steps：
1) setting time length of window Δ T, according to set time window length Δ T and measured signal sample rate v
The spectral range of measurement is determined to, the spectral range is：1/ Δ T to v/2；
2) measured signal is intercepted with time window, obtains pending signal burst corresponding to current point in time；
3) discrete frequency sequence is set in the range of step 1) determination, for each frequency in frequency sequence, with frequency
Rate value is equal to current frequency, and constant phase difference is 90 degree of two sinusoidal reference signals, respectively to currently pending signal point
Piece carries out correlation computations；It is multiple using correlation calculation result corresponding to described two reference signals as real and imaginary parts composition
Number, the formed modulus of complex number and argument is calculated, using the mould and argument as current point in time, the range value of current frequency
And phase value；
4) next time point is set as current point in time, step 2) is repeated to 3), until obtaining measured signal
Range value and phase value corresponding to each time point and frequency combination.
Wherein, in the step 1), the identified spectral range is：2/ Δ T to v/5.
Wherein, the step 3) also includes：For each current frequency f, the current period k/f corresponding to it is calculated, from
Cast out the one piece of data at pending signal burst end in the current pending signal burst, to ensure to participate in correlation computations
The time span of pending signal be integral multiple that current frequency corresponds to Cycle Length 1/f；Also, each reference signal
Time span with it is described participation correlation computations pending signal time span it is consistent.
Wherein, the step 3) also includes：By linearly taking a little or non-linear taking in the range of the step 1) determination
The described discrete frequency sequence of point setting.
Wherein, in the step 3), non-linear take a little includes：Logarithm uniformly takes a little, and polynomial function uniformly takes a little
Or inverse uniformly takes a little.I.e. in the range of step 1) determination, along logarithm, multinomial or reciprocal function are in axis of abscissas
Upper progress uniformly takes a little, and the ordinate of taken point is exactly taken value of frequency point, and so resulting discrete frequency sequence will edge
Logarithm, multinomial or reciprocal function arrangement, so as to more neatly obtain required time-frequency spectrum.
Wherein, in the step 3), when the described discrete frequency sequence of setting is using linear take, for discrete frequency
Any one frequency f in sequence, makes the integral multiple that time window length Δ T is Cycle Length 1/f corresponding to frequency f.
Compared with prior art, the present invention has following technique effect：
1st, phase time-frequency spectrum can accurately be measured while accurately amplitude time-frequency spectrum is measured.
2nd, anti-noise ability is strong.
3rd, fast response time.
4th, time sense is high.
Brief description of the drawings
Fig. 1 shows the schematic diagram of the technology of the present invention principle；
Fig. 2 shows the flow chart of one embodiment of the invention；
Fig. 3 shows the time domain beamformer of a signal to be analyzed in one embodiment of the invention；
Fig. 4 shows the analyzed signal for Fig. 3, the amplitude and phase frequency spectrum surveyed according to one embodiment of the invention
(gray line expression) and the amplitude that traditional Fourier transformation scheme is surveyed compare with phase frequency spectrum (expression of black box line)
Schematic diagram；
Fig. 5 shows the time domain beamformer of another signal to be analyzed in one embodiment of the invention；
Fig. 6 shows the analyzed signal for Fig. 5, the amplitude spectrum surveyed according to one embodiment of the invention；
Fig. 7 shows the analyzed signal for Fig. 5, and the time-frequency combination surveyed according to one embodiment of the invention analyzes width
Spend spectrogram；
Fig. 8 shows the analyzed signal for Fig. 5, and the time-frequency combination surveyed according to one embodiment of the invention analyzes phase
Position spectrogram；
Fig. 9 shows the time domain beamformer of another signal to be analyzed in one embodiment of the invention；
Figure 10 shows the analyzed signal for Fig. 9, the amplitude spectrogram surveyed according to one embodiment of the invention；
Figure 11 shows the analyzed signal for Fig. 9, according to one embodiment of the invention institute under compared with very noisy situation
Signal time domain distribution map and frequency spectrum profile of 116 microseconds surveyed to the signal burst between 124 microseconds.
The time domain and frequency domain spectra of ambient noise when wherein a) b) being respectively free of echo signal；C) d) it is respectively single measurement
The time domain and frequency domain spectra with noise targets signal；E) f) be respectively 10 sub-band noise targets signal measurements average time domain and frequency
Compose in domain；G) h) be respectively 100 sub-band noise targets signal measurements average time domain and frequency domain spectra；I) j) it is respectively that 1000 sub-band are made an uproar
The average time domain and frequency domain spectra of acoustic target signal measurement.
Embodiment
Below, the present invention will be further described in conjunction with the accompanying drawings and embodiments.
For ease of understanding, the measuring principle of the present invention is introduced first.Fig. 1 shows the schematic diagram of the technology of the present invention principle,
The present invention proposes the method that is combined with correlator of phaselocked loop to realize the quick and precisely measurement of the amplitude of high density spectrum and phase,
The now measurement of phase is directly related to measured signal progresss and acquisition respectively by the two paths of signals of phaselocked loop, without repeatedly
Phase is scanned, greatlys save processing time.Specifically, the general principle for the lock phase time and frequency measurement that the present invention uses is：First
The π f of frequencies omega to be measured=2 are set, are responsible for producing the two-way sine wave signal that constant phase difference is 90 degree by phaselocked loop, such as cos (ω
T) with sin (ω t), i.e. complex signal eiωt；Then the locked two paths of signals of phase is allowed to carry out such as formula with measured signal respectively
(1a) or (1b) related operation, obtain plural number (real and imaginary parts, or amplitude and phase) of the signal under the setpoint frequency.It is former
Reason formula is expressed as follows：
(continuous situation) (1a)
(discrete situation) (1b)
Wherein complex function S (ω) is complex signal S (t) frequency spectrum, SkFor complex discrete signal sequence, i be imaginary unit be-
1 square root, n are each cycle numeral sample number, and N is n natural several times, and signal length T is 1/f natural several times.For
Common signal, complex function S (t) imaginary part is zero, and now complex function S (t) is equal to real-number function S (t), and plural S
The real and imaginary parts of (ω) are represented respectively, i.e., wherein, according to formula (1a), plural S (ω) is represented respectively by real and imaginary parts,
Formula (2a) and (3a) are obtained, according to formula formula (1b), plural S (ω) is represented respectively by real and imaginary parts, obtains formula
(2b) and (3b)
(continuous situation) (2a)
(discrete situation) (2b)
(continuous situation) (3a)
(discrete situation) (3b)
It is pointed out that the general principle used in the present invention, i.e. formula (1a) and (1b), the product with Fourier transformation
Point or summation it is closely similar in form because the formula of the present invention possesses time domain to frequency domain or the real space to density space
Convert the feature generally having.In fact, the time resolution lock facies principle that the present invention uses is fundamentally different from Fourier
Conversion.Specifically, Fourier transformation assumes primary signal in positive and negative infinite district, and it is former only to meet that the ideal is assumed
Orthogonality between two frequencies of meaning just can guarantee that, and then frequency spectrum accuracy is ensured.But the ideal situation is in reality
In and it is not present, because the time window of signal is not infinity in practical application, this deviation causes in actual Fu
It cannot be guaranteed that continuous orthogonal, its accuracy on some Frequency points partly can even completely lose leaf transformation spectrum, and in phase
In frequency spectrum, this problem is especially prominent.The present invention is for the processing method of the actual signal of finite time length：For frequency spectrum
Interior arbitrary frequency point, enough natural several times (examples are taken fully from primary signal (i.e. measured signal) according to its corresponding cycle
Such as 2 times, 3 times etc.) time span, 90 degree of orthogonal signalling are then locked in a pair of phase differences of the Frequency point and carry out phase
Close, real part and imaginary part of the signal in the Frequency point are such as obtained respectively by formula (2b) and (3b), with regard to primary signal phase can be obtained
Time slicing is answered in the range value and phase value of corresponding frequency.Also, this scheme largely avoid other frequencies
Measurement of the signal energy to the Frequency point bring interference, thus the continuity of Frequency point and the measurement accuracy of each Frequency point can
It is guaranteed simultaneously.
Based on above-mentioned analysis, Fig. 2 shows a kind of digital time-frequency measurement provided according to one embodiment of present invention
The schematic flow sheet of method, this method comprise the following steps：
Step 101：Obtain time-domain digital signal.The time-domain digital signal both can be the data signal directly received,
Can be that obtained data signal is sampled to analog signal.
Step 102：Initialized, time point variable Ti to be scanned is set, start time point is set to T0 (now i
=0), time window length Δ T, time point movement pace dt are set, it is true according to the sample rate v of acquired time-domain digital signal
Surely the spectral range that can be measured, the spectral range between 1/ Δ T and v/2, wherein, 1/ Δ T is low frequency edge, too low frequency
Being decreased obviously for measurement accuracy just occurs in rate, and according to Shannon's sampling theorem, v/2 is high frequency limit.Preferably, the frequency spectrum
Scope can so increase certain engineering nargin between 2/ Δ T and v/5, such as when the upper limit takes v/5, upper frequency limit increases
2.5 times of engineering nargin is added.
According to identified spectral range generation frequency sequence, each frequency f in the frequency sequence is satisfied by condition：
Time window length Δ T sampled point number is the integral multiple of the sampled point number corresponding to frequency f Cycle Lengths (i.e. 1/f).
Such as：Taken frequency can be：2/ Δ T, 3/ Δ T ..., n/ Δ T.Wherein n can be selected as needed, such as can be tens of arrive
It is hundreds of, when selecting n, it should be noted that ensure that n/ Δs T is less than the upper limit for determining spectral range, be, for example, less than v/5.
For ease of description, frequency is hereafter designated as Fj, j is 1 natural number for arriving N, and j initial values are that 1, N is composition frequency sequence
Frequency points.
Step 103：The time-domain digital signal to be measured of Ti to Ti+ Δ T periods is extracted, when obtaining corresponding to current point in time Ti
Domain data signal fragment.
Step 104：Phaselocked loop corresponding to Fj frequencies is produced, that is, produces the two-way reference signal that constant phase difference is 90 degree
Cos (ω t) and sin (ω t), wherein ω are exactly angular frequency corresponding with Fj frequencies, the π Fj of ω=2.Step 103 and step 104 can
It is parallel to perform.
Step 105：Believed respectively with the time domain in actual time window with two-way reference signal cos (ω t) and sin (ω t)
Number carry out related operation, obtain two correlated results.
Step 106：A plural number, Ran Houji are formed using two correlated results of step 105 as real and imaginary parts
The plural mould and argument are calculated, using mould as time point Ti, frequency Fj range value, A (Ti, Fj) is designated as, when argument is used as
Between point Ti, frequency Fj phase value, be designated as Ψ (Ti, Fj), then j from increase 1.
Step 107：Judge whether j is more than N, if the judgment is No, return to step 104, produce next frequency, and continue
Time-domain digital signal fragment corresponding with current point in time Ti carries out relevant treatment, if the judgment is Yes, then into step 108.
Step 108：I is reset to 1 from 1, j is increased.Due to having set time point movement pace dt, therefore this step during initialization
In, when i is from when increasing 1, Ti increases dt certainly.
Step 109：Judge whether current Ti+ Δs T surmounts the scope of signal time-domain digital signal to be measured, if it is, into
Step 110, if it is not, then returning to step 103, next time-domain digital signal fragment and lock corresponding with current frequency Fj are produced
Phase ring carries out related operation.
Step 110：All Ti time-frequency range value A (Ti, Fj) corresponding with Fj and time-frequency phase value Ψ (Ti, Fj) are exported,
Form the time-frequency amplitude spectrum (such as two-dimentional spectrogram shown in Fig. 7) and time-frequency phase spectrum (such as the two-dimensional spectrum shown in Fig. 8 of two dimension
Figure).
Referring again to Fig. 1, it can therefrom find out the signal flow direction of the present invention, more illustratively show digital time domain letter to be measured
Number each stage disposition.Digital time domain signal to be measured is first cut into time-domain signal fragment, then by time-domain signal
Fragment carries out related operation with digital frequency conversion phaselocked loop, obtains two-way correlated results, this two-way correlated results is respectively as one
Real and imaginary part, so by the mould and argument of calculated complex with regard to amplitude time-frequency spectrum and phase time-frequency spectrum can be obtained.
Further, in the step 102, when setting spectral range, the sampled point number in time window length Δ T
It is 2 times of the sampled point number corresponding to the minimum frequency of determined spectral range.Now, the measurement of frequency, amplitude and phase
Uncertainty is can be controlled within 10%.And in another embodiment, time window length Δ T sampled point number is to be determined
The multiple value of sampled point number corresponding to the minimum frequency of spectral range can also be 3, now frequency, amplitude and phase
Uncertainty of measurement can be down within 2%, but computation complexity can increased.Certainly, above-mentioned multiple also can value more than 3
Integer, this is that those skilled in the art are understandable.
In step 102 described previously, frequency sequence is a little obtained by carrying out linear take in identified spectral range
.In another embodiment of the invention, frequency sequence can also take a strategy to obtain by non-linear, such as logarithm uniformly takes
Point, polynomial function uniformly take point, reciprocal uniformly taken a little etc..It is this to take a strategy more neatly to obtain with required minute
The frequency spectrum of resolution.Meanwhile using it is non-linear take strategy when, one section of the time window end that length is Δ T can be cast out
Data, it is adopting corresponding to frequency f Cycle Lengths (i.e. 1/f) to ensure to participate in the sampled point number of the time window of correlation computations
The integral multiple of sampling point number, so that it is guaranteed that the accuracy of phase spectrum.
The effect of above-described embodiment is described further below by three specific signal measurements.
Example 1：The frequency of each frequency component, amplitude and phase in unknown signaling are measured
Set a signal, it by three frequencies without direct frequency doubling relation be respectively 2.3kHz, 37.7kHz with
397.3kHz, amplitude are respectively 1.1V, 0.2V and 0.7V, phase is respectively 30 degree, 60 degree with 120 degree of sinusoidal signal phase adduction
Into its expression formula, as shown in formula (4)：
The time domain waveform of the signal is as shown in Figure 3.Fig. 4 shows the analyzed signal for Fig. 3, is surveyed according to the present invention
The amplitude surveyed with traditional discrete Fourier transform scheme of amplitude and phase frequency spectrum (gray line expressions) and phase frequency spectrum (black
Square frame line represent) control schematic diagram.With reference to figure 4, it can be seen that under logarithmic coordinates, the coordinate points of Fourier transformation acquisition
Compared in low frequency wanted under high frequency it is sparse a lot, and using the frequency spectrum that obtains of the present invention under linear or logarithmic coordinates all
Can uniformly it take a little.In addition control of the inventor also to the two progress window effect is investigated, the frequency spectrum meeting that Fourier transformation obtains
There is significant change, and the present invention does not have significant change then.The result of unknown signaling is measured with setting by two kinds of frequency spectrum analysis methods
The control of definite value, as shown in table 1, it can be seen that the frequency spectrum that the frequency spectrum that the present invention obtains obtains with Fourier transformation frequency spectrum is in frequency
The measurement of point, amplitude especially phase all has a clear superiority, wherein last three rows data are the measurement of comprehensive three Frequency points
The uncertainty of measurement average value of value and setting value difference, the uncertainty of measurement of Fourier transform pairs frequency, amplitude and phase
Respectively 3.9%, 5.5% and 98.8%, and using the uncertainty that measures of the present invention be only respectively then 0.17%, 1.1% with
6.7%.Table 1 is shown using the unknown signaling measurement result pair of the invention with usual discrete Fourier transform frequency spectrum to example 1
According to
Table 1
Example 2：Joint time frequency analysis is carried out to pulse and its derivative signal
According to the sinc function combining simulation impulse waveform P (t) shown in formula (5), three pulse P are designed1(t)、P2(t)、
P3(t), and the white noise acoustic jamming W (t) that changes at random between -1 and 1 of a voltage, according to formula (6) by four weightings
Combination, the final simulation waveform for obtaining experiment pulse and its derivative signal, its time domain beamformer is as shown in figure 5, Fig. 6 is shown
For Fig. 5 analyzed signal, the amplitude spectrum surveyed according to one embodiment of the invention.Wherein,
P (t)=sinc (2 π t × 300000) -2 × sinc (2 π t × 600000)
(5)
W (t)=Random (- 1,1)
S2(t)=P1(t)+0.5P2(t)+0.2P3(t)+0.005W(t) (6)
Measured signal energy is mainly distributed between 100kHz and 1MHz as can be seen from Figure 6, in order to which Integrative expression goes out this
The time-frequency characteristic that signal includes, the time-frequency combination amplitude spectrogram and phase spectrogram of the signal are obtained using the present invention, respectively as schemed
7th, shown in Fig. 8, therefrom it is clear that the frequency spectrum of pulse signal and its derivative signal with the differentiation of time.
Example 3：Anti-noise analysis is carried out to the echo signal flooded in special time period by noise
Signal generation process is similar with example 2, simply simulates harsher practical application, i.e., for some reason,
P3(t) pulse signal is highly suppressed, and is reduced to original 5%, and ambient noise enhancing synthesized to original 100 times
Journey such as formula 7：
S3(t)=P1(t)+0.5P2(t)+0.01P3(t)+0.5W(t) (7)
Time domain waveform corresponding to the example signal as shown in figure 9, Figure 10 shows the analyzed signal for Fig. 9, although
Fig. 6 from its overall spectrum of Figure 10 with respect to example 2 does not have notable difference, i.e. spectrum energy is still mainly distributed on 100kHz
Between 1MHz, but three feel the pulse and rush P3 (t) and can not almost be distinguished compared with Fig. 5.In order to which the accurate judgement period believes
Number the presence or absence of and frequency spectrum it is strong and weak, analysis is focused to the period.Figure 11 shows the analyzed signal for Fig. 9, compared with
When under very noisy situation according to the signal of 116 microseconds that one embodiment of the invention is surveyed to the signal burst between 124 microseconds
Domain distribution map and frequency spectrum profile.The time domain and frequency domain spectra of ambient noise when wherein a) b) being respectively free of echo signal；c)d)
The respectively time domain and frequency domain spectra with noise targets signal of single measurement；E) f) it is respectively 10 sub-band noise targets signal measurements
Average time domain and frequency domain spectra；G) h) be respectively 100 sub-band noise targets signal measurements average time domain and frequency domain spectra；I) j) divide
Not Wei 1000 sub-band noise targets signal measurements average time domain and frequency domain spectra.As shown in figure 11, Integrated comparative no pulse is passed through
When background, and using how subsynchronous cumulative mean method, it can be seen that although can't see P from time domain3(t) pulse, but
It by the technology of the present invention, may determine that the signal is implicitly present in from the one-shot measurement of the period frequency spectrum, and pass through 10 times
Measurement and cumulative mean can its frequency spectrum of Accurate Determining in 500-700kHz, amplitude is in 0.01V or so.
In actual test, the reflected signal of known target is received with certain radar, then the method according to the invention is analyzed
The reflected signal obtains time-frequency spectrum (i.e. width of the reflected signal in each frequency of set each time window of the signal
Angle value and phase value), then further according to the amplitude spectrum obtained by time-frequency spectrum and phase spectrum information, the orientation and velocity of target is calculated,
Acquired results and the true bearing and speed of the known target coincide.
Finally it should be noted that above example is only describing technical scheme rather than to this technology method
Limited, the present invention can above extend to other modifications, change, application and embodiment, and it is taken as that institute in application
There are such modification, change, application, embodiment all in the range of the spirit or teaching of the present invention.
Claims (9)
1. a kind of digital time-frequency measuring method of time-domain signal, comprises the following steps：
1) data signal to be measured is received, according to the sample rate v setting time length of window Δ T of measured signal, determines time and frequency measurement
Spectral range, the spectral range is between 1/ Δ T to v/2, wherein 1/ Δ T<v/2；
2) measured signal is intercepted with time window, obtains pending signal burst corresponding to current point in time；
3) discrete frequency sequence is set in the range of step 1) determination, for each frequency in discrete frequency sequence, with frequency
Rate value is equal to current frequency, and constant phase difference be 90 degree of two sinusoidal signals as reference signal, respectively to currently waiting to locate
Manage signal burst and carry out correlation computations；Using correlation calculation result corresponding to two reference signals as real
And imaginary part, then calculate the plural mould and argument, and using the mould and argument as current point in time, current frequency
Range value and phase value；
4) next time point is set as current point in time, repeats step 2) to 3), it is each until obtaining measured signal
Range value and phase value corresponding to time point and frequency combination.
2. the digital time-frequency measuring method of time-domain signal according to claim 1, it is characterised in that in the step 1),
The identified spectral range is：2/ Δ T to v/5.
3. the digital time-frequency measuring method of time-domain signal according to claim 2, it is characterised in that the step 3) is also wrapped
Include：For each current frequency f, the current period k/f corresponding to it is calculated, is given up from the current pending signal burst
The one piece of data at pending signal burst end is removed, is current to ensure to participate in the time span of the pending signal of correlation computations
Frequency corresponds to Cycle Length 1/f integral multiple.
4. the digital time-frequency measuring method of time-domain signal according to claim 3, it is characterised in that the step 3) is also wrapped
Include：The time span of each reference signal is consistent with the time span of the pending signal of the participation correlation computations.
5. the digital time-frequency measuring method of time-domain signal according to claim 3, it is characterised in that the step 3) is also wrapped
Include：By linearly being taken in the spectral range that is determined in the step 1) a little or non-linear taking a described discrete frequency sequence of setting
Row.
6. the digital time-frequency measuring method of time-domain signal according to claim 5, it is characterised in that in the step 3),
Non-linear take a little includes：Logarithm uniformly takes a little, and polynomial function uniformly takes a little or inverse uniformly takes a little.
7. the digital time-frequency measuring method of time-domain signal according to claim 3, it is characterised in that in the step 3),
When the described discrete frequency sequence of setting is using linear take, for any one frequency f in discrete frequency sequence, when making
Between length of window Δ T be Cycle Length 1/f corresponding to frequency f integral multiple.
8. the digital time-frequency measuring method of time-domain signal according to claim 1, it is characterised in that in the step 3),
Two reference signals are：Cos (ω t) and sin (ω t), t represent the time, and ω represents the angular frequency corresponding to current frequency.
9. a kind of target identification method, it is characterised in that comprise the following steps：
1) reflected signal that target obtains target is detected；
2) reflected signal is obtained with the digital time-frequency measuring method of time-domain signal according to any one of claims 1 to 6
Amplitude time-frequency spectrum and phase time-frequency spectrum；
3) the amplitude time-frequency spectrum according to obtained by step 2) and phase time-frequency spectrum calculate the orientation and velocity of target.
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| CN106453170B (en) * | 2016-09-27 | 2019-05-17 | 工业和信息化部电信研究院 | The measurement of signal nonlinear time-domain and analogy method and application |
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| CN107328993B (en) * | 2017-08-17 | 2020-07-24 | 中国科学院物理研究所 | Frequency measuring device and frequency measuring method |
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| JP3838654B1 (en) * | 2005-06-17 | 2006-10-25 | アンリツ株式会社 | Time interval measuring device and jitter measuring device |
| CN101251390A (en) * | 2008-04-10 | 2008-08-27 | 中国科学院长春光学精密机械与物理研究所 | Apparatus for detecting weak signal based on time-frequency transformation |
| CN101776752B (en) * | 2010-01-29 | 2011-09-21 | 中国科学院空间科学与应用研究中心 | Precise tracking and measuring method of high dynamic signal of air fleet link |
| CN102495280B (en) * | 2011-11-25 | 2014-10-01 | 中国科学院物理研究所 | Anti-noise wide-range frequency measurement method and phase locking frequency meter |
| CN103258400B (en) * | 2013-04-22 | 2016-08-10 | 常州工学院 | Millimeter wave wireless sensing periphery intrusion preventing method |
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