CN111352083A - Automatic calibration method and device for gain of multiple receiving channels of high-frequency ground wave radar - Google Patents
Automatic calibration method and device for gain of multiple receiving channels of high-frequency ground wave radar Download PDFInfo
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Abstract
The invention discloses a method and a device for automatically calibrating the gain of multiple receiving channels of a high-frequency ground wave radar, wherein the method comprises the following steps: step 1, collecting ocean echo data by a radar; step 2, installing a wind direction mark to record a real-time average wind direction; step 3, calculating a power spectrum on the reference antenna, and searching a positive side first-order spectral maximum value and a negative side first-order spectral maximum value; step 4, performing sliding window interception on each frame of echo data on each antenna channel to obtain a maximum array snapshot sequence; step 5, calculating the correction value of each group of candidate channels to obtain a snapshot after channel correction; step 6, calculating an arrival angle corresponding to the maximum spectral peak by using a spatial spectrum estimation algorithm; step 7, calculating the total wind direction estimation root mean square error; and 8, searching the minimum overall wind direction estimation root-mean-square error, wherein the corresponding correction value is the optimal correction value. The invention solves the inconsistency of the gain of the receiving channel in the high-frequency ground wave radar, and realizes the automatic correction of the channel gain by linking the maximum first-order spectrum peak value with the wind direction.
Description
Technical Field
The invention relates to the field of electricity, in particular to a method and a device for automatically calibrating gains of multiple receiving channels of a high-frequency ground wave radar.
Background
The high-frequency ground wave radar is a remote sensing device for sea surface state parameters, which can be installed on a coast, a sea surface floating platform or a ship. High-frequency electromagnetic waves emitted to the sea surface by a radar are scattered by sea waves and then received by a radar receiving antenna to obtain Doppler spectrum distribution on each distance and orientation unit, so that parameters such as ocean surface flow velocity, wave height and wind speed are inverted.
The radar adopts a plurality of antenna unit arrays to carry out direction finding. At present, high-frequency ground wave radar antenna arrays are commonly adopted in two forms: the antenna comprises an array antenna which is distributed in space and a monopole/crossed loop antenna which is in a common phase center. Whatever the form of the antenna, the gain of the receiving channel (including the antenna) is required to be kept uniform to obtain the desired directional performance. However, different types of antennas have different circuit structures, and in practice, the electronic components may not be completely identical, so that there is always a gain amplitude and phase inconsistency between the antenna receiving channels. Channel inconsistency will seriously affect radar directional performance, so that inter-channel gain inconsistency must be corrected before subsequent spatial spectrum estimation or arrival angle estimation is performed.
Aiming at the inconsistency of amplitude and phase between receiving channels, the currently adopted method mainly adopts a passive method and an active method. The passive method does not need a cooperative signal source, and adopts any unknown signal source received by the radar to calculate the amplitude and phase errors among the antenna channels. The available unknown signal sources comprise ocean first-order Bragg scattering echo signals and ionosphere reflecting echo signals, the space distribution whip antenna array can be used for amplitude correction, and the phase correction rule is only suitable for a nonlinear array; for a monopole/crossed-loop array, phase correction is appropriate, while amplitude correction is less accurate. Active methods include the use of transponders, single frequency beacons and Automatic Identification System (AIS) information for vessels, all of which require additional dedicated equipment for auxiliary measurements, and the use of signals of known orientation to resolve inter-channel amplitude and phase errors. The auxiliary beacon method is difficult to implement under the conditions of certain applications such as erection on a cliff, a sea floating platform and the like, a ship must be adopted to carry a beacon for navigation measurement, and the method is limited by sea states; the AIS information assisted correction laws are limited by the size, number and orientation of the surface vessels and often do not allow sufficient orientation samples to be obtained. Furthermore, the active method requires additional hardware cost and measurement cost.
The advantages and disadvantages of the channel amplitude and phase correction method are comprehensively analyzed, and in order to perform channel correction timely and efficiently, signal calibration information which can be obtained conveniently and timely needs to be searched for to assist in calculating the amplitude and phase difference of signals among channels. Wind direction is the quantity that indicates the orientation of the strongest first order Bragg scattered echo. Because the first-order Bragg scattering cross section in the radar sea echo is in direct proportion to the directed wave spectrum value on the radar wave beam, the positive first-order spectrum has a maximum value in the direction of the wind direction; and in the wind heading direction, the negative first order spectrum is maximum. In a short-distance range measured by a high-frequency ground wave radar, the wind direction can be considered to be consistent, so that a wind vane is installed at a radar station, and the real-time wind direction can be obtained. And the sea surface wind direction is obtained, so that the first-order spectrum of the corresponding direction can be separated and further used for channel correction.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method and a device for automatically calibrating the gain of multiple receiving channels of a high-frequency ground wave radar aiming at the defects of the amplitude-phase correction technology of the receiving channels of the high-frequency ground wave radar in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the invention provides a high-frequency ground wave radar multi-receiving-channel gain automatic calibration method, which comprises the following steps:
step 1, normally collecting ocean echo data by a radar to obtain S (nT, mT)sR) where T is the coherent integration time, N is 0, …, N-1 is the time frame number, TsIn the frame sampling period, M is 0, …, M-1 is the sampling sequence number in the frame, r is the sequence number of the distance element;
step 2, installing one or more wind vanes at or near the radar station, and recording the real-time average wind direction
Wherein t is time;
and 3, for each frame of radar data with the time of nT, on a plurality of distance elements with the distance less than a certain threshold value, wherein the distance element r is Nr1,…,Nr2Selecting a reference antenna and calculating a power spectrum P (nT, f, r) on the antenna, wherein f is the Doppler frequency; dividing first order Bragg spectrum region, searching positive side and negative side first order spectrum maximum, taking the maximum, and recording its corresponding frequency as fmax(n,r)；
Step 4, calculating fourier transform of a sliding window interception sequence of each frame of echo data on each antenna channel in the step 3 to obtain Y (nT, f, r, K, Q), wherein K is 0, …, K-1 is a sliding window sequence number, Q is 1, …, and Q is an antenna channel sequence number; obtaining a maximum value array snapshot sequence Y (nT, f)max(n,r),r,k,q)；
And step 5, determining a channel correction value search interval and step length, and respectively obtaining channel corrected snapshot Z (nT, f) for each group of candidate channel correction values g (Q, L), wherein Q is 0, …, Q-1, L is 0, … and L-1max(n,r),r,k,q)＝Y(nT,fmax(n,r),r,k,q)/g(q,l)；
Step 6, calculating the arrival angle β (nT, r, l) corresponding to the maximum spectrum peak by using a space spectrum estimation algorithm, and calculating the frequency fmaxThe wind direction was estimated to be β when (n, r) was positivew(nT, r, l) β (nT, r, l), when the frequency f is higher than the predetermined frequencymaxThe wind direction estimate is β when (n, r) is negativew(nT, r, l) β (nT, r, l) + pi, and θ is obtained by averaging the wind direction estimates obtained for each range binw(nT, l) wind direction estimation error of
Step 7, calculating the root mean square error of the total wind direction estimation according to the wind direction estimation at all times;
step 8, searching the minimum total wind direction estimation root mean square error, and the serial number l thereofminCorresponding correction value g (q, l)min) Namely the optimal correction value is obtained.
Further, the formula for calculating the power spectrum P (nT, f, r) on the antenna in step 3 of the present invention is:
wherein M issIs the length of the sliding window, Ms< M, w (M) is a window function, M is 0, …, Ms1, d is the number of interval points intercepted by adjacent sliding windows, and K is the total number of sections intercepted by the sliding windows; the original time sequence S (nT, mT) is expressed by the formulas,r)，m＝0,…,Ms-1 sliding and cutting out the length M at d points in sequencesCalculating the square of the modulus of the windowed Fourier transform of each sub-sequence, and averaging to obtain the final power spectrum estimation.
Further, in step 4 of the present invention, the fourier transform of the sliding window clipping sequence of each frame of echo data on each antenna channel is performed to obtain a calculation formula of Y (nT, f, r, k, q) as follows:
the original time sequence S (nT, mT) is expressed by the formulasR) sliding and cutting out length M at d points in sequencesComputing the fourier transform of each sub-sequence segment.
Further, in step 5 of the present invention, the snapshot Z (nT, f) after channel correction is obtained by calculating the correction values of each group of candidate channels respectivelymax(n, r), r, k, q) with the formula:
namely, the q channel is compensated and corrected by the amplitude inconsistency factor by using the formula.
Further, in step 6 of the present invention, the formula for calculating the arrival angle β (nT, r, l) corresponding to the maximum spectral peak by using the spatial spectrum estimation algorithm is:
where a (θ) is the antenna steering vector and u is the array snapshot Z (nT, f)maxMaximum singular value pair in singular value decomposition formula of (n, r), r, k, q)Corresponding left vector, here assuming that the signal has only one angle of arrival; calculating to obtain multiple signal classification method space spectrum estimation under the condition of single arrival angle by using the formula; the position of the maximum of the spatial spectrum is the signal orientation estimate.
Further, the formula for calculating the root mean square error in step 7 of the present invention is:
where N is 0, …, N-1 is a time frame number, T is a coherent accumulation time, L is 0, …, L-1 is a candidate amplitude correction value number, L is the number of amplitude correction value candidates, and δ (nT, L) is a wind direction estimation error calculated by the nth frame signal under the L-th amplitude correction value.
The invention provides a high-frequency ground wave radar multi-receiving channel gain automatic calibration device, which comprises:
a data management unit for managing radar echo data and field measurement wind direction data, wherein the radar data S (nT, mT)sR) where T is the coherent integration time, N is 0, …, N-1 is the time frame number, TsIn the frame sampling period, M is 0, …, M-1 is the sampling sequence number in the frame, r is the sequence number of the distance element; on-site wind direction data measurement
Wherein t is time;
the radar Doppler spectrum detection unit is used for calculating a power spectrum and detecting a maximum first-order spectral peak; for each frame of radar data with time of nT, on several distance elements whose distance is less than a certain threshold value, distance element r is Nr1,…,Nr2Selecting a reference antenna and calculating a power spectrum P (nT, f, r) on the antenna, wherein f is the Doppler frequency; dividing first order Bragg spectrum region, searching positive side and negative side first order spectrum maximum, taking the maximum, and recording its corresponding frequency as fmax(n,r)；
The array snapshot acquisition unit is used for orienting the detected maximum first-order spectral peak and solving an arrival angle; calculating sliding window interception of each frame of echo data on each antenna channelFourier transform of the sequence to obtain Y (nT, f, r, K, Q), where K is 0, …, K-1 is the sliding window number, Q is 1, …, Q is the antenna channel number; obtaining a maximum value array snapshot sequence Y (nT, f)max(n,r),r,k,q)；
A channel correction value traversal unit, configured to determine a channel correction value search interval and a step size, and obtain, for each group of candidate channel correction values g (Q, L), where Q is 0, …, Q-1, and L is 0, …, and L-1, a post-channel-correction snapshot Z (nT, f) respectivelymax(n,r),r,k,q)＝Y(nT,fmax(n, r), r, k, q)/g (q, l); circularly counting until the correction value is traversed and stopping;
a wind direction estimation and error calculation unit for calculating the arrival angle β (nT, r, l) corresponding to the maximum spectral peak by using a space spectrum estimation algorithm and the current frequency fmaxThe wind direction was estimated to be β when (n, r) was positivew(nT, r, l) β (nT, r, l), when the frequency f is higher than the predetermined frequencymaxThe wind direction estimate is β when (n, r) is negativew(nT, r, l) β (nT, r, l) + pi, and θ is obtained by averaging the wind direction estimates obtained for each range binw(nT, l) wind direction estimation error of
A correction value optimizing unit for searching for the minimum total wind direction estimation root mean square error with the sequence number lminCorresponding correction value g (q, l)min) Namely the optimal correction value is obtained.
The invention has the following beneficial effects: the invention relates to a method and a device for automatically calibrating the gain of multiple receiving channels of a high-frequency ground wave radar. The invention reduces the dependency on the buoy and the cooperative information source, and provides a method and a device for automatically correcting the amplitude-phase error of the receiving channel with extremely low cost and high accuracy for the high-frequency ground wave radar, thereby promoting the development, popularization and application of the high-frequency radar.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a flow chart of a method for automatically correcting amplitude and phase errors of a receiving channel of a high-frequency ground wave radar according to an embodiment of the invention;
FIG. 2 is a schematic structural diagram of an apparatus for automatically correcting amplitude-phase errors of a receiving channel of a high-frequency ground wave radar according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a method and a device for automatically correcting amplitude-phase errors of a receiving channel of a high-frequency ground wave radar, which are mainly based on the directional wave spectrum weathered space direction distribution characteristic and the high-frequency electromagnetic wave sea surface scattering characteristic. The method considers the randomness in the high-frequency radar measurement sample, and reduces the estimation error by a long-time statistical averaging method. The correction value result obtained by the invention is more accurate.
The method utilizes the known wind direction information to search the optimal correction value of the receiving channel error through the high-frequency radar echo wind direction estimation error result. The embodiment specifically explains the technical scheme of the invention by taking the echo spectrum received by a monopole/crossed loop antenna in a high-frequency ground wave radar as an example, and the following steps are carried out:
example 1:
as shown in fig. 1, the method for automatically correcting the amplitude-phase error of the receiving channel of the high-frequency ground wave radar in the embodiment of the present invention includes the following steps:
step 1, collecting ocean echo data by a radar to obtain S (nT, mT)sR) where T is the coherent integration time, N is 0, …, N-1 is the time frame number, TsIn the frame sampling period, M is 0, …, M-1 is the sampling sequence number in the frame, r is the sequence number of the distance element;
step 2, installing one or more wind vanes at or near the radar station, and recording the real-time average wind direction
Wherein t is time;
and 3, for each frame of radar data with the time of nT, carrying out a plurality of closer distance elements (r is N)r1,…,Nr2) Selecting a reference antenna and calculating a power spectrum P (nT, f, r) on the antenna, wherein f is the Doppler frequency; dividing first order Bragg spectrum region, searching positive side and negative side first order spectrum maximum, taking the maximum, and recording its corresponding frequency as fmax(n,r)；
Step 4, calculating fourier transform of a sliding window interception sequence of each frame of echo data on each antenna channel in the step 3 to obtain Y (nT, f, r, K, Q), wherein K is 0, …, K-1 is a sliding window sequence number, Q is 1, …, and Q is an antenna channel sequence number; obtaining a maximum value array snapshot sequence Y (nT, f)max(n,r),r,k,q)；
Step 5, determining a channel correction value search interval and a step size, and obtaining channel-corrected snapshot Z (nT, f) for each group of candidate channel correction values g (Q, L) (Q is 0, …, Q-1, L is 0, …, and L-1) respectivelymax(n,r),r,k,q)＝Y(nT,fmax(n,r),r,k,q)/g(q,l)；
Step 6, calculating the arrival angle β (nT, r, l) corresponding to the maximum spectrum peak by using a space spectrum estimation algorithm, and calculating the frequency fmaxThe wind direction was estimated to be β when (n, r) was positivew(nT, r, l) β (nT, r, l), when the frequency f is higher than the predetermined frequencymaxThe wind direction estimate is β when (n, r) is negativew(nT, r, l) β (nT, r, l) + pi, and θ is obtained by averaging the wind direction estimates obtained for each range binw(nT, l) wind direction estimation error of
Step 7, calculating the root mean square error of the total wind direction estimation according to the wind direction estimation at all times (N is 0, …, N-1)
Step 8, searching the minimum total wind direction estimation root mean square error, and the serial number l thereofminCorresponding correction value g (q, l)min) Namely the optimal correction value is obtained.
The formula for calculating the power spectrum P (nT, f, r) on the antenna in step 3 is:
wherein M issIs the length of the sliding window, Ms< M, w (M) is a window function, M is 0, …, Ms1, d is the number of interval points intercepted by adjacent sliding windows, and K is the total number of sections intercepted by the sliding windows; the original time sequence S (nT, mT) is expressed by the formulas,r)，m＝0,…,Ms-1 sliding and cutting out the length M at d points in sequencesCalculating the square of the modulus of the windowed Fourier transform of each sub-sequence, and averaging to obtain the final power spectrum estimation.
In step 4, the fourier transform of the sliding window interception sequence of each frame of echo data on each antenna channel to obtain a calculation formula of Y (nT, f, r, k, q) is as follows:
the original time sequence S (nT, mT) is expressed by the formulasR) sliding and cutting out length M at d points in sequencesComputing the fourier transform of each sub-sequence segment.
In step 5, calculating each group of candidate channel correction values respectively to obtain a snapshot Z (nT, f) after channel correctionmax(n, r), r, k, q) with the formula:
namely, the q channel is compensated and corrected by the amplitude inconsistency factor by using the formula.
In step 6, the arrival angle β (nT, r, l) corresponding to the maximum spectral peak is calculated by using a spatial spectrum estimation algorithm according to the formula:
where a (θ) is the antenna steering vector and u is the array snapshot Z (nT, f)maxOdds of (n, r), r, k, q)A left vector corresponding to a maximum singular value in the singular value decomposition formula, wherein the signal is supposed to have only one arrival angle; calculating to obtain multiple signal classification method space spectrum estimation under the condition of single arrival angle by using the formula; the position of the maximum of the spatial spectrum is the signal orientation estimate.
The formula for calculating the root mean square error in step 7 is:
where N is 0, …, N-1 is a time frame number, T is a coherent accumulation time, L is 0, …, L-1 is a candidate amplitude correction value number, L is the number of amplitude correction value candidates, and δ (nT, L) is a wind direction estimation error calculated by the nth frame signal under the L-th amplitude correction value.
In the embodiment, in the step 1, the marine echo data is collected according to the radar, the signal to noise ratio is high, and in the data set selected in the embodiment, the first-order spectral peak of the Doppler spectrum is at least 30dB higher than the noise level;
in step 2, one or more wind vanes are arranged at or near the radar station, and the real-time average wind direction is recorded
Here the wind vane should be as close to the sea as possible and as high as possible above the ground to reduce the influence of the land;
in step 3, selecting a monopole antenna as a reference antenna;
in step 4, calculating the fourier transform of the sliding window interception sequence of each frame of echo data on each antenna channel in step 3 to obtain Y (nT, f, r, k, q), wherein a Hamming (Hamming) window can be selected for a window, the length of the window can be half of the length of an original sequence, for example, the original sequence is 1024 sampling points, the window length is 512, the number of sliding interval points is 32, and the number of sliding windows is 17;
step 5, determining a channel correction value search interval and step length, wherein a monopole antenna is selected as a reference antenna in step 3, and because the monopole antenna and the crossed loop antenna share a phase center, a spectrum value with a high signal-to-noise ratio (for example, greater than 30dB) is selected in a radar echo spectrum, an average value of phase differences among channels of the radar echo spectrum can be calculated first to serve as a channel phase correction value, and then only a channel amplitude correction value needs to be estimated; the monopole amplitude can be set to be 1, and only 2 loop antennas need to be subjected to amplitude search, for example, the amplitude search interval is set to be 0.1-10 for both loop 1 and loop 2, and the step length is 0.1;
in step 6, the arrival angle corresponding to the maximum spectral peak is calculated by using a spatial spectrum estimation algorithm, and a multiple signal classification (MUSIC) algorithm can be adopted.
Example 2:
as shown in fig. 2, the apparatus for automatically correcting gain of a receiving channel of a high-frequency ground wave radar according to an embodiment of the present invention includes:
a data management unit for managing radar echo data and field measurement wind direction data, wherein the radar data S (nT, mT)sR) where T is the coherent integration time, N is 0, …, N-1 is the time frame number, TsIn the frame sampling period, M is 0, …, M-1 is the sampling sequence number in the frame, r is the sequence number of the distance element; on-site wind direction data measurement
Wherein t is time;
the radar Doppler spectrum detection unit is used for calculating a power spectrum and detecting a maximum first-order spectral peak; at a number of closer distance elements (r ═ N)r1,…,Nr2) Selecting a reference antenna, calculating a power spectrum P (nT, f, r) on the antenna, dividing a first-order Bragg spectrum region, searching maximum values of first-order spectrums on the positive side and the negative side, and taking the maximum value, wherein the corresponding frequency is recorded as fmax(n,r)；
The array snapshot acquisition unit is used for orienting the detected maximum first-order spectral peak and solving an arrival angle; calculating Fourier transform of a sliding window interception sequence of each frame of echo data on each antenna channel to obtain Y (nT, f, r, K, Q), wherein K is 0, …, K-1 is a sliding window serial number, Q is 1, …, and Q is an antenna channel serial number; obtaining a maximum value array snapshot sequence Y (nT, f)max(n,r),r,k,q)；
A channel correction value traversal unit for determining a channelFor each of the channel correction value search intervals and step lengths, channel-corrected snapshot Z (nT, f) is obtained for each of the sets of candidate channel correction values g (Q, L) (Q is 0, …, Q-1, L is 0, …, L-1), respectivelymax(n,r),r,k,q)＝Y(nT,fmax(n, r), r, k, q)/g (q, l); circularly counting until the correction value is traversed and stopping;
a wind direction estimation and error calculation unit for calculating the arrival angle β (nT, r, l) corresponding to the maximum spectral peak by using a space spectrum estimation algorithm and the current frequency fmaxThe wind direction was estimated to be β when (n, r) was positivew(nT, r, l) β (nT, r, l), when the frequency f is higher than the predetermined frequencymaxThe wind direction estimate is β when (n, r) is negativew(nT, r, l) β (nT, r, l) + pi, and θ is obtained by averaging the wind direction estimates obtained for each range binw(nT, l) wind direction estimation error of
A correction value optimizing unit for searching for the minimum total wind direction estimation root mean square error with the sequence number lminCorresponding correction value g (q, l)min) Namely the optimal correction value is obtained.
It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
Claims (7)
1. A high-frequency ground wave radar multi-receiving-channel gain automatic calibration method is characterized by comprising the following steps:
step 1, normally collecting ocean echo data by a radar to obtain S (nT, mT)sR) where T is the coherent integration time, N is 0, …, N-1 is the time frame number, TsIn the frame sampling period, M is 0, …, M-1 is the sampling sequence number in the frame, r is the sequence number of the distance element;
step 2, installing one or more wind vanes at or near the radar station, and recording the real-time average wind direction
Wherein t is time;
and 3, for each frame of radar data with the time of nT, on a plurality of distance elements with the distance less than a certain threshold value, wherein the distance element r is Nr1,…,Nr2Selecting a reference antenna and calculating a power spectrum P (nT, f, r) on the antenna, wherein f is the Doppler frequency; dividing first order Bragg spectrum region, searching positive side and negative side first order spectrum maximum, taking the maximum, and recording its corresponding frequency as fmax(n,r)；
Step 4, calculating fourier transform of a sliding window interception sequence of each frame of echo data on each antenna channel in the step 3 to obtain Y (nT, f, r, K, Q), wherein K is 0, …, K-1 is a sliding window sequence number, Q is 1, …, and Q is an antenna channel sequence number; obtaining a maximum value array snapshot sequence Y (nT, f)max(n,r),r,k,q)；
And step 5, determining a channel correction value search interval and step length, and respectively obtaining channel corrected snapshot Z (nT, f) for each group of candidate channel correction values g (Q, L), wherein Q is 0, …, Q-1, L is 0, … and L-1max(n,r),r,k,q)＝Y(nT,fmax(n,r),r,k,q)/g(q,l)；
Step 6, calculating the arrival angle β (nT, r, l) corresponding to the maximum spectrum peak by using a space spectrum estimation algorithm, and calculating the frequency fmaxThe wind direction was estimated to be β when (n, r) was positivew(nT, r, l) β (nT, r, l), when the frequency f is higher than the predetermined frequencymaxThe wind direction estimate is β when (n, r) is negativew(nT, r, l) β (nT, r, l) + pi, and θ is obtained by averaging the wind direction estimates obtained for each range binw(nT, l) wind direction estimation error of
Step 7, calculating the root mean square error of the total wind direction estimation according to the wind direction estimation at all times;
step 8, searching the minimum total wind direction estimation root mean square error, and the serial number l thereofminCorresponding correction value g (q, l)min) Namely the optimal correction value is obtained.
2. The method for automatically calibrating gain of multiple receiving channels of high-frequency ground wave radar according to claim 1, wherein the formula for calculating the power spectrum P (nT, f, r) on the antenna in step 3 is as follows:
wherein M issIs the length of the sliding window, Ms< M, w (M) is a window function, M is 0, …, Ms1, d is the number of interval points intercepted by adjacent sliding windows, and K is the total number of sections intercepted by the sliding windows; the original time sequence S (nT, mT) is expressed by the formulas,r)，m＝0,…,Ms-1 sliding and cutting out the length M at d points in sequencesCalculating the square of the modulus of the windowed Fourier transform of each sub-sequence, and averaging to obtain the final power spectrum estimation.
3. The method according to claim 2, wherein in step 4, the calculation formula of Y (nT, f, r, k, q) obtained by performing fourier transform on the sliding window clipping sequence of each frame of echo data on each antenna channel is:
the original time sequence S (nT, mT) is expressed by the formulasR) sliding and cutting out length M at d points in sequencesComputing the fourier transform of each sub-sequence segment.
4. The method according to claim 3, wherein in step 5, the fast-beat Z (nT, f) after channel correction is calculated for each group of candidate channel correction values respectivelymax(n, r), r, k, q) with the formula:
namely, the q channel is compensated and corrected by the amplitude inconsistency factor by using the formula.
5. The method for automatically calibrating gain of multiple receiving channels of high frequency ground wave radar according to claim 4, wherein the formula for calculating the arrival angle β (nT, r, l) corresponding to the maximum spectral peak by using the spatial spectrum estimation algorithm in step 6 is as follows:
where a (θ) is the antenna steering vector and u is the array snapshot Z (nT, f)max(n, r), r, k, q) left vector corresponding to the largest singular value in the singular value decomposition equation, where it is assumed that the signal has only one angle of arrival; calculating to obtain multiple signal classification method space spectrum estimation under the condition of single arrival angle by using the formula; the position of the maximum of the spatial spectrum is the signal orientation estimate.
6. The method for automatically calibrating the gain of multiple receiving channels of the high-frequency ground wave radar according to claim 5, wherein the formula for calculating the root mean square error in the step 7 is as follows:
where N is 0, …, N-1 is a time frame number, T is a coherent accumulation time, L is 0, …, L-1 is a candidate amplitude correction value number, L is the number of amplitude correction value candidates, and δ (nT, L) is a wind direction estimation error calculated by the nth frame signal under the L-th amplitude correction value.
7. The utility model provides a many receiving channel gains of high frequency ground wave radar automatic calibration device which characterized in that includes:
a data management unit for managing radar echo data and field measurement wind direction data, wherein the radar data S (nT, mT)sR) where T is the coherent integration time, N is 0, …, N-1 is the time frame number, TsIn the frame sampling period, M is 0, …, M-1 is the sampling sequence number in the frame, r is the sequence number of the distance element; on-site wind direction data measurement
Wherein t is time;
the radar Doppler spectrum detection unit is used for calculating a power spectrum and detecting a maximum first-order spectral peak; for each frame of radar data with time of nT, on several distance elements whose distance is less than a certain threshold value, distance element r is Nr1,…,Nr2Selecting a reference antenna and calculating a power spectrum P (nT, f, r) on the antenna, wherein f is the Doppler frequency; dividing first order Bragg spectrum region, searching positive side and negative side first order spectrum maximum, taking the maximum, and recording its corresponding frequency as fmax(n,r)；
The array snapshot acquisition unit is used for orienting the detected maximum first-order spectral peak and solving an arrival angle; calculating Fourier transform of a sliding window interception sequence of each frame of echo data on each antenna channel to obtain Y (nT, f, r, K, Q), wherein K is 0, …, K-1 is a sliding window serial number, Q is 1, …, and Q is an antenna channel serial number; obtaining a maximum value array snapshot sequence Y (nT, f)max(n,r),r,k,q)；
A channel correction value traversal unit, configured to determine a channel correction value search interval and a step size, and obtain, for each group of candidate channel correction values g (Q, L), where Q is 0, …, Q-1, and L is 0, …, and L-1, a post-channel-correction snapshot Z (nT, f) respectivelymax(n,r),r,k,q)＝Y(nT,fmax(n, r), r, k, q)/g (q, l); circularly counting until the correction value is traversed and stopping;
a wind direction estimation and error calculation unit for calculating the arrival angle β (nT, r, l) corresponding to the maximum spectral peak by using a space spectrum estimation algorithm and the current frequency fmaxThe wind direction was estimated to be β when (n, r) was positivew(nT, r, l) β (nT, r, l), when the frequency f is higher than the predetermined frequencymaxThe wind direction estimate is β when (n, r) is negativew(nT, r, l) β (nT, r, l) + pi, and θ is obtained by averaging the wind direction estimates obtained for each range binw(nT, l) wind direction estimation error of
A correction value optimizing unit for searching for the minimum total wind direction estimation root mean square error with the sequence number lminCorresponding correction valueg(q,lmin) Namely the optimal correction value is obtained.
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