CN105301605B - A kind of navigation anti-interference method based on difference beam - Google Patents
A kind of navigation anti-interference method based on difference beam Download PDFInfo
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- CN105301605B CN105301605B CN201510594954.4A CN201510594954A CN105301605B CN 105301605 B CN105301605 B CN 105301605B CN 201510594954 A CN201510594954 A CN 201510594954A CN 105301605 B CN105301605 B CN 105301605B
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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
- G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
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- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
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Abstract
The present invention provides a kind of navigation anti-interference methods based on difference beam, and steering vector is constructed using aeronautical satellite location information, and array antenna received signals are carried out using the steering vector and difference is handled, array pattern is made to be directed toward satellite-signal direction.Signal after Beam synthesis enters the adaptive-filtering processing that DLMS algoritic modules carry out space-time two-dimensional, because array antenna is directed toward navigation satellite signal position, therefore useful satellite-signal does not lose, interference signal is inhibited under conditions of useful signal is not lost, the level of the output signal-noise ratio after adaptive-filtering can be significantly improved.
Description
Technical field
The present invention relates to Anti-Jamming Techniques, more particularly to satellite navigation Anti-Jamming Technique.
Background technology
In existing navigation system, navigation signal is highly prone to the interference of outer signals, either artificial deliberately interference
Or the interference of ambient noise, the presence of interference signal can cause the high-precision having originally, the navigation signal of stabilization to reduce it
Effect in addition it is entirely ineffective, this for as aircraft etc., some are deathblows for the very necessary equipment of navigation information,
Therefore anti-interference be obtained in military and civilian field of navigation signal is widely applied.It can resist enemy people in military affairs
For intentional signal interference, play an important role in terms of precise guidance；And in civil field, it can be used for stablizing to visitor
Satellite communication of machine etc..
Anti-interference simple and classical solution is exactly adaptive-filtering, i.e. adaptive nulling technology.It is mainly
Adjust the weight vector of sef-adapting filter so that response of the wave filter on interference radiating way is zero, so as to allow reception system can not
Interference signal is received, achievees the purpose that inhibit interference.Adaptive nulling technology can realize adaptive filtering on spatial domain, according to
The variation of external signal environment automatically adjusts the weighting coefficient of each array element in antenna array, is ensureing except the day on interference radiating way
Line directional diagram is kept on the basis of omnidirectional so that null alignment interference signal direction.Adaptive nulling technology mainly has spatial domain filter
Ripple and space-time filtering are (see document：Xiao-bo Y.An Improved GPS Receiver Anti-jammer Algorithm
Based on Space-time Adaptive Processing[C]//Computer Distributed Control and
Intelligent Environmental Monitoring(CDCIEM),2012International Conference
on.IEEE,2012:What 106-109.), no matter filtering technique to realize anti-interference using, it is required for obtaining each antenna array
The weighted value of member.
Adaptive beamformer determined by different criterions it is adaptive weighted, and using different adaptive algorithms come
It realizes.Main criterion has：Least mean-square error MSE criterions；Maximum signal to noise ratio SNR criterions；Maximum likelihood ratio LH criterions；It is minimum
Noise variance NV criterions etc..All it is to use certain algorithm adjustment array beam directional diagram no matter which type of criterion selected, from
And realize self adaptive control.Wherein, there are the HA algorithms that Howells et al. is proposed according to maximum output signal-to-noise ratio criterion；Reed etc.
The SMI algorithms of proposition and it is usually used in the jamproof Power-inversion algorithm of satellite communication (see document：Lu Dan, Wu Renbiao, Wang Lei
A kind of general GPS multiple kinds of interference suppression method [J] signal processings, 2010,26 (5):682-686.).Power-inversion algorithm exists
It is simple among realization, and the orientation angles information of interference and satellite is required no knowledge about, therefore it is frequently utilized for actual satellite-signal
Among anti-interference.But traditional power inversion anti-interference method is inhibiting interference signal because without any prior information
While, useful satellite-signal can be inhibited, so as to which the power of satellite-signal can be greatly reduced.Evaluate adaptive nulling
The good and bad key index of algorithm is the signal-to-noise ratio for exporting signal after adaptive nulling.The signal-to-noise ratio has reacted adaptive nulling
The antijamming capability of algorithm.The key of anti-interference research so the signal-to-noise ratio for how carrying high output signal always navigates.
The content of the invention
The present invention is to solve above-mentioned technical problem the technical scheme adopted is that be directed in existing anti-interference method, because defending
Star pickup electrode is weak and influences the problem of system normal navigation works, and provides a kind of enhancing useful signal intensity, improves output letter
Make an uproar than navigation anti-interference method.
The present invention to solve above-mentioned technical problem the technical scheme adopted is that a kind of navigation based on difference beam resist it is dry
Method is disturbed, is comprised the following steps:
Step a. constructs steering vector using the location information of aeronautical satellite；
Step b. control array antennas are directed toward angle where aeronautical satellite, and four-element array antenna is connect using steering vector
The signal received carries out and difference beam synthesis, obtains and signal and difference signal；
Step c. carries out difference signal adaptive using, as reference signal, being realized with signal using the DLMS of Power-inversion algorithm
It should filter.
The present invention constructs steering vector using aeronautical satellite location information, and array antenna received is believed using the steering vector
It number carries out and difference processing, array pattern is made to be directed toward satellite-signal direction.Signal after Beam synthesis enters DLMS algorithm moulds
Block carries out the adaptive-filtering processing of space-time two-dimensional, because array antenna is directed toward navigation satellite signal position, therefore useful satellite-signal
It does not lose, interference signal is inhibited under conditions of useful signal is not lost, after adaptive-filtering being significantly improved
Output signal-noise ratio is horizontal.
The invention has the advantages that carrying out Beam synthesis to the useful navigation signal that array antenna receives, improve and connect
The power of the collection of letters number, while angle where array antenna direction aeronautical satellite does not influence the jamproof effect in rear end, improves anti-
Disturb the signal-to-noise ratio of output.
Description of the drawings
Fig. 1 compares for jamproof system simulation result of the present invention.
Specific embodiment
Aeronautical satellite is exactly to need the target satellite being directed toward in the present invention.Navigation jamproof system front end array antenna form
Can be arbitrary, such as uniform circular array, linear array.Embodiment is arranged in the case of quaternary antenna array, for four array elements, is resisted dry
The spatial domain degree of freedom for disturbing system is 3, while Anti-interference algorithm uses space-time two-dimensional Combined Treatment, can be in frequency domain and spatial domain to dry
Signal is disturbed to be inhibited, therefore the system is at best able to inhibit the interference signal in 3 directions, interference signal form can be that single-frequency is done
It disturbs or broadband interference.
The difference beam navigation anti-disturbance method of jamproof system is as follows：
A. steering vector is solved according to aeronautical satellite location information
Using the location information (pitch angle of aeronautical satellite and azimuth) of aeronautical satellite as prior information, if incidence wave arrives
Up to array element time than the time lead (bear for hysteresis) of reference point (a certain array element or a certain fixed coordinate points), i.e. m
A array element compared with reference point delay τmFor：
Wherein, θ represent aeronautical satellite pitch angle,Represent that the azimuth of aeronautical satellite, m are array element label, xmRepresent the
Abscissa, y of the m array element compared with reference pointmRepresent ordinate of m-th of the array element compared with reference point, c represents the light velocity；
For narrow band signal, corresponding signal phase shift is
Wherein, λ is reception signal wavelength.
So the steering vector of 4 array element arrays can be expressed as：
The location information for predicting aeronautical satellite is converted into steering vector and is related to triangulo operation.According to coordinate rotation number
Word calculates cordic algorithm, and operation time is too long, is unsatisfactory for requirement of real-time.Arrow is oriented to it is therefore preferable that being calculated using look-up table
Amount first stores the corresponding steering vector value of each orientation angles with ROM, and when anti-interference process need to only search according to angle value to be corresponded to
Value.First according to the requirement of orientation angle precision, the pitch angle in entire spatial domain is divided into M parts, azimuth is divided into N,
It is provided by Array ModelComputational methods, each angle is correspondingValue is calculated by Matlab
It arrives, then establishes corresponding ROM tables in programmable gate array FPGA at the scene, interface is external given satellite angle information, i.e.,
The exportable steering vector value to be calculated.
B. using steering vector to array signal carry out and it is poor
Assuming that navigation satellite signal s0(n) fromDirection is incident, wherein θ0For pitch angle,For azimuth, arrow is oriented to
Amount is expressed asThe signal phasor x that then antenna receives in aeronautical satellite direction0(n) it is
It is with channel signal
Wherein ()HFor conjugate transposition, x (n) is the signal phasor of array antenna received.
Poor channel signal is
Wherein, subscript (i+1) represents the i+1 element of steering vector, and * is conjugate of symbol.Steering vector is believed with input
Number multiplication is completed using multiplier, synchronous for ease of signal, and multiplier uses pipeline organization, that is, adds in latch.It is meanwhile right
Four road signals carry out delay process, ensure that signal stream is synchronous.
Pair c. and difference signal carries out least-mean-square error algorithm LMS adaptive-filterings
Common 1 iteration of LMS algorithm needs to do 2 multiplication and 1 sub-addition, i.e. critical path is 2 multiplication, 1 sub-addition.
According to combinational logic computing, the attainable clock frequency of FPGA system institute can be influenced, system throughput is caused to be adopted less than system
Sample rate, is unsatisfactory for requirement of real-time.Therefore DLMS algorithms is used to realize LMS iteration.The thought of DLMS is to increase latch to shorten
Critical path meets the requirements system throughput.It is respectively D1, D2 to make the delay of add tree and multiplication tree, then iterative process：
WhereinFor the sef-adapting filter weights at n+1 moment,For the adaptive weight at n moment, μ is repeatedly
It rides instead of walk length, u (n) is the input vector at n moment, D1For addition time total delay, D2It is always delayed for the multiplication time.
In weights iterative process, desired signal is the 5th road signal.The road filter weights are always 1, ensure that wave beam begins
Orientation where being directed toward target eventually.
Fig. 1 give Beam synthesis and not by Beam synthesis it is anti-interference after result after matched filtering.
Signal-to-noise ratio is 32.88dB after matched filtering in Fig. 1 a, and signal-to-noise ratio is 27.73dB after matched filtering in Fig. 1 b, is
Matched filtering after anti-interference does not have as a result, will become apparent from the signal strength with Beam synthesis matched filtering result after anti-interference and be higher than
The anti-interference rear matched filtering of Beam synthesis is as a result, under conditions of dry make an uproar than for 60dB, and Beam synthesis Anti-interference algorithm is not only
It can realize anti-jamming effectiveness (matched filtering has signal output), moreover it is possible to significantly improve output signal-to-noise ratio.
Claims (3)
1. a kind of navigation anti-interference method based on difference beam, which is characterized in that comprise the following steps:
Step a. obtains steering vector using the location information of aeronautical satellite；
Step b. control array antennas are directed toward angle where aeronautical satellite, and four-element array antenna is received using steering vector
Signal carry out and difference beam synthesis, obtain and signal and difference signal；
Step c. using Power-inversion algorithm DLMS, as reference signal, to be realized with signal and carry out adaptive-filtering to difference signal.
2. a kind of navigation anti-interference method based on difference beam as described in claim 1, which is characterized in that utilize aeronautical satellite
Location information obtain the concrete mode of steering vector and be：
M-th of array element compared with reference point delay τmFor：
Wherein, θ represent aeronautical satellite pitch angle,Represent that the azimuth of aeronautical satellite, m are array element label, xmIt represents m-th
Abscissa, y of the array element compared with reference pointmRepresent ordinate of m-th of the array element compared with reference point, c represents the light velocity；
M-th of array element receives signal phase shiftFor：
Wherein, for λ to receive signal wavelength, W represents array element sum；
The steering vector of array element arrayFor：
3. a kind of navigation anti-interference method based on difference beam as described in claim 1, which is characterized in that utilize aeronautical satellite
Location information steering vector is obtained by look-up table.
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