CN106597421A - Prediction model-based delay and delay rate fast search method applied to very long baseline antenna array - Google Patents
Prediction model-based delay and delay rate fast search method applied to very long baseline antenna array Download PDFInfo
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Abstract
The present invention discloses a prediction model-based delay and delay rate fast search method applied to a very long baseline antenna array. The method includes the steps of prediction value calculation, prediction model fitting and residual search. According to the delay and delay rate fast search method of the invention, the prediction model of delay and delay rates is introduced; the search range of the delay and delay rate is effectively limited; and therefore, the search efficiency of cross-correlation processing is greatly improved, and the delay and delay rates of each antenna in the very long baseline antenna array can be obtained fast, and support can be supported for subsequent antenna array data processing.
Description
Technical field
The present invention relates to the signal in field of deep space exploration, more particularly to a kind of strange land antenna array based on forecast model
The method for fast searching of time delay and time delay rate.
Background technology
With the continuous expansion of mankind's survey of deep space activity, the flying distance of spacecraft is more and more remote, Spacecraft Launch
Signal also increases more and more weaker with distance.Because there is engineering pole in the bore of one side antenna and the technical specification of receiver system
Limit, needs to reach the lowest signal-to-noise received required for signal by antenna array technology.The purpose of antenna array is briefly general
Include for：Under identical transmission code rate, antenna array technology can increase in the face of spacecraft reception distance；In identical reception
Under distance, antenna array technology can improve the transmission bit rate between ground and spacecraft.
The existing large aperture antenna for being distributed in zones of different of utilization that strange land antenna array refers to while observe spacecraft, then
To be recorded, synthesized from the signal of each antenna by Digital Signal Processing, to reach to improve signal noise is received
The purpose of ratio.The advantage of this antenna array technology is can be using existing antenna and receiving device, it is only necessary to after increase
End data processing equipment can just realize antenna array, and the lead time is short and low cost.
With the project verification of mars exploration engineering, the survey of deep space activity of China has also begun to the expansion from the moon to Mars.
Because Mars is very remote apart from the earth, signal is decayed huge during space propagation, and relative to the moon, Mars distance increases
1000 times, signal space decay increases about 60dB.The detector signal that ground receiver is arrived is very faint, such as adopts existing list
Antenna is received, it is impossible to meet the science data downstream-on-demand of detector.If the bigger single antenna of newly-built bore is carrying out data
Receive, due to being limited by all many conditions such as the single antenna engineering limit, Development Schedule, research funds so that whole project is present
Great developing risk.
The content of the invention
(1) technical problem to be solved
In view of this, present invention is primarily targeted at provide in a kind of strange land antenna array based on forecast model time delay and
Time delay rate method for fast searching, quickly to obtain strange land antenna array in each antenna time delay and time delay rate value.
(2) technical scheme
The present invention provides a kind of time delay and time delay rate method for fast searching based on forecast model, comprises the steps：Step
Rapid 1：According to aerial position and Observed Position, primary Calculation goes out observed object to the latency prediction value between antenna；Step
2：Least square models fitting is carried out to calculated latency prediction value, the latency prediction model of Time Continuous is obtained；Step
3：Observing antenna array data using the latency prediction model for obtaining carries out preliminary time delay and the compensation of time delay rate, then using mutual
Correlation technique carries out cross correlation process to antenna data, and the residual error between time delay true value and latency prediction value is scanned for.
In such scheme, the step 1 includes：Step 101：Read observed object tracking listed files (t, ra, dec) and
Each antenna geographical coordinate (x in the battle array of strange landi, yi, zi), wherein (t, ra, dec) is represented in t, the right ascension of observed object and
Declination value；(xi, yi, zi) represent terrestrial space rectangular coordinate system in each aerial position, subscript i be used for distinguish different days
Line, there is N number of antenna in battle array, then have N group (xi, yi, zi), i takes 0,1...N-1；Step 102：According to classical celestial body time-delay calculation side
Method calculating observation target is to antenna and the geometric delays predictive value of reference point.
In such scheme, classical celestial body time-delay calculation method includes described in step 102：Step A1：Input survey station coordinate
And detector position；Step A2：The survey station local coordinate system error that amendment is caused by tide, plate motion etc.；Step A3：By the earth's core
Terrestrial coordinate system is transformed into the earth's core celestial coordinate system；Step A4：The earth's core celestial coordinate system is transformed to too by Lorentz transformation
Sun system barycenter celestial coordinate system, calculates geometric delays in solar system barycenter celestial coordinate system, and corrects solar system gravitating
The signal transmission path bending error for causing；Step A5：Solar system barycenter celestial coordinate system is switched back to by Lorentz transformation
The earth's core celestial coordinate system, obtains required geometric delays predictive value.
In such scheme, the step 2 includes：Step 201：By each antenna for obtaining with regard to the earth's core reference point geometry
Latency prediction value τi(tj) read in, according to the kinetic characteristic of observed object, M segmentations being divided into above-mentioned prediction value list, M is nature
Number；Step 202：Using method of least square, fitting of a polynomial is carried out to above-mentioned one section of predictive value, obtain multinomial model y；Step
203：Assessment multinomial model y fitting precision, fitting precision meets requirement, obtains latency prediction model.
In such scheme, method of least square described in step 202 carries out least square fitting using 5 rank multinomials.
In such scheme, the step 203 includes：According to formulaAn algnment accuracy is calculated, f is sight
Signal frequency is surveyed, unit is Hz；Error of fitting is by formulaTry to achieve, y in formulajRepresent polynomial module
Type y works as X=j moment values, τ0(j), τ1In (j) correspondence geometric delays result of calculation table during the geometry at Miyun station and Station in Kunming j moment
Prolong value of calculation, n represents the number of each piecewise prediction value；Error of fitting RMS is needed less than algnment accuracy；Will if precision meets
Ask, then this group of multinomial coefficient, if fitting precision is unsatisfactory for requiring, can return step as the latency prediction model of the antenna
Rapid 201, adjustment is segmented or increases polynomial order, re-starts fitting, requires until fitting precision meets.
In such scheme, the residual error between time delay true value described in step 3 and latency prediction value includes remaining time delay and residual
Remaining time delay rate.
In such scheme, the step 3 includes：Step 301：The maximum antenna of antenna array medium caliber is chosen as referring to day
Line, 1 latency prediction model value that antenna array is obtained in selecting step 203 deducts the forecast model value of reference antenna, obtains it
Delay inequality value prediction model y (i, the t of his antenna relative to reference antennaj)；Step 302：Read in reference antenna observation data OR
(tj) and battle array in other antenna observe data Oi(tj), the DC component of observation data is removed, obtain Oa R(tj), Oa i(tj)；
Step 303：From Oa R(tj) 2 are taken in datanIndividual data, delay inequality value prediction model y (i, the t obtained using step 301j) to seeing
Survey data Oa i(tj) carry out delay compensation and the compensation of time delay rate, 2 after being compensatednIndividual data [Oa i(tj- y (i, tj))]；Step
304：Respectively to Oa R(tj), [Oa i(tj- y (i, tj))] fast fourier transform is carried out, and cross-correlation is carried out, obtain cross-correlation frequency
Spectrum fft (OR a(tj))×fft*([Oa i(tj- y (i, tj))])；Seek cross-correlation frequency spectrum fft (OR a(tj))×fft*([Oa i(tj- y (i,
tj))]) phase value, then to phase value solution wind, then once linear letter is carried out to phase curve using least square method
Number fitting, obtain this 2nThe remaining time delay Δ τ of individual data1；Step 305：Remove 2nIndividual data, equally carry out above-mentioned 304 step meter
Calculate, obtain down 2nThe remaining time delay Δ τ of individual data2, it is calculated time delay rate
Step 306：The remaining time delay Δ τ that above-mentioned search is obtained1With time delay rateBe added to corresponding delay inequality value prediction model y (i,
tj) in, you can obtain the true Time Delay Model for being available for subsequent antenna group battle array data processing to use.
(3) beneficial effect
Time delay and time delay rate method for fast searching that the present invention is provided, the good effect having is：
The forecast model of time delay and time delay rate is introduced, effective restriction to the hunting zone of time delay and time delay rate, greatly
Improve the search efficiency of cross correlation process, such that it is able to quickly obtain strange land antenna array in each antenna time delay and time delay
Rate value, for follow-up antenna array data processing support is provided.
Description of the drawings
Fig. 1 is that strange land antenna array signal receives schematic diagram；
Fig. 2 is the time delay and time delay rate method for fast searching flow chart in strange land antenna array of the present invention based on forecast model；
Fig. 3 is classical celestial body time-delay calculation flow chart；
Fig. 4 is that a kind of model calculation value of specific embodiment of the present invention and fitting of a polynomial value are contrasted；
Fig. 5 is a kind of cross-correlation coefficient of the presence time delay of specific embodiment of the present invention；
Fig. 6 is a kind of cross-correlation interference fringe of the presence remnants time delay rates of specific embodiment of the present invention；
Fig. 7 is the cross-correlation coefficient after a kind of remaining delay compensation of specific embodiment of the present invention；
Fig. 8 is a kind of postrotational interference fringe of striped of specific embodiment of the present invention；
Fig. 9 is a kind of front cross-correlation phase spectrum of fractional delay adjustment of specific embodiment of the present invention；
Figure 10 is the cross-correlation phase spectrum after a kind of fractional delay adjustment of specific embodiment of the present invention.
Specific embodiment
To make the object, technical solutions and advantages of the present invention become more apparent, below in conjunction with specific embodiment, and reference
Accompanying drawing, the present invention is described in further detail.
In order to meet mars exploration mission requirements, intend expiring by the way of strange land group battle array is received in mars exploration task
The demand of sufficient data receiver.Compared with local group battle array, due to the path difference of pick-up probe downstream signal, the day of different location
The signal that line is received can produce larger time delay and time delay rate, and the amendment of time delay and time delay rate is to signal combined coefficient, synthesis
The amplitude of signal has a major impact.In consideration of it, the invention provides in a kind of strange land antenna array based on forecast model time delay and
Time delay rate method for fast searching.
In embodiments of the present invention, strange land antenna array is made up of N number of antenna, can be finally reduced to multiple 2 antenna arrays and be entered
Row data processing, here is that illustrative example is used to explain the present invention with 2 antenna arrays, but not as the limit to the present invention
Fixed, one of antenna is located at Beijing, and another antenna is located at Kunming, as shown in figure 1, Fig. 1 is strange land antenna array signal connecing
Receive schematic diagram.
τ represents the geometric delays (time difference) that spacecraft is reached between two antennas in Fig. 1,Represent spacecraft and reach two
Geometric delays rate (time difference rate of change) between individual antenna, g represents the geometry distance that spacecraft is reached between two antennas
Difference, c represents the light velocity.As can be seen from Figure 1 signal is during spatial transmission, due to the earth and Spacecraft Relative Motion,
The many factors such as atmospheric refraction, ionospheric disturbance and reception channel, its time delay value and time delay rate for reaching Liang Ge earth stations are
It is continually changing.In order to the data in the antenna array of strange land are carried out into signal synthesis, it is necessary to which time delay value and time delay rate are entered
Row compensation.Time delay extends to the part of atmospheric time delay three and constitutes when mainly being caused by geometric delays, clock.Geometric delays are
An accounting maximum part in Yanzhong when whole, mainly the geometric position by residing for observation station is with observed object cause.Knowing sight
In the case of geometric position residing for survey station and observed object, can be by being calculated the predictive value of geometric delays.Due to having
The restriction of predictive value, follow-up time delay and the residual error search efficiency of time delay rate will be greatly improved.
Fig. 2 is the time delay and time delay rate method for fast searching flow chart in strange land antenna array of the present invention based on forecast model,
The method is comprised the following steps：Predictor calculation, forecast model fitting and residual error search, wherein：
Step 1：Predictor calculation is that, according to aerial position and Observed Position, primary Calculation goes out observed object to antenna
Between geometric delays predictive value, the step specifically includes：
Step 101：Read each antenna geographical coordinate in observed object tracking listed files (t, ra, dec) and strange land battle array
(xi, yi, zi), wherein (t, ra, dec) is represented in t, the right ascension and declination value of observed object；(xi, yi, zi) represent the earth
Each aerial position in rectangular coordinate system in space, subscript i is used for distinguishing different antennas, there is N number of antenna in battle array, then have N groups
(xi, yi, zi), i takes 0,1...N-1.
Observed object tracking file be one group by Observed Position data set into list.If observed object is to defend
Star, then observed object tracking file is exactly by the calculated one group of satellite position data of orbit elements of satellite.For convenience
Understand that observed object tracks file data form, provide observed object tracking text by taking No. three Satellite Tracking files of the goddess in the moon as an example below
Part data form：
| Year | MM | UU | HH | MM | SS | Distance | RA | DEC |
| 2015 | 5 | 10 | 0 | 0 | 0 | 374602 | 20.0849 | -15.1805 |
| 2015 | 5 | 10 | 0 | 1 | 0 | 374600 | 20.0856 | -15.188 |
| 2015 | 5 | 10 | 0 | 2 | 0 | 374597 | 20.0862 | -15.1771 |
| 2015 | 5 | 10 | 0 | 3 | 0 | 374595 | 20.0869 | -15.155 |
| 2015 | 5 | 10 | 0 | 4 | 0 | 374593 | 20.0875 | -15.1738 |
| 2015 | 5 | 10 | 0 | 5 | 0 | 374591 | 20.0882 | -15.1721 |
| 2015 | 5 | 10 | 0 | 6 | 0 | 374589 | 20.0888 | -15.1704 |
| 2015 | 5 | 10 | 0 | 7 | 0 | 374587 | 20.0895 | -15.1688 |
| 2015 | 5 | 10 | 0 | 8 | 0 | 374585 | 20.0901 | -15.1671 |
| 2015 | 5 | 10 | 0 | 9 | 0 | 374583 | 20.0908 | -15.1654 |
Parameters are meant that in form：Year MM DD HH MM SS express times mark, form be year the moon
Day when point the second；Distance represents spacecraft to the distance in earth the earth's core；RA (Right ascension) represents observation mesh
Target right ascension value；DEC (Declination) represents the declination value of the observed object.
The geographical coordinate of each antenna in the antenna array of strange land is read, now, N=2 there are 2 antennas, is located at respectively, Kunming
And Beijing, it is as shown in the table：
| Name | X(m) | Y(m) | Z(m) |
| Km | -1281152.939 | 5640864.407 | 2682653.403 |
| Bj | -2201304.82 | 4324789.045 | 4125367.718 |
Each antenna code name in the antenna array of Name strange lands in table, Km represents 40 meters of antennas of Station in Kunming, and Bj represents Miyun Region of Beijing
Stand 50 meters of antennas；X (m) Y (m) Z (m) represent X-axis of each antenna in geocentric rectangular coordinate system respectively, Y-axis, Z axis numerical value,
Unit is rice.
Step 102：During according to the geometry of classical celestial body time-delay calculation method calculating observation target to antenna and reference point
Prolong predictive value.
In the category of ICRF (ICRF) definition, with the earth's core as reference point, calculating observation target is to antenna
And the latency prediction value list τ of reference pointi(tj), wherein tjExpress time, subscript i is used for distinguishing different antennas, has in battle array
N number of antenna, then have N row geometric delays predictive value τi(tj), i takes 0,1...N-1.
In Celestial Reference System, Celestial Reference System is approximately inertial coodinate system.In the coordinate system, the origin of acquiescence is
Solar system barycenter, the equatoriat plane is defined as the plane that (J2000) equator of epoch 2000 and the first point of Aries determine.In terrestrial coordinate system,
The major axes orientation that determined using conventional international origin (CIO) (CIO, Conventional International Origin) and corresponding
The equatoriat plane.Using the baseline vector between the orbital data and antenna of detector, calculating process such as Fig. 3 institutes of geometric delays are carried out
Show.Fig. 3 is classical celestial body time-delay calculation flow chart, and survey station coordinate and detector position are input into first, is then corrected by tide, plate
The survey station local coordinate system errors that cause such as block motion, by the earth's core terrestrial coordinate system be transformed into the earth's core celestial coordinate system (the amendment precession of the equinoxes,
The error that nutating, perturbation are caused), subsequently the earth's core celestial coordinate system is transformed to by solar system barycenter celestial sphere by Lorentz transformation and sat
Mark system, calculates geometric delays in solar system barycenter celestial coordinate system, and corrects the signal transmission that solar system gravitating is caused
Path bending error, the earth's core celestial coordinate system is switched back to finally by Lorentz transformation by solar system barycenter celestial coordinate system, is obtained
To required geometric delays.
According to above-mentioned calculating, with the earth's core as reference point, the geometric delays of calculating observation target to antenna and reference point are pre-
Measured value list τi(tj), wherein tjExpress time, subscript i is used for distinguishing different antennas, there is 2 antennas in battle array, then have 2 row several
When predictive value τ is prolongedi(tj), i takes 0,1...N-1.
The calculating process of latency prediction value is understood for convenience, shown below is one group with No. three landers of the goddess in the moon as observation
Target (2 points -59 seconds 0 second when the time period is 10 days 00 May in 2015), 40 meters of antennas of Station in Kunming and the antenna conduct of 50 meters of Miyun station
Strange land group array antenna, geometric delays predictor calculation result (the earth's core is the geometric delays value of reference point).Geometric delays are predicted
Value result of calculation was segmented according to 60 seconds, and this is wherein one section.
Geometric delays result of calculation table
Step 2：Forecast model is fitted, and is to utilize least square method, and above-mentioned calculated latency prediction value is carried out
Least square models fitting, obtains the geometric delays forecast model of Time Continuous；The step is specifically included：
Step 201：Above-mentioned steps 1 are calculated into each antenna and predict value list with regard to the geometric delays of the earth's core reference point
τi(tj) read in, according to the kinetic characteristic of observed object, M segmentations being divided into above-mentioned prediction value list, M is natural number.Correspond to
In stating calculated examples, Miyun station in table and Station in Kunming latency prediction value are read in, and be segmented with 60 second time.
Step 202：Using method of least square, fitting of a polynomial is carried out to above-mentioned one section of predictive value, obtain multinomial model
y。
In corresponding to above-mentioned calculated examples, with reference to detector motion characteristic and through the assessment of multiple fitting precision, 5 are adopted
Rank multinomial carries out least square fitting, disclosure satisfy that follow-up calculating requires.The multinomial model for obtaining is：
Y=6212.21513+0.110956058X+ (- 1.236351374e-05X2)+(-3.101422866e-10X3)+
(3.286324942e-12X4)+(-1.306814583e-14X5)。
Step 203：Assessment multinomial model y fitting precision, fitting precision meets requirement, obtains latency prediction model.
Error of fitting RMS needs to be less thanF is observation signal frequency, and unit is Hz.If precision meets required,
Then this group of multinomial coefficient can be as the forecast model of the antenna, if fitting precision is unsatisfactory for requiring, return to step 201,
Adjustment segmentation increases polynomial order, re-starts fitting, requires until fitting precision meets, the M group multinomial coefficients
Can be used as the forecast model of the antenna.Then successively above-mentioned models fitting work is carried out to all of antenna, obtains whole different
The forecast model of ground antenna array.
In corresponding to above-mentioned calculated examples, multinomial model y=6212.21513+0.110956058X+ (-
1.236351374e-05X2)+(-3.101422866e-10X3)+(3.286324942e-12X4)+(-1.306814583e-
14X5) error of fitting RMS=2.862e-07us, it is root-mean-square error.The error of fitting is by formulaTry to achieve, y in formulajMultinomial model y is represented as X=j moment values, τ0(j), τ1(j) correspondence geometric delays
The geometric delays value of calculation at Miyun station and Station in Kunming j moment in result of calculation table.
The model calculation value for being illustrated in figure 4 a kind of specific embodiment of the present invention is contrasted with fitting of a polynomial value, transverse axis
For the time, the longitudinal axis is time delay, has been described in conjunction with the embodiments fitting of a polynomial value and model calculation value error very little, it is possible to use intended
Conjunction obtains multinomial model as Time Delay Model.
Step 3：Residual error is searched for, and is to carry out preliminary time delay and time delay to antenna array observation data using above-mentioned forecast model
Rate is compensated, and then cross correlation process is carried out to antenna data using cross-correlation method, to residual between time delay true value and predictive value
Difference is scanned for；The step is specifically included：
Step 301：The maximum antenna of antenna array medium caliber is chosen as reference antenna, in selecting step 203 antenna is obtained
1 latency prediction model value of battle array deducts the forecast model value of reference antenna, obtain other antennas relative to reference antenna when
Prolong difference forecast model y (i, tj)。
In corresponding to above-mentioned calculated examples, 50 meters of station of Miyun aperture antenna is chosen as reference antenna,
Step 302：Read in reference antenna observation data OR(tj) and battle array in other antenna observe data Oi(tj), go
Except the DC component of observation data, Oa R(tj), Oa i(tj) obtain.
In corresponding to above-mentioned calculated examples, as a example by reference antenna, the record data of one section of Miyun station antenna is read respectively
OR(tj), ask for the meansigma methodss (DC component) of this segment dataThen by this segment record data OR
(tj) deductObtain Oa R(tj), the process of other antennas the like.
Step 303：From Oa R(tj) 2 are taken in datanIndividual data, delay inequality value prediction model y obtained using step 301
(i, tj) to observing data Oa i(tj) carry out delay compensation and the compensation of time delay rate, 2 after being compensatednIndividual data [Oa i(tj- y (i,
tj))]。
In corresponding to above-mentioned calculated examples, it is assumed that first from Oa R(tj) in take 256 data, then take forecast model tj=0,
Obtain the latency prediction value τ=6.21221513e-03s at the moment, time delay rate predictive valueBy
In the sampling rate of antenna record data be 1e+07, the sampling time Ts=1e-07s of this each data, that delay compensation number
According to digit=τ/1e-7=62122, delay compensation is carried out to another antenna data, it is necessary to which the identical record moment jumps backward
Cross time delay offset data digit, read 256 data of data, this data just with 256 data integer-bits of reference antenna
Alignment, alignment error is less than a sampling Ts.
Then, then to this segment data carry out Doppler shift compensation.
Step 304：Respectively to Oa R(tj), [Oa i(tj- y (i, tj))] fast fourier transform is carried out, and cross-correlation is carried out,
Obtain cross-correlation frequency spectrum fft (OR a(tj))×fft*([Oa i(tj- y (i, tj))])；Seek cross-correlation frequency spectrum fft (OR a(tj))×
fft*([Oa i(tj- y (i, tj))]) phase value, then phase value solution is wound, it is then bent to phase place using least square method
Line carries out once linear Function Fitting, obtain this 2nThe remaining time delay Δ τ of individual data1。
Step 305：Remove 2nIndividual data, equally carry out above-mentioned 304 step and calculate, and obtain the remaining time delay of lower 2n data
Δτ2, it is calculated time delay rate
Step 306：The remaining time delay Δ τ that above-mentioned search is obtained1With time delay rateIt is added to corresponding geometric delays prediction
Y (i, tj) in, you can obtain the true Time Delay Model for being available for subsequent antenna group battle array data processing to use.
Correspond to Δ τ in the present embodiment1=5e-7s,So true Time Delay Model
Computing to being left M-1 groups Data duplication step 201 to step 306, you can obtain all observation data of the antenna
Corresponding true Time Delay Model.
Above-mentioned steps 101 are carried out to step 306 all operations to remaining other antennas in antenna array, it is possible to obtain institute
There is the corresponding true Time Delay Model of antenna observation data.
In corresponding to above-mentioned calculated examples, two station data are carried out with preliminary time delay and the correction of time delay rate, it is right after the completion of correction
Two station data carry out cross correlation process, obtain cross-correlation coefficient, related streak as shown in Figure 5 and Figure 6.
A kind of cross-correlation coefficient figure of the presence time delay of specific embodiment of the present invention is illustrated in figure 5, transverse axis is the time,
The longitudinal axis is cross-correlation coefficient amplitude, has been described in conjunction with the embodiments because remaining time delay is present, and the maximum of cross-correlation coefficient does not have
, there is certain deviation in time of occurrence zero point.
A kind of cross-correlation interference fringe picture of the presence remnants time delay rates of specific embodiment of the present invention is illustrated in figure 6,
Transverse axis is the time, and the longitudinal axis is cross-correlation interference fringe phase place, has been described in conjunction with the embodiments because remaining time delay rate is present, cross-correlation
Interference fringe phase slope is not zero.
From cross correlation results as can be seen that because the estimated value of model has certain error, correlation coefficient and related frequency
There is certain deviation in the phase place of spectrum, this deviation is exactly between model time delay value and true time delay with preferable autocorrelation spectrum
Residual error.Estimate to obtain remaining time delay for 5e-7s by further time delay and time delay rate, time delay rate 4.11e-11s/s.
The cross-correlation coefficient figure being illustrated in figure 7 after a kind of remaining delay compensation of specific embodiment of the present invention, transverse axis
For the time, the longitudinal axis is cross-correlation coefficient amplitude, has been described in conjunction with the embodiments due to being compensated remaining time delay, cross correlation
Several maximums occur in time zero.
Be illustrated in figure 8 the cross-correlation interference fringe picture of remaining time delay rate compensation, transverse axis for when ask, the longitudinal axis is dry for cross-correlation
Fringe phase is related to, has been described in conjunction with the embodiments due to being compensated remaining time delay rate, cross-correlation interference fringe phase slope
It is substantially zeroed.
Cross-correlation phase frequency spectrum figure before fractional delay adjustment is illustrated in figure 9, transverse axis is frequency, and the longitudinal axis is phase place, with reference to
Embodiment illustrates that phase slope is not zero in cross-correlation phase frequency spectrum figure due to the presence of fractional bits time delay.
It is as shown in Figure 10 the cross-correlation phase frequency spectrum figure after fractional delay adjustment, transverse axis is frequency, and the longitudinal axis is phase place, knot
Close embodiment and illustrate that due to compensating to fractional bits time delay phase slope is substantially zeroed in cross-correlation phase frequency spectrum figure.
From cross correlation results as can be seen that cross-correlation coefficient, striped and phase spectrum are consistent with preferable autocorrelation spectrum.
The time delay and time delay rate method for fast searching of the present invention introduces the forecast model of time delay and time delay rate, to time delay and
The hunting zone of time delay rate has carried out effective restriction, the search efficiency of cross correlation process is greatly improved, such that it is able to quick
The time delay of each antenna and time delay rate value in the antenna array of strange land are obtained, for follow-up antenna array data processing support is provided.
Particular embodiments described above, has been carried out further in detail to the purpose of the present invention, technical scheme and beneficial effect
Describe in detail bright, it should be understood that the foregoing is only the specific embodiment of the present invention, be not limited to the present invention, it is all
Within the spirit and principles in the present invention, any modification, equivalent substitution and improvements done etc. should be included in the protection of the present invention
Within the scope of.
Claims (8)
1. a kind of time delay and time delay rate method for fast searching based on forecast model, it is characterised in that comprise the steps：
Step 1：According to aerial position and Observed Position, primary Calculation goes out observed object to the latency prediction between antenna
Value；
Step 2：Least square models fitting is carried out to calculated latency prediction value, the latency prediction mould of Time Continuous is obtained
Type；
Step 3：Observing antenna array data using the latency prediction model for obtaining carries out preliminary time delay and the compensation of time delay rate, so
Afterwards cross correlation process is carried out to antenna data using cross-correlation method, the residual error between time delay true value and latency prediction value is carried out
Search.
2. the time delay and time delay rate method for fast searching based on forecast model according to claim 1, it is characterised in that institute
Stating step 1 includes：
Step 101：Read each antenna geographical coordinate (x in observed object tracking listed files (t, ra, dec) and strange land battle arrayi,
yi, zi), wherein (t, ra, dec) is represented in t, the right ascension and declination value of observed object；(xi, yi, zi) represent terrestrial space
Each aerial position in rectangular coordinate system, subscript i is used for distinguishing different antennas, there is N number of antenna in battle array, then have N group (xi,
yi, zi), i takes 0,1...N-1；
Step 102：It is pre- to the geometric delays of antenna and reference point according to classical celestial body time-delay calculation method calculating observation target
Measured value.
3. the time delay and time delay rate method for fast searching based on forecast model according to claim 2, it is characterised in that step
Classical celestial body time-delay calculation method includes described in rapid 102：
Step A1：Input survey station coordinate and detector position；
Step A2：The survey station local coordinate system error that amendment is caused by tide, plate motion etc.；
Step A3：The earth's core terrestrial coordinate system is transformed into into the earth's core celestial coordinate system；
Step A4：The earth's core celestial coordinate system is transformed to by solar system barycenter celestial coordinate system by Lorentz transformation, in the solar system
Geometric delays are calculated in barycenter celestial coordinate system, and corrects the signal transmission path bending error that solar system gravitating is caused；
Step A5：Solar system barycenter celestial coordinate system is switched back to by the earth's core celestial coordinate system by Lorentz transformation, obtains required
Geometric delays predictive value.
4. the time delay and time delay rate method for fast searching based on forecast model according to claim 1, it is characterised in that institute
Stating step 2 includes：
Step 201：By each antenna for obtaining with regard to the earth's core reference point geometric delays predictive value τi(tj) read in, according to observation
The kinetic characteristic of target, M segmentations are divided into above-mentioned prediction value list, and M is natural number；
Step 202：Using method of least square, fitting of a polynomial is carried out to above-mentioned one section of predictive value, obtain multinomial model y；
Step 203：Assessment multinomial model y fitting precision, fitting precision meets requirement, obtains latency prediction model.
5. the time delay and time delay rate method for fast searching based on forecast model according to claim 4, it is characterised in that step
Method of least square carries out least square fitting using 5 rank multinomials described in rapid 202.
6. the time delay and time delay rate method for fast searching based on forecast model according to claim 4, it is characterised in that institute
Stating step 203 includes：
According to formulaAn algnment accuracy is calculated, f is observation signal frequency, and unit is Hz；Error of fitting is logical
Cross formulaTry to achieve, y in formulajMultinomial model y is represented as X=j moment values, τ0(j), τ1J () correspondence is several
When the geometric delays value of calculation in result of calculation table Miyun station and Station in Kunming j moment is prolonged, and n represents the individual of each piecewise prediction value
Number；Error of fitting RMS is needed less than algnment accuracy；If precision meets required, this group of multinomial coefficient can be used as the day
The latency prediction model of line, if fitting precision is unsatisfactory for requiring, return to step 201, adjustment is segmented or increases order of a polynomial
Number, re-starts fitting, requires until fitting precision meets.
7. the time delay and time delay rate method for fast searching based on forecast model according to claim 1, it is characterised in that step
Residual error described in rapid 3 between time delay true value and latency prediction value includes remaining time delay and remaining time delay rate.
8. the time delay and time delay rate method for fast searching based on forecast model according to claim 1, it is characterised in that institute
Stating step 3 includes：
Step 301：The maximum antenna of antenna array medium caliber is chosen as reference antenna, the 1 of antenna array is obtained in selecting step 203
Individual latency prediction model value deducts the forecast model value of reference antenna, obtains time delay difference of other antennas relative to reference antenna
Forecast model y (i, tj)；
Step 302：Read in reference antenna observation data OR(tj) and battle array in other antenna observe data Oi(tj), remove observation
The DC component of data, obtains Oa R(tj), Oa i(tj)；
Step 303：From Oa R(tj) 2 are taken in datanIndividual data, delay inequality value prediction model y (i, the t obtained using step 301j)
To observing data Oa i(tj) carry out delay compensation and the compensation of time delay rate, 2 after being compensatednIndividual data [Oa i(tj- y (i, tj))]；
Step 304：Respectively to Oa R(tj), [Oa i(tj- y (i, tj))] ' fast fourier transform is carried out, and cross-correlation is carried out, obtain
Cross-correlation frequency spectrum fft (OR a(tj))×fft*([Oa i(tj- y (i, tj))]′)；Seek cross-correlation frequency spectrum fft (OR a(tj))×fft*
([Oa i(tj- y (i, tj))] ') phase value, then to phase value solution wind, then using least square method to phase curve
Carry out once linear Function Fitting, obtain this 2nThe remaining time delay △ τ of individual data1；
Step 305：Remove 2nIndividual data, equally carry out above-mentioned 304 step and calculate, and obtain down 2nThe remaining time delay △ τ of individual data2,
It is calculated time delay rate
Step 306：The remaining time delay △ τ that above-mentioned search is obtained1With time delay rateIt is added to corresponding delay inequality value prediction model y
(i, tj) in, you can obtain the true Time Delay Model for being available for subsequent antenna group battle array data processing to use.
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