A high-resolution ultra-wide swath imaging method and system based on intra-pulse multi-beam

Abstract

The application discloses a kind of high-resolution ultra-wide imaging method and system based on intra-pulse multi-beam, wherein the method comprises: each sub-pulse echo signal is filtered to obtain each sub-mapping band echo signal;Each sub-mapping band echo signal is processed to obtain the output signal of each receiving channel;According to the time-varying weighting coefficient of each receiving channel and the output signal of each receiving channel, the signal after DBF processing of each receiving channel is obtained;Each receiving channel DBF processed signal is processed to obtain each sub-mapping band signal;Each sub-mapping band signal is two-dimensionally focused to obtain the SAR image of each sub-mapping band region;The SAR image of each sub-mapping band region is spliced in range direction, and high-resolution ultra-wide SAR image is obtained.The application effectively solves the problem that traditional spaceborne SAR system is difficult to realize high-resolution and ultra-wide imaging simultaneously.

Description

Technical Field

[0001] This invention belongs to the field of signal processing technology, and particularly relates to a high-resolution ultrawide imaging method and system based on intrapulse multibeams. Background Technology

[0002] In recent years, with the increasing demands for spatial resolution and imaging swath width in applications such as Earth environmental monitoring, traditional classical single-channel SAR systems, limited by minimum antenna area, cannot simultaneously meet the requirements of high resolution and wide swath width. Furthermore, the amount of received data corresponding to large areas will increase dramatically, placing a huge storage and processing burden on payloads and satellite platforms, and posing new challenges to engineering applications. Traditional elevation-oriented multibeam (MEB) technology achieves ultra-wide swath width by simultaneously illuminating multiple sub-mapped areas during each burst period. However, severe mutual interference exists between multiple receiving sub-beams, significantly degrading system performance such as noise equivalent backscattering coefficient (NESZ) and range ambiguity ratio (RASR), severely hindering practical engineering applications.

[0003] Traditional spaceborne SAR systems struggle to achieve both high resolution and ultra-wide swath imaging simultaneously. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a high-resolution ultra-wide swath imaging method and system based on intra-pulse multibeams. This effectively solves the problem that traditional spaceborne SAR systems cannot simultaneously achieve high-resolution and ultra-wide swath imaging, while effectively reducing the amount of effective data acquired and recorded by the payload without losing the imaging swath width.

[0005] The objective of this invention is achieved through the following technical solution: a high-resolution ultra-wide swath imaging method based on intra-pulse multibeams, comprising: transmitting multiple different sub-pulses within the same pulse repetition period, each sub-pulse illuminating a sub-mapped zone corresponding to each sub-pulse to obtain the echo signal of each sub-pulse; filtering each sub-pulse echo signal to obtain the echo signal of each sub-mapped zone; converting each sub-mapped zone echo signal to the range frequency domain and performing matched filtering to obtain the output signal of each receiving channel; obtaining the azimuth-directed DBF-processed signal of each receiving channel based on the time-varying weighting coefficients of each receiving channel and the output signal of each receiving channel; converting the azimuth-directed DBF-processed signal of each receiving channel to the range Doppler domain and performing unambiguous signal reconstruction to obtain the reconstructed signal, i.e., the signal of each sub-mapped zone; performing two-dimensional focusing processing on each sub-mapped zone signal to obtain the SAR image of each sub-mapped zone region; and stitching the SAR images of each sub-mapped zone region in the range direction to obtain a high-resolution ultra-wide swath SAR image.

[0006] In the above-mentioned high-resolution ultrawide imaging method based on intrapulse multibeams, the echo signal of each sub-mapped band is obtained by the following formula:

[0007]

[0008] Among them, s tk (τ) represents the echo signal of the k-th sub-mapped zone, τ is the fast time, and T is the fast time. p f is the pulse width. k Let K be the carrier frequency of the k-th sub-beam. r T is the frequency modulation of the LFM signal. pk This is the transmission delay for the k-th sub-beam, where k is the sub-beam number.

[0009] In the above-mentioned high-resolution ultrawide imaging method based on intrapulse multibeams, the output signal of each receiving channel is obtained by the following formula:

[0010]

[0011] Among them, s rn,m (τ) represents the azimuth output signal from the m-th receiving channel to the n-th receiving channel, where τ is the fast time, and T is the pitch output signal. pk For the transmission delay of the k-th sub-beam, f k Let k be the carrier frequency of the kth sub-beam. Let d be the distance from the radiation center of the phased array antenna to the scattering target within the k-th sub-mapping band. n θ is the distance between the nth receiving channel and the reference receiving channel. k α represents the normal offset angle corresponding to the target within the k-th sub-mapped area. k For the echo of the k-th sub-map, λ k Let σ be the wavelength of the beam corresponding to the k-th sub-mapped zone. k Let be the backscattering coefficient of the k-th sub-mapped zone, and c be the speed of light.

[0012] In the above-mentioned high-resolution ultrawide imaging method based on intrapulse multibeams, the time-varying weighting coefficients of each receiving channel are obtained by the following formula:

[0013]

[0014] in, Here are the time-varying weighting coefficients for the nth receiving channel, where τ is the fast time and d is the weighting coefficient. n λ is the distance between the nth receiving channel and the reference receiving channel. k Let θ be the wavelength of the beam corresponding to the k-th sub-mapped zone. k (τ i ) is τ i The normal offset angle τ corresponding to the target within the k-th sub-mapped area at time k.i Let N be the time corresponding to the i-th sampling point, where i is the index of the sampling point, and N is the time corresponding to the i-th sampling point. r τ represents the total number of sampling points along the distance. start The SAR system starts sampling echo signals within the first sub-scanning band at time H, where H is the platform height and F is the platform height. r β is the range sampling frequency, β is the normal installation angle of the SAR antenna, and c is the speed of light.

[0015] In the above-mentioned high-resolution ultrawide imaging method based on intrapulse multibeams, the signal after DBF processing for each receiving channel in the azimuth direction is obtained by the following formula:

[0016]

[0017] Among them, R m,DBF (τ) represents the signal processed by DBF in the m-th receiving channel from the elevation direction, and τ is the fast time. For the time-varying weighting coefficients of the pitch direction towards the nth receiving channel, s rn,m (τ) is the output signal of the m-th azimuth receiving channel to the n-th elevation receiving channel, where m is the azimuth channel number and M is the total number of azimuth channels.

[0018] In the above-mentioned high-resolution ultrawide imaging method based on intrapulse multibeams, the reconstructed signal is obtained by the following formula:

[0019]

[0020] Among them, R out For the reconstructed signal, R m,DBF (f a P represents the pitch signal processed by the DBF of the m-th receiving channel after conversion to the range-Doppler domain. m (f a f is the reconstruction filter corresponding to the m-th receiving channel in the azimuth direction. a denoted as azimuth frequency, m as azimuth channel number, and M as the total number of azimuth channels.

[0021] A high-resolution ultra-wide swath imaging system based on intra-pulse multibeam imaging includes: a first module for transmitting multiple different sub-pulses within the same pulse repetition period, each sub-pulse illuminating a corresponding sub-mapped area to obtain the echo signal of each sub-pulse; a second module for filtering each sub-pulse echo signal through a bandpass filter to obtain the echo signal of each sub-mapped area; a third module for converting each sub-mapped area echo signal to the range-frequency domain and performing matched filtering to obtain the output signal of each receiving channel; a fourth module for obtaining the DBF-processed signal of each receiving channel based on the time-varying weighting coefficients and the output signal of each receiving channel; a fifth module for converting the DBF-processed signal of each receiving channel to the range-Doppler domain and performing unambiguous signal reconstruction to obtain the reconstructed signal, i.e., the signal of each sub-mapped area; a sixth module for performing two-dimensional focusing processing on each sub-mapped area signal to obtain the SAR image of each sub-mapped area; and a seventh module for stitching the SAR images of each sub-mapped area in the range direction to obtain a high-resolution ultra-wide swath SAR image.

[0022] In the aforementioned high-resolution ultrawide swath imaging system based on intrapulse multibeams, the echo signal of each sub-mapped zone is obtained using the following formula:

[0023]

[0024] Among them, s tk (τ) represents the echo signal of the k-th sub-mapped zone, τ is the fast time, and T is the fast time. p f is the pulse width. k Let K be the carrier frequency of the k-th sub-beam. r T is the frequency modulation of the LFM signal. pk This is the transmission delay for the k-th sub-beam, where k is the sub-beam number.

[0025] In the aforementioned high-resolution ultrawide imaging system based on intrapulse multibeams, the output signal of each receiving channel is obtained using the following formula:

[0026]

[0027] Among them, s rn,m (τ) represents the azimuth output signal from the m-th receiving channel to the n-th receiving channel, where τ is the fast time, and T is the pitch output signal. pk For the transmission delay of the k-th sub-beam, f k Let k be the carrier frequency of the kth sub-beam. Let d be the distance from the radiation center of the phased array antenna to the scattering target within the k-th sub-mapping band. n θ is the distance between the nth receiving channel and the reference receiving channel. kα represents the normal offset angle corresponding to the target within the k-th sub-mapped area. k For the echo of the k-th sub-map, λ k Let σ be the wavelength of the beam corresponding to the k-th sub-mapped zone. k Let be the backscattering coefficient of the k-th sub-mapped zone, and c be the speed of light.

[0028] In the aforementioned high-resolution ultrawide imaging system based on intrapulse multibeams, the time-varying weighting coefficients for each receiving channel are obtained using the following formula:

[0029]

[0030] in, Here are the time-varying weighting coefficients for the nth receiving channel, where τ is the fast time and d is the weighting coefficient. n λ is the distance between the nth receiving channel and the reference receiving channel. k Let θ be the wavelength of the beam corresponding to the k-th sub-mapped zone. k (τ i ) is τ i The normal offset angle τ corresponding to the target within the k-th sub-mapped area at time k. i Let N be the time corresponding to the i-th sampling point, where i is the index of the sampling point, and N is the time corresponding to the i-th sampling point. r τ represents the total number of sampling points along the distance. start The SAR system starts sampling echo signals within the first sub-scanning band at time H, where H is the platform height and F is the platform height. r β is the range sampling frequency, β is the normal installation angle of the SAR antenna, and c is the speed of light.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] This invention solves the problem that traditional spaceborne SAR systems cannot simultaneously achieve high resolution and ultra-wide swath imaging. At the same time, it can effectively reduce the amount of data collected and recorded by the payload without sacrificing the imaging swath width. This method can be applied to SAR satellite high-resolution and wide-swath Earth observation missions, enabling the system's quality factor to exceed 200, and has significant practical application value. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0034] Figure 1 This is a geometrical schematic diagram of high-resolution ultrawide imaging based on intrapulse multibeams provided in an embodiment of the present invention;

[0035] Figure 2 This is a flowchart of high-resolution ultrawide imaging signal processing based on intrapulse multibeams provided in an embodiment of the present invention;

[0036] Figure 3 These are timing diagrams for the four Burst modes provided in this embodiment of the invention;

[0037] Figure 4 This is a schematic diagram of the NESZ for the four Burst modes provided in this embodiment of the invention;

[0038] Figure 5 This is a schematic diagram of the RASR for the four Burst modes provided in the embodiments of the present invention;

[0039] Figure 6 This is a schematic diagram of the AASR for the four Burst modes provided in the embodiments of the present invention. Detailed Implementation

[0040] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Two-dimensional multi-channel system architecture provides additional spatial degrees of freedom for high-resolution ultra-wide swath imaging in the azimuth and elevation directions. Intra-pulse multibeam technology can effectively reduce data volume without sacrificing imaging swath width, provided that mutual interference between different sub-beams can be effectively suppressed. Combining intra-pulse multibeam technology with a two-dimensional multi-channel system architecture can increase the system's quality factor Q (Q = swath width km / resolution m) to over 200. However, it is necessary to solve the problems of intra-pulse multibeam imaging and signal processing under the two-dimensional multi-channel system architecture, laying an important application foundation for high-resolution ultra-wide swath Earth observation missions of SAR satellites.

[0042] like Figure 2 As shown, this high-resolution ultrawide imaging method based on intrapulse multibeams includes:

[0043] Within the same pulse repetition period, a total of K different sub-pulses are emitted, and each sub-pulse illuminates a sub-mapped band corresponding to each sub-pulse to obtain the echo signal of each sub-pulse; wherein, the total swath width in the range direction is divided into K sub-mapped bands; K is a positive integer;

[0044] Each sub-pulse echo signal is filtered through a bandpass filter to obtain each sub-mapped band echo signal;

[0045] The echo signal of each sub-mapped zone is converted to the range frequency domain and subjected to matched filtering to obtain the output signal of each receiving channel;

[0046] The azimuth signal after DBF processing for each receiving channel is obtained based on the time-varying weighting coefficients of each receiving channel and the output signal of each receiving channel;

[0047] After converting the DBF-processed signal of each receiving channel to the range Doppler domain, unambiguous signal reconstruction is performed to obtain the reconstructed signal, which is the signal of each sub-mapped zone.

[0048] Two-dimensional focusing processing is performed on the signal of each sub-mapped area to obtain the SAR image of each sub-mapped area;

[0049] The SAR images of each sub-mapped area are stitched together in the range direction to obtain a high-resolution ultra-wide SAR image.

[0050] Specifically, the method includes the following steps:

[0051] Step 1: Modulate different sub-pulse LFM (linear frequency modulation) signals onto carrier frequencies with different center frequencies within the same pulse repetition period (PRT).

[0052] Assume that the phased array antenna of a two-dimensional multi-channel SAR system is divided into M and N sub-apertures in the azimuth and range directions, respectively. Within the same pulse repetition period, K different sub-pulses are transmitted, each corresponding to a transmit sub-beam. The LFM signal within each sub-beam is modulated onto a carrier frequency with a different center frequency and illuminates a sub-mapped band. The total swath width in the range direction is divided into K (K≤M) sub-mapped bands. See the geometric diagram below. Figure 1 As shown.

[0053] Step 2: Filter each sub-pulse echo signal through a bandpass filter to obtain each sub-mapped echo signal.

[0054] The echo signal received in the range direction is filtered by a bandpass filter to obtain the echo of the transmitted signal of the kth sub-beam, which can be expressed as:

[0055]

[0056] Among them, s tk (τ) represents the echo signal of the k-th sub-mapped zone, τ is the fast time, and T is the fast time. p f is the pulse width. k Let K be the carrier frequency of the k-th sub-beam. rT is the frequency modulation of the LFM signal. pk =(k-1)·(T) p +Δτ p ) represents the transmission delay of the k-th sub-beam, Δτ p This represents the time interval between each transmitting sub-beam.

[0057] Step 3: Convert the echo signal of each sub-mapped band to the distance frequency domain and perform matched filtering to obtain the output signal of each receiving channel.

[0058] After bandpass filtering, amplification, down-conversion, sampling, and range-matched filtering, the output signal from the m-th azimuth receiving channel to the n-th elevation receiving channel can be simplified as follows:

[0059]

[0060]

[0061] in, d is defined as the distance from the radiation center of the phased array antenna to the scattering target P within the k-th sub-mapping band. n θ represents the distance between the nth receiving channel and the reference receiving channel. k α represents the normal offset angle corresponding to the target within the k-th sub-mapped area. k For the echo of the k-th sub-map, λ k Let σ be the wavelength of the beam corresponding to the k-th sub-mapped zone. k Let be the backscattering coefficient of the k-th sub-mapped zone, and c be the speed of light.

[0062] Step 4: After matched filtering, the pitch direction is weighted in real time and phase mismatch is calibrated for each receiving channel.

[0063] The time-varying weighting coefficients for the pitch direction towards the nth receiving channel can be expressed as:

[0064]

[0065] Wherein, the normal offset angle corresponding to the scattering target within the k-th sub-mapping zone can be expressed as:

[0066]

[0067] Where τ start F represents the start time of echo signal sampling by the SAR system within the first sub-mapped area. r Where N is the range sampling frequency. r H is the total number of sampling points in the range direction, H is the platform height, β is the normal installation angle of the SAR antenna, and λ is the total number of sampling points in the range direction. k Let θ be the wavelength of the beam corresponding to the k-th sub-mapped zone. k (τi ) is τ i The normal offset angle τ corresponding to the target within the k-th sub-mapped area at time k. i Let be the time corresponding to the i-th sampling point, where i is the i-th sampling point and c is the speed of light.

[0068] By multiplying the aforementioned time-varying weighting coefficients by the signals from each receiving channel, and simultaneously using a cross-coherence method to correct the phase error, the output of the echo signal from the k-th sub-mapped zone after phase error correction and DBF processing can be written as follows:

[0069]

[0070] Among them, R m,DBF (τ) represents the signal processed by DBF in the m-th receiving channel from the elevation direction, and τ is the fast time. For the time-varying weighting coefficients of the pitch direction towards the nth receiving channel, s rn,m (τ) is the output signal of the m-th azimuth receiving channel to the n-th elevation receiving channel, where m is the azimuth channel number and M is the total number of azimuth channels.

[0071] Step 5: After range-direction DBF processing, the azimuth signals from each receiving channel are converted to the range-Doppler domain and then reconstructed into unambiguous signals.

[0072] After range-direction DBF processing, the echo signals from the M azimuth receiving channels undergo FFT processing to convert them to the range-Doppler domain. Then, the echo signal from the kth sub-mapped zone is processed using a traditional reconstruction filter P. m (f a Azimuth-unambiguous signal reconstruction is performed on M receiving channels in the azimuth direction. The reconstructed signal can be represented as follows:

[0073]

[0074] Among them, R out For the reconstructed signal, R m,DBF (f a P represents the pitch signal processed by the DBF of the m-th receiving channel after conversion to the range-Doppler domain. m (f a f is the reconstruction filter corresponding to the m-th receiving channel in the azimuth direction. a Here, m represents the azimuth frequency, m represents the azimuth channel number, and M represents the total number of azimuth channels. Step Six: Perform two-dimensional focusing processing on the signal of each sub-mapped area to obtain the SAR image of the k-th sub-mapped area.

[0075] The echo signal of the kth sub-mapped zone is focused using a traditional two-dimensional focusing algorithm to obtain a well-focused SAR image;

[0076] Step 7: The SAR images of the k sub-mapped areas are stitched together in the range direction to obtain a high-resolution ultra-wide SAR image.

[0077] By stitching together the SAR images of k sub-mapped areas in the range direction, a high-resolution ultra-wide SAR image can be obtained.

[0078] In summary, the specific process for high-resolution ultra-wide swath imaging signal processing proposed in this invention is as follows: Figure 2 As shown, it mainly includes the above seven steps, which are applicable to spaceborne SAR systems under a two-dimensional multi-channel system architecture and have the ability to significantly improve the high-resolution ultra-wide swath imaging performance of future SAR systems.

[0079] To fully demonstrate the effectiveness of this invention patent, an embodiment of a system design scheme in strip mode is given, and the specific parameters of the embodiment are shown in Table 1. Four independent Bursts are designed within the lower viewing angle range [10.2°, 48.2°]. Each Burst contains three sub-beams that cover three consecutive sub-mapping zones. Each sub-mapping zone has a swath width of 66km, and each Burst covers a total swath width of 200km. Figure 3 , Figure 4 , Figure 5 and Figure 6 The system performance evaluation results at 1m / 200km (resolution / swath width) are presented, including system sensitivity and blur ratio. Figure 3 The timing diagrams are for four Burst modes. Figure 4 NESZ with 4 Burst modes Figure 5 For RASR with 4 Burst patterns, Figure 6 The AASR is for four Burst modes. Based on the above comparative analysis, within each Burst mode, the azimuth ambiguity ratio (AASR) is below -28.07 dB, the range ambiguity ratio (RASR) is below -31.95 dB, and the system sensitivity (NESZ) is below -20.0 dB, all of which meet the requirements for practical engineering applications.

[0080] Table 1. Main system parameters for simulation experiment.

[0081] parameter numerical values center carrier frequency 8.4 / 9.6 / 10.8GHz Platform Height 750km Antenna physical dimensions 18.85m(A) × 1.87m(R) Antenna mounting angle 32.5° Lower field of view 10.2°～48.2° Number of channels 10(A)×8(R) Sub-pulse width 30us Number of sub-pulses 3 Sub-pulse interval 5us signal bandwidth 500 / 330 / 250 / 210MHz sampling frequency 600 / 396 / 300 / 252MHz PRF 780~980Hz Peak power 16600W System losses 3.5dB Duty cycle 7.02％～8.84％ Imaging mode Strip mode

[0082] This embodiment also provides a high-resolution ultra-wide swath imaging system based on intra-pulse multibeams. The system includes: a first module for transmitting multiple different sub-pulses within the same pulse repetition period, each sub-pulse illuminating a corresponding sub-mapped area to obtain an echo signal for each sub-pulse; a second module for filtering each sub-pulse echo signal using a bandpass filter to obtain an echo signal for each sub-mapped area; a third module for converting each sub-mapped area echo signal to the range-frequency domain and performing matched filtering to obtain the output signal of each receiving channel; a fourth module for obtaining the DBF-processed signal for each receiving channel based on the time-varying weighting coefficients and the output signal of each receiving channel; a fifth module for converting the DBF-processed signal of each receiving channel to the range-Doppler domain and performing unambiguous signal reconstruction to obtain the reconstructed signal, i.e., the signal for each sub-mapped area; a sixth module for performing two-dimensional focusing processing on each sub-mapped area signal to obtain a SAR image of each sub-mapped area; and a seventh module for stitching the SAR images of each sub-mapped area in the range direction to obtain a high-resolution ultra-wide swath SAR image.

[0083] This embodiment, by fully combining the advantages of intra-pulse beam pointing and digital beamforming technology on the basis of a two-dimensional multi-channel system architecture, enables the system's quality factor Q to reach over 200, effectively solving the problem that traditional spaceborne SAR systems cannot simultaneously achieve high resolution and ultra-wide swath imaging. At the same time, it can effectively reduce the amount of effective data acquired and recorded by the payload without sacrificing the imaging swath width, and significantly reduce the storage burden of large-scale data acquisition and recording on the satellite platform.

[0084] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A high-resolution ultrawide imaging method based on intrapulse multibeams, characterized in that... include: Multiple different sub-pulses are emitted within the same pulse repetition period, and each sub-pulse illuminates a sub-mapped strip corresponding to each sub-pulse to obtain the echo signal of each sub-pulse. Each sub-pulse echo signal is filtered to obtain the echo signal of each sub-mapped band; The echo signal of each sub-mapped zone is converted to the range frequency domain and subjected to matched filtering to obtain the output signal of each receiving channel; The azimuth signal after DBF processing for each receiving channel is obtained based on the time-varying weighting coefficients of each receiving channel and the output signal of each receiving channel; After converting the DBF-processed signal of each receiving channel to the range Doppler domain, unambiguous signal reconstruction is performed to obtain the reconstructed signal, which is the signal of each sub-mapped zone. Two-dimensional focusing processing is performed on the signal of each sub-mapped area to obtain the SAR image of each sub-mapped area; The SAR images of each sub-mapping zone are stitched together in the range direction to obtain a high-resolution ultra-wide SAR image. The signal processed by DBF for each receiving channel in the azimuth direction is obtained using the following formula: ； in, For the direction of the first The signal after DBF processing in each receiving channel To save time, To pitch towards the first Time-varying weighting coefficients for each receiving channel, For the azimuth direction, the elevation direction is to the m-th receiving channel. The output signal of each receiving channel This is the azimuth receiving channel number. This represents the total number of pitch-side receiving channels; The time-varying weighting coefficients for each receiving channel are obtained using the following formula: ； ； in, To pitch towards the first Time-varying weighting coefficients for each receiving channel, To save time, To pitch towards the first The spacing between each receiving channel and the reference receiving channel For the first The wavelength of the beam corresponding to the echo in the individual mapping band. for Time of the first The normal offset angle corresponding to the target within the sub-mapping band echo. For the first The time corresponding to each sampling point The sampling point number is... The total number of sampling points in the distance direction. The starting time for the SAR system to sample the echo signal within the first sub-mapped area. For platform height, For the range sampling frequency, This is the normal installation angle of the SAR antenna. It is the speed of light.

2. The high-resolution ultrawide imaging method based on intrapulse multibeams according to claim 1, characterized in that: The echo signal for each sub-mapped area is obtained using the following formula: ； in, For the first Individual mapping with echo signal, To save time, The pulse width. For the first Carrier frequency of each sub-beam For LFM signal frequency modulation, For the first Individual mapping of echo transmission delay The sequence number of the sub-map with echo.

3. The high-resolution ultrawide imaging method based on intrapulse multibeams according to claim 1, characterized in that: The output signal of each receiving channel is obtained using the following formula: ； ； in, For the azimuth direction, the elevation direction is to the m-th receiving channel. The output signal of each receiving channel To save time, For the first Individual mapping of echo transmission delay For the first Individual mapping of carrier frequencies with echo, From the radiation center of the phased array antenna to the... The distance of scattering targets within the sub-mapping zone. To pitch towards the first The spacing between each receiving channel and the reference receiving channel Indicates the first The normal offset angle corresponding to the target within the sub-mapping band echo. For the k-th sub-map, echo, Let be the wavelength of the beam corresponding to the echo of the k-th sub-mapped band. Let be the backscattering coefficient of the echo from the k-th sub-mapped zone. It is the speed of light.

4. The high-resolution ultrawide imaging method based on intrapulse multibeams according to claim 1, characterized in that: The reconstructed signal is obtained using the following formula: ； in, For the reconstructed signal, To convert to the azimuth direction after the distance to the Doppler domain The signal after DBF processing in each receiving channel For the direction of the first The reconstruction filter corresponding to each receiving channel For azimuth frequency, This is the azimuth receiving channel number. This represents the total number of azimuth receiving channels.

5. A high-resolution ultra-wide swath imaging system based on intrapulse multibeams, characterized in that... include: The first module is used to transmit multiple different sub-pulses within the same pulse repetition period, with each sub-pulse illuminating a sub-mapping strip corresponding to each sub-pulse to obtain the echo signal of each sub-pulse. The second module is used to filter each sub-pulse echo signal through a bandpass filter to obtain each sub-mapping band echo signal. The third module is used to convert the echo signal of each sub-mapping band to the range frequency domain and perform matched filtering to obtain the output signal of each receiving channel. The fourth module is used to obtain the DBF-processed signal of each receiving channel based on the time-varying weighting coefficients of each receiving channel and the output signal of each receiving channel; The fifth module is used to convert the signal after DBF processing of each receiving channel to the range Doppler domain and then perform unambiguous signal reconstruction processing to obtain the reconstructed signal, which is the signal of each sub-mapped zone. The sixth module is used to perform two-dimensional focusing processing on the signals of each sub-mapped area to obtain the SAR image of each sub-mapped area. The seventh module is used to stitch together the SAR images of each sub-mapped area in the range direction to obtain a high-resolution ultra-wide SAR image; The signal processed by DBF for each receiving channel in the azimuth direction is obtained using the following formula: ； in, For the direction of the first The signal after DBF processing in each receiving channel To save time, To pitch towards the first Time-varying weighting coefficients for each receiving channel, For the azimuth direction, the elevation direction is to the m-th receiving channel. The output signal of each receiving channel This is the azimuth receiving channel number. This represents the total number of pitch-side receiving channels; The output signal of each receiving channel is obtained using the following formula: ； ； in, For the azimuth direction, the elevation direction is to the m-th receiving channel. The output signal of each receiving channel To save time, For the first Individual mapping of echo transmission delay For the first Individual mapping of carrier frequencies with echo, From the radiation center of the phased array antenna to the... The distance of scattering targets within the sub-mapping zone. To pitch towards the first The spacing between each receiving channel and the reference receiving channel Indicates the first The normal offset angle corresponding to the target within the sub-mapping band echo. For the k-th sub-map, echo, Let be the wavelength of the beam corresponding to the echo of the k-th sub-mapped band. Let be the backscattering coefficient of the echo from the k-th sub-mapped zone. It is the speed of light.

6. The high-resolution ultra-wide swath imaging system based on intrapulse multibeams according to claim 5, characterized in that: The echo signal for each sub-mapped area is obtained using the following formula: ； in, For the first Individual mapping with echo signal, To save time, The pulse width. For the first Carrier frequency of each sub-beam For LFM signal frequency modulation, For the first Individual mapping of echo transmission delay The sequence number of the sub-map with echo.

7. The high-resolution ultra-wide swath imaging system based on intrapulse multibeams according to claim 5, characterized in that: The time-varying weighting coefficients for each receiving channel are obtained using the following formula: ； ； in, To pitch towards the first Time-varying weighting coefficients for each receiving channel, To save time, To pitch towards the first The spacing between each receiving channel and the reference receiving channel For the first The wavelength of the beam corresponding to the echo in the individual mapping band. for Time of the first The normal offset angle corresponding to the target within the sub-mapping band echo. For the first The time corresponding to each sampling point The sampling point number is... The total number of sampling points in the distance direction. The starting time for the SAR system to sample the echo signal within the first sub-mapped area. For platform height, For the range sampling frequency, This is the normal installation angle of the SAR antenna. It is the speed of light.

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