CN108957419B - Asynchronous interference suppression method based on notch filtering processing - Google Patents
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The invention discloses an asynchronous interference suppression method based on notch filtering processing, which mainly comprises the following steps: determining an airborne radar, wherein a target exists in a detection range of the airborne radar, and an echo signal received after the airborne radar transmits a signal to the detection range and is reflected by the target is recorded as an original radar echo data matrix; obtaining a distance-Doppler domain data matrix according to the radar original echo data matrix; then determining the main lobe clutter; calculating the Doppler frequency of the mainlobe clutter and obtaining a column vector g with the length of R; wherein R is a positive integer greater than 1; determining a reference threshold
Obtaining the result g after modification treatment in sequence pro And the normalized power sum vector G to obtain a notch filtering weight coefficient vector F; and performing sliding window processing on the radar original echo data matrix by using a trapped wave filtering weight coefficient vector F to obtain a result after the sliding window processing, wherein the result after the sliding window processing is an asynchronous interference suppression result based on the wave-limiting filtering processing.
Description
Technical Field
The invention belongs to the technical field of radars, and particularly relates to an asynchronous interference suppression method based on notch filtering processing, which is suitable for suppressing the echo asynchronous interference of an airborne radar.
Background
The airborne radar is regarded as a strategic weapon capable of controlling battlefield situation by the military of each country based on the unique operational characteristics. The interference suppression performance is a main factor influencing whether the airborne radar can be normally detected, so that the interference suppression technology of the airborne radar is emphasized by researchers in various countries.
In a radar signal environment, interference is always present; common interference can be mainly divided into deception interference, blocking interference, dot frequency (vertical stripe) interference and asynchronous interference; the Asynchronous Interference (Asynchronous Interference) mainly comes from electromagnetic radiation of industrial production equipment, communication equipment, other radars and the like, and is characterized by randomly appearing in a narrow pulse form and having amplitude far larger than a noise substrate, so that the Asynchronous Interference is also called Singular Value; in the source, the radar has a certain periodicity, but the frequency of the occurrence of the radar is inconsistent with the working pace of the radar; therefore, the time when the asynchronous interference occurs in the radar receiver is not fixed and shows a large randomness.
On the other hand, the amplitude of asynchronous interference is very large and far greater than the signal and noise level values, and sometimes even reaches the clutter level; asynchronous interference appears in a Pulse Doppler (PD) diagram as horizontal stripes with a certain width in the range domain and full Doppler domain; in signal detection of radar, because its width is similar to the target echo signal, it is usually detected as a target; in automatic detection, a trace point agglomeration technology is usually adopted to reduce the number of original trace points; due to the fact that the intensity of the asynchronous interference is too strong, if a target appears nearby, the asynchronous interference covers the target appearing in the neighborhood range due to a point trace condensation algorithm, the target is lost or wrong (specifically, a singular value is detected by a radar) at some time, and therefore the detection performance of the radar on the target is affected; in addition, the radar usually adopts an accumulation mode to improve the discovery probability of the target, and due to the existence of asynchronous interference signals, the noise floor of each accumulated channel is obviously improved, and the detection probability of the target is reduced.
The asynchronous interference has high probability and high intensity in certain frequency bands (especially meter waves) and certain occasions, and has little influence or even no influence in other environments; therefore, an adaptive method must be designed in radar signal processing to handle asynchronous interference, and when asynchronous interference occurs, the asynchronous interference is suppressed and eliminated, and when no asynchronous interference occurs, no suppression operation is performed, so as to reduce signal processing loss.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide an asynchronous interference suppression method based on notch filtering, which can adaptively suppress asynchronous interference, adaptively calculate corresponding filtering weight coefficients to eliminate asynchronous interference when asynchronous interference occurs, and do not perform suppression operation when asynchronous interference does not occur, so as to reduce signal processing loss.
The main idea for realizing the purpose of the invention is as follows: the method is characterized in that the characteristic that asynchronous interference is shown as a thin line of a single or a plurality of range gates after windowing Fourier transform is carried out on a pulse dimension before pulse compression is carried out on a radar original data matrix is utilized, and a self-adaptive notch wave filtering weight coefficient is calculated to restrain the radar original data matrix.
In order to achieve the technical purpose, the invention adopts the following technical scheme to realize.
An asynchronous interference suppression method based on notch filtering processing comprises the following steps:
step 1, determining an airborne radar, wherein a target exists in a detection range of the airborne radar, and an echo signal received after the airborne radar transmits a signal to the detection range and is reflected by the target is recorded as an original radar echo data matrix; obtaining a range-Doppler domain data matrix according to the radar original echo data matrix; then determining the main lobe clutter;
step 2, calculating the Doppler frequency of the main lobe clutter, and obtaining a column vector g with the length of R according to the distance-Doppler domain data matrix; wherein R is a positive integer greater than 1;
step 3, determining a reference threshold according to the column vector g with the length of R
Step 4, obtaining a result g after modification processing according to the reference threshold and the column vector with the length of R pro ；
Step 5, according to the result g after modification treatment pro And a reference threshold
Obtaining normalized power and vector G;
step 6, obtaining a notch filtering weight coefficient vector F according to the normalized power and the vector G;
and 7, performing sliding window processing on the radar original echo data matrix by using the notch filtering weight coefficient vector F to obtain a result after the sliding window processing, wherein the result after the sliding window processing is an asynchronous interference suppression result based on the notch filtering processing.
Compared with the prior art, the invention has the following advantages:
firstly, the invention can adaptively inhibit asynchronous interference of different distances and frequencies, and when data without asynchronous interference is processed, the adaptive filter weight coefficients are all 1, so as to ensure that no processing loss is caused to the signal data.
Secondly, the existing asynchronous interference suppression method adopts two-pulse delay cancellation, and the cancellation result is modulo and delayed by one frame; FAR processing and distance clutter map establishment and updating; detecting the threshold value, recording the distance unit position, and filling a threshold table; examining a threshold table and determining a singular value position; the method for interpolating and replacing the signals at the asynchronous interference position by the adjacent signals has complex calculation process and long consumed time; the method of the invention directly carries out windowing processing on the original data through self-adaptive weight, and has the advantages of less calculated amount, simple process and shorter time consumption.
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The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a flow chart of an asynchronous interference suppression method based on notch filtering according to the present invention;
FIG. 2 is a range-Doppler spectrogram of a radar raw echo data matrix;
FIG. 3 is a schematic diagram of the results obtained after a windowed Fourier transform of a radar raw echo data matrix along a pulse dimension;
FIG. 4 is a graph of the calculated adaptive weights;
figure 5 is a graphical representation of the results obtained after suppression by the present invention followed by pulse compression and range-doppler processing.
Detailed Description
Referring to fig. 1, it is a flowchart of an asynchronous interference suppression method based on notch filtering processing according to the present invention; the asynchronous interference suppression method based on notch filtering processing comprises the following steps:
step 1, determining an airborne radar, wherein a target exists in a detection range of the airborne radar, and an echo signal received after the airborne radar transmits a signal to the detection range and is reflected by the target is recorded as an original radar echo data matrix B N×M'×R Array B of radar raw echo data N×M'×R The data block is formed by multiplying the array element number N by the pulse number M' by the range gate number R, and the radar original echo data matrix B N×M'×R Is a three-dimensional matrix of NxM 'xR, N represents the total number of array elements included by the airborne radar, M' represents the total number of pulses transmitted by the airborne radar in a Coherent Processing Interval (CPI), R represents the total number of range gates included after the airborne radar divides the detection range of the airborne radar,
PRF denotes the pulse repetition frequency and B denotes the bandwidth of the signal transmitted by the airborne radar into its detection range.
Directly carrying out pulse compression processing on a radar original echo data matrix B N×M'×R Fast Fourier Transform (FFT) of the Chebyshev window is added along the pulse dimension to obtain a three-dimensional matrix B of NxMxR after the FFT ceil (ii) a The post-Fast Fourier Transform (FFT) NxMxR three-dimensional matrix B ceil Each array element in the array corresponds to a two-dimensional matrix with the size of R multiplied by M, namely:
B ceil ＝[B ceil (1) B ceil (2) … B ceil (i) … B ceil (N)]
wherein, i is 1,2, …, N, B ceil (i) Three-dimensional matrix B representing N × M × R after Fast Fourier Transform (FFT) ceil The ith array element in the array is corresponding to a two-dimensional matrix with the size of R multiplied by M, and a three-dimensional matrix B of N multiplied by M multiplied by R after Fast Fourier Transform (FFT) transformation ceil Large corresponding to the ith array elementTwo-dimensional matrix B as small as R × M ceil (i) Includes R × M data, whose expression is:
wherein, b 11 (i) Three-dimensional matrix B representing NxMxR after Fast Fourier Transform (FFT) ceil The ith array element in the matrix is corresponding to a two-dimensional matrix B with the size of R multiplied by M ceil (i) Data at inner 1 st range gate, 1 st Doppler channel, b 1M (i) Three-dimensional matrix B representing NxMxR after Fast Fourier Transform (FFT) ceil The ith array element in the matrix is corresponding to a two-dimensional matrix B with the size of R multiplied by M ceil (i) Data at the 1 st range gate, Mth Doppler channel, b R1 (i) Three-dimensional matrix B representing N × M × R after Fast Fourier Transform (FFT) ceil The ith array element in the matrix is corresponding to a two-dimensional matrix B with the size of R multiplied by M ceil (i) Inner Rth range gate, data at 1 st Doppler channel, b RM (i) Three-dimensional matrix B representing NxMxR after Fast Fourier Transform (FFT) ceil The ith array element in the matrix is corresponding to a two-dimensional matrix B with the size of R multiplied by M ceil (i) Inner Rth range gate, Mth Doppler channel.
The three-dimensional matrix B of N × M × R after Fast Fourier Transform (FFT) ceil Each array element in the array is accumulated corresponding to a two-dimensional matrix with the size of R multiplied by M, and then a frequency domain data block after transformation is obtained and is marked as a distance-Doppler domain data matrix B FFT The calculation expression is as follows:
at this time, the range-Doppler domain data matrix B FFT Is a two-dimensional matrix of R × M, and a range-Doppler domain data matrix B FFT Comprises R × M range-Doppler domain data, M represents a range-Doppler domain data matrix B FFT Including the total number of Doppler channels, and is coherent with oneThe total number M' of pulses transmitted by the airborne radar in the Processing Interval (CPI) is equal; r represents the total number of range gates included after the detection range of the airborne radar is divided,
PRF denotes the pulse repetition frequency and B denotes the bandwidth of the signal transmitted by the airborne radar into its detection range.
Defining the maximum radiation beam of the signals transmitted by the airborne radar within the detection range as a mainlobe beam, defining the irradiation direction of the mainlobe beam as the main lobe beam direction, and defining an echo signal generated by irradiating the mainlobe beam on the ground and reflecting the mainlobe beam on the ground as a mainlobe clutter; the main lobe clutter is compressed and concentrated because the fast fourier transform transforms the signal from the time domain to the frequency domain, and appears in the range-doppler plot as a vertical line with a certain width at a certain doppler frequency (reflected in the doppler channel), such as the doppler channel No. 30 in fig. 2.
Step 2, calculating the Doppler frequency f of the mainlobe clutter d ：
Wherein v is the flight speed of the airborne radar carrier, lambda is the wavelength of the signal transmitted by the airborne radar to the detection range, phi 0 The included angle between the main beam direction and the flight speed direction of the airborne radar carrier can be obtained according to the flight geometric relationship of the airborne radar carrier:
wherein the content of the first and second substances,
azimuth angle, theta, directed by the main beam 0 Sin denotes a sine function and cos denotes a cosine function for the pitch angle at which the main beam is directed.
Obtaining the Doppler frequency f of the main lobe clutter d Then, the data matrix B in the range-Doppler domain is required FFT Removing Doppler frequency at f d Nearby clutter data is used for eliminating the influence of main lobe clutter energy to obtain data of a clear region part; here along the doppler-pulse frequency domain data matrix B FFT Finding the Doppler frequency f of the mainlobe clutter in the Doppler direction d And selecting the Doppler frequency f of the clutter with the mainlobe d Is central and has a length of
Region of width R, noted
A two-dimensional matrix of
In a two-dimensional matrix of
All range-Doppler domain data are eliminated, and a range-Doppler domain data matrix B is obtained FFT As described in
Sequentially splicing the rest two areas after all the range-Doppler domain data are eliminated, namely
Two-dimensional matrix of (A) and
sequentially splicing the two-dimensional matrixes to obtain
A two-dimensional matrix B of
Two-dimensional matrix B ofIs a clear area, and
each range-doppler domain data in the two-dimensional matrix B is clear area data.
Then to the
Each row of the two-dimensional matrix B
Adding Doppler-pulse frequency domain data, recording the added result as the power sum of a range gate to further obtain the power sum of R range gates, and recording the power sum of the R range gates as a column vector g with the length of R; wherein, R represents the total number of range gates included after the detection range of the airborne radar is divided.
Step 3, according to the previous analysis, the amplitude of the asynchronous interference in the radar signal is far larger than the noise floor, so that the asynchronous interference is embodied as singular points in clutter data, and the singular points need to be removed, and the specific method is as follows:
sorting the power sums of R range gates in a column vector g with the length of R from small to large, and recording the result obtained after sorting from small to large as a sorted column vector g with the length of R sort And removing the sorted column vector g of length R sort Medium power point, due to the sorted column vector g of length R sort Is the sum of the powers of R range gates ordered from small to large, so that only the ordered column vector g of length R is needed sort To select data of a suitable location.
The specific method comprises the following steps: sorting column vector g with length R sort Power sum of the 1 st range gate to
Power sum of a distance gate, and
the power sum of every distance gate and the power sum of every R distance gate are completely removed, and the rest power sum is
The power sums of the range gates are sequentially added, and the added result is divided by
Further obtaining a statistical average value which is used as a reference threshold
The calculation expression is as follows:
wherein, the first and the second end of the pipe are connected with each other,
g sort (i') represents a sorted column vector g of length R sort The power sum of the ith' range gate, R represents the total number of range gates included after the detection range of the airborne radar is divided,
PRF denotes the pulse repetition frequency and B denotes the bandwidth of the signal transmitted by the airborne radar into its detection range.
Here, the sorted column vector g of length R is removed sort Power sum to the 1 st range gate
The sum of the power of the range gates is to ensure accuracy and prevent too small samples from interfering with the overall data sample.
Step 4, taking reference threshold
Obtained after a certain multiple k
As a threshold value for performing detection and judgment later, k is a set proportional parameter, where k is greater than 1 and less than 10, and k is 4 in this embodiment; according to different conditions, modification processing can be carried out, and all column vectors g with the length of R are smaller than
Is replaced by the power sum of the distance door
All column vectors g with length R are greater than or equal to
The power sum of the distance gate of (1) is kept constant; further, a result g after modification processing is obtained pro At this time, the processed result g is modified pro Is a column vector of length R; wherein, R represents the total number of range gates included after the airborne radar divides the detection range.
Step 5, modifying the result g after the processing pro With respect to the reference threshold determined in step 3
And carrying out normalization processing to obtain a normalized power sum vector G, wherein the calculation expression is as follows:
at this time, the normalized power sum vector G is a column vector with a length of R, and R represents the total number of range gates included after the airborne radar divides the detection range.
And 6, carrying out inversion operation on the normalized power sum vector G obtained in the step 5, and recording a result obtained after the inversion operation as a notch filtering weight coefficient vector F, wherein the calculation expression is as follows:
F＝1/G
at this time, the notch filter weight coefficient vector F is a column vector with the length of R, and R represents the total number of range gates included after the detection range of the airborne radar is divided.
Step 7, using a sliding window algorithm to perform filtering on the radar original echo data matrix B by using the notch filtering weight coefficient vector F obtained in the step 6 N×M'×R Performing sliding window processing along a pulse dimension to obtain a result after the sliding window processing, wherein the result after the sliding window processing is an asynchronous interference suppression result based on notch filtering processing; where M' represents the total number of pulses transmitted by the on-board radar within one Coherent Processing Interval (CPI).
The advantages of the present invention can be further illustrated by the following simulation experiments.
(I) experimental parameters and experimental conditions
The parameters used in this experiment were as follows:
1) the airborne radar antenna adopts a 2-row and 16-column planar array, the array element interval is half wavelength of the transmitted waveform of the airborne radar, and radar echo data with the size of NxMxR can be obtained after pitching filtering; the radar array surface is obliquely arranged side by side.
2) Transmitting 101 coherent accumulation pulses within the same coherent processing interval CPI, the pulse repetition frequency being 2.203 kHz; the distance sampling frequency is 2 MHz; the main beam is directed to form an included angle of 176 degrees with the aircraft nose, and the yaw angle is 5 degrees; the height of the carrier is 8.3 kilometers, the carrier flies at a constant horizontal speed, and the speed is 149 m/s; the earth radius is 6378 km.
(II) analysis of experiment content and results
A. In the experiment, normal pulse compression and pulse Doppler processing are firstly carried out on the radar original echo data matrix, and the processing result is shown in FIG. 2; wherein the abscissa represents the number of doppler channels of the signal and the ordinate represents the number of range gates of the signal, and as can be seen from fig. 2, there are a large number of obvious horizontal stripes at the range gates of 50-150 and 670-770, and a small number of weaker horizontal stripes at the range gate of 300, which are asynchronous interference.
B. Processing radar echo data according to the process of the invention; fig. 3 is a schematic diagram of a result obtained after a radar original echo data matrix is subjected to windowed fourier transform along a pulse dimension, and it can be seen by comparing fig. 2 that at this time, energy of asynchronous interference is concentrated on distance gates No. 50, 70, 90, 270, and 680, and a plurality of thin transverse lines with concentrated energy are formed; fig. 4 is a diagram of adaptive weights obtained through calculation, and it can be seen that adaptive notch notches are formed in an interference concentration dividing region to suppress interference, and weights of the rest portions are all 1, so that original radar echo data are not changed.
C. Fig. 5 is a schematic diagram of the result obtained after the suppression by the present invention and the pulse compression and the range-doppler processing, and it can be clearly seen from the comparison of fig. 2 that the horizontal stripes of the corresponding portion of fig. 2 have disappeared in fig. 5, which illustrates that the asynchronous interference has been effectively suppressed; from the results shown in fig. 5, the method of the present invention can effectively suppress the asynchronous interference, and the suppression effect is very good.
In conclusion, the simulation experiment verifies the correctness, the effectiveness and the reliability of the method.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention; thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (8)
1. An asynchronous interference suppression method based on notch filtering processing is characterized by comprising the following steps:
step 1, determining an airborne radar, wherein a target exists in a detection range of the airborne radar, and an echo signal received after the airborne radar transmits a signal to the detection range and is reflected by the target is recorded as an original radar echo data matrix; obtaining a range-Doppler domain data matrix according to the radar original echo data matrix; then determining the main lobe clutter;
step 2, calculating the Doppler frequency of the mainlobe clutter, and obtaining a column vector g with the length of R according to the distance-Doppler domain data matrix; wherein R is a positive integer greater than 1;
step 3, determining a reference threshold according to the column vector g with the length of R
Step 4, obtaining a result g after modification processing according to the reference threshold and the column vector with the length of R pro ；
Step 5, according to the result g after modification treatment pro And a reference threshold
Obtaining normalized power and vector G;
step 6, obtaining a notch filtering weight coefficient vector F according to the normalized power and the vector G;
step 7, performing sliding window processing on the radar original echo data matrix by using a notch filtering weight coefficient vector F to obtain a result after sliding window processing, wherein the result after sliding window processing is an asynchronous interference suppression result based on notch filtering processing;
in step 1, the radar original echo data matrix is B N×M'×R And the radar original echo data matrix B N×M'×R Is a three-dimensional matrix of NxM 'xR, N represents the total number of array elements included by the airborne radar, M' represents the total number of pulses transmitted by the airborne radar in one coherent processing interval, R represents the total number of range gates included after the airborne radar divides the detection range,
PRF represents pulse repetition frequency, B represents the bandwidth of a signal transmitted to the detection range of the airborne radar;
the distance-Doppler domain data matrix is obtained by the following steps:
for radar original echo data matrix B N×M'×R Fast Fourier transform of a Chebyshev window is added along the pulse dimension to obtain an NxMxR three-dimensional matrix B after the fast Fourier transform ceil The expression is as follows:
B ceil ＝[B ceil (1) B ceil (2)…B ceil (i)…B ceil (N)]
wherein, i is 1,2, …, N, B ceil (i) Three-dimensional matrix B representing NxMxR after fast Fourier transform ceil The size of the corresponding ith array element is R multiplied by M two-dimensional matrix; m represents a range-Doppler domain data matrix B FFT The total number of the included Doppler channels is equal to the total number M' of pulses transmitted by the airborne radar in a coherent processing interval;
the three-dimensional matrix B of N multiplied by M multiplied by R after the fast Fourier transform ceil Each array element corresponds to a two-dimensional matrix with the size of R multiplied by M to be accumulated, and then a frequency domain data block after transformation is obtained and is marked as a distance-Doppler domain data matrix B FFT The calculation expression is as follows:
the range-Doppler domain data matrix B FFT Is a two-dimensional matrix of R × M, and a range-Doppler domain data matrix B FFT Including R x M doppler-pulse frequency domain data.
2. The asynchronous interference suppression method based on notch filtering processing as claimed in claim 1, wherein in step 1, the mainlobe clutter is determined by:
the method comprises the steps of defining the maximum radiation beam of an emission signal of the airborne radar in the detection range of the airborne radar as a main lobe beam, defining the irradiation direction of the main lobe beam as the main lobe beam direction, and defining an echo signal generated by irradiating the main lobe beam on the ground and reflecting the main lobe beam on the ground as a main lobe clutter.
3. The asynchronous interference suppression method based on notch filtering process as claimed in claim 1 or 2, wherein in step 2, the doppler frequency of the mainlobe clutter is f d The calculation expression is as follows:
wherein v is the flight speed of the airborne radar carrier, and λ is the wavelength of the signal transmitted by the airborne radar to the detection range, phi 0 The included angle between the main beam direction and the flight speed direction of the airborne radar carrier is formed;
the column vector with the length of R is obtained by the following steps:
along the Doppler-pulse frequency domain data matrix B FFT Finding the Doppler frequency f of the mainlobe clutter in the Doppler direction d And selecting the Doppler frequency f of the clutter with the mainlobe d Is central and has a length of
Region of width R, noted
Of a two-dimensional matrix of
In a two-dimensional matrix of
All range-Doppler domain data are eliminated, and a range-Doppler domain data matrix B is obtained FFT As described in
Sequentially splicing the rest two areas after all the range-Doppler domain data are eliminated, namely
Two-dimensional matrix of
Two dimensions ofSplicing the matrixes in sequence to obtain
A two-dimensional matrix B;
then to the
Each row of the two-dimensional matrix B
Adding Doppler-pulse frequency domain data, recording the added result as the power sum of a range gate to further obtain the power sum of R range gates, and recording the power sum of the R range gates as a column vector g with the length of R; wherein, R represents the total number of range gates included after the detection range of the airborne radar is divided.
4. A method for asynchronous interference suppression based on notch filtering process as claimed in claim 3, characterized in that in step 3, said reference threshold is set
The determination process comprises the following steps:
sorting column vector g with length R sort Power sum to the 1 st range gate
Power of a distance gate, and
the power sum of every distance gate and the power sum of every R distance gate are all removed, and the rest power sum is
The power sums of the range gates are sequentially added, and the added result is divided by
Further obtaining a statistical average value which is used as a reference threshold
The calculation expression is as follows:
wherein, the first and the second end of the pipe are connected with each other,
g sort (i') represents a sorted column vector g of length R sort The power sum of the ith' range gate, R represents the total number of range gates included after the detection range of the airborne radar is divided,
PRF denotes the pulse repetition frequency and B denotes the bandwidth of the signal transmitted by the airborne radar into its detection range.
5. The asynchronous interference suppression method based on notch filtering process as claimed in claim 1, wherein in step 4, the modified result g is obtained pro The obtaining process is as follows:
all column vectors g with length R are smaller than
Is replaced by the power sum of the distance door
All column vectors g with length R are greater than or equal to
Power and maintenance of the distance gateThe change is not changed; further, a result g after modification processing is obtained pro Modifying the processed result g pro Is a column vector of length R; wherein k represents a set proportion parameter, and k is more than 1 and less than 10; r represents the total number of range gates included after the detection range of the airborne radar is divided,
PRF denotes the pulse repetition frequency and B denotes the bandwidth of the signal transmitted by the airborne radar into its detection range.
6. The method as claimed in claim 1, wherein in step 5, the normalized power sum vector G is obtained by:
for result g after modification processing pro With respect to reference threshold
Carrying out normalization processing to obtain normalized power and vector G, wherein the calculation expression is as follows:
the normalized power sum vector G is a column vector with the length of R, R represents the total number of range gates included after the detection range of the airborne radar is divided,
PRF denotes the pulse repetition frequency and B denotes the bandwidth of the signal transmitted by the airborne radar into its detection range.
7. The asynchronous interference suppression method based on notch filtering process as claimed in claim 1, wherein in step 6, said notch filtering weight coefficient vector F is calculated by the expression:
F＝1/G
the vector F of the notch filtering weight coefficient is a column vector with the length of R, R represents the total number of range gates included after the airborne radar divides the detection range,
PRF denotes the pulse repetition frequency and B denotes the bandwidth of the signal transmitted by the airborne radar into its detection range.
8. The asynchronous interference suppression method based on notch filtering process as claimed in claim 5, wherein in step 7, the result after the sliding window process is to radar original echo data matrix B by using the notch filtering weight coefficient vector F using the sliding window algorithm N×M'×R Performing sliding window processing along the pulse dimension to obtain a result; wherein, M' represents the total number of pulses transmitted by the airborne radar in one coherent processing interval.
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| CN111007466B (en) * | 2019-12-03 | 2023-05-26 | 西安电子科技大学 | DCAR interference suppression method and system based on introduced range gate degree of freedom |
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