CN117008159A - Antenna anti-interference processing method and device - Google Patents
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Abstract
According to the antenna anti-interference processing method and device, after input data are processed based on a power inversion algorithm, the obtained reference array element is optimized, the input data are processed through the optimal reference array element obtained through screening, and therefore optimal anti-interference performance is obtained; and then, a first-stage filter is formed by a power inversion algorithm to inhibit interference, the signal-to-noise ratio of satellite signals is improved through relevant despreading, after a spatial feature vector of the satellite signals is estimated, the first-stage filter output signals are weighted through a second-stage filter based on the obtained spatial feature vector, and a main beam pointing to the direction is formed to further improve the carrier-to-noise ratio, so that satellite signal loss caused by interference inhibition is reduced, the carrier-to-noise ratio is improved, the tracking capacity of a receiver under a complex electromagnetic environment is improved, and the high-precision positioning effect is ensured.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to an anti-interference processing method and apparatus for an antenna.
Background
Currently, global navigation satellite systems such as beidou, GPS and GSNS (Galileo satellite navigation system ) have been widely used in various fields. However, with the continuous development of communication technology, the requirements on positioning accuracy are also increasing. At present, an anti-interference active antenna based on an antenna array has become an important means for resisting interference of satellite navigation at present. The basic principle of the antenna array for suppressing interference is to adjust the synthetic pattern of the antenna array, form nulls in the interference direction and attenuate the interference power. Array signals are processed in a variety of ways, including spatial filtering, space-time filtering, and space-frequency filtering. However, the existing processing method cannot be used for optimizing the reference array element, so that the optimal anti-interference performance cannot be obtained.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: the anti-interference processing method and device for the antenna are provided, and the anti-interference effect and the positioning accuracy are improved.
In order to solve the technical problems, the invention adopts the following technical scheme:
an anti-interference processing method for an antenna comprises the following steps:
acquiring input data, and processing the input data through a power inversion algorithm to obtain optimal array weight vectors corresponding to different reference array elements;
generating an input data matrix from the input data, and obtaining an output vector corresponding to each reference array element according to the optimal array weight vector corresponding to each reference array element and the input data matrix;
calculating a test statistic corresponding to each reference array element according to the output vector, and selecting the reference array element with the maximum test statistic as an optimal reference array element;
obtaining a first-stage filtering output signal corresponding to the input data matrix and a space feature vector according to the optimal reference array element;
and weighting the first-stage filtering output signal according to the spatial feature vector to obtain a filtering array output signal.
In order to solve the technical problems, the invention adopts the following technical scheme:
an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of an antenna anti-interference processing method as described above when the computer program is executed.
The invention has the beneficial effects that: after processing input data based on a power inversion algorithm, optimizing the obtained reference array element, and processing the input data through the optimal reference array element obtained by screening to obtain optimal anti-interference performance; the method comprises the steps of forming a first-stage filter by an optimal power inversion algorithm to inhibit interference, improving the signal-to-noise ratio of satellite signals through correlation despreading, estimating a spatial feature vector of the satellite signals, then carrying out weighting processing on output signals of the first-stage filter based on the obtained spatial feature vector through a second-stage filter, and forming a main beam pointing to the direction to further improve the carrier-to-noise ratio, so that satellite signal loss caused by interference inhibition is reduced, simultaneously, the carrier-to-noise ratio is improved, the tracking capability of a receiver in a complex electromagnetic environment is improved, and the high-precision positioning effect is ensured.
Drawings
Fig. 1 is a flowchart of steps of an anti-interference processing method for an antenna according to an embodiment of the present invention;
FIG. 2 is a block diagram of a GNSS antenna receiver in an antenna anti-interference processing method according to an embodiment of the present invention;
fig. 3 is a block diagram of a two-stage filtering algorithm in an anti-interference processing method for an antenna according to an embodiment of the present invention;
fig. 4 is a loop structure and a signal flow of a tracking channel of a receiver in an anti-interference processing method of an antenna according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an anti-interference processing device for an antenna according to an embodiment of the present invention.
Detailed Description
In order to describe the technical contents, the achieved objects and effects of the present invention in detail, the following description will be made with reference to the embodiments in conjunction with the accompanying drawings.
Referring to fig. 1, an antenna anti-interference processing method includes:
acquiring input data, and processing the input data through a power inversion algorithm to obtain optimal array weight vectors corresponding to different reference array elements;
generating an input data matrix from the input data, and obtaining an output vector corresponding to each reference array element according to the optimal array weight vector corresponding to each reference array element and the input data matrix;
calculating a test statistic corresponding to each reference array element according to the output vector, and selecting the reference array element with the maximum test statistic as an optimal reference array element;
obtaining a first-stage filtering output signal corresponding to the input data matrix and a space feature vector according to the optimal reference array element;
and weighting the first-stage filtering output signal according to the spatial feature vector to obtain a filtering array output signal.
From the above description, the beneficial effects of the invention are as follows: after processing input data based on a power inversion algorithm, optimizing the obtained reference array element, and processing the input data through the optimal reference array element obtained by screening to obtain optimal anti-interference performance of the antenna; the optimal power inversion algorithm forms a first-stage filter to inhibit interference, improves the signal-to-noise ratio of satellite signals through relevant despreading, carries out weighting processing on the output signals of the first-stage filter based on the obtained spatial feature vectors through a second-stage filter after estimating the spatial feature vectors of the satellite signals, and forms a main beam pointing to the direction to further improve the carrier-to-noise ratio, so that satellite signal loss caused by interference inhibition is reduced, the carrier-to-noise ratio is improved, the tracking capacity of a receiver in a complex electromagnetic environment is improved, and the high-precision positioning effect is ensured.
Further, the generating the input data into an input data matrix includes:
acquiring a preset data format;
and forming the input data into the input data matrix according to the data format.
As can be seen from the above description, the input data is formed into the input data matrix by the preset snapshot number, and the input data is processed in a matrix manner, so as to improve the data processing effect.
Further, the obtaining the output vector corresponding to each reference array element according to the optimal array weight vector corresponding to each reference array element and the input data matrix includes:
wherein y is (n) (t) is an output vector, and the superscript n indicates that the output vector is obtained by taking the nth array element as a reference array element;the optimal array weight vector corresponding to the nth reference array element; x (t) is the input data matrix.
From the above description, n array elements are selected as reference array elements to process the input data matrix, so as to realize effective array anti-interference processing on the input data and improve signal accuracy.
Further, the calculating the test statistic corresponding to each reference array element according to the output vector includes:
acquiring a local reference signal vector;
obtaining vector-related data according to the local reference signal vector and the output vector;
obtaining autocorrelation data corresponding to the output vector according to the output vector;
obtaining test statistics corresponding to the reference array elements according to the vector correlation data and the autocorrelation data, and specifically:
d(f,τ)＝[d(t-(K-1)T s ,f,τ),...,d(t-T,f,τ),d(t,f,τ)]；
wherein T (y) (n) ) Is a test statistic; gamma is a detection threshold, and the detection threshold is determined by a given false alarm probability;is autocorrelation data, is scalar; />Vector-related data, scalar; d (f, τ) represents the local reference signal vector, which is a K-dimensional row vector; wherein: d (t, f, τ) =p (t- τ) e j2πft P (t) is the pseudo code sequence of the satellite signal, f is the carrier Doppler frequency, and τ is the pseudo code phase.
As can be seen from the above description, the reference array element is preferably selected based on the generalized likelihood ratio test (Generalized Likelihood Ratio Test), so that the optimal reference array element can be effectively selected, and the optimal array output signal is output based on the optimal reference array element.
Further, the obtaining the first-stage filtering output signal and the spatial feature vector corresponding to the input data matrix according to the optimal reference array element includes:
wherein j is k (t) receiving interference signals for each path; c (C) n Is an N-dimensional column vector with 0 for all elements except for the nth element which is 1; r is R xx Is an autocorrelation covariance matrix of the signal; x (t) is an input data matrix;is a spatial feature vector;is the projected noise vector.
As can be seen from the above description, the first stage filtering is formed based on the power inversion algorithm to process the input initial array output signals, thereby improving the signal-to-noise ratio of the satellite signals through correlation despreading, and the spatial feature vector of the satellite signals is estimated for the second stage filtering process.
Further, the weighting the first stage filtered output signal according to the spatial feature vector to obtain a filtered array output signal includes:
constructing a local reference signal according to the first stage filtered output signal;
and obtaining a cross-correlation vector through the local reference signal and the first-stage filtering output signal, wherein the cross-correlation vector is specifically:
wherein,is the code phase; />Is Doppler frequency; />An initial carrier phase estimate;
correcting the space feature vector according to the cross correlation vector to obtain a weighted vector;
the array output signal is output through the weight vector and the first stage filtered output signal.
As can be seen from the above description,
after the first stage of filtering, although the interference is suppressed; however, since the satellite signals are submerged in noise before the relevant despreading, it is difficult to accurately estimate the projection guide vector of the satellite signals; the related despreading can bring the spreading gain, so that the signal to noise ratio of the signal is greatly improved, and therefore, the projection guide vector estimated after despreading is easier, and the second-stage filtering performs weighting processing on the first-stage filtering output signal based on the obtained spatial feature vector, so that the carrier to noise ratio can be effectively improved, the tracking capability of the receiver in a complex electromagnetic environment is further improved, and the high-precision positioning effect is ensured.
Further, the weighting processing is performed on the first stage filtering output signal according to the spatial feature vector, and after obtaining a filtering array output signal, the method further includes:
obtaining a baseband signal according to the output signal of the filter array;
demodulating the baseband signal to obtain the navigation message.
From the above description, it can be seen that, after the baseband signal is obtained based on the output signal of the filter array, the navigation message is obtained by demodulating the baseband signal, so as to achieve an accurate positioning effect.
Another embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor implements the steps in an antenna anti-interference processing method as described above when the computer program is executed.
The anti-interference processing method and device for the antenna can be applied to an anti-interference active antenna of an antenna array to improve the interference suppression performance of the antenna array, and the method and device are described in the following specific embodiments:
example 1
Referring to fig. 1, an antenna anti-interference processing method includes:
s1, acquiring input data, and processing the input data through a power inversion algorithm to obtain optimal array weight vectors corresponding to different reference array elements, wherein the optimal array weight vectors are specifically:
referring to fig. 2, in the field of satellite navigation anti-interference, a Power Inversion (PI) algorithm is one of the most widely used spatial filtering anti-interference techniques; as shown in fig. 2, after the GNSS spatial filtering input data quality is weighted and summed by the array vector, the final array output is obtained as follows:
in the method, in the process of the invention,w＝[w 1 ,w 2 ,...,w N ] H for N-dimensional array weight vectors, each row corresponds to the weight of one array element; the array weight vector is determined by the statistical characteristics of the input data vector and the adopted carding algorithm, and the optimization targets of different processing algorithms are different; the optimization objective of the PI algorithm is to minimize the output power of the array, in order to avoid the array weight vector from being hand-chained to the full solution zero, a certain element is usually selected as a reference element and the corresponding weight is fixed to be 1, and if the nth element is selected as the reference element, the optimization objective can be expressed as
Wherein, c n Is an N-dimensional column vector with 0 for all elements except for the nth element which is 1; the weight of the n-th array element is equal to 1, and w= [ w ] is adjusted 1 ,w 2 ,...,w n-1 ,w n+1 ,w N ] T Minimizing array output power; if not constrained, an unobjectionable solution w is obtained 1 ＝w 2 ＝...＝w N ＝0，R xx Is the autocorrelation covariance matrix of the signal.
Solving the above method to obtain the optimal array weight vector of the PI algorithm as follows
In the array weight vectorThe upper right-hand corner upper label n represents an n-th array element as a reference array element;it normalizes the array weight vector for complex constants, which will be ignored in practice since the multiplication or division of the array weight vector by a complex constant does not affect the array performance,the method comprises the following steps:
as can be seen from the formula, when the nth array element is selected as a reference, the array weight vector of the PI algorithm is equal to the nth column of the autocorrelation matrix; the signal quality of the array output can generally be estimated by signal-to-interference-and-noise ratio, which is defined as the ratio of signal power to interference-plus-noise power, i.e.:
wherein P is s Representing the power of satellite signals, P n And P j Respectively representing noise power and interference power.
S2, generating an input data matrix from the input data, and obtaining an output vector corresponding to each reference array element according to the optimal array weight vector corresponding to each reference array element and the input data matrix; because the traditional PI algorithm cannot optimize the reference array element, the optimal anti-interference performance cannot be obtained; for a GNSS antenna array receiver, signals enter a capturing stage after being subjected to array anti-interference processing, and the amplitude of a capturing correlation peak is directly determined by the signal-to-interference-and-noise ratio or equivalent carrier-to-noise ratio of the array signals; the higher the output signal-to-interference-and-noise ratio of the array is, the larger the corresponding capturing correlation peak is; thus(s)
Capturing a selection standard of which the correlation peak value is the maximum of the optimal reference array element through an optimal reference array element power inversion algorithm, so that optimal anti-interference performance cannot be obtained; the signal acquisition process is a binary hypothesis test problem for determining whether a satellite signal exists in received data, namely, in hypothesis (H0): no satellite signal is present in the received data, and the alternative assumption (H1): making a decision between satellite signals present in the received data; under two assumptions, the above problem is also a compound hypothesis testing problem, since parameters such as the pseudo code phase and the carrier doppler frequency of the satellite signal arriving at the receiver are unknown, and the probability density function of the received data is not completely known, specifically:
the generating the input data into an input data matrix includes: acquiring a preset data format; the input data is formed into the input data matrix according to the data format, for example, taking the snapshot number as a preset data format, if the snapshot number used at the capturing place is set to be K, the array input data matrix X (t) formed by the snapshots K can be expressed as:
X(t)＝[x(t-(K-1)T s ),...,x(t-T),x(t)]； (1.5)
wherein the matrix X (T) comprises N rows and K columns, T s Is the sampling period;
further, the output vector corresponding to each reference array element is obtained according to the optimal array weight vector corresponding to each reference array element and the input data matrix; that is, according to the above analysis, when the nth element is selected as the reference element, the output vector of the power inversion array after the anti-interference processing of the array may be expressed as:
wherein y is (n) (t) is an output vector, and the superscript n indicates that the output vector is obtained by taking the nth array element as a reference array element;and the optimal array weight vector corresponding to the nth reference array element.
S3, calculating test statistics corresponding to each reference array element according to the output vector, and selecting the reference array element with the maximum test statistics as an optimal reference array element, wherein the test statistics are specifically:
for an anti-interference active antenna of an antenna array, the acquisition processing is to an array vector y (n) (t) performing hypothesis testing; since GLRT (generalized likelihood ratio test ) is easy to implement and is strictly assumed to be small, it can be obtained according to the principle of GLRT in the present embodimentTo the GLRT detector is:
d(f,τ)＝[d(t-(K-1)T s ,f,τ),...,d(t-T,f,τ),d(t,f,τ)]； (1.9)
wherein T (y) (n) ) For test statistics, i.e., capturing correlation peaks; gamma is a detection threshold, and the detection threshold is determined by a given false alarm probability;for autocorrelation data (i.e., is an estimate of the array output vector autocorrelation function), as a scalar;vector correlation data (i.e., is an estimate of the cross-correlation between the array output vector and the local reference signal vector) is scalar; d (f, τ) represents a local reference signal vector consisting of K snapshots, which is a K-dimensional row vector; wherein: d (t, f, τ) =p (t- τ) e j2πft P (t) is a pseudo code sequence of a satellite signal, f is a carrier Doppler frequency, and tau is a pseudo code phase;
for different reference array elements, test statistics T (y (n) ) N=1, 2, N, then, T (y (n) ) Taking the maximum value to obtain a reference array element as an optimal reference array element, namely:
n opt ＝max T(y (n) )； (1.11)
s4, obtaining a first-stage filtering output signal corresponding to the input data matrix and a spatial feature vector according to the optimal reference array element; after obtaining the optimal reference array element, sending the array output corresponding to the optimal reference array element and the synchronous parameters obtained by searching into a signal tracking and subsequent processing module; the optimal reference array element power inversion algorithm can reduce satellite signal loss caused by interference suppression, but when the carrier-to-noise ratio is low, the positioning accuracy is usually deteriorated, and even the tracking loop is unlocked and cannot capture signals completely; in order to solve the problem, in the design of the anti-interference active antenna, the information after despreading by the pseudo code is required to be further utilized for beam forming, so that the carrier-to-noise ratio is improved, and the tracking capability of the receiver in a complex electromagnetic environment is improved.
Referring to fig. 3, the adaptive beamforming algorithm based on two-stage filtering performs cascade (serial) processing on null formation and beamforming, suppresses interference by first-stage filtering (null-stuffing formation), improves signal-to-noise ratio of satellite signals through correlation despreading, estimates spatial feature vectors of satellite signals, and performs weighting processing on output signals of the first-stage filtering by using the estimated spatial feature vectors of satellite signals by second-stage filtering (beamforming), thereby forming a main beam pointing in a direction to further improve carrier-to-noise ratio; the two-stage filtering adaptive beam forming algorithm comprises two-stage filtering results, as shown in fig. 3, wherein the part outside the dotted line frame is the optimal reference array element power inversion algorithm, i.e. the optimal reference array element power inversion algorithm is the first-stage filtering; the part inside the dotted line part is added with second-stage filtering for carrying out beam forming to improve the carrier-to-noise ratio, in particular:
if the first array element is used as a reference, the power inversion algorithm is adopted to process the input array signal, and a first path of output signal of the first-stage filtering can be obtained as follows:
because the optimal reference array element power inversion algorithm suppresses most of interference, the approximate equal sign in the formula is vertical; similarly, the 2 nd, 3 rd, … th and nth array elements are taken as references respectively, and the first filtering can obtain N paths of output signals in total, which can be expressed as:
wherein j is k (t) receiving interference signals for each path; c (C) n Is an N-dimensional column vector with 0 for all elements except for the nth element which is 1; r is R xx Is an autocorrelation covariance matrix of the signal; x (t) is an input data matrix;is a spatial feature vector (i.e., a projected steering vector of the satellite signal); />Is the projected noise vector. After the first-stage filtering treatment, although the interference is suppressed, the satellite signals are submerged in noise before relevant despreading, so that the projection guide vector of the satellite signals is difficult to estimate accurately; the spreading gain can be brought by the relevant despreading, so that the signal to noise ratio of the signal is greatly improved, and therefore, the projection guide vector estimated after despreading is easier.
S5, weighting the first-stage filtering output signals according to the spatial feature vector to obtain filtering array output signals, and specifically:
s51, constructing a local reference signal according to the first-stage filtering output signal, constructing a reference signal locally in a despreading process, and performing cross-correlation operation with a received signal; in order to keep the relative phase relation of the N paths of signals of the first-stage filtering output unchanged, the same local reference signal (the pseudo code phase and the carrier phase are the same) and the first-stage filtering output are required to be subjected to correlation processing; the expression of the local reference signal can be written as:
wherein,for code phase->For Doppler frequency, ++>The parameter values can be obtained from a code tracking loop and a carrier tracking loop for initial carrier phase estimation values;
s52, obtaining a cross-correlation vector through the local reference signal and the first-stage filtering output signal; after constructing the local reference signal r (t), the cross-correlation vector of this signal with the first stage filtered output y (t) can be further obtained:
r yr ＝E[y(t)r * (t)]； (1.15)
s53, correcting the space feature vector according to the cross correlation vector to obtain a weighted vector; since the satellite signal and noise are independent of each other, substitution (1.13) and (1.14) into (1.15) can be obtained:
where A is a constant, i.e. the cross-correlation vector r yr Projection steering vector proportional to satellite signalThe method comprises the relative phase relation of N paths of output signals of the first-stage filtering, so that the carrier-to-noise ratio can be improved by realizing the same superposition of signals through array weighting;
and S54, outputting the array output signals through the weighting vector and the first-stage filtering output signals, namely, performing weighted summation processing on N paths of output signals after the first-stage filtering by using the estimated satellite signal projection guide vector through the second-stage filtering to finish beam forming. The final array output signal can be expressed as:
the method further comprises the following steps of: obtaining a baseband signal according to the output signal of the filter array; demodulating the baseband signal to obtain the navigation message.
Example two
The embodiment limits the processing mode of the digital intermediate frequency signal output by the radio frequency front end;
referring to fig. 1, a baseband signal processing module copies carrier signals and pseudo code signals consistent with satellites received by a receiver by processing digital intermediate frequency signals output by a radio frequency front end of the receiver, so as to realize capturing and tracking of GNSS signals, thereby down-converting the intermediate frequency signals into baseband signals; the measurement values such as pseudo range, carrier phase and the like can be obtained through the baseband signals, and the navigation message is demodulated; the digital intermediate frequency signal comprises all visible satellite signals received by an antenna, so that the baseband signal processing module adopts a multi-signal channel mode, all channel signals have the same structure, and each channel respectively processes different visible satellite signals; the processing of the visible satellite signals tracked by each channel of the receiver baseband signal processing module can be divided into the stages of acquisition, tracking, bit synchronization, frame synchronization and the like. Before the receiver resumes tracking of a satellite signal, it is necessary to search for, acquire, and obtain from the received signal, a rough value of the carrier and C/a code phase of the satellite signal, and then the loop will enter the tracking phase.
Referring to fig. 4, a receiver tracking channel loop structure and a signal processing flow are shown; in the process of tracking the loop, the carrier loop outputs Doppler shift, integral Doppler and carrier phase measurement values according to the state of the copied carrier signal, and meanwhile, the code loop outputs code phase and pseudo-range measurement values according to the state of the copied C/A code signal, and in addition, the carrier loop discriminator can additionally demodulate navigation message data bits of the satellite signal.
The phase lock loop is one of the carrier loop realization forms aiming at locking the phase of an input carrier signal, and can closely track the signal and output a carrier phase measurement value accurately compared with the frequency lock loop. It is composed of phase discriminator, loop filter and voltage controlled oscillator:
it is assumed that the input signal and the output signal of the loop can be expressed as:
u i (t)＝U i sin(ω i t+θ i )
u o (t)＝U o cos(ω i t+θ o )； (1.18)
the phase detector is mainly used for identifying the input signal u i (t) and output signal u d (t) the phase difference between them, which can be regarded as a multiplier; when the input signal and the output signal are multiplied by the phase discriminator, the phase discrimination result u d (t) is equal to:
u d (t)＝u i (t)u o (t)
＝U i U o sin(ω i t+θ i )cos(ω o t+θ o )
＝K d {sin[(ω i +ω o )t+θ i +θ o ]+sin[(ω i -ω o )t+θ i -θ o ]}； (1.19)
the gain of the phase detector is as follows:
the loop filter is usually a low-pass filter, and aims to reduce noise in a loop, so that a filtering result can truly reflect the phase change condition of an input signal and prevent an over-excited adjusting voltage-controlled oscillator due to noise; when the phase discriminator outputs a signal u f (t) passing through an ideal low pass loop; after filtering, its high frequency signal component and noise are filtered out, so that the output signal u of the filter f (t) is equal to u d The low frequency component in (t), namely:
u f ＝K d K f sinθ e (t)； (1.21)
wherein the coefficient K f Is the filtering gain, the phase difference theta e (t) is the phase difference between the phase locked loop input signal and the output signal, namely:
θ e (t)＝θ i -θ o ： (1.22)
although the initial phase θ of the input signal i Will generally vary with time, but not only will the angular frequency omega of the output signal be output when the signal is locked by the phase-locked loop o Equal to omega i And when the initial phase value theta of the output signal o Should also be close to theta i I.e. phase difference theta e The value of (t) is also around zero. Thus, the loop filter outputs the signal u in the locked state of the phase locked loop f The expression of (t) can be approximated as:
u f (t)≈K d K f θ e (t)； (1.23)
the above shows that the filtered value u of the phase discrimination result f (t) phase difference θ between input and output signals e (t) is in linear proportional relationship; however, when the phase difference theta e When the absolute value of (t) is large, the linearization process is no longer true; after the phase discrimination result is filtered, the output signal u of the loop filter f (t) then as a control voltage (or current) signal input to the voltage controlled oscillator; the basic function of the voltage-controlled oscillator is to generate a periodic oscillation signal u with a certain frequency o (t), and the frequency variation of the signal is compared with the control signal u f The size of (t); this control relationship of the voltage controlled oscillator can be expressed as:
wherein the coefficient K o Is the gain, omega of the voltage-controlled oscillator o (t) is the instantaneous output angular power of the voltage controlled oscillator; the integral of angular frequency with respect to time is a phase change amount, and the integral of angular frequency change amount corresponds to the change amount of the initial phase. Thus, according to the equation, the output signal u of the voltage-controlled oscillator can be obtained o Instantaneous of (t)Initial phase θ between o (t) is:
the above assumes an initial phase θ at time zero o (t) is equal to zero.
An I/Q demodulation method is adopted in the anti-interference active antenna to help complete the tasks of carrier stripping, phase discrimination, data demodulation and the like of an input signal; continuous time signal as system input in phase locked loop:
and D (t) represents a data code modulated on a carrier wave, the sine wave and cosine wave replica signals can be expressed as:
wherein, the magnitudes of the navigation message data codes do not contain the data code D (t), and the navigation message data codes broadcasted by satellites are generally unpredictable in reality; ignoring other scaling factors of the input signal and the amplitude of each replica signal, making a branch of the input signal mixed with the sine carrier replica signal a homodromous branch (I branch for short), and another loop branch mixed with the cosine carrier replica signal a quadrature branch (Q branch for short); one function of the I/Q demodulation method is to demodulate the input signal u i Demodulating the data code D (t) in (t);
when inputting signal u i (t) reproducing the signal u with a sinusoidal carrier on the I-branch os (t) multiplying and mixing, the product i p (t) is
Wherein the first term to the right of the last equal sign is the high frequency component and the second term is the low frequency component, ω e And theta e Respectively input signal u i (t) and replica Signal u os Carrier frequency differences and initial phase differences between (t), namely:
ω e ＝ω i -ω o ； (1.30)
ω e ＝θ i -θ o ； (1.31)
mixing result i p (t) filtering the high frequency component contained in the filter by a low pass filter to obtain the following filtering result:
I p (t)＝aD(t)cos(ω e t+θ e )； (1.32)
similarly, input signal u i (t) reproducing signal u with cosine carrier on Q branch oc (t) multiplying and mixing, and the obtained mixing result q p And (t) obtaining after passing through a low-pass filter:
Q P (t)＝aD(t)sin(ω e t+θ e )； (1.33)
the same I after low pass filtering p (t) and quadrature signal Q P (t) together, may be written as a complex vector r of the form p (t), namely:
wherein,
A p (t)＝aD(t)； (1.35)
φ e (t)＝ω e t+θ e ； (1.36)
complex vector r p Amplitude A of (t) p (t) contains data code information with a phase angle phi e (t) reflecting a phase difference between the input signal and the replica signal including a frequency difference; due to vector r p (t) the phase angle is equal to the phase angle between the input signal and the replica signalPhase difference phi e (t), then the phase-locked loop calculates r p After (t), it is equivalent to completing the phase discrimination task.
In the carrier tracking loop, the digital intermediate frequency signal is subjected to carrier stripping and C/A code correlation to obtain two paths of baseband signals i p And q p Then entering an integrating-zero clearing device; integration for i p And q p For a period of time T coh The result before the integration is completed is stored in a register unit, and then the integration result I is output p And Q p Meanwhile, the cleaner cleans up the register unit, and then integrates the next period, and the process is repeated continuously; since the integration operation is performed separately from the signals on the I and Q axes, rather than mixing the two, this integration is called coherent integration; the corresponding integration time is called the coherent integration time T coh The method comprises the steps of carrying out a first treatment on the surface of the If t 1 Representing the initial time of integration, for the correlation result i p For up to T coh The integral of (2) can be obtained:
similarly, for the correlation result signal q p And (t) integrating to obtain:
example III
Referring to fig. 5, an electronic device includes a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of an antenna anti-interference processing method according to any one of the first and second embodiments when executing the computer program.
In summary, according to the method and the device for processing the anti-interference of the antenna provided by the invention, after the input data is processed based on the power inversion algorithm, the obtained reference array element is optimized, and the input data is processed through the optimal reference array element obtained through screening, so that the optimal anti-interference performance is obtained; and then, a first-stage filter is formed by a power inversion algorithm to inhibit interference, the signal-to-noise ratio of satellite signals is improved through relevant despreading, after a spatial feature vector of the satellite signals is estimated, the first-stage filter output signals are weighted through a second-stage filter based on the obtained spatial feature vector, and a main beam pointing to the direction is formed to further improve the carrier-to-noise ratio, so that satellite signal loss caused by interference inhibition is reduced, the carrier-to-noise ratio is improved, the tracking capacity of a receiver under a complex electromagnetic environment is improved, and the high-precision positioning effect is ensured.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent changes made by the specification and drawings of the present invention, or direct or indirect application in the relevant art, are included in the scope of the present invention.
Claims (10)
1. An anti-interference processing method for an antenna is characterized by comprising the following steps:
acquiring input data, and processing the input data through a power inversion algorithm to obtain optimal array weight vectors corresponding to different reference array elements;
generating an input data matrix from the input data, and obtaining an output vector corresponding to each reference array element according to the optimal array weight vector corresponding to each reference array element and the input data matrix;
calculating a test statistic corresponding to each reference array element according to the output vector, and selecting the reference array element with the maximum test statistic as an optimal reference array element;
obtaining a first-stage filtering output signal corresponding to the input data matrix and a space feature vector according to the optimal reference array element;
and weighting the first-stage filtering output signal according to the spatial feature vector to obtain a filtering array output signal.
2. The method of claim 1, wherein generating the input data into an input data matrix comprises:
acquiring a preset data format;
and forming the input data into the input data matrix according to the data format.
3. The method of claim 1, wherein the obtaining the output vector corresponding to each reference element according to the optimal array weight vector corresponding to each reference element and the input data matrix comprises:
wherein y is (n) (t) is an output vector, and the superscript n indicates that the output vector is obtained by taking the nth array element as a reference array element;the optimal array weight vector corresponding to the nth reference array element; x (t) is the input data matrix.
4. The method of claim 1, wherein the calculating test statistics corresponding to each of the reference array elements according to the output vector comprises:
acquiring a local reference signal vector;
obtaining vector-related data according to the local reference signal vector and the output vector;
obtaining autocorrelation data corresponding to the output vector according to the output vector;
and obtaining the test statistic corresponding to the reference array element according to the vector related data and the autocorrelation data.
5. The method for antenna anti-interference processing according to claim 4, wherein said obtaining test statistics corresponding to the reference array element according to the vector correlation data and the autocorrelation data comprises:
d(f,τ)＝[d(t-(K-1)T s ,f,τ),...,d(t-T,f,τ),d(t,f,τ)]；
wherein T (y) (n) ) Is a test statistic; gamma is a detection threshold, and the detection threshold is determined by a given false alarm probability;is autocorrelation data, is scalar; />Vector-related data, scalar; d (f, τ) represents the local reference signal vector, which is a K-dimensional row vector; wherein: d (t, f, τ) =p (t- τ) e j2πft P (t) is the pseudo code sequence of the satellite signal, f is the carrier Doppler frequency, and τ is the pseudo code phase.
6. The method for anti-interference processing of an antenna according to claim 1, wherein said obtaining the output signal of the input data matrix corresponding to the first stage filtering and the spatial feature vector according to the optimal reference array element comprises:
wherein C is n Is an N-dimensional column vector with 0 for all elements except for the nth element which is 1; r is R xx Is an autocorrelation covariance matrix of the signal; x (t) is an input data matrix;is a spatial feature vector; />Is the projected noise vector.
7. The method of claim 1, wherein the weighting the first-stage filtered output signal according to the spatial feature vector to obtain a filtered array output signal comprises:
constructing a local reference signal according to the first stage filtered output signal;
obtaining a cross-correlation vector through the local reference signal and the first-stage filtering output signal;
correcting the space feature vector according to the cross correlation vector to obtain a weighted vector;
the array output signal is output through the weight vector and the first stage filtered output signal.
8. The method of claim 7, wherein said constructing a local reference signal from said first stage filtered output signal comprises:
wherein,is the code phase; />Is Doppler frequency; />Is the initial carrier phase estimate.
9. The method for antenna anti-interference processing according to claim 7, wherein said weighting the first-stage filtered output signal according to the spatial feature vector, after obtaining a filtered array output signal, further comprises:
obtaining a baseband signal according to the output signal of the filter array;
demodulating the baseband signal to obtain the navigation message.
10. An antenna anti-interference process comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of an antenna anti-interference process method according to any one of claims 1-9 when the computer program is executed by the processor.
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| CN117630978B (en) * | 2024-01-26 | 2024-04-05 | 中国人民解放军国防科技大学 | Satellite navigation super-freedom degree interference suppression method and device based on array element optimization |
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