CN109633698A - Based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method - Google Patents
Based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/22—Multipath-related issues
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/35—Constructional details or hardware or software details of the signal processing chain
- G01S19/37—Hardware or software details of the signal processing chain
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/40—Correcting position, velocity or attitude
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Abstract
The invention discloses a kind of based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method, it include: that pseudolite receiver receives the composite signal formed by direct signal and multipath signal that pseudo satellite, pseudolite is sent, and composite signal high frequency signal frequency reducing is obtained intermediate frequency composite signal；It is divided into I and Q two paths of signals, by adjusting symbol width early caused by local digital controlled oscillator, late and between punctual signal, the pseudo satellite, pseudolite carrier wave composite signal received is tracked, the pseudorange, carrier wave and carrier-to-noise ratio for measuring pseudo satellite, pseudolite to receiver are tracked by delay-locked loop；Pseudo satellite, pseudolite list difference and double difference observation equation after establishing linearisation；Observation error equation and status predication equation are obtained based on adaptive filtering principle, state vector is calculated and tests rear covariance matrix, observation equivalent matrice, adaptive factor and observation equivalent weight matrix are adjusted according to carrier-to-noise ratio, different filter solutions is acquired and exports pseudolite receiver position.Influence of the multipath error to pseudolite positioning precision can be effectively reduced in the present invention, and the influence for positioning multipath error to pseudorange is below meter level.
Description
Technical field
The present invention relates to based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method, belongs to satellite and lead
Boat field of locating technology.
Background technique
In recent years, pseudo satellite technology had at home and abroad obtained extensive research, similar to GNSS satellite, and pseudo satellite, pseudolite utilizes
The time parameter of signal is positioned, and as pseudo satellite, pseudolite application prospect is known, will have more scholars to carry out pseudo satellite, pseudolite
Further investigation.Over nearly twenties years, pseudo satellite, pseudolite is used for many fields by people, such as the deformation detection of dam and bridge, high speed
Train is tracked, and the positioning etc. in mars exploration and subterranean tunnel has scholar to propose pseudo satellite, pseudolite being used for indoor positioning recently, real
Existing high-precision indoor positioning target, the technology have unlimited potentiality.
It will appear many new problems, multipath effect, near-far interference and time synchronization etc. in pseudo satellite, pseudolite application.Its
In, multipath effect is due to caused by the multipath propagation of satellite-signal, i.e., receiver antenna receives in receive process
Not just ground wave signal, there are also one or many reflection wave signals of the various media of surrounding.These signals and directly propagation
The signal that comes over generates interference so that observation deviates true value, so as to cause interference time delay effect be referred to as multipath effect.
As GNSS signal, multipath effect, Er Qiegeng also can inevitably occur in communication process in GNSS Pseudolite signal
Hardly possible is eliminated.
For GNSS satellite, the multipath component of transmission is typically small.Due to being arrived from GNSS reference station and receiver
The unit vector of a certain particular satellite is substantially the same, and differential technique can be used and directly eliminate multipath effect.Due to pseudo satellite, pseudolite
Position laying, signal strength, working environment etc. it is different from GNSS, it is more stronger than the Multipath Errors of GNSS signal, more
Complexity is also more difficult to eliminate, this is also an important factor for consideration in data processing.It studies and tests through domestic and foreign scholars, multipath
Effect has the feature that
1) GNSS multipath signal forms multipath interference signal, and Pseudolite signal typical from the surface of emission lower than antenna
Multipath effect be generally from the transmitting signal of the surface of emission formation higher than antenna, or even be also from pseudo satellite, pseudolite itself.Cause
This, receiver antenna can shield some multi-path jammings for GNSS signal, but cannot generally shield the more of Pseudolite signal
Diameter interference.
2) compared with GNSS, the elevation angle of receiver to pseudo satellite, pseudolite is smaller, therefore, the multipath effect from pseudo satellite, pseudolite than
GNSS signal is serious more.The low elevation angle (10 ° or 15 °) is usually removed in GNSS measurement, to be used to reduce multipath effect and ratio
More serious troposphere delay problem, and pseudo satellite, pseudolite cannot then do this technical treatment.
3) pseudo satellite, pseudolite is generally fixed to known location (accurately to measure in advance), so if receiver is also stationary
, its multipath effect will form the deviation for being not easy to eliminate.Unlike GNSS satellite signal, multipath effect is generally obtained
Averagely it is reduced to a certain degree.Pseudolite signal multipath error generally can not be by smoothly weakening.
4) pseudo satellite, pseudolite is normally at ground, and GNSS satellite is then located at space, therefore from the more of GNSS transmitting signal
Diameter effect is than being much smaller from pseudo satellite, pseudolite.Because space remote away means that any multipath effect is believed in transmitting
Slowly varying deviation can be generated during number, these multipath signals are on space observation point with height at certain correlation.
5) GNSS multipath error generally can be used as noise smoothing processing, and Huang Ding hair etc. is measured pseudo-code multipath and is about
10M, carrier phase multipath error are up to 1/4 wavelength, i.e. 5CM or so.And pseudo satellite, pseudolite multipath is far longer than above-mentioned value, maximum shadow
It rings value and does not have relatively good statistics also at present, under without fine disposition, ambiguity of carrier phase can not generally be consolidated
It is fixed.
Error size caused by multipath effect is determined by the characteristic of correlator and tracking lock ring in receiver.Mesh
Before, carrier phase multipath becomes the important errors source for restricting high-precision GNSS and pseudo satellite, pseudolite measurement or deformation monitoring.Multipath
Effect not only influences carrier observations, also influences carrier-to-noise ratio SNR, and the observed quantity is more sensitive to carrier phase multipath.
The method for solving Multipath Errors at present substantially can point three classes: one kind is to use some antenna skills that can inhibit multipath
Art, such as technology is positioned using choke coil, suppression diameter plate and multiple antennas；Second is that tracking ring, delay lock to receiver inside carrier
The improvement of ring performance and the adjustment of loop bandwidth, such as narrow the relevant technologies, leading edge detection technology；Third is that pseudorange, position field
Signal post-processing method carries out numerical analysis the representative are semi-parameter model method, using small echo in such method
Method, the spectral analysis method based on carrier-to-noise ratio.The resolving of these methods is all complex, and the wherein more difficult grasp of committed step.
Preceding two class is the angle from hardware design, the third is the angle from Data Post.
Summary of the invention
Technical problem to be solved by the present invention lies in pseudo satellite, pseudolite multipath seriously affects the positioning accuracy of receiver, usually
Will lead to receiver when ambient enviroment is more complicated can not track and then losing lock, and ambiguity of carrier phase can not fix,
The problem of can only resolving using pseudorange or float-solution when positioning, the advantage of pseudo satellite, pseudolite can not be played, one kind is provided and is based on
Narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method, weakens pseudo satellite, pseudolite multipath effect and observes pseudo satellite, pseudolite
The influence of value, to reach the target for improving positioning accuracy.
The present invention specifically uses following technical scheme to solve above-mentioned technical problem:
Based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method, comprising the following steps:
Pseudolite receiver receives the composite signal formed by direct signal and multipath signal that satellite is sent, and will synthesis
Signal high frequency signal frequency reducing obtains intermediate frequency composite signal；
The intermediate frequency composite signal that pseudolite receiver obtains is divided into I and Q two paths of signals, pair generated using local carrier
Calibration signal is tracked respectively, and is carried out related operation and obtained the alignment correlation in same phase channel；According to the alignment in same phase channel
The carrier wave that correlation and local digital controlled oscillator generate, measures the time delay estimation of intermediate frequency composite signal, and by delay-locked loop with
Track measures pseudo satellite, pseudolite to the pseudorange, carrier wave and carrier-to-noise ratio of pseudolite receiver；
According to the pseudorange, carrier wave and carrier-to-noise ratio of the pseudo satellite, pseudolite measured to pseudolite receiver, the puppet after establishing linearisation is defended
Star double difference observation equation, and carry out determining power to each observation in pseudo satellite, pseudolite double difference observation equation according to carrier-to-noise ratio；
The double difference observation equation of pseudo satellite, pseudolite after being weighed surely according to observation, based on the composition observation of adaptive filtering principle
Error equation and status predication equation；It is adjusted to obtain observation equivalent matrice according to the carrier-to-noise ratio of observation in observation error equation,
By adaptive factor and observation equivalent weight matrix, status predication equation, acquires different filter solutions and acquire and export puppet
Satellite receiver position.
Further, during as a preferred technical solution of the present invention, in the method, pseudolite receiver is obtained
Frequency composite signal, specifically:
Wherein, s (t) is the intermediate frequency composite signal after frequency reducing；M is multipath signal number；αiFor signal amplitude fading coefficients；
A is carrier amplitude；D (t) is navigation data information；c(t-τi) it is t- τiThe pseudo satellite, pseudolite spread-spectrum pseudorandom codes at moment；w0It is defended for puppet
The IF frequency of star direct signal；φiIt (t) is the phase of i-th of signal under moment t；τiFor the time delay of pseudo satellite, pseudolite non line of sight
Estimation.
Further, as a preferred technical solution of the present invention, in the method local carrier generate to definite message or answer
Number, specifically:
Wherein, pI(t) and pQ(t) it is respectively the mutually orthogonal registration signal in local that pseudolite receiver generates, when t is
It carves；ForThe pseudo satellite, pseudolite spread-spectrum pseudorandom codes at moment, whereinEstimate for the time delay of pseudo satellite, pseudolite direct signal；w0
For the IF frequency of pseudo satellite, pseudolite direct signal；Estimate for the carrier phase of pseudo satellite, pseudolite direct signal.
Further, carried out as a preferred technical solution of the present invention, in the method related operation obtain it is same
The alignment correlation IP in phase channel, specifically:
Wherein, M is multipath signal number；αiFor signal amplitude fading coefficients；R (τ) is the auto-correlation of electromagnetic wave spreading code
Function；Estimate for the time delay of pseudo satellite, pseudolite direct signal；τiEstimate for the time delay of pseudo satellite, pseudolite non line of sight；φiFor i-th of puppet
The carrier phase of satellite non line of sight is estimated；Estimate for the carrier phase of pseudo satellite, pseudolite direct signal.
Further, the pseudo satellite, pseudolite after linearisation is established as a preferred technical solution of the present invention, in the method
Single poor and double difference combination observation equation, specifically:
Wherein, εkFor pseudo satellite, pseudolite observation noise；AkFor observational equation coefficient matrix；LkFor observation vector；WithPoint
It Wei not tkAnd tk-1The state estimation vector at moment；Φk,k-1For state-transition matrix；δkFor state-noise.
The present invention by adopting the above technical scheme, can have the following technical effects:
Most important error is the influence of multidiameter in pseudolite positioning, the method for the present invention from base band signal process and after
Issue weaken according to fusion the research of multipath error, and base band signal process adjusts symbol width using the technology of narrow correlator difference
And track loop bandwidth, signal after treatment are output in data calculation module, are dropped using adaptive filtering technology
The weight of low multipath observation weakens influence of the multipath error to pseudolite positioning precision；The present invention is based on the carrier-to-noise ratios of signal
SNR can reflect signal quality, and when there is multipath effect generation, this period SNR value of upper satellite observation can be reduced accordingly, from
And the variation according to SNR value is proposed to weaken the method for multipath effect.
Therefore, influence of the multipath error to pseudolite positioning precision can be effectively reduced in the method for the present invention, make multipath error pair
The influence of pseudorange positioning is below meter level；Influence to carrier phase positioning is below Centimeter Level.
Detailed description of the invention
Fig. 1 is pseudo satellite, pseudolite indoor locating system structural schematic diagram of the present invention.
Fig. 2 is that the present invention is based on the principle signals of narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method
Figure.
Specific embodiment
Embodiments of the present invention are described with reference to the accompanying drawings of the specification.
The present invention devises a kind of based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method, the party
The system that method is used is as shown in Figure 1, include that software connects including hardware, softwares such as Pseudolite signal transmitter, radio receivers
Receipts machine SDR etc..
As shown in Fig. 2, the present invention is based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath methods, specifically
The following steps are included:
Step 1 carries out narrow correlation delay track loop.
Step 11, pseudolite receiver receive the composite signal formed by direct signal and multipath signal that satellite is sent,
And composite signal high frequency signal frequency reducing is obtained into intermediate frequency composite signal s (t), it can indicate are as follows:
Wherein, i=0 indicates pseudo satellite, pseudolite direct signal, and other is M multipath signal, and M is multipath signal number；αiFor letter
Number amplitude fading coefficient；A is carrier amplitude；D (t) is navigation data information；c(t-τi) it is t- τiThe pseudo satellite, pseudolite at moment spreads pseudo-
Random code；w0For the IF frequency of pseudo satellite, pseudolite direct signal, present embodiment assumes that direct signal and multi-path signal have it is identical
Frequency；φiIt (t) is the phase of i-th of signal under moment t；τiEstimate for the time delay of pseudo satellite, pseudolite non line of sight.
Multipath signal generally has certain time-delay, and amplitude has decaying relative to intracardiac signal (LOS), when multipath delay is small
When 2 symbol widths, multipath signal just has certain correlation with intracardiac signal, and otherwise, the influence of multipath signal can be ignored.
The intermediate frequency composite signal that pseudolite receiver obtains is divided into I and Q two paths of signals by step 12, using local carrier
The registration signal of generation is tracked respectively, and is carried out related operation and obtained the alignment correlation in same phase channel；It is communicated according to same
The tracking carrier wave that the alignment correlation and local digital controlled oscillator in road generate, measures the time delay estimation of intermediate frequency composite signal, and by
Delay-locked loop tracking measures pseudo satellite, pseudolite to the pseudorange, carrier wave and carrier-to-noise ratio of pseudolite receiver；It is specific as follows:
Assuming that local carrier correctly tracks the frequency for receiving signal, then locally generated registration signal may be expressed as:
Wherein, pI(t) and pQ(t) it is respectively the mutually orthogonal registration signal in local that pseudolite receiver generates, when t is
It carves；ForThe pseudo satellite, pseudolite spread-spectrum pseudorandom codes at moment, whereinEstimate for the time delay of pseudo satellite, pseudolite direct signal；w0
For the IF frequency of pseudo satellite, pseudolite direct signal；Estimate for the carrier phase of pseudo satellite, pseudolite direct signal.
Received signal, which carries out related operation with local signal, may be expressed as: with the alignment correlation in phase channel
In formula:Estimate for pseudo satellite, pseudolite direct signal time delay,Estimate for the carrier phase of pseudo satellite, pseudolite direct signal, φi
For the carrier phase estimation of i-th of pseudo satellite, pseudolite non line of sight；R (τ) is the auto-correlation function of electromagnetic wave spreading code, expression formula
Are as follows:
Wherein, TcFor the symbol width of pseudo satellite, pseudolite electromagnetic wave C/A code.
General GNSS receiver passes through correlation using alignment Prompt, advanced Early and lag tri- correlators of Late
Technology capture, tracking pseudo noise code, measure pseudo satellite, pseudolite direct signal time delay and are estimated as τ0, τ is then tracked by delay-locked loop0, into
And measure pseudo satellite, pseudolite to pseudolite receiver pseudorange.
The carrier phase tracking circuit of receiver is phase-locked loop pll, delay track loop DLL.I and Q be respectively with mutually and
Reverse phase energy signal, sin, cos signal are the carrier wave replica signal that carrier phase tracking circuit generates, and consider Doppler frequency shift
Carrier wave, E, L, P be respectively it is early, late and punctual signal caused by local digital controlled oscillator, required according to invention, local numerical control
Oscillator reduces the symbol width between E, L, P.The electromagnetic wave signal received, such as above-mentioned formula (1), by PLL, with local
The carrier multiplication of generation obtains baseband signal, and correlator sooner or later, the base after correlator withers solution sooner or later are admitted to after circuit stability
Band signal carries out code relevant calculation in delay track loop, that is, the signal after demodulating is multiplied with locally generated E, L, P respectively,
When the correlation maximum of Pseudolite signal and punctual code, show that the signal that receives in the time of spatial, and then is realized
The demodulation of pseudorange, the navigation message and carrier wave i.e. observation of output.Correlation output is compared by phase discriminator, current to control
The delay time of code or symbol, make the pseudo noise code of itself and next input signal match.For the bandwidth of receiver loop
Selection needs to consider two factors: needing loop bandwidth to narrow when by noise jamming to can be reduced noise
It influences, improves carrier-to-noise ratio；It needs that loop is made to broaden when being influenced by carriers of high dynamic to can be reduced Doppler frequency shift
Influence capture signal.The present invention according to the carrier-to-noise ratio size exported in loop can in real time adjustment loop bandwidth.Sooner or later
The design of correlator and phase discriminator, loop bandwidth plays critically important work to the elimination of multipath error and the tracking of signal
With.
The foundation of step 2, pseudo satellite, pseudolite combination observation model.Puppet of the satellite measured according to step 1 to pseudolite receiver
Away from the numerical value such as, carrier wave and carrier-to-noise ratio, pseudo satellite, pseudolite double difference observation equation after establishing linearisation, and it is double to pseudo satellite, pseudolite according to carrier-to-noise ratio
Each observation carries out determining power in poor observational equation；It is specific as follows:
Assuming that i-th of epoch, two observation station T1, T2 simultaneous observation to k pseudo satellite, pseudolite, the distance between two survey stations is less than 1km,
The reference star that the epoch is chosen is r, then the pseudo satellite, pseudolite list difference and double difference combination observation equation after linearizing are respectively formula (8) and formula
(9) shown in.
WhereinFor the phase value observed；For the distance of pseudolite receiver to pseudo satellite, pseudolite；λ is pseudo satellite, pseudolite carrier wave
Wavelength；tiFor pseudolite receiver clock deviation, tjThe clock deviation of pseudo satellite, pseudolite；MPi jFor pseudo satellite, pseudolite carrier wave multipath error；It is defended for puppet
Star tropospheric error；For receiver noise.
SD is single eikonal equation between station,For 1 and 2 survey station phase observations list differences；It is single poor for survey station distance；For single poor fuzziness；δt1,2It is poor for survey station receiver clock-offsets list；It is poor for multipath list；For troposphere list
Difference；For single poor noise.
Wherein, DD is double-difference equation between station,The double difference phase observation value of respectively the m pseudo satellite, pseudolite,For
Survey station is apart from double difference；For double difference fuzziness；For the poor tropospheric delay amount of list of jth pseudo satellite, pseudolite,
For the double difference Multipath Errors of the m pseudo satellite, pseudolite；For troposphere double difference；For double difference noise.(above equation is
It is reference station with 1,2 be rover station, and γ is reference satellite)
It is unfolded by Taylor's formula, error equation can be formed according to pseudo satellite, pseudolite double difference observation equation are as follows:
Wherein,Xr=
[ΔXr,ΔYr,ΔZr]TFor position vector matrix,For double difference fuzziness, L is scalar matrix,It is arrived for rover station
The distance of i-th satellite,For rover station initial value coordinate, xi、yi、ziFor the coordinate of i-th satellite,To see
Survey noise.
At this time, error equation can be established to double difference phase observation value, and then adjustment asks fixed according to the principle of least square
Basic lineal vector.For zonule (usual zone radius < 10km) short time (10-30min) static immobilization, by
Relatively fixed in pseudo satellite, pseudolite transmitting signal, baseline is shorter, it is believed that tropospheric delay errorIt is 0, without considering,
Multipath effectIt obeys and it is expected the not normal distribution for 0.However in actual observation, signal can in communication process
The mutation that contingency can occur, causes multipath effect not exclusively to obey above-mentioned distribution.Therefore, in data handling procedure,
In order to separate the carrier phase observable influenced by exceptional value, it is considered that: in [c ,-c], double difference observation equation residual error main body clothes
From normal distribution, (c takes twice of first verification certificate to the small part such as double difference observation containing distracter in [- ∞ ,-c] and [c ,+∞]
Position power in error) Normal Distribution and other distribution synthesis.
The determination of observation weight on known Ll, L2 carrier wave and their mean square deviation are inversely proportional, and multipath is more serious, carry
It makes an uproar than observation with regard to smaller, the mean square deviation of observation is bigger, and it can be by approximate equation:
Indicate the mean square deviation of the observation on Ll carrier wave, wherein B is the noise bandwidth of receiver phaselocked loop, c/n0To carry
It makes an uproar specific strength.Above formula shows: the size of pseudo satellite, pseudolite observation variance is connect by the carrier-to-noise ratio value SNR and pseudo satellite, pseudolite of the epoch observation
Bandwidth B in receipts machine determines.Due to pseudo satellite, pseudolite observation mean square deviation withIt is linear, so being defended for the same B value
Mean square deviation between star observation each epoch is than being that weight remains unchanged.Therefore the size of B value has no effect on same satellite and respectively goes through
Weight relationship between first observation can determine weight, the small observation of carrier-to-noise ratio to an observation according to the size of carrier-to-noise ratio
A smaller weight is assigned, the influence to positioning result is weakened.
Step 3, the fusion of adaptive robust.The double difference observation equation of pseudo satellite, pseudolite after being weighed surely according to observation, based on adaptive
Answer Robust filtering principle composition observation error equation and status predication equation；According to the carrier-to-noise ratio of observation in observation error equation
Adjustment obtains observation equivalent matrice, by adaptive factor and observation equivalent weight matrix, status predication equation, acquires different
Filter solution simultaneously acquires and exports pseudolite receiver position.It is specific as follows:
Using carrier wave and pseudorange double difference as observation model, such as above-mentioned formula (2).Filtering stochastic model use side of the invention
The observation of multipath error is regarded as observation that is, using multipath error as a part of stochastic model by poor inflationary model
Variance changes, but its mathematic expectaion is constant, convenient to change star, using coordinate vector and single poor fuzziness as state to be asked to
Amount, it is assumed that observe 7 pseudo satellite, pseudolites, using No. 2 stars as reference satellite, form double difference observation model, being seen by formula (10) can must see
Survey error equation and status predication equation:
In formula,WithRespectively tkAnd tk-1The state estimation vector at moment,
To demodulate the pseudorange obtained and carrier observations double difference value；
Φk,k-1For unit matrix；εkFor pseudo satellite, pseudolite observation noise；
LkFor observation vector；Φk,k-1For state-transition matrix；δkFor state-noise；
AkIt for double difference coefficient matrix, is acquired by formula (10), the adaptive filtering principle of building are as follows:
In formula,For observation vector LkCovariance matrix,SkActual measurement load to demodulate is made an uproar
Than αkFor adaptive factor, Xk|k-1For one-step prediction matrix, Pk|k-1For predicted state vector one-step prediction covariance matrix.Root
It is obtained after seeking extreme value according to condition least square:
In formula,For by the position of filtered pseudolite receiver, according to Inversion formula of matrix, above formula again can be with
Equivalence is write as:
WhereinFor equivalent gain matrix, specifically:
Wherein,
State vector tests rear covariance matrix are as follows:
With adaptive factor αkWith observation equivalent weight matrixDifference, available different filter solution, observation etc.
Valence matrixIt can be adjusted according to the carrier-to-noise ratio of observation, its principle is as shown in Figure 2.
After baseband signal and the processing of robust adaptive-filtering, the position of output receiver, by preliminary identification, data
Reliability and positioning accuracy have significant improvement, an order of magnitude can be improved in indoor positioning result.
Influence of the multipath data to positioning accuracy can be weakened in order to verify the method for the present invention, a verifying example is enumerated and carry out
Explanation.
Verifying example 1,
This verifying example is to rely on middle electric 54 pseudo satellite, pseudolite projects, by the pseudo satellite, pseudolite indoor locating system built,
As shown in Figure 1, research is unfolded in the Major Difficulties multipath effect around indoor positioning.According to the pseudo satellite, pseudolite experimental situation built,
Pseudolite signal is received using software receiver, is carried out by being adjusted in loop bandwidth and Data Post in base band signal process
Robust adaptively merges, and weakens influence of more neck effects to positioning.This verifying example process is divided into:
1, software receiver baseband signal processing in, using more correlators narrow correlator difference technology carry out signal with
Track, while according to the phase difference dynamic adjustment loop bandwidth in phase discriminator, the experiment proved that, it can effectively weaken Multipath Errors pair
The influence of accuracy of observation.
2, post-processing link is sent to after the signal decoding by base band signal process carry out the fusion of robust adaptive-filtering,
According to the weight of the carrier-to-noise ratio adjustment observation in observation data, finally by adaptive factor and observation equivalent weight matrix, state
Predictive equation acquires different filter solutions and acquires and export pseudolite receiver position, and multipath is reduced when resolving and is missed
The biggish observation weight of difference is to reach the influence for weakening multipath data to positioning accuracy.
To sum up, the method for the present invention proposes the variation according to SNR value to weaken the method for multipath effect, can be effectively reduced
Influence of the multipath error to pseudolite positioning precision, the influence for positioning multipath error to pseudorange is below meter level；To carrier wave phase
The influence of position positioning is below Centimeter Level.
Embodiments of the present invention are explained in detail above in conjunction with attached drawing, but the present invention is not limited to above-mentioned implementations
Mode within the knowledge of a person skilled in the art can also be without departing from the purpose of the present invention
It makes a variety of changes.
Claims (5)
1. based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method, which is characterized in that including following step
It is rapid:
Pseudolite receiver receives the composite signal formed by direct signal and multipath signal that satellite is sent, and by composite signal
High frequency signal frequency reducing obtains intermediate frequency composite signal；
The intermediate frequency composite signal that pseudolite receiver obtains is divided into I and Q two paths of signals, using local carrier generation to definite message or answer
It number is tracked respectively, and carries out related operation and obtain the alignment correlation in same phase channel；It is related according to the alignment in same phase channel
The tracking signal that value and local digital controlled oscillator generate, measures the time delay estimation of intermediate frequency composite signal, and by delay-locked loop with
Track measures pseudo satellite, pseudolite to the pseudorange, carrier wave and carrier-to-noise ratio of pseudolite receiver；
According to the pseudorange, carrier wave and carrier-to-noise ratio of the pseudo satellite, pseudolite measured to pseudolite receiver, the pseudo satellite, pseudolite after establishing linearisation is double
Poor observational equation, and carry out determining power to each observation in pseudo satellite, pseudolite double difference observation equation according to carrier-to-noise ratio；
The double difference observation equation of pseudo satellite, pseudolite after being weighed surely according to observation forms observation error based on adaptive filtering principle
Equation and status predication equation；It is adjusted to obtain observation equivalent matrice according to the carrier-to-noise ratio of observation in observation error equation, by certainly
Adaptation factor and observation equivalent weight matrix, status predication equation, acquire different filter solutions and acquire and export pseudo satellite, pseudolite
Receiver location.
2. special according to claim 1 based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method
Sign is, the intermediate frequency composite signal that pseudolite receiver obtains in the method, specifically:
Wherein, s (t) is the intermediate frequency composite signal after frequency reducing；M is multipath signal number；αiFor signal amplitude fading coefficients；A is to carry
Wave amplitude；D (t) is navigation data information；c(t-τi) it is t- τiThe pseudo satellite, pseudolite spread-spectrum pseudorandom codes at moment；w0It is through for pseudo satellite, pseudolite
The IF frequency of signal；φiIt (t) is the phase of i-th of signal under moment t；τiEstimate for the time delay of pseudo satellite, pseudolite non line of sight.
3. special according to claim 1 based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method
Sign is, the registration signal that local carrier generates in the method, specifically:
Wherein, pI(t) and pQ(t) it is respectively the mutually orthogonal registration signal in local that pseudolite receiver generates, t is the moment；ForThe pseudo satellite, pseudolite spread-spectrum pseudorandom codes at moment, whereinEstimate for the time delay of pseudo satellite, pseudolite direct signal；w0For puppet
The IF frequency of satellite direct signal；Estimate for the carrier phase of pseudo satellite, pseudolite direct signal.
4. special according to claim 1 based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method
Sign is, the alignment correlation IP in the same phase channel that related operation obtains is carried out in the method, specifically:
Wherein, M is multipath signal number；αiFor signal amplitude fading coefficients；R (τ) is the auto-correlation function of electromagnetic wave spreading code；Estimate for the time delay of pseudo satellite, pseudolite direct signal；τiEstimate for the time delay of pseudo satellite, pseudolite non line of sight；φiIt is non-for i-th of pseudo satellite, pseudolite
The carrier phase of direct signal is estimated；Estimate for the carrier phase of pseudo satellite, pseudolite direct signal.
5. special according to claim 1 based on narrow related and robust adaptive-filtering indoor pseudo satellite, pseudolite anti-multipath method
Sign is, carries out robust adaptive-filtering to pseudo satellite, pseudolite double difference observation equation according in the method, using formula:
Wherein, εkFor pseudo satellite, pseudolite observation noise；AkFor observational equation coefficient matrix；LkFor observation vector；WithRespectively tk
And tk-1The state estimation vector at moment；Φk,k-1For state-transition matrix；δkFor state-noise.
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