CN103117781B - A kind of antenna array calibration method under complex electromagnetic environment and device thereof - Google Patents

Abstract

The present invention discloses a kind of antenna array calibration method under complex electromagnetic environment and device thereof.This device passes through heart point transmitting calibration signal in an antenna array, according to the principle of sef-adapting filter, utilizes Wei Na to separate form, extracts amplitude inconsistency and the Sensor gain and phase perturbations parameter of array antenna and receiving front-end.In the complex electromagnetic environment that there is intensive interference, automatically can suppress same frequency by a small margin or the impact of adjacent frequency interference on this frequency array calibration result; And when with frequently or the Amplitude Ratio of adjacent frequency interference is comparatively large so that when having a considerable influence to channel parameters, the channel parameters extracted can be processed, eliminate or greatly weaken the impact that this interference brings, then broadband compensation or many narrow-band compensations are carried out to the array signal received, eliminate the error that difference between channels causes.Under the present invention is applicable to complex electromagnetic environment, in real time channel parameters extraction and auto-compensation are carried out to the circular antenna array and receive path being operated in optional frequency scope.

Description

A kind of antenna array calibration method under complex electromagnetic environment and device thereof

Technical field

The present invention relates to Array Signal Processing field, be specially a kind of antenna array calibration method under complex electromagnetic environment and device thereof.Complex electromagnetic environment refers to that the external world exists the environment of intensive interference signal.Circular array refers to that antenna is circumferentially evenly distributed.The present invention, under complex electromagnetic environment, extracts circular array channel amplitude and Sensor gain and phase perturbations error and compensates.

Background technology

Along with the develop rapidly of communication theory and technology, array antenna plays more and more important role in the radio systems such as mobile communication, broadcasting station, radar system and navigation, and the quality of Array Signal Processing performance will directly affect the performance of whole communication system.Inconsistency due to each passage of array antenna greatly reduces the performance of array receiver system, these parameters mainly comprise amplitude and the phase place of each reception antenna and receiver front end equipment, therefore, various technology and means must be adopted to solve the inconsistency of array antenna passage as much as possible, each passage is carried out to the calibration of amplitude inconsistency and Sensor gain and phase perturbations.

At present, most of array calibration document is to the calibration in narrow band signal, or the calibration carried out under the environment that external interference closeness is very little and interference signal amplitude is little, realizes background fairly simple." Sensorarraycalibrationinthepresenceofmutualcouplingandun knownsensorgainsandphases " (C.M.SSee, ElectronLett, 1994,30 (5): 373-374) propose to send calibration auxiliary signal, ask the covariance matrix of the array signal of reception, and combine Estimation of Spatial Spectrum, try to achieve channel amplitude inconsistency and Sensor gain and phase perturbations, but this applied environment is restricted, external interference will less and faint, and in intensive external interference and interference signal is stronger, the method is just inapplicable.

Generally, the assisted calibration signal of transmission is all easily identify, and the simple signal that the waveform on frequency domain can not change.But meanwhile, exactly because the attribute that simple signal is intrinsic, the reception that external interference pulse will affect this auxiliary signal differentiates, then affect the result of array calibration.Feature of the present invention solves existing array calibration method not consider external interference and can only in the problem of arrowband internal calibration, can Acquisition channel parameter (comprising channel amplitude inconsistency parameter and channel phases inconsistency parameter) accurately, and compensate in broadband.

Summary of the invention

The invention provides a kind of antenna array calibration method under complex electromagnetic environment and device thereof, the present invention in any frequency band range and under the complex electromagnetic environment that there is intensive interference, can suppress same frequency by a small margin or the impact of adjacent frequency interference on this frequency array calibration result automatically.

Antenna array calibration method under a kind of complex electromagnetic environment provided by the invention, comprises the following steps:

1st step sends calibrating signal;

2nd step utilizes circular array to receive the calibrating signal sent, and each road signal received is carried out analog-to-digital conversion, obtains array digital signal;

3rd step utilizes the array digital signal obtained, extract amplitude and the phase place of each passage, again using the amplitude of a certain passage and phase place as benchmark, ask the amplitude of other each passage and the relative value of phase place and benchmark, i.e. channel amplitude inconsistency and channel phases inconsistency;

4th step judges whether all frequencies are calibrated complete, if so, then enters the 5th step, otherwise, be switched to next frequency, repeat the 1st step to the 3rd step, until complete the extraction of the channel parameters of all frequencies;

5th step stops sending calibrating signal;

6th step processes channel parameters, eliminates the impact of interference;

On 7th step circular array, each reception antenna receives aerial signal, and each road signal received is carried out analog-to-digital conversion, obtains array digital signal;

8th step compensates the array digital signal obtained, and is compensated output signal.

Antennas array calibration arrangement under a kind of complex electromagnetic environment provided by the invention, it is characterized in that, this device comprises signal generator unit, circular antenna array element, array acceptor front end unit, array channel parameter extraction unit, channel parameters processing unit and channel compensation unit;

Described circular antenna array element is used for Received signal strength and transmitting calibration signal, the center of circle battle array places one for sending the calibrating signal transmitting antenna of calibrating signal, the circumferentially also even of described circular array places many reception antennas, distance between every adjacent reception antenna is all equal, this reception antenna, at extraction array channel parametric step, receives the calibrating signal being mixed with external interference; In compensated array signal phase, receive required array signal to be calibrated, described signal generator unit for generation of simple signal as the calibrating signal in array calibration process;

Described array acceptor front end unit is used for amplifying the signal received, filtering, analog-to-digital conversion process, and be supplied to described array channel parameter extraction unit;

Described array channel parameter extraction unit separates form for the array signal that receives and reference signal according to the Wei Na of sef-adapting filter, carries out computing, extracts channel parameters, and be supplied to described channel parameters processing unit;

If described channel parameters processing unit processes under being used for there is strongly disturbing situation to calibration frequency or adjacent frequency place, and the data after process are supplied to channel compensation unit; Somely disturb less, signal interference ratio is larger, then do not process, and obtains final channel parameters;

Described channel compensation unit comprises broadband compensation unit and/or many narrow-band compensations unit, the array channel error that the signal that elimination receives comprises.

The present invention can in any frequency band range and under the complex electromagnetic environment that there is intensive interference, automatic suppression same frequency by a small margin or the impact of adjacent frequency interference on this frequency array calibration result, if when the Amplitude Ratio of interference is larger, can this frequency channel parameters of automatic rejection, and interpolation replaces it, obtain final array channel parameter accurately, and carry out many narrow-band compensations, or disposable compensation in broad frequency range.Compared with other array calibration technology, the present invention has following characteristics:

(1) the present invention is according to the principle of sef-adapting filter, and use Wei Na solution form to carry out the extraction of channel parameters, operand is little, calculates simple, and easily realizes.

(2) can at complex electromagnetic environment, when namely there is intensive interference, the interference magnitude size according to calibration frequency or adjacent frequency place processes channel parameters.Avoid conventional array calibration method easily by the impact of external interference.

(3) array channel compensates and can carry out many narrow-band compensations or broadband compensation, and broadband compensation is then structure calibration filters, realizes the disposable compensation in required frequency band; Many narrow-band compensations are then the signal channellizations that will receive, and are divided into multiple arrowband, then compensate in each arrowband.Avoid conventional array channel compensation and require that the signal of compensation to be calibrated is the signal in arrowband.

(4) apparatus of the present invention can be based upon on the basis of any band limits, and avoiding general array calibration can only in narrow bandwidth range, and disturb when wanting smaller just feasible in this frequency range.

Accompanying drawing explanation

Fig. 1 is the method flow schematic diagram of example of the present invention;

Fig. 2 is channel parameters extracting method block diagram;

Fig. 3 is channel parameters processing method block diagram;

Fig. 4 is broadband compensation method block diagram;

Fig. 5 is many narrow-band compensations method block diagram;

Fig. 6 is the apparatus structure schematic diagram of example of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described further.It should be noted that at this, the explanation for these execution modes understands the present invention for helping, but does not form limitation of the invention.In addition, if below in described each execution mode of the present invention involved technical characteristic do not form conflict each other and just can mutually combine.

As shown in Figure 1, the array calibration method that example of the present invention provides, comprises the following steps:

(1) calibrating signal is sent

Signal generator produces simple signal according to the parameter of calibrating signal pending, after digital-to-analogue conversion, is sent by calibrating signal transmitting antenna.The parameter of calibrating signal comprises type, the amplitude and frequency etc. of signal.

(2) data acquisition

After transmission calibrating signal, utilize circular array to receive each road signal, after analog-to-digital conversion, obtain digital signal, extract by passage ginseng later and calculate.

(3) channel parameters extraction algorithm is carried out

The each railway digital signal obtained is utilized to carry out computing, extract amplitude and the phase place of each passage, again using the amplitude of a certain passage and phase place as benchmark, ask the amplitude of other each passage and the relative value of phase place and benchmark, i.e. channel amplitude inconsistency and channel phases inconsistency.As shown in Figure 3, concrete steps are as follows:

(3.1) each reception antenna of circular array receives the calibrating signal sent from calibrating signal transmitting antenna, and the interference signal such as air broadcast radio station, air communications, the signal that i-th reception antenna receives through analog-to-digital conversion postscript be s _in (), n is the sequence number of sampled point.

(3.2) the single-frequency sequence cos2 π fn of frequency identical with calibrating signal is produced, as reference signal 1, and sin2 π fn, as the calibration signal frequency with reference to signal 2, f being transmitting.

(3.3) according to the signal of reference signal and reception, carry out related operation, extract channel parameters, described in specific as follows:

The calibrating signal that the calibrating signal transmitting antenna supposing to be positioned at circular array center is launched is cos2 π ft, t is the time of launching.I-th reception antenna receives this calibrating signal and through amplifying, after filtering and analog-to-digital conversion, its output signal is a _ifor this multi-channel output signal amplitude, for the phase shift of this multi-channel output signal, they reflect the amplitude of this receive path introducing and the inconsistency of phase place indirectly, and its value based on lowest mean square criterion, can be separated form with the Wei Na of sef-adapting filter, namely calculate in the steps below:

Calculate the ASSOCIATE STATISTICS amount w of this passage _opt:

$w_{\mathrm{opt}}=\left[\begin{array}{c}{I}_i\\ Q_i\end{array}\right]=\frac{2}{N}\left[\begin{array}{c}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\left\{s_i\left(n\right)\cos 2\mathrm{\πfn}\right\}\\ -\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\{s_i\left(n\right)\sin 2\mathrm{\πfn}\end{array}\right]$

In above formula, f is the frequency of launched calibrating signal, and N is for calculating ASSOCIATE STATISTICS amount w _opttotal number of sample points, obtain weights I _iand Q _i, and utilize following formula to calculate the amplitude A of the i-th passage _i, phase place

$A_i=\sqrt{I_i^2+Q_i^2},$

(3.4) according to A _iwith ask for the amplitude of each passage and the relative value of phase place and benchmark, i.e. the amplitude inconsistency of passage and Sensor gain and phase perturbations, as channel parameters.Can by the amplitude of first passage and phase parameter A ₁, as benchmark, ask for the amplitude of each passage and the deviation of phase place and this benchmark, obtain channel amplitude inconsistency parameter A _i'=A _i/ A ₁with Sensor gain and phase perturbations parameter wherein, i is channel position, and 1≤i≤P, P is array received total number of channels.

(4) judge that frequency has been calibrated no

The present invention is applicable in any frequency range, if need to ask the channel parameters within the scope of broad frequency band, then needs the calibrating signal sending multiple frequency.Send first frequency calibrating signal and after extracting the channel parameters of this frequency, judge that frequency has been calibrated no, when frequency has not been calibrated, be switched to next frequency, repeat (1) ~ (3) step, until complete the extraction of the channel parameters of all frequencies.

(5) stop sending calibrating signal

After channel parameters extracts, then each reception antenna does not need to receive calibrating signal, and therefore, stop sending calibrating signal, shutdown signal generator, makes calibrating signal transmitting antenna no longer send calibrating signal.

(6) treatment channel parameter

The present invention processes channel parameters, and eliminate the impact of interference, processing procedure as shown in Figure 4.The concrete processing procedure of this step is:

(6.1) the multiple calibration frequencies supposing to arrange in the working frequency range of required calibration are f _k, k=1,2 ..., K, K are the total number of calibration frequency arranged, and the channel amplitude relative value extracted at each calibration frequency is A ' _{i, k}, and phase place relative value is i is channel position.If have external interference at this calibration frequency place or adjacent frequency place, but interference magnitude is smaller, then the channel parameters at this frequency place is directly taken as A ' _{i, k}with if external interference Amplitude Ratio is comparatively large, then need to process.

Example of the present invention is according to obtained Phase-Frequency curve burr situation determine whether to process the channel parameters at this frequency place.Wherein, A ' _{i, k}with represent the amplitude at the i-th passage, a kth frequency place, Sensor gain and phase perturbations parameter.

At Phase-Frequency curve in, judge and process the method for burr point: a threshold value T is set, when and then judge this frequency place for burr, at this moment by the channel amplitude relative value A ' at this frequency place _{i, k}with phase place relative value delete.T by adjacent calibration frequency interval, passage length, and signaling rate is determined because the unit of T is degree, and Δ f is the difference on the frequency of two calibrating signals, and c is the transmission speed of signal, and l is the length of passage.

(6.2) at the deleted enterprising row interpolation of frequency of channel parameters, deleted channel parameters is replaced with interpolation result, as the channel parameters at this frequency place.

Concrete interpolation method can be the methods such as three rank polynomial interopolations, to ensure the Phase-Frequency curve after interpolation level and smooth in whole working frequency range.On the basis of calibrated frequency points, can also carry out according to demand doubling or many times of interpolation, namely increase the total number K of calibration frequency, obtain the channel parameters that more intensive frequency is corresponding.

(6.3) repeat step (6.1) ~ (6.2), obtain the channel parameters after all passage process.

(7) data acquisition

Aerial signal on circular array needed for each reception antenna reception, synchronous acquisition each road signal.

(8) channel compensation

Channel compensation has broadband compensation method and many narrow-band compensations method.

As shown in Figure 5, the invention provides the method for the signal of each channel reception being carried out to amplitude and phase compensation in broadband, concrete steps are as follows for broadband compensation process:

(a1), structural wideband compensating filter, according to the symmetry of FIR filter parameter, by each calibration channel parameters A ' of obtaining of frequency place of the i-th paths _{i, k}with as the frequency domain response H of broadband compensation filter _if the parameter on () positive frequency band, by A ' _{j, k}with as H _iparameter on the negative frequency band of (f), then to H _if () carries out Fourier inversion, can obtain the time domain impulse response h of broadband compensation filter _i(n).

(a2) the signal x to be calibrated, the i-th channel reception arrived _in () enters in digital compensation filter, respond h with the time domain impulse of broadband compensation filter _in () carries out convolution, that is:

$S_i^{\′}=h_i\left(n\right)\⊗x_i\left(n\right)$

S ' _{i (n)}for the signal after the i-th channel compensation.

(a3), repeat step (a1) ~ (a2), obtain the Received signal strength after all channel compensations.

The present invention also the signal of each channel reception can carry out many narrow-band compensations, and as shown in Figure 6, concrete steps are as follows for process:

(b1), by the wideband digital signal x of the i-th channel reception _in (), through channelizing process, namely dedicated bandwidth is Δ f, centre frequency is respectively f _mseveral band pass filters to the Received signal strength x of Whole frequency band _in () carries out filtering, obtain channelizing output signal:

$y_{i,m}\left(n\right)=x_i\left(n\right)\⊗g_{i,m}\left(n\right)$

G _{i, m}n () is the impulse response of m channel band-pass filter of the i-th passage, m=1,2 ..., M, M are channel number.

After channelizing process, by wideband received signal x _in () becomes multiple arrowband complex signal y _{i, m}(n) (channelized signal).

(b2), according to channel parameters, the compensating factor r in the i-th passage, a m channel is constructed _{i, m}:

J Shi Xu unit, e is the truth of a matter of natural logrithm, A ' _{i, m}be the amplitude inconsistency parameter in the i-th passage, a m channel, it is the Sensor gain and phase perturbations parameter in the i-th passage, a m channel.

(b3), the channel parameters in the i-th passage, a m channel is compensated in the arrowband complex signal of respective channels, obtain the compensation output signal s at this passage, this channel place " _{i, m}(n):

s″ _i，m(n)＝r _i，my _i，m(n)

The Received signal strength utilizing above formula to obtain this passage is positioned at the compensation output signal at all narrow band channel places.

(b4), repeat (b1) ~ (b3), try to achieve the compensation output signal of all passages at each narrow band channel place.

The present invention is based on circular antenna array, under the complex electromagnetic environment that there is intensive interference, to the calibration of each passage.Circular array center places one for sending the calibrating signal transmitting antenna 10 of calibrating signal, and the simple signal that signal generator unit 11 produces is as the calibrating signal in array calibration process.P root reception antenna 12 evenly placed by circular array, at extraction array channel parametric step, receives the calibrating signal being mixed with external interference; In compensated array signal phase, receive the array signal of required calibration.

As shown in Figure 1, array acceptor front end 13 can comprise the modules such as amplification, filtering, frequency conversion, analog-to-digital conversion to array calibration device of the present invention.In array channel parameter extraction unit 14, the array signal of reception and reference signal separate form according to the Wei Na of sef-adapting filter, carry out related operation, extract channel parameters.If channel parameters processing unit 15 processes under there is strongly disturbing situation to calibration frequency or adjacent frequency place, somely disturb less, signal interference ratio is larger, then do not process, and obtains final channel parameters.Channel compensation unit 16 comprises broadband compensation unit 160 and many narrow-band compensations unit 161, i.e. two kinds of compensation methodes, the array channel error that the signal that elimination receives comprises.

The above is preferred embodiment of the present invention, but the present invention should not be confined to the content disclosed in this embodiment and accompanying drawing.The equivalence completed under not departing from spirit disclosed in this invention so every or amendment, all fall into the scope of protection of the invention.

Claims (4)

1. the antenna array calibration method under complex electromagnetic environment, comprises the following steps:

1st step sends calibrating signal;

2nd step utilizes circular array to receive the calibrating signal sent, and each road signal received is carried out analog-to-digital conversion, obtains array digital signal;

3rd step utilizes the array digital signal obtained, extract amplitude and the phase place of each passage, again using the amplitude of a certain passage and phase place as benchmark, ask the amplitude of other each passage and the relative value of phase place and benchmark, i.e. channel amplitude inconsistency and channel phases inconsistency;

4th step judges whether all frequencies are calibrated complete, if so, then enters the 5th step, otherwise, be switched to next frequency, repeat the 1st step to the 3rd step, until complete the extraction of the channel parameters of all frequencies;

5th step stops sending calibrating signal;

6th step processes channel parameters, eliminates the impact of interference; Specifically comprise following process:

(6.1) being located at the multiple calibration frequencies arranged in the working frequency range of required calibration is f _k, k=1,2 ..., K, K are the total number of calibration frequency arranged, and the channel amplitude relative value extracted at each calibration frequency is A ' _i,k, and phase place relative value is i is channel position; According to obtained Phase-Frequency curve burr situation judge certain calibration frequency place whether have external interference, if any, then reject the channel parameters of this frequency: when and then judge this frequency place for burr, by the channel amplitude relative value A ' at this frequency place _i,kwith phase place relative value delete, wherein, T is the threshold value preset;

(6.2) at the deleted enterprising row interpolation of frequency of channel parameters, deleted channel parameters is replaced with interpolation result, as the channel parameters at this frequency place;

(6.3) repeat step (6.1) ~ (6.2), obtain the channel parameters after all frequency process of all passages;

On 7th step circular array, each reception antenna receives aerial signal, and each road signal received is carried out analog-to-digital conversion, obtains array digital signal;

8th step carries out broadband compensation to the array digital signal obtained, and is compensated output signal; Broadband compensation carries out according to following process:

(8.1) structural wideband compensating filter, according to the symmetry of FIR filter parameter, by the channel parameters A ' that each calibration frequency place of the i-th paths obtains _{i, k}with as the frequency domain response H of broadband compensation filter _if the parameter on () positive frequency band, by A ' _i,kwith as H _iparameter on the negative frequency band of (f), then to H _if () carries out Fourier inversion, namely obtain the time domain impulse response h of broadband compensation filter _i(n);

(8.2) the signal x to be calibrated the i-th channel reception arrived _in () enters in digital compensation filter, respond h with the time domain impulse of broadband compensation filter _in () carries out convolution, that is:

$s_i^{\′}\left(n\right)=h_i\left(n\right)\⊗x_i\left(n\right)$

S ' _in () is the signal after the i-th channel compensation;

(8.3) repeat step (8.1) ~ (8.2), obtain the Received signal strength after all channel compensations.

2. antenna array calibration method according to claim 1, is characterized in that, the 3rd step specifically comprises following process:

(3.1) each reception antenna of circular array receives the calibrating signal sent from calibrating signal transmitting antenna, and interference signal, the signal that i-th reception antenna receives through analog-to-digital conversion postscript be s _i(n), n is the sequence number of sampled point;

(3.2) the single-frequency sequence cos2 π fn of frequency identical with calibrating signal is produced, as reference signal 1, and sin2 π fn, as the calibration signal frequency with reference to signal 2, f being transmitting;

(3.3) according to the signal of reference signal and reception, carry out related operation, extract channel parameters, comprise amplitude A _i, phase place

(3.4) using the amplitude of one of them passage and phase parameter as benchmark, ask for the amplitude of each passage and the deviation of phase value and this benchmark, obtain channel amplitude inconsistency parameter and Sensor gain and phase perturbations parameter.

3. antenna array calibration method according to claim 2, it is characterized in that, 3rd step comprises following process: step (3.3) for: the calibrating signal that the calibrating signal transmitting antenna supposing to be positioned at circular array center is launched is cos2 π ft, t is the time of launching, i-th reception antenna receives this calibrating signal and through amplifying, after filtering and analog-to-digital conversion, its output signal is a _ibe the amplitude of the i-th multi-channel output signal, for the phase shift of this multi-channel output signal, calculate the ASSOCIATE STATISTICS amount w of this passage _opt:

$w_{opt}=\left[\begin{array}{c}{I}_i\\ Q_i\end{array}\right]=\frac{2}{N}\left[\begin{array}{c}\underset{n=1}{\overset{N}{\Σ}}\left\{s_i\right(n\left)cos2\mathrm{\π}fn\right\}\\ -\underset{n=1}{\overset{N}{\Σ}}\left\{s_i\right(n\left)sin2\mathrm{\π}fn\right\}\end{array}\right]$

In above formula, f is the frequency of launched calibrating signal, and N is for calculating ASSOCIATE STATISTICS amount w _opttotal number of sample points, obtain weights I _iand Q _i, and utilize calculate the amplitude A of the i-th passage _i, phase place

4. the antennas array calibration arrangement under a complex electromagnetic environment, it is characterized in that, this device comprises signal generator unit, circular antenna array element, array acceptor front end unit, array channel parameter extraction unit, channel parameters processing unit and channel compensation unit;

Described circular antenna array element is used for Received signal strength and transmitting calibration signal, the center of circle battle array places one for sending the calibrating signal transmitting antenna of calibrating signal, the circumferentially even of circular array places many reception antennas, distance between every adjacent reception antenna is all equal, this reception antenna is used for receiving at extraction array channel parametric step the calibrating signal being mixed with external interference, in compensated array signal phase, receive array signal required to be calibrated; Described signal generator unit for generation of simple signal as the calibrating signal in array calibration process;

Described array acceptor front end unit is used for amplifying the signal received, filtering, analog-to-digital conversion process, and be supplied to described array channel parameter extraction unit;

Described array channel parameter extraction unit is used for the array signal received and reference signal to separate form according to the Wei Na of sef-adapting filter, carries out computing, extracts channel parameters, and be supplied to described channel parameters processing unit;

If described channel parameters processing unit processes under being used for there is strongly disturbing situation to calibration frequency or adjacent frequency place, and the data after process are supplied to channel compensation unit; Somely disturb less, signal interference ratio is larger, then do not process, and obtains final channel parameters;

Described channel compensation unit is broadband compensation unit, or is made up of broadband compensation unit and many narrow-band compensations unit, utilizes the channel parameters extracted, the array channel broadband error that the signal that elimination receives comprises.