CN105227400B - A kind of adaptive estimation method for time-varying ADS-B message time delays - Google Patents
A kind of adaptive estimation method for time-varying ADS-B message time delays Download PDFInfo
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Abstract
The invention belongs to Adaptive Signal Processing technical fields, provide a kind of ADS-B message time delay adaptive estimation methods based on impulse noise mitigation.The method is characterized by the radio signal emission sources for assuming auxiliary near course line first, and are obtained not by the Doppler frequency shift indicatrix of time delay influence by carrier frequency estimation method；It is decoded secondly by ADS-B messages, the Doppler frequency shift indicatrix obtained by time delay influence is calculated using formula；Finally, instantaneous ADS-B message time delays are estimated using the adaptive algorithm of impulse noise mitigation, and provide theoretical foundation for delay compensation.The estimation and tracking of the time delay of time-varying ADS-B messages may be implemented in the present invention, and the delay compensation for ADS-B messages provides foundation, by compensation, improves the accuracy and reliability of the position and speed information of ADS-B messages carrying.
Description
Technical field
The present invention relates to Adaptive Signal Processing technical fields, are related to the delay time estimation method of civil aviaton's ADS-B messages, special
Be not related to using the maximal correlation entropy recurrence adaptive algorithm based on extension to the ADS-B messages of time-varying carry out time delay estimation and
The method of tracking.
Background technology
Automatic dependent surveillance broadcast ADS-B (Automatic Dependent Surveillance-Broadcast) system
System is that the data that Airplane Navigation Equipment and positioning system generate are broadcasted by aircraft automatically by broadcast mode data chain
Monitoring system, it is all advantageous in all various aspects such as turnover rate, connection type and transmission mode compared with conventional radar, thus by
Gradually become the indispensable means of air traffic control (Air Traffic Control, ATC).
But the ADS-B messages of the information such as state of flight such as position and speed as carrying civil aviaton aircraft were but because should
The message information acquisition of system and message generting machanism, and there are the random delay of time-varying.Such when postpone a meeting or conference reduce ADS-B messages
The accuracy and reliability of the information such as the position and speed of carrying.Since ADS-B technologies are an emerging technologies, for ADS-B
The delay time estimation method of message need further perfect.
Invention content
The technical problem to be solved in the invention is to be directed in the prior art not carrying out the ADS-B message time delays of time-varying
Dynamically, the defect estimated and tracked in real time, provides a kind of method of ADS-B message time delays dynamic estimation and tracking, use
Technical solution is by there is the adaptive filter algorithm compared with high inhibition ability to realize to civil aviaton's ADS-B messages impulsive noise
The dynamic estimation of time delay and tracking.Used adaptive filter algorithm is the recurrence maximal correlation entropy adaptive algorithm of extension.
The present invention is the ADS-B message time delay adaptive estimation methods based on impulse noise mitigation, is estimated first by carrier frequency
Meter obtains the Doppler frequency shift indicatrix not influenced by ADS-B message time delays carried from aircraft scattered signal, then sharp
The Doppler frequency shift indicatrix influenced by ADS-B message time delays is obtained with Doppler shift formula calculating, is finally utilized
The adaptive filter algorithm of impulse noise mitigation estimates the time delay of time-varying ADS-B messages technical solution includes following tool
Body step：
The first step, being obtained using carrier frequency estimation method based on auxiliary source are not affected by the influence of ADS-B message time delays
Doppler frequency shift time-frequency curve.
(1) modulated signal emission source of the transmitting with carrier component near civil air route.
(2) zero intermediate frequency is mixed to the modulated signal by aircraft scattering, and is sampled and is received.
(3) signal received is segmented.The data obtained in the first step (2) are carried out etc. to the overlapping of time spans
It is segmented, time span can be chosen at 0.5-2 seconds in range shared by every segment data.In addition to first segment and final stage, other sections are equal
With the data overlap before this section and after this section, overlap length is the half of the segment length.
(4) estimate the Doppler frequency shift corresponding to every one piece of data.To quick Fu is carried out in the first step (3) per one piece of data
In leaf transformation, and obtain the frequency spectrum of corresponding data, it is corresponding with the segment data how general according to the location estimation of peak value in frequency spectrum
Strangle frequency displacement.The formula of Fourier transformation is：
Wherein, x (t) indicates that the signal of t variations at any time, X (j Ω) indicate the how corresponding frequency spectrum of signal.
(5) Doppler frequency shift curve is formed.It is not affected by ADS-B reports using Doppler frequency shift composition is obtained in the first step (4)
The Doppler frequency shift curve of literary time delay influence, since everywhere Doppler frequency shift both corresponds to the data segment of different moments, therefore should
Doppler frequency shift curve is the curve about time variable.
(6) more dense Doppler frequency shift curve is obtained.Doppler frequency shift curve in the first step (5) is linearly inserted
Value and extraction, a certain moment in 0.05-0.2 seconds ranges is accurate to by the time point of Doppler curve, more dense to obtain
What is changed over time is not affected by the Doppler frequency shift indicatrix of ADS-B message time delays influence.
Second step, speed message and position message based on ADS-B calculate the Doppler frequency shift time-frequency by time delay influence
Curve.
(1) linear interpolation is carried out to the speed message of ADS-B and position message information, obtained at each whole time precision
The position and speed information of aircraft.The time of reception of speed message and position message is rounded to 0.05-0.2 seconds first
Sometime precision in range, the time precision is identical as the time precision in the first step (6), then according to this time precision
Into row interpolation, the position and speed information of the more dense aircraft changed over time is obtained.
(2) the position and speed information of the aircraft obtained after interpolation is utilized, what calculating was influenced by ADS-B message time delays
Doppler frequency shift curve.Since speed message is different with the start/stop time of position message after interpolation, therefore with location information and speed
Effective time range of the simultaneous longest time range of information as ADS-B messages, and using in the effective range
It is special to calculate the Doppler frequency shift influenced by ADS-B message time delays by Doppler shift formula for location information and velocity information
Levy curve, Doppler shift formula fΔ(t)=fc(1-vp(t)T·dpt(t)/c)(1-vp(t)T·dpr(t)/c)-fc, wherein
dpt(t) unit direction vector that aircraft position is directed toward by the transmitter of auxiliary source, d are indicatedpr(t) it indicates to be directed toward by receiver to fly
The unit direction vector that seat in the plane is set, in addition vpIndicate the velocity information of aircraft, fcIndicate that the carrier frequency of transmitting signal, c indicate light
Speed.
Third walk, using impulse noise mitigation adaptive approach to time-varying ADS-B message time delays carry out dynamic estimation and
Tracking.
(1) with the simultaneous maximum time model of two Doppler frequency shift indicatrixes acquired in the first step and second step
Subject to enclosing, the Doppler frequency shift indicatrix in the time range is chosen respectively.It is not affected by ADS-B reports by what the first step obtained
Input signal of the Doppler frequency shift curve of literary time delay influence as adaptive algorithm, is denoted as fP(n).By second step obtain by
Desired signal of the Doppler frequency shift curve influenced to ADS-B message time delays as adaptive algorithm, is denoted as fC(n)；Wherein, n
For integer, discrete-time variable is indicated.
(2) by the input signal and desired signal pair of initial time to current timeInput constraint arteries and veins
It rushes in the adaptive algorithm of noise, the time delay of time-varying is estimated and tracked；Wherein, N indicates current time.This is adaptively calculated
Religious name is the recurrence maximal correlation entropy adaptive algorithm of extension, and flow is：
First, at the n=0 moment, signal parameter is initialized
W (0)=0, P (0)=λ-1I,
Wherein w indicates that the weight coefficient vector of filter, P indicate that the inverse matrix of this section of input signal autocorrelation matrix, λ indicate
Forgetting factor, I indicate unit matrix.
Secondly, as n >=1, the coefficient of recursive resolve filter as follows：
E (n)=d (n)-uT(n)w(n-1)
W (n)=α w (n-1)+e (n) k (n)
P (n)=α2P(n-1)-αk(n)uT(n)P(n-1)
(3) adaptive algorithm in (2) is walked by third, the weight coefficient vector of each moment filter can be obtained,
Further ADS-B time delays are estimated according to usual adaptive-filtering delay time estimation method using maximum weight coefficient.It is logical
Above-mentioned adaptive algorithm is crossed, is not only able to estimate non-time-varying ADS-B message time delays, additionally it is possible to which the ADS-B of time-varying is reported
Literary time delay is estimated and is tracked.
The estimation and tracking of the time delay of time-varying ADS-B messages may be implemented in the present invention, and is the delay compensation of ADS-B messages
Foundation is provided, by compensation, improves the accuracy and reliability of the position and speed information of ADS-B messages carrying.
Description of the drawings
Attached drawing 1 is the overview flow chart of the ADS-B message time delay methods of estimation of the present invention.
Attached drawing 2 is the flow chart of the adaptive algorithm with impulse noise mitigation in the present invention.
Attached drawing 3 is the T/F spectrum of aircraft scattered signal in the present invention.
Attached drawing 4 is not estimate in the present invention and Doppler frequency shift indicatrix comparison diagram when delay compensation.
Attached drawing 5 is to have estimated in the present invention and Doppler frequency shift indicatrix comparison diagram when delay compensation.
Specific implementation mode
A kind of ART network side for time-varying ADS-B message time delays is described in detail with technical solution below in conjunction with the accompanying drawings
Method, overall flow figure are as shown in Figure 1：
First step being obtained using carrier frequency estimation method based on auxiliary source is not affected by the influence of ADS-B message time delays
Doppler frequency shift time-frequency curve.
(1) modulated signal emission source of the transmitting with carrier component near civil air route.For electromagnetic wave energy space
Rule and transmitter power is lost, in the position of course line auxiliary radio signal emitting-source selected around, the communication of evacuation civil aviaton
Frequency range, even if to ensure that transmission power is smaller, the signal for still being able to the aircraft obtained at receiver scattering has higher letter
It makes an uproar ratio.
(2) modulated signal by aircraft scattering is received, and is mixed to zero intermediate frequency.Emit signal with auxiliary source
The signal received is mixed to zero intermediate frequency by carrier frequency as mixing foundation.
(3) Frequency Estimation is carried out to the signal received, is used in combination the estimated result at each moment to constitute and is not affected by ADS-B
The Doppler frequency shift curve that message time delay influences.First, in order to ensure estimation Doppler frequency shift indicatrix slickness and
Ensure 0.5 hertz of frequency resolution, the data of acquisition be subjected to Overlapping Fragment, every section of length is 1 second, other than first section with
The last period, each section 1 second Chong Die with the last period, and other than latter end, each section 1 second Chong Die with latter section.Then to each segment length
The data that degree is 2 seconds carry out the frequency spectrum that Fast Fourier Transform (FFT) obtains corresponding data, and estimating Doppler frequency shift features accordingly, then
As the Doppler frequency shift feature corresponding to this segment data central instant.
(4) by linear interpolation and extraction, the time point of Doppler curve is accurate to 0.1 second.It will be obtained in the first step (3)
The data taken are rounded to 0.1 second precision at the time of correspondence, then according to the density of every 0.1 second 1 data point, into line
Property interpolation, obtain the more dense Doppler frequency shift indicatrix for being not affected by the influence of ADS-B message time delays changed over time.
Speed message and position message of the second step based on ADS-B calculate the Doppler frequency shift time-frequency by time delay influence
Curve.
(1) linear interpolation is utilized, the position and speed information of the aircraft at each 0.1 second is obtained.First by message
The time of reception is rounded to 0.1 second precision, is then obtained more into row interpolation according to the density of every 0.1 second 1 data point
For the position and speed information curve of the intensive aircraft changed over time.
(2) using the flight parameter at each moment obtained by ADS-B message informations, when calculating by ADS-B messages
Prolong the Doppler frequency shift curve of influence.In view of speed message is different with the start/stop time of position message, with the position after interpolation
Confidence ceases and effective time range of the simultaneous maximum duration range of velocity information as ADS-B messages, and using effectively
Position and speed information in range calculates the Doppler's frequency influenced by ADS-B message time delays using Doppler shift formula
Move indicatrix.Wherein, Doppler shift formula fΔ(t)=fc(1-vp(t)T·dpt(t)/c)(1-vp(t)T·dpr(t)/
c)-fc, wherein dpt(t) unit direction vector that aircraft position is directed toward by the transmitter of auxiliary source, d are indicatedpr(t) it indicates by receiving
Machine is directed toward the unit direction vector of aircraft position, in addition vpIndicate the velocity information of aircraft, fcIndicate the carrier frequency of transmitting signal
Rate, c indicate the speed of light.
Third walks time delays of the using the ADS-B messages of the ART network time-varying of impulse noise mitigation.
(1) be subject to two kinds of Doppler frequency shift indicatrixes while existing time range, choose the time model respectively
Enclose interior Doppler frequency shift Characteristic Curve data.
(2) the Doppler frequency shift curve of ADS-B message time delays influence will be not affected by as the input signal of adaptive algorithm,
It is denoted as fP(n), as shown in Figure 2.
(3) using the Doppler frequency shift curve influenced by ADS-B message time delays as the desired signal of adaptive algorithm, note
Make fC(n), as shown in Figure 2.
(4) input signal and desired signal pair by current time (n=N) are utilizedPass through suppression
The adaptive algorithm of impulsive noise processed is estimated and is compensated to the time delay of time-varying.Due to the general range of ADS-B message time delays
It it is [0, the 2] second, according to 0.1 second time interval, the exponent number for choosing sef-adapting filter was 21 ranks, and it is [h that its weight, which is arranged,0
(n),h1(n),…,h19(n),h20(n)].The coefficient that sef-adapting filter is trained using input signal and desired signal, acquires filter
The maximum position of wave device weight, i.e.,Then utilize m (n) when moment n estimates
Between postpone, finally the position and speed information at each moment in ADS-B message datas is compensated.True scattering letter
Number time-frequency spectrum as shown in figure 3, two Doppler frequency shift curve comparison figures before estimation compensation and after estimation compensation respectively such as Fig. 4
Shown in Fig. 5.
Claims (2)
1. a kind of adaptive estimation method for time-varying ADS-B message time delays, which is characterized in that include the following steps：
The first step, being obtained using carrier frequency estimation method based on auxiliary source are not affected by the how general of ADS-B message time delays influence
Strangle frequency displacement time-frequency curve；
(1) auxiliary source of the transmitting with carrier component near civil air route；
(2) zero intermediate frequency is mixed to the auxiliary signal by aircraft scattering, is sampled and is received；
(3) signal received is segmented, the data obtained in step (2) is carried out etc. to the Overlapping Fragment of time spans；
In addition to first segment and final stage, for other sections with the data overlap before this section and after this section, overlap length is the segment length
The half of degree；
(4) Doppler frequency shift corresponding to every one piece of data is estimated, to pressing formula in step (3) per one piece of dataFast Fourier Transform (FFT) is carried out, the frequency spectrum of corresponding data is obtained, according to the position of peak value in frequency spectrum
Estimation Doppler frequency shift corresponding with the segment data；
Wherein, x (t) indicates that the signal of t variations at any time, X (j Ω) indicate the how corresponding frequency spectrum of signal；
(5) it utilizes and obtains the Doppler frequency shift time-frequency that Doppler frequency shift composition is not affected by the influence of ADS-B message time delays in step (4)
Curve；
(6) linear interpolation and extraction are carried out to the Doppler frequency shift time-frequency curve in step (5), by Doppler's time-frequency curve when
Between point be accurate to a certain moment, to obtain the more dense Doppler for being not affected by the influence of ADS-B message time delays changed over time
Frequency displacement time-frequency curve；
Second step, speed message and position message based on ADS-B calculate the Doppler frequency shift time-frequency curve by time delay influence；
(1) linear interpolation is carried out to the speed message of ADS-B and position message information, obtains the flight at each whole time precision
The position and speed information of device；The time of reception of speed message and position message is rounded to sometime precision first,
The time precision is identical as the time precision in the first step (6), is then obtained more dense into row interpolation according to this time precision
The position and speed information of the aircraft changed over time；
(2) the position and speed information of the aircraft obtained after interpolation, calculating is utilized how general to be influenced by ADS-B message time delays
Strangle frequency displacement time-frequency curve；Since speed message is different with the start/stop time of position message after interpolation, believed with location information and speed
Effective time range of the simultaneous longest time range as ADS-B messages is ceased, and utilizes the position in the effective range
Confidence ceases and velocity information；The Doppler frequency shift time-frequency influenced by ADS-B message time delays is calculated by Doppler shift formula
Curve；
Doppler shift formula is fΔ(t)=fc(1-vp(t)T·dpt(t)/c) (1-vp(t)T·dpr(t)/c)-fc, wherein dpt
(t) unit direction vector that aircraft position is directed toward by the transmitter of auxiliary signal in a steady stream, d are indicatedpr(t) it indicates to be directed toward by receiver
The unit direction vector of aircraft position, vpIndicate the velocity information of aircraft, fcIndicate that the carrier frequency of transmitting signal, c indicate light
Speed；
Third walks, and dynamic estimation and tracking are carried out to time-varying ADS-B message time delays using the adaptive approach of impulse noise mitigation；
(1) ranging from two Doppler frequency shift time-frequency curve simultaneous maximum times acquired in the first step and second step
Standard chooses the Doppler frequency shift time-frequency curve in the time range respectively；It is not affected by ADS-B message time delays by what the first step obtained
Input signal of the Doppler frequency shift time-frequency curve of influence as adaptive algorithm, is denoted as fP(n)；By second step obtain by
Desired signal of the Doppler frequency shift time-frequency curve that ADS-B message time delays influence as adaptive algorithm, is denoted as fC(n)；Wherein,
N is integer, indicates discrete-time variable；
(2) by the input signal and desired signal pair of initial time to current timeInput constraint pulse is made an uproar
In the adaptive algorithm of sound, the time delay of time-varying is estimated and tracked；Wherein, N indicates current time；
(3) adaptive algorithm in (2) is walked by third, the weight coefficient vector of each moment filter can be obtained, utilized
Maximum weight coefficient estimates ADS-B time delays according to usual adaptive-filtering delay time estimation method.
2. a kind of adaptive estimation method for time-varying ADS-B message time delays as described in claim 1, which is characterized in that
Adaptive algorithm its flow in third step (2) is：
First, at the n=0 moment, signal parameter is initialized
W (0)=0, P (0)=λ-1I,
Wherein w indicate filter weight coefficient vector, P indicate input signal autocorrelation matrix inverse matrix, λ indicate forget because
Element, I indicate unit matrix；
Secondly, as n >=1, the coefficient of recursive resolve filter as follows：
E (n)=d (n)-uT(n)w(n-1)
W (n)=α w (n-1)+e (n) k (n)
P (n)=α2P(n-1)-αk(n)uT(n)P(n-1)
Wherein, u (n) indicates the input signal of adaptive algorithm, and f in (1) is walked from thirdP(n) it is obtained in the data for being included, d
(n) it indicates desired signal, f in (1) is walked by thirdC(n) data for being included are constituted, and e (n) indicates that error, k (n) indicate gain；
α chooses in [0.9,0.9999] range, embodies the time-varying degree of time delay；It indicates
Gaussian kernel function.
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| CN101915928A (en) * | 2010-07-14 | 2010-12-15 | 中国电子科技集团公司第十研究所 | Method and device for double-star time difference/frequency difference combined positioning |
| CN104618088A (en) * | 2014-10-16 | 2015-05-13 | 烟台三航雷达服务技术研究所有限公司 | ADS-B (Automatic Dependent Surveillance-Broadcast) signal based wide-area multi-station time synchronizing method |
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| CN104618088A (en) * | 2014-10-16 | 2015-05-13 | 烟台三航雷达服务技术研究所有限公司 | ADS-B (Automatic Dependent Surveillance-Broadcast) signal based wide-area multi-station time synchronizing method |
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