CN103117781A - Method and device for antenna array calibration under complex electromagnetic environment - Google Patents

Abstract

The invention discloses an antenna array calibration method and a device thereof in complex electromagnetic environments. The device transmits a calibration signal at the center point of the antenna array, and uses the Wiener solution form to extract the amplitude inconsistency and phase inconsistency parameters of the array antenna and the receiving front end according to the principle of the adaptive filter. In a complex electromagnetic environment with dense interference, it can automatically suppress the influence of small-amplitude same-frequency or adjacent-frequency interference on the calibration results of the frequency point array; and when the amplitude of the same-frequency or adjacent-frequency interference is relatively large so that it has a greater impact on channel parameters When the impact is large, the extracted channel parameters can be processed to eliminate or greatly reduce the impact of the interference, and then perform wideband compensation or multi-narrowband compensation on the received array signal to eliminate errors caused by channel inconsistency. The invention is suitable for complex electromagnetic environment, and real-time channel parameter extraction and automatic compensation for circular antenna arrays and receiving channels working in any frequency range.

Description

Method and device for calibrating antenna array in complex electromagnetic environment

technical field

The invention relates to the field of array signal processing, in particular to an antenna array calibration method and a device thereof in a complex electromagnetic environment. A complex electromagnetic environment refers to an environment where there are dense interference signals from the outside world. A circular antenna array means that the antennas are evenly arranged on the circumference. The invention extracts and compensates the inconsistency errors of the channel amplitude and phase of the circular antenna array under the complex electromagnetic environment.

Background technique

With the rapid development of communication theory and technology, array antennas play an increasingly important role in radio systems such as mobile communications, radio stations, radar systems, and navigation, and the performance of array signal processing will directly affect the entire communication system. system performance. Due to the inconsistency of each channel of the array antenna greatly reduces the performance of the array receiver system, these parameters mainly include the amplitude and phase of each receiving antenna and receiver front-end equipment, therefore, various techniques and means must be used to solve the array receiver system as much as possible. For the inconsistency of the antenna channels, calibrate the amplitude inconsistency and phase inconsistency of each channel.

At present, most of the array calibration literature is for the calibration within the narrowband signal, or the calibration is carried out in the environment where the external interference density is small and the interference signal amplitude is small, and the implementation background is relatively simple. "Sensor array calibration in the presence of mutual coupling and unknown sensor gains and phases" (C.M.S See, Electron Lett, 1994, 30(5): 373-374) proposes to send calibration auxiliary signals and find the covariance matrix of the received array signals, Combined with spatial spectrum estimation to obtain the channel amplitude inconsistency and phase inconsistency, but the application environment is limited, the external interference is small and weak, and in the case of dense external interference and the interference signal is relatively strong, this method does not Be applicable.

Generally, the sent auxiliary calibration signals are single-frequency signals that are easily identifiable and whose waveforms in the frequency domain do not change. But at the same time, precisely because of the inherent properties of the single-frequency signal, external interference pulses will affect the reception and discrimination of the auxiliary signal, which will affect the result of array calibration. The feature of the present invention is to solve the problem that the existing array calibration method does not consider external interference and can only calibrate in a narrow band, and can accurately obtain channel parameters (including channel amplitude inconsistency parameters and channel phase inconsistency parameters), and can be used in broadband in-band compensation.

Contents of the invention

The invention provides an antenna array calibration method and its device in a complex electromagnetic environment. The invention can automatically suppress small-amplitude same-frequency or adjacent-frequency interference to the Influence of Point Array Calibration Results.

A method for calibrating an antenna array in a complex electromagnetic environment provided by the present invention comprises the following steps:

Step 1 Send calibration signal;

The second step is to use the circular antenna array to receive the sent calibration signal, and perform analog-to-digital conversion on the received signals to obtain the array digital signal;

Step 3 Use the obtained array digital signal to extract the amplitude and phase of each channel, and then use the amplitude and phase of a certain channel as a reference to find the relative value of the amplitude and phase of other channels and the reference, that is, the channel amplitude inconsistency Inconsistency with channel phase;

Step 4 judge whether all frequency points are calibrated, if yes, go to step 5, otherwise, switch to the next frequency point, repeat step 1 to step 3, until the extraction of channel parameters of all frequency points is completed;

Step 5 stop sending calibration signal;

The sixth step is to process the channel parameters to eliminate the influence of interference;

Step 7: Each receiving antenna on the circular antenna array receives air signals, and performs analog-to-digital conversion on the received signals to obtain array digital signals;

Step 8 Compensate the obtained array digital signal to obtain a compensated output signal.

An antenna array calibration device in a complex electromagnetic environment provided by the present invention is characterized in that the device includes a signal generator unit, a circular antenna array unit, an array receiver front-end unit, an array channel parameter extraction unit, and a channel parameter processing unit and channel compensation unit;

The circular antenna array unit is used to receive signals and transmit calibration signals, a calibration signal transmitting antenna for sending calibration signals is placed in the center of the circular array, and multiple receiving antennas are evenly placed on the circumference of the circular antenna array , the distance between each adjacent receiving antenna is equal, the receiving antenna receives the calibration signal mixed with external interference in the phase of extracting the array channel parameters; in the phase of compensating the array signal, receives the required array signal to be calibrated, and the signal occurs The single-frequency signal generated by the detector unit is used as a calibration signal in the array calibration process;

The front-end unit of the array receiver is used for amplifying, filtering, and analog-to-digital conversion processing on the received signal, and providing it to the array channel parameter extraction unit;

The array channel parameter extraction unit is used to perform operations on the received array signal and reference signal according to the Wiener solution form of the adaptive filter, extract channel parameters, and provide them to the channel parameter processing unit;

The channel parameter processing unit is used to process the calibration frequency point or if there is strong interference at the adjacent frequency, and provide the processed data to the channel compensation unit; if the interference is small and the signal-to-interference ratio is relatively large, then Without processing, get the final channel parameters;

The channel compensation unit includes a broadband compensation unit and/or a multi-narrowband compensation unit to eliminate array channel errors contained in received signals.

The present invention can automatically suppress the influence of small-amplitude same-frequency or adjacent-frequency interference on the calibration results of the frequency point array within any frequency band and in complex electromagnetic environments with dense interference. If the amplitude of the interference is relatively large, it can be automatically eliminated. The channel parameters of the frequency point are replaced by interpolation to accurately obtain the final array channel parameters, and perform multi-narrowband compensation, or one-time compensation within a wide frequency range. Compared with other array calibration techniques, the present invention has the following characteristics:

(1) According to the principle of the adaptive filter, the present invention uses the Wiener solution form to extract the channel parameters, which has a small amount of calculation, simple calculation, and easy implementation.

(2) In a complex electromagnetic environment, that is, in the case of dense interference, the channel parameters can be processed according to the magnitude of the interference amplitude at the calibration frequency point or adjacent frequency points. It avoids that the conventional array calibration method is easily affected by external interference.

(3) Array channel compensation can perform multi-narrowband compensation or broadband compensation. Broadband compensation is to construct a calibration filter to achieve one-time compensation in the required frequency band; multi-narrowband compensation is to channelize the received signal and divide it into multiple narrowbands. , and then compensate within each narrow band. It avoids the requirement of conventional array channel compensation that the signal to be calibrated and compensated is a signal within a narrow band.

(4) The device of the present invention can be established on the basis of any frequency band range, avoiding that the general array calibration can only be performed in a narrow band range, and the interference in this frequency band is relatively small.

Description of drawings

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

Fig. 2 is a block diagram of channel parameter extraction method;

Fig. 3 is a block diagram of a channel parameter processing method;

Fig. 4 is a block diagram of broadband compensation method;

Fig. 5 is a multi-narrowband compensation method block diagram;

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

Detailed ways

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings. It should be noted here that the descriptions of these embodiments are used to help understand the present invention, but are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

As shown in Figure 1, the array calibration method provided by the example of the present invention includes the following steps:

(1) Send calibration signal

The signal generator generates a single-frequency signal according to the parameters of the calibration signal to be sent, and after digital-to-analog conversion, it is sent out by the calibration signal transmitting antenna. The parameters of the calibration signal include the type, amplitude and frequency of the signal.

(2) Data collection

After sending the calibration signal, the circular antenna array is used to receive each signal, and the digital signal is obtained after analog-to-digital conversion, which is used for the subsequent channel parameter extraction calculation.

(3) Perform channel parameter extraction algorithm

Use the obtained digital signals to perform calculations, extract the amplitude and phase of each channel, and then use the amplitude and phase of a certain channel as a reference to find the relative value of the amplitude and phase of other channels and the reference, that is, the channel amplitude inconsistency and channel phase inconsistency. As shown in Figure 3, the specific steps are as follows:

(3.1) Each receiving antenna of the circular antenna array receives the calibration signal sent by the calibration signal transmitting antenna, as well as interference signals such as air broadcasting stations and aviation communications. The signal received by the i-th receiving antenna is denoted as s _i (n ), n is the serial number of the sampling point.

(3.2) Generate a single-frequency sequence cos2πfn at the same frequency as the calibration signal as reference signal 1, and sin2πfn as reference signal 2, where f is the frequency of the transmitted calibration signal.

(3.3) According to the reference signal and the received signal, perform correlation calculations to extract channel parameters, as follows:

A_i为该通道输出信号的幅度、

为该通道输出信号的相移，它们间接反映了该接收通道引入的幅度和相位的不一致性，其值可基于最小均方准则，用自适应滤波器的维纳解形式，即按下述步骤计算：Assume that the calibration signal transmitted by the calibration signal transmitting antenna located in the center of the circular antenna array is cos2πft, and t is the transmission time. The i-th receiving antenna receives the calibration signal and after amplification, filtering and analog-to-digital conversion, its output signal is

A _i is the amplitude of the output signal of the channel,

is the phase shift of the output signal of the channel, which indirectly reflects the inconsistency of the amplitude and phase introduced by the receiving channel, and its value can be based on the least mean square criterion, using the Wiener solution form of the adaptive filter, that is, according to the following steps calculate:

Compute the correlation statistic w _opt for this channel:

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; opt</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\\ {\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\left[\begin{array}{c}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;fn</span>}<span\; class="notranslate">\; \}</span>\\ <span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;fn</span>}\end{array}\right]$

In the above formula, f is the frequency of the transmitted calibration signal, N is the total number of sampling points used to calculate the relevant statistic w _opt , the weights I _i and Q _i are obtained, and the i-th channel is calculated using the following formula Amplitude A _i , phase

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

求取各通道的幅度和相位与基准的相对值，即通道的幅度不一致性和相位不一致性，作为通道参数。可将第一通道的幅度和相位参数A₁、

作为基准，求取各通道的幅度和相位与该基准的偏差，得到通道幅度不一致性参数A_i′＝A_i/A₁和相位不一致性参数

其中，i为通道序号，1≤i≤P，P为阵列接收通道总数。(3.4) According to A _i and

Calculate the relative value of the amplitude and phase of each channel to the reference, that is, the amplitude inconsistency and phase inconsistency of the channel, as the channel parameters. The amplitude and phase parameters A ₁ ,

As a benchmark, calculate the deviation of the amplitude and phase of each channel from the benchmark, and obtain the channel amplitude inconsistency parameter A _i ′=A _i /A ₁ and phase inconsistency parameter

Wherein, i is the channel number, 1≤i≤P, and P is the total number of receiving channels of the array.

(4) Judging whether the frequency point calibration is completed

The present invention is applicable to any frequency range, and if channel parameters within a wider frequency band are required, calibration signals of multiple frequency points need to be sent. After sending the calibration signal of the first frequency point and extracting the channel parameters of this frequency point, judge whether the frequency point is calibrated or not. If the frequency point is not calibrated, switch to the next frequency point and repeat steps (1) to (3). Until the extraction of channel parameters of all frequency points is completed.

(5) Stop sending the calibration signal

After the channel parameters are extracted, each receiving antenna does not need to receive the calibration signal. Therefore, it is necessary to stop sending the calibration signal and turn off the signal generator so that the calibration signal transmitting antenna no longer sends the calibration signal.

(6) Processing channel parameters

The present invention processes channel parameters to eliminate the influence of interference, and the processing process is shown in FIG. 4 . The specific process of this step is:

i为通道序号。如果在该校准频点处或相邻频点处有外界干扰，但干扰幅度比较小，则该频点处的通道参数直接取为A′_i，k和

若外界干扰幅度比较大，则需要进行处理。(6.1) Assume that the multiple calibration frequency points set in the working frequency band to be calibrated are f _k , k=1, 2, ..., K, K is the total number of calibration frequency points set, in each calibration The relative value of the channel amplitude extracted by the frequency point is A′ _{i, k} , and the relative value of the phase is

i is the channel number. If there is external interference at the calibration frequency point or adjacent frequency points, but the interference amplitude is relatively small, then the channel parameters at this frequency point are directly taken as A′ _{i, k} and

If the external interference is relatively large, it needs to be dealt with.

表示第i通道、第k个频点处的幅度、相位不一致性参数。Example of the present invention is based on the obtained phase-frequency curve The glitch condition of the frequency determines whether to process the channel parameters at this frequency point. Among them, A′ _{i, k} and

Indicates the amplitude and phase inconsistency parameters at the i-th channel and the k-th frequency point.

中，判断并处理毛刺点的方法：设置一个阈值T，当

且则判定该频点处的为毛刺，这时将该频点处的通道幅度相对值A′_i，k和相位相对值

删除。T由相邻的校准频点间隔，通道长度，以及信号传输速度确定，因为

T的单位为度，Δf为两校准信号的频率差，c为信号的传输速度，l是通道的长度。In the phase-frequency curve

, the method of judging and dealing with glitch points: setting a threshold T, when

and Then determine the frequency point at the is a glitch, then the channel amplitude relative value A' _{i, k} and phase relative value at this frequency point

delete. T is determined by the adjacent calibration frequency interval, channel length, and signal transmission speed, because

The unit of T is degrees, Δf is the frequency difference between the two calibration signals, c is the transmission speed of the signal, and l is the length of the channel.

(6.2) Perform interpolation at the frequency point where the channel parameter has been deleted, and replace the deleted channel parameter with the interpolation result as the channel parameter at the frequency point.

在整个工作频段内是平滑的。还可以在已校准的频点个数的基础上，根据需求进行加倍或多倍插值，即增加校准频点总个数K，得到更密集频点对应的通道参数。The specific interpolation method can be third-order polynomial interpolation and other methods to ensure the phase-frequency curve after interpolation

It is smooth over the entire operating frequency band. Based on the number of calibrated frequency points, doubling or multi-fold interpolation can be performed according to requirements, that is, the total number K of calibrated frequency points can be increased to obtain channel parameters corresponding to denser frequency points.

(6.3) Steps (6.1) to (6.2) are repeated to obtain the channel parameters after all channels are processed.

(7) Data collection

Each receiving antenna on the circular antenna array receives the required air signal, and collects each signal synchronously.

(8) Channel Compensation

Channel compensation has a broadband compensation method and a multi-narrowband compensation method.

The wideband compensation process is shown in Figure 5. The present invention provides a method for performing wideband amplitude phase compensation on signals received by each channel. The specific steps are as follows:

作为宽带补偿滤波器的频域响应H_i(f)正频带上的参数，将A′_j，k和

作为H_i(f)的负频带上的参数，再对H_i(f)进行傅里叶反变换，即可得到宽带补偿滤波器的时域冲击响应h_i(n)。(a1), construct broadband compensating filter, according to the symmetry of FIR filter parameter, the channel parameter A ' _{i that obtains at each calibration frequency point place of i channel, k} and

As the parameters on the positive frequency band of the frequency domain response H _i (f) of the broadband compensation filter, A′ _{j, k} and

As a parameter on the negative frequency band of H _i (f), the time-domain impulse response h _i (n) of the broadband compensation filter can be obtained by inverse Fourier transform of H _i (f).

(a2), enter the signal x _i (n) to be calibrated received by the i channel into the digital compensation filter, and convolve it with the time-domain impulse response h _i (n) of the broadband compensation filter, namely:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$

s' _i(n) is the compensated signal of the i-th channel.

(a3). Steps (a1) to (a2) are repeated to obtain the compensated received signals of all channels.

The present invention can also carry out multi-narrowband compensation for signals received by each channel, the process is shown in Figure 6, and the specific steps are as follows:

(b1), the wideband digital signal x _i (n) received by the i channel is processed through channelization, that is, several bandpass filters whose bandwidth is Δf and center frequency are respectively f _m are used to process the received signal x of the full frequency band _i (n) is filtered to obtain the channelized output signal:

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; g</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$

g _{i, m} (n) is the impulse response of the m-th channel bandpass filter of the i-th channel, m=1, 2, . . . , M, and M is the number of channels.

After channelization processing, the wideband received signal x _i (n) is transformed into multiple narrowband complex signals y _i,m (n) (channelized signals).

(b2), according to the channel parameters, construct the compensation factor r _{i, m} in the i-th channel and the m-th channel:

为第i通道、第m个信道内的相位不一致性参数。j is the imaginary unit, e is the base of the natural logarithm, A′ _{i, m} is the amplitude inconsistency parameter in the i-th channel and the m-th channel,

is the phase inconsistency parameter in the i-th channel and the m-th channel.

(b3), compensating the channel parameters in the i channel and the m channel to the narrowband complex signal of the corresponding channel, obtaining the channel, the compensation output signal s″ _{i at the channel place, m} (n):

s″ _{i, m} (n) = r _{i, m} y _{i, m} (n)

Use the above formula to obtain the compensation output signal where the received signal of this channel is located at all narrowband channels.

(b4). Repeat (b1) to (b3) to obtain the compensation output signals of all channels at each narrowband channel.

The invention is based on a circular antenna array, and calibrates each channel in a complex electromagnetic environment with dense interference. A calibration signal transmitting antenna 10 for sending calibration signals is placed in the center of the circular antenna array, and the single-frequency signal generated by the signal generator unit 11 is used as the calibration signal during the array calibration process. P receiving antennas 12 are evenly placed on the circular antenna array, and the calibration signal mixed with external interference is received in the stage of extracting the array channel parameters; in the stage of compensating the array signal, the array signal to be calibrated is received.

The array calibration device of the present invention is shown in FIG. 1 , and the array receiver front end 13 may include modules such as amplification, filtering, frequency conversion, and analog-to-digital conversion. In the array channel parameter extraction unit 14, the received array signal and the reference signal are correlated according to the Wiener solution form of the adaptive filter to extract the channel parameters. The channel parameter processing unit 15 is to process if there is strong interference at the calibration frequency point or adjacent frequency, if the interference is small and the signal-to-interference ratio is relatively large, no processing is performed to obtain the final channel parameters. The channel compensation unit 16 includes a wideband compensation unit 160 and a multi-narrowband compensation unit 161 , namely two compensation methods, to eliminate array channel errors contained in received signals.

The above description is only a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment and the accompanying drawings. Therefore, all equivalents or modifications that do not deviate from the spirit disclosed in the present invention fall within the protection scope of the present invention.

Claims (9)

1. An antenna array calibration method under a complex electromagnetic environment, comprising the following steps: Step 1 Send calibration signal; The second step is to use the circular antenna array to receive the sent calibration signal, and perform analog-to-digital conversion on the received signals to obtain the array digital signal; Step 3 Use the obtained array digital signal to extract the amplitude and phase of each channel, and then use the amplitude and phase of a certain channel as a reference to find the relative value of the amplitude and phase of other channels and the reference, that is, the channel amplitude inconsistency Inconsistency with channel phase; Step 4 judge whether all frequency points are calibrated, if yes, go to step 5, otherwise, switch to the next frequency point, repeat step 1 to step 3, until the extraction of channel parameters of all frequency points is completed; Step 5 stop sending calibration signal; The sixth step is to process the channel parameters to eliminate the influence of interference; Step 7: Each receiving antenna on the circular antenna array receives air signals, and performs analog-to-digital conversion on the received signals to obtain array digital signals; Step 8 Compensate the obtained array digital signal to obtain a compensated output signal. 2. antenna array calibration method according to claim 1, is characterized in that, the 3rd step specifically comprises the following process: (3.1) Each receiving antenna of the circular antenna array receives the calibration signal sent by the calibration signal transmitting antenna and the interference signal. The signal received by the i-th receiving antenna is recorded as s _i (n) after analog-to-digital conversion, and n is the number of sampling points serial number; (3.2) Generate a single-frequency sequence cos2πfn at the same frequency as the calibration signal, as reference signal 1, and sin2πfn, as reference signal 2, and f is the frequency of the transmitted calibration signal; (3.3) According to the reference signal and the received signal, perform correlation calculations to extract channel parameters, including amplitude A _i , phase

(3.4) Taking the amplitude and phase parameters of one of the channels as a reference, calculate the deviation between the amplitude and phase values of each channel and the reference, and obtain the channel amplitude inconsistency parameter and phase inconsistency parameter. 3. The antenna array calibration method according to claim 2, characterized in that the third step includes the following process: step (3.3) is: the calibration signal transmitted by the calibration signal transmitting antenna assumed to be located in the center of the circular antenna array is cos2πft, t is the transmission time, the i-th receiving antenna receives the calibration signal and after amplification, filtering and analog-to-digital conversion, its output signal is

A _i is the amplitude of the i-th channel output signal,

For the phase shift of the output signal of this channel, calculate the correlation statistic w _opt of this channel: ${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; opt</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\\ {\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\left[\begin{array}{c}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;fn</span>}<span\; class="notranslate">\; \}</span>\\ <span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;fn</span>}<span\; class="notranslate">\; \}</span>\end{array}\right]$ In the above formula, f is the frequency of the transmitted calibration signal, N is the total number of sampling points used to calculate the correlation statistic w _opt , the weights I _i and Q _i are obtained, and using

Calculate the amplitude A _i and phase of the i-th channel 4. The antenna array calibration method according to claim 1, 2 or 3, wherein the 6th step specifically comprises the following process: Assume that the multiple calibration frequency points set in the working frequency band to be calibrated are f _k , k=1,2,...,K, K is the total number of calibration frequency points set, and each calibration frequency point is extracted The channel amplitude relative value of is A′ _i,k , and the phase relative value is i is the channel number; if there is external interference at a calibration frequency point or an adjacent frequency point, but the interference amplitude is relatively small, the channel parameters at this frequency point are directly taken as A′ _{i, k} and

Otherwise, remove the channel parameters of the frequency point, and then perform interpolation processing to replace the previous channel parameters to eliminate the influence of interference. 5. antenna array calibration method according to claim 4, is characterized in that, in the 6th step, according to the obtained phase-frequency curve

The glitch condition of the frequency determines whether to process the channel parameters at this frequency point. 6. antenna array calibration method according to claim 5, is characterized in that, in phase-frequency curve

In , the method of judging and dealing with glitch points: (6.1) when and

Then determine the frequency point at the

is a glitch, then the channel amplitude relative value A' _{i, k} and phase relative value at this frequency point Delete, wherein, T is a preset threshold; (6.2) Perform interpolation at the frequency point where the channel parameter has been deleted, and replace the deleted channel parameter with the interpolation result as the channel parameter at the frequency point; (6.3) Repeat steps (6.1)~(6.2) to obtain the channel parameters after all channel processing. 7. according to the line array calibration method described in any one of claim 1 to 6, it is characterized in that, the 8th step carries out broadband compensation according to the following process: (a1), construct broadband compensation filter, according to the symmetry of FIR filter parameter, the channel parameter A ' _{i, k} that obtains at each calibration frequency point place of the i-th road channel obtains and

As parameters on the positive frequency band of the frequency domain response H _i (f) of the broadband compensation filter, A′ _{i, k} and

As a parameter on the negative frequency band of H _i (f), then inverse Fourier transform is performed on H _i (f), that is, the time-domain impulse response h _i (n) of the broadband compensation filter is obtained; (a2), enter the signal x _i (n) to be calibrated received by the i channel into the digital compensation filter, and convolve it with the time-domain impulse response h _i (n) of the broadband compensation filter, namely: ${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$ s' _i(n) is the compensated signal of the i-th channel; (a3). Steps (a1)~(a2) are repeated to obtain the received signals after compensation of all channels. 8. According to the antenna array calibration method described in any one of claims 1 to 6, it is characterized in that the 8th step carries out multi-narrowband compensation according to the following process: (b1), the signal x _i (n) to be calibrated received by the i-th channel is channelized to obtain a channelized output signal: ${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CircleTimes;</span>{\mathrm{<span\; class="notranslate">\; g</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>$ g _{i, m} (n) is the impulse response of the m-th channel bandpass filter of the i-th channel, m=1,2,...,M, M is the number of channels, After channelization processing, the wideband received signal x _i (n) is transformed into multiple narrowband complex signals y _i,m (n); (b2), according to the channel parameters, construct the compensation factor r _i,m in the i-th channel and the m-th channel: j is the imaginary unit, e is the base of the natural logarithm, A′ _{i, m} is the amplitude inconsistency parameter in the i-th channel and the m-th channel,

is the phase inconsistency parameter in the i-th channel and the m-th channel; (b3), compensating the channel parameters in the i channel and the m channel to the narrowband complex signal of the corresponding channel, obtaining the channel, the compensation output signal s″ _{i at the channel place, m} (n): s″ _{i, m} (n) = r _{i, m} y _{i, m} (n) Use the above formula to find the compensation output signal where the received signal of this channel is located at all narrowband channels; (b4). Repeat (b1)~(b3) to obtain the compensation output signals of all channels at each narrowband channel. 9. An antenna array calibration device in a complex electromagnetic environment, characterized in that the device includes a signal generator unit, a circular antenna array unit, an array receiver front-end unit, an array channel parameter extraction unit, a channel parameter processing unit and a channel compensation unit; The circular antenna array unit is used to receive signals and transmit calibration signals. A calibration signal transmitting antenna for sending calibration signals is placed in the center of the circular array. Multiple receiving antennas are evenly placed on the circumference of the circular antenna array. Each phase The distances between adjacent receiving antennas are all equal, and the receiving antennas are used to receive calibration signals mixed with external interference in the phase of extracting array channel parameters, and receive required array signals to be calibrated in the phase of compensating array signals; the signal generator unit The single-frequency signal used for generation is used as a calibration signal in the array calibration process; The front-end unit of the array receiver is used for amplifying, filtering, and analog-to-digital conversion processing on the received signal, and providing it to the array channel parameter extraction unit; The array channel parameter extraction unit is used to perform operations on the received array signal and the reference signal according to the Wiener solution form of the adaptive filter, extract channel parameters, and provide them to the channel parameter processing unit; The channel parameter processing unit is used to process the calibration frequency point or if there is strong interference at the adjacent frequency, and provide the processed data to the channel compensation unit; if the interference is small and the signal-to-interference ratio is relatively large, then Without processing, get the final channel parameters; The channel compensation unit includes a broadband compensation unit and/or a multi-narrowband compensation unit to eliminate array channel errors contained in received signals.

Images