CN109884626B - Radar based on matched filtering pulse pressure is associated with three-D imaging method - Google Patents
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Abstract
The invention discloses a kind of, and the radar based on matched filtering pulse pressure is associated with three-D imaging method.This method comprises: obtaining initial echo vector；Initial echo vector makees the processing of matched filtering pulse pressure；Separate initial pulse pressure type echo vector；Construct pulse pressure type reference signal matrix；Two-dimensional imaging and three-dimensionalreconstruction.Radar association three-D imaging method based on matched filtering pulse pressure of the invention is based on matched filtering pulse compression technology, for using random frequency hopping, the radar relevance imaging of Step Frequency or linear FM signal form, parse the pulse pressure type echo vector in the different distance unit of three-dimensional imaging region, reconstruct the target information of different distance unit respectively according to the pulse pressure type echo vector and corresponding pulse pressure type reference signal matrix isolated, it has been able to solve the problem that reference signal matrix size is huge in objective high-resolution imaging, accelerate image taking speed, effectively increase echo-signal signal-to-noise ratio and object reconstruction precision.
Description
Technical Field
The invention relates to the technical field of three-dimensional imaging, in particular to a radar-associated three-dimensional imaging method based on matched filtering pulse pressure.
Background
With the development of society, radar high-resolution imaging plays an increasingly important role in ensuring national strategic safety and promoting national economic development. In the existing radar imaging technology, an optical radar can image forward, the wavelength is short, the resolution is high, the imaging speed is high, but the penetration capability to smoke, dust, fog, obstacles and the like is poor depending on target radiation, and the optical radar is easily influenced by environmental factors; the microwave radar can actively detect and has strong penetration capability, but because of low microwave frequency, long wavelength and low angular resolution, and because of the limitation of the imaging principle, imaging accumulation time is needed, and forward-looking high frame frequency and high resolution imaging cannot be realized; synthetic Aperture Radar (SAR) and Inverse Synthetic Aperture Radar (ISAR) imaging, although capable of obtaining high resolution in the lateral direction through synthetic aperture, both rely on relative motion of the radar and the target, and are unable to look ahead imaging; the real aperture array radar and the phased array radar have the disadvantages of large number of array elements, complex structure and high construction and maintenance cost; the microwave correlation imaging technology can realize high-resolution imaging under forward looking and staring conditions, and is used for obtaining a detection signal of a region where a target is located by constructing array signals which are uncorrelated in time and orthogonal in space as a transmitting signal, then obtaining target information by calculating and deducing, and obtaining the target information by correlation processing between the detection signal and a target echo signal.
The radar correlation imaging can realize complex and various space wave modulation by modulating electromagnetic beams in real time through the array coded aperture. Specifically, the electromagnetic wave beams are coded and modulated in real time through the array coding aperture, so that a time-space two-dimensional randomly distributed radiation field is formed, and finally high-resolution, forward-looking and staring imaging is realized by utilizing a detection echo and radiation field reference signal matrix through a matrix equation solving mode, so that the defect that synthetic aperture high-resolution imaging depends on target motion is overcome. At present, radar correlation three-dimensional imaging methods are mainly divided into two types, one method is to finely mesh the whole three-dimensional imaging area and then construct a huge reference signal matrix, and the calculation difficulty of radar correlation imaging depends on the scale of the reference signal matrix, so the method has extremely high requirements on imaging calculation capacity; according to the other method, the whole three-dimensional imaging area is firstly divided into a plurality of three-dimensional imaging units, and then all the three-dimensional imaging units are respectively scanned in a block mode in a mechanical scanning or electronic scanning mode.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a radar-associated three-dimensional imaging method based on matched filtering pulse pressure, which can realize high-resolution imaging on a three-dimensional target under the condition of low signal-to-noise ratio.
Therefore, the invention discloses a radar correlation three-dimensional imaging method based on matched filtering pulse pressure. The method comprises the following steps:
acquiring an initial echo vector: the feed source transmits random frequency hopping signals, step frequency signals or linear frequency modulation signals, the signals are transmitted by the transmitting array elements of the coded aperture antenna array and then scattered by the three-dimensional imaging area, and the receiving array elements of the coded aperture antenna array receive echo signals scattered by the three-dimensional imaging area so as to obtain an initial echo vector and an initial reference signal matrix;
and performing matched filtering pulse pressure processing on the initial echo vector: performing the matched filtering pulse pressure processing on the initial echo vector to obtain an initial pulse pressure type echo vector corresponding to the initial echo vector;
separating the initial pulse pressure type echo vector: extracting and separating echoes at different peak positions in the initial pulse pressure type echo according to the initial pulse pressure type echo vector, and constructing pulse pressure type echo vectors of different distance units corresponding to the different peak positions according to the echoes;
constructing a pulse pressure type reference signal matrix: performing the matched filtering pulse pressure processing on the initial reference signal matrix to obtain an initial pulse pressure type reference signal matrix, and respectively constructing pulse pressure type reference signal matrixes corresponding to the pulse pressure type echo vectors according to the initial pulse pressure type reference signal matrix;
two-dimensional imaging and three-dimensional reconstruction: and according to the pulse pressure type echo vector and the pulse pressure type reference signal matrix, carrying out two-dimensional imaging on different distance units with target scattering information, and combining all two-dimensional imaging information to obtain complete three-dimensional reconstruction information.
Further, the matched filtering based pulseIn the radar-associated three-dimensional imaging method, the random frequency hopping signal is a signal S transmitted by the transmitting array element of the coded aperture antenna array1(t) is:
wherein the random frequency hopping signal comprises M sub-pulses with a width of TpPulse signal of AiIs the signal amplitude, f, at the ith transmit array elementcIs the center frequency, f, of the electromagnetic wavemFor discrete frequency points randomly distributed over a certain bandwidth, fc+fmIs the mth sub-pulse frequency, pi is the circumferential ratio, j is the imaginary unit,the code phase loaded at the ith transmitting array element at the time t, rect (u) is a rectangular window function,
further, in the radar-associated three-dimensional imaging method based on matched filtering pulse pressure, the echo signal received by the receiving array element and scattered by the three-dimensional imaging region is the initial echo vector, and the initial echo vector sr (t) is:
wherein, betakIn order to divide the three-dimensional imaging region into K grid cells, ti,kFor the time delay through the ith transmitting array element and the kth grid unit and finally to the receiving array element, ti,k＝ri,k/c，ri,kIs given asi,kThe corresponding distance delay.
Further, in the radar-associated three-dimensional imaging method based on matched filtering pulse pressure, the initial reference signal matrix S is:
wherein the matrix element S (t)nAnd k) is:
further, in the radar-associated three-dimensional imaging method based on matched filtering pulse pressure, performing the matched filtering pulse pressure processing on the initial echo vector to obtain the initial pulse pressure type echo vector corresponding to the initial echo vector, includes:
performing frequency mixing processing on the initial echo vector and a local oscillator signal to obtain a baseband echo signal;
constructing a matched filter;
and performing time domain convolution processing on the baseband echo signal and the matched filter to obtain the initial pulse pressure type echo vector.
Further, in the radar-associated three-dimensional imaging method based on matched filtering pulse pressure, the local oscillator signal Slocal(t) is:
further, in the radar-associated three-dimensional imaging method based on matched filtering pulse pressure, the baseband echo signal Srbase(t) is:
wherein,is Slocal(t) complex conjugate number.
Further, in the radar correlation three-dimensional imaging method based on the matched filtering pulse pressure, the matched filter is obtained by firstly carrying out time inverse folding on a baseband transmitting signal and then taking complex conjugation;
the baseband transmission signal s (t) is:
the matched filter h (t) is:
further, in the radar correlation three-dimensional imaging method based on the matched filtering pulse pressure, the initial pulse pressure type echo vector Srh(t) is:
wherein,τ＝t-(m-1)Tp+(l-1)Tp-tik。
further, in the radar correlation three-dimensional imaging method based on matched filtering pulse pressure, a matrix element S of the initial pulse pressure type reference signal matrixif(t, k) is:
the technical scheme of the invention has the following main advantages:
the radar correlation three-dimensional imaging method based on the matched filtering pulse pressure is based on the matched filtering pulse pressure technology, pulse pressure type echo vectors in different distance units in a three-dimensional imaging area are analyzed aiming at radar correlation imaging adopting random frequency hopping signals, step frequency signals or linear frequency modulation signals, then a pulse pressure type reference signal matrix after matched filtering pulse pressure processing is established aiming at the distance units containing target information, and finally target information of different distance units is respectively reconstructed according to the separated pulse pressure type echo vectors and the corresponding pulse pressure type reference signal matrix so as to obtain the completed three-dimensional reconstruction information.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a radar-associated three-dimensional imaging method based on matched filtering pulse pressure according to an embodiment of the present invention;
fig. 2 is a schematic structural principle diagram of a radar-associated three-dimensional imaging method based on matched filtering pulse pressure according to an embodiment of the present invention;
fig. 3 is a schematic diagram illustrating a principle of separation of pulse-pressure type echo vectors in a radar-associated three-dimensional imaging method based on matched filtering pulse pressure according to an embodiment of the present invention;
FIG. 4 is a graph comparing imaging results of an imaging target at a distance of 1.5m under different signal-to-noise ratios by using a radar-associated three-dimensional imaging method based on matched filtering pulse pressure provided by an embodiment of the present invention and a conventional method;
FIG. 5 is a graph comparing imaging results of an imaging target at a distance of 2m under different signal-to-noise ratios by using a radar-associated three-dimensional imaging method based on matched filtering pulse pressure provided by an embodiment of the present invention and a conventional method;
FIG. 6 is a graph comparing imaging results of an imaging target at a distance of 2.5m under different signal-to-noise ratios by using a radar-associated three-dimensional imaging method based on matched filtering pulse pressure provided by an embodiment of the present invention and a conventional method;
fig. 7 is a graph comparing imaging results of an imaging target at a distance of 3m under different signal-to-noise ratios by using the radar-associated three-dimensional imaging method based on matched filtering pulse pressure provided by the embodiment of the invention and the existing method.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
The technical scheme provided by the embodiment of the invention is described in detail below with reference to the accompanying drawings.
As shown in fig. 1, an embodiment of the present invention provides a radar-associated three-dimensional imaging method based on matched filter pulse pressure, including the following steps:
acquiring an initial echo vector: the feed source transmits random frequency hopping signals, step frequency signals or linear frequency modulation signals, the signals are transmitted by the transmitting array elements of the coded aperture antenna array and then scattered by the three-dimensional imaging area, and the receiving array elements of the coded aperture antenna array receive echo signals scattered by the three-dimensional imaging area so as to obtain an initial echo vector and an initial reference signal matrix;
performing matched filtering pulse pressure processing on the initial echo vector: performing matched filtering pulse pressure processing on the initial echo vector to obtain an initial pulse pressure type echo vector corresponding to the initial echo vector;
separating the initial pulse pressure type echo vector: extracting and separating echoes at different peak positions in the initial pulse pressure type echo according to the initial pulse pressure type echo vector, and constructing pulse pressure type echo vectors of different distance units corresponding to different peak positions according to the echoes;
constructing a pulse pressure type reference signal matrix: performing matched filtering pulse pressure processing on the initial reference signal matrix to obtain an initial pulse pressure type reference signal matrix, and respectively constructing pulse pressure type reference signal matrixes corresponding to pulse pressure type echo vectors according to the initial pulse pressure type reference signal matrix;
two-dimensional imaging and three-dimensional reconstruction: and according to the pulse pressure type echo vector and the pulse pressure type reference signal matrix, performing two-dimensional imaging on different distance units with target scattering information, and combining all two-dimensional imaging information to obtain complete three-dimensional reconstruction information.
Wherein the random frequency hopping signal is the signal S transmitted by the transmitting array element of the coded aperture antenna array1(t) is:
in the above formula 1, the random frequency hopping signal includes M sub-pulses with a duration TpPulse signal of AiIs the signal amplitude, f, at the ith transmit array elementcIs the center frequency, f, of the electromagnetic wavemFor discrete frequency points randomly distributed over a certain bandwidth, fc+fmIs the mth sub-pulse frequency, pi is the circumferential ratio, j is the imaginary unit,the code phase loaded at the ith transmitting array element at the time t, rect (u) is a rectangular window function,
the echo signals received by the receiving array elements and scattered by the three-dimensional imaging area are initial echo vectors, and the initial echo vector Sr (t) is as follows:
in the above formula 3, βkIn order to divide the three-dimensional imaging region into K grid cells, ti,kFor the time delay through the ith transmit array element and the kth grid element and finally to the receive array element, ti,k＝ri,k/c，ri,kIs given asi,kCorresponding toThe distance is delayed.
The initial reference signal matrix S is:
in the above equation 4, the matrix element S (t)nAnd k) is:
further, in the embodiment of the present invention, performing matched filtering pulse pressure processing on the initial echo vector to obtain an initial pulse pressure type echo vector corresponding to the initial echo vector includes:
performing frequency mixing processing on the initial echo vector and the local oscillator signal to obtain a baseband echo signal;
constructing a matched filter;
and performing time domain convolution processing on the baseband echo signal and the matched filter to obtain an initial pulse pressure type echo vector.
Wherein the local oscillator signal Slocal(t) is:
baseband echo signal Srbase(t) is:
wherein,is Slocal(t) complex conjugate number.
The matched filter is obtained by firstly carrying out time unwrapping on a baseband transmitting signal and then carrying out complex conjugation;
the baseband transmission signal s (t) is:
the matched filter h (t) is:
initial pulse pressure type echo vector Srh(t) is:
wherein,τ＝t-(m-1)Tp+(l-1)Tp-tik。
matrix element S of initial pulse pressure type reference signal matrixif(t, k) is:
the following describes the radar-associated three-dimensional imaging method based on matched filtering pulse pressure according to the present invention with reference to specific embodiments.
As shown in fig. 2, in which: a represents a feed source, B represents a coded aperture antenna array, C represents a three-dimensional imaging region, the x axis is an axis passing through a central bisector of the coded aperture antenna array in the vertical direction, the y axis is an axis passing through a central bisector of the coded aperture antenna array in the horizontal direction, the coordinate center o is at the central position of the coded aperture antenna array, and the z axis is an axis passing through the centers of the feed source and the coded aperture antenna array. For convenience of explanation, the three-dimensional imaging region is represented as four two-dimensional imaging planes a, b, c and d with different distances, but in practical application, the three-dimensional imaging region is not limited to four two-dimensional imaging planes, the three-dimensional imaging region may be divided into a plurality of two-dimensional imaging planes, and the number of the two-dimensional imaging planes may be set according to practical situations.
Taking a feed source to transmit random frequency hopping signals as an example, the radar associated three-dimensional imaging method based on matched filtering pulse pressure provided by the invention comprises the following specific steps:
1) an initial echo vector and an initial reference signal matrix are obtained.
The feed source A transmits random frequency hopping signals, the signals irradiate the coded aperture antenna array B as plane waves, namely, the initial phases are the same, the coded aperture antenna array B is set to contain 1 receiving array element and I transmitting array elements, as shown in figure 2, the receiving array element is positioned in the center of the coded aperture antenna array B and is represented by a solid circle, the transmitting array elements are distributed on the coded aperture antenna array B in an array form and are represented by a square frame, wherein the solid frame and the hollow frame respectively represent the phases of loading pi and 0 after the signals pass through the transmitting array elements. In summary, the random frequency hopping signal passes through the signal S of the transmitting array element of the coded aperture antenna array B1(t) is expressed as:
wherein the random frequency hopping signal comprises M sub-pulses with a width of TpPulse signal of AiIs the signal amplitude, f, at the ith transmit array elementcIs the center frequency, f, of the electromagnetic wavemFor discrete frequency points randomly distributed over a certain bandwidth, fc+fmIs the mth sub-pulse frequency, pi is the circumferential ratio, j is the imaginary unit,the code phase loaded at the ith transmitting array element at the time t, rect (u) is a rectangular window function,
the coded aperture antenna array B may adopt a 1-bit discrete phase modulation mode, an amplitude modulation mode, a high-bit depth modulation mode, or a continuous modulation mode, and for convenience of explanation, the coded aperture antenna array B of the present embodiment adopts a 1-bit discrete phase modulation mode.
Then, the three-dimensional imaging area C is divided into K grid units, and then a signal S is obtained1(t) the echo signal sr (t) received and detected by the receiving array element after being scattered by the three-dimensional imaging region C is represented as:
wherein, betakIn order to divide the three-dimensional imaging region into K grid cells, ti,kFor the time delay through the ith transmit array element and the kth grid element and finally to the receive array element, ti,k＝ri,k/c，ri,kIs given asi,kThe corresponding distance delay.
The echo signal sr (t) is also an initial echo vector.
Discretizing the formula 3 to obtain a mathematical model of radar-associated three-dimensional imaging, specifically:
Sr＝S·β
wherein S is an initial reference signal matrix, represented as:
matrix element S (t) in initial reference signal matrix SnAnd k) is represented as:
2) and performing matched filtering pulse pressure processing on the initial echo vector to obtain an initial pulse pressure type echo vector.
Firstly, the echo signal received by the receiving array element and the local oscillator signal are subjected to frequency mixing processing to obtain a baseband echo signal. Specifically, in the embodiment of the present invention, the local oscillator signal Slocal(t) is:
then, the baseband echo signal Srbase(t) is:
wherein,is Slocal(t) complex conjugate number.
Next, a matched filter is constructed.
Specifically, the matched filter is obtained by time-unwrapping and then complex conjugation of a baseband transmission signal;
according to equation 1, the baseband transmit signal s (t) is:
then, the matched filter h (t) is:
and finally, performing time domain convolution processing on the baseband echo signal and the matched filter to obtain an initial pulse pressure type echo vector.
Specifically, the initial pulse-pressure type echo vector Srh(t) is:
wherein,τ＝t-(m-1)Tp+(l-1)Tp-tik。
from the above equation 10, the initial pulse type echo vector is a sinc function, and the shape thereof is mainly determined by the rect () function and the sinc () functionDetermining when m is equal to l and the sampling time t is equal to tikWhen a peak occurs, the target information in the same range unit is gathered at the same peak, so that four peaks will occur in the echo after matched filtering pulse pressure processing in the four scattered range units a, b, c and d.
In addition, in the embodiment of the present invention, the time domain convolution is equivalent to a frequency domain product, so that the initial pulse pressure type echo vector can be further calculated by the following formula in a frequency domain product manner:
Sh(t)＝ifft(fft(Srbase(t),Nfft)·(fft(h(t),Nfft) ) (formula 13)
Wherein fft (-) and ifft (-) denote Fourier transform and inverse Fourier transform, respectively, NfftThe length of the fourier transform is expressed and can be adjusted according to the need of computational efficiency.
3) And separating the initial pulse pressure type echo vector to obtain the pulse pressure type echo vector.
The initial echo vector after the matched filtering pulse pressure processing is defined as SrhAs shown in fig. 3, the echo after the matched filtering pulse pressure processing has four obvious peaks, and the echoes at the positions of the four peaks are respectively extracted to construct four new pulse pressure type echo vectorsAnd
4) and constructing a pulse pressure type reference signal matrix.
Knowing that target information exists in the four two-dimensional imaging planes, respectively constructing time domain reference signal matrixes S corresponding to the four two-dimensional imaging planes according to a formula 4, a formula 5, a formula 9 and a formula 12a、Sb、ScAnd SdAnd a pulse pressure type reference signal matrixAnd
specifically, the initial pulse pressure type reference signal matrix is obtained by performing matched filtering pulse pressure processing column by column on the initial reference signal matrix.
Taking the kth column signal S (t, k) of the initial reference signal matrix as an example, the initial pulse pressure type reference signal matrix Sif(t, k) is represented by:
since the initial reference signal matrix and the initial echo vector line number are the same, as shown in FIG. 3, they are respectively decimated Andcorresponding to the initial pulse pressure type reference signals of the row to form a pulse pressure type reference signal matrix required by the final imaging Andwherein, in FIG. 3, Ka、Kb、KcAnd KdThe grid cell numbers corresponding to the two-dimensional imaging planes a, b, c and d, respectively.
5) And performing two-dimensional imaging and three-dimensional reconstruction.
The mathematical model of radar-associated three-dimensional imaging after matched filtering pulse pressure processing can be expressed as:
wherein,andrespectively corresponding to the two-dimensional imaging plane x, and a pulse pressure type echo vector and a pulse pressure type reference signal matrix, NxAnd KxCorresponding to the sampling time and the number of grid cells.
According to equation 14, usingAndandandtarget scattering coefficients at two-dimensional imaging planes a, b, c and d can be reconstructed respectively, and then complete three-dimensional reconstruction information can be obtained by combining all two-dimensional target information.
Similarly, the step frequency signal or the chirp signal transmitted by the feed source can also be calculated and processed with reference to the embodiment.
The radar correlation three-dimensional imaging method based on matched filtering pulse pressure provided by the invention is compared with the existing method through a specific embodiment.
The experimental parameters were controlled as follows: the size of the coded aperture antenna array is 25 multiplied by 25, and the size is 0.5 multiplied by 0.5 m; a single two-dimensional imaging plane is divided into 30 multiplied by 30 grids, and the size of a single grid unit is 2.5mm multiplied by 2.5 mm; the bandwidth of the linear frequency modulation signal is 20GHz, the carrier frequency is 340GHz, and the pulse width is 100 ns; the original objects in the shapes of 'T', 'C', 'a', and 'I' are placed at distances of 1.5m 2m, 2.5m, 3m, respectively.
The radar correlation imaging is carried out by respectively adopting the radar correlation three-dimensional imaging method based on the matched filtering pulse pressure and the existing method, the echo signals with different signal-to-noise ratios are processed, and the results are respectively shown in the attached drawings 4 to 7, wherein a to e in the attached drawings represent imaging result graphs of the existing method, and f to j represent imaging result graphs of the radar correlation three-dimensional imaging method based on the matched filtering pulse pressure. The method can find that the target can not be reconstructed by a time domain method under a signal-to-noise ratio of-30 db, and the target can still be accurately reconstructed by the radar-associated three-dimensional imaging method based on the matched filtering pulse pressure. In addition, when the number of sampling times is the same, that is, the number of rows of the reference signal matrix is the same, assuming that the number is 1200 times, the reference signal matrix size of the radar-associated three-dimensional imaging method based on matched filtering pulse pressure provided by the invention is only 1200 × 900, whereas in the existing method, on the premise that the imaging plane with the target information is known, the matrix size of the reference signal still needs to reach 1200 × 900 × N because of N two-dimensional imaging planes.
It can be seen that, the radar-associated three-dimensional imaging method based on matched filtering pulse pressure provided in the embodiments of the present invention is based on a matched filtering pulse pressure technology, analyzes pulse pressure type echo vectors in different range units in a three-dimensional imaging region for radar-associated imaging using random frequency hopping signals, step frequency signals, or chirp signals, then constructs a pulse pressure type reference signal matrix after matched filtering pulse pressure processing for the range units including target information, and finally reconstructs target information of different range units according to the separated pulse pressure type echo vectors and corresponding pulse pressure type reference signal matrices, so as to obtain completed three-dimensional reconstruction information.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, "front", "rear", "left", "right", "upper" and "lower" in this document are referred to the placement states shown in the drawings.
Finally, it should be noted that: the above examples are only for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A radar-associated three-dimensional imaging method based on matched filtering pulse pressure is characterized by comprising the following steps:
acquiring an initial echo vector: the method comprises the steps that a random frequency hopping signal is transmitted by a feed source, the signal is transmitted by a transmitting array element of a coded aperture antenna array and then scattered by a three-dimensional imaging region, and a receiving array element of the coded aperture antenna array receives an echo signal scattered by the three-dimensional imaging region so as to obtain an initial echo vector and an initial reference signal matrix;
and performing matched filtering pulse pressure processing on the initial echo vector: performing the matched filtering pulse pressure processing on the initial echo vector to obtain an initial pulse pressure type echo vector corresponding to the initial echo vector;
separating the initial pulse pressure type echo vector: extracting and separating echoes at different peak positions in the initial pulse pressure type echo according to the initial pulse pressure type echo vector, and constructing pulse pressure type echo vectors of different distance units corresponding to the different peak positions according to the echoes;
constructing a pulse pressure type reference signal matrix: performing the matched filtering pulse pressure processing on the initial reference signal matrix to obtain an initial pulse pressure type reference signal matrix, and respectively constructing pulse pressure type reference signal matrixes corresponding to the pulse pressure type echo vectors according to the initial pulse pressure type reference signal matrix;
two-dimensional imaging and three-dimensional reconstruction: and according to the pulse pressure type echo vector and the pulse pressure type reference signal matrix, carrying out two-dimensional imaging on different distance units with target scattering information, and combining all two-dimensional imaging information to obtain complete three-dimensional reconstruction information.
2. The matched filter pulse pressure-based radar correlation three-dimensional imaging method according to claim 1, wherein the random frequency hopping signal is a signal S after being transmitted by the transmitting array elements of the coded aperture antenna array1(t) is:
wherein the random frequency hopping signal comprises M sub-pulses with a width of TpPulse signal of AiIs the signal amplitude, f, at the ith transmit array elementcIs the center frequency, f, of the electromagnetic wavemFor discrete frequency points randomly distributed over a certain bandwidth, fc+fmIs the mth sub-pulse frequency, pi is the circumferential ratio, j is the imaginary unit,the code phase loaded at the ith transmitting array element at the time t, rect (u) is a rectangular window function,
3. the radar-associated three-dimensional imaging method based on matched filtering pulse pressure according to claim 2, wherein the echo signals received by the receiving array element and scattered by the three-dimensional imaging region are the initial echo vector, and the initial echo vector sr (t) is:
wherein, betakIn order to divide the three-dimensional imaging region into K grid cells, ti,kFor the time delay through the ith transmitting array element and the kth grid unit and finally to the receiving array element, ti，k＝ri，k/c，ri，kIs given asi，kThe corresponding distance delay.
4. The matched filter pulse pressure based radar correlation three-dimensional imaging method according to claim 3, wherein the initial reference signal matrix S is:
wherein the matrix element S (t)nAnd k) is:
5. the matched filtering pulse pressure based radar related three-dimensional imaging method according to claim 4, wherein the matched filtering pulse pressure processing is performed on the initial echo vector to obtain the initial pulse pressure type echo vector corresponding to the initial echo vector, and the method comprises:
performing frequency mixing processing on the initial echo vector and a local oscillator signal to obtain a baseband echo signal;
constructing a matched filter;
and performing time domain convolution processing on the baseband echo signal and the matched filter to obtain the initial pulse pressure type echo vector.
6. The matched filtering pulse pressure-based radar correlation three-dimensional imaging method according to claim 5, wherein the local oscillator signal Slocal(t) is:
7. the matched filtering pulse pressure based radar related three-dimensional imaging method according to claim 6, wherein the baseband echo signal Srbase(t) is:
wherein,is Slocal(t) complex conjugate number.
8. The matched filter pulse pressure-based radar-associated three-dimensional imaging method according to claim 7, wherein the matched filter is obtained by time deconvolving and then complex conjugate extracting a baseband transmission signal;
the baseband transmission signal s (t) is:
the matched filter h (t) is:
9. the matched filter pulse pressure-based radar-associated three-dimensional imaging method according to claim 8, wherein the initial pulse pressure type echo vector Srh(t) is:
wherein,τ＝t-(m-1)Tp+(l-1)Tp-tik。
10. the matched filter pulse pressure based radar-associated three-dimensional imaging method according to claim 9, wherein a matrix element S of the initial pulse pressure type reference signal matrixif(t, k) is:
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