CN114415179A - Method and device for simultaneously realizing stripe mode and wide area MTI mode by airborne SAR - Google Patents

Abstract

The present disclosure provides a method for an airborne SAR to simultaneously implement a stripe mode and a wide area MTI mode, which includes: acquiring working parameters of a stripe mode and a wide area MTI mode; performing the stripe mode and the wide-area MTI mode simultaneously in an aperture-split manner; processing the received echo data of the strip mode and the wide area MTI mode to obtain a strip SAR image and trace point information of the moving target, and correlating the trace point information of the moving target to form track information of the moving target; and the track information is superposed to the corresponding position on the strip SAR image, so that the SAR image processing method has the capability of simultaneously obtaining the SAR high-resolution image and the ground/sea surface dynamic target track information, and the dynamic target track information can be marked on the SAR image, so that the accuracy of reconnaissance and monitoring of a moving target can be improved, the advantages of a multifunctional radar can be played in an all-around and multi-dimensional manner, and efficient situation perception is provided for radar users. The disclosure also provides a device for simultaneously realizing the stripe mode and the wide area MTI mode by the airborne SAR.

Description

Method and device for simultaneous realization of strip mode and wide-area MTI mode for airborne SAR

technical field

The present disclosure relates to the technical field of airborne synthetic aperture radar, and in particular, to a method and device for simultaneously realizing strip mode and wide-area MTI mode for airborne dual-channel SAR, which is suitable for multi-channel with azimuth ultra-wideband electronically controlled scanning capability radar system.

Background technique

Synthetic Aperture Radar (SAR, Synthetic Aperture Radar) is an imaging radar, which, through the relative motion between the radar loading platform and the observed target, converts the broadband received by the radar at different spatial and temporal positions within a certain accumulation time. The echo signals are coherently processed to obtain a two-dimensional image of the target area, thereby helping people to analyze and understand the ground object information in the area. Compared with optical imaging, SAR has the advantages of all-day, all-weather and strong penetration, so it has a wide range of applications in various fields. SAR imaging has a variety of working modes, mainly including strip mode and spot mode. The strip mode works in oblique side view or front side view, and the illuminated area on the ground is in strip shape, which can obtain continuous images of the target area, provide users with a large amount of valuable observation data, and help users make corresponding decisions. .

As an important application of airborne radar, wide-area moving target indication (MT) has broad application prospects and provides strong technical support for various applications. The wide-area MTI mode can simultaneously obtain Doppler Beam Sharpen (DBS) low-resolution images and ground/sea moving target trajectory information; wide-area MTI can be applied to the guidance of agriculture, forestry, animal husbandry and fishery, traffic control and environmental protection During monitoring: monitor the road sections that are prone to traffic jams and provide effective diversion strategies, record and control the entry and exit of ships in ports, locate and track fishing boats at sea during storms, etc. The detection and monitoring and positioning technologies of moving targets are very effective. plays a key role.

With the continuous development of electronic information technology, multi-function is also a major development direction of the SAR system. At present, the SAR system basically has the imaging mode and the MTI mode, but in use, the radar system can only choose one working mode at the same time. The observation efficiency is low. At the same time, although the SAR/GMTI mode can obtain SAR images and moving target trace information at the same time, the imaging resolution is low, and the moving target cannot be observed multiple times, so the point (track) information cannot be formed.

SUMMARY OF THE INVENTION

The purpose of the present disclosure is to provide a method and device for simultaneously realizing strip mode and wide-area MTI mode in an airborne dual-channel SAR, simultaneously obtaining high-resolution SAR images and the ability of moving target trajectory information on the ground/sea surface, and enabling The target trajectory information is marked on the SAR image to improve the accuracy of moving target reconnaissance and surveillance. It can give full play to the advantages of multi-function radar in all directions and multiple dimensions, and provide radar users with efficient situational awareness.

In order to achieve the above object, embodiments of the present disclosure provide a method for simultaneously implementing a strip mode and a wide-area MTI mode for an airborne SAR, including:

Get the working parameters of stripe mode and wide-area MTI mode;

simultaneously executing the stripe mode and the wide-area MTI mode in a split-aperture manner;

The received echo data of the strip mode and the wide-area MTI mode are processed to obtain strip SAR images and the dot trace information of the moving target, and the dot traces of the moving target are associated to form the moving target track information; and

The track information is superimposed on the corresponding position on the strip SAR image.

According to some embodiments of the present disclosure, the acquiring operating parameters of the stripe mode and the wide-area MTI mode includes:

Calculate the operating parameters of the strip mode according to the first preset index requirement or the first input condition;

Calculate the operating parameters of the wide-area MTI mode according to the second preset index requirement or the second input condition;

Calculate the number of dwell pulses in the wide-area MTI mode according to the requirements of the scanning range of the wide-area MTI mode and the operating parameters of the wide-area MTI mode;

calculating the revisit time required for one cycle of scanning of the wide-area MTI mode according to the dwell pulse number; and

Judging whether the revisit time meets the requirements for target association tracking, if so, output the working parameters of the stripe mode and the working parameters of the wide-area MTI mode, if not, modify the first preset index A request or a first input condition recalculates the operating parameters of the stripe mode and the wide-area MTI mode.

According to some embodiments of the present disclosure, the pulse repetition frequency of the stripe mode and the wide-area MTI mode is the same, and both are the same as the pulse repetition frequency of the actual transmission, so as to realize the simultaneous execution of the stripe in a sub-aperture manner a band mode and the wide-area MTI mode; and

The pulse repetition frequency of the stripe mode is greater than or equal to α times the azimuth Doppler bandwidth, where the value of α ranges from 1.2 to 1.3.

According to some embodiments of the present disclosure, after determining the value range of the stripe mode pulse repetition frequency, the method further includes:

Combining the first preset index requirement or the first input condition to calculate the spatial constraints of the wave position and form a wave position map, so as to ensure that the echoes in the observation band corresponding to the wave position can be received completely and without interference; and

The signal pulse width and the pulse repetition frequency of the stripe mode are selected from the wave position map so that the off-camera point echo interference does not fall within the receiving window.

According to some embodiments of the present disclosure, the modifying the preset index requirement or input condition to recalculate the working parameters of the stripe mode and the wide-area MTI mode includes:

The signal pulse width and the pulse repetition frequency of the stripe mode are reselected from the wave position map so that the off-camera point echo interference does not fall within the receiving window.

According to some embodiments of the present disclosure, the first preset index includes platform flight height, flight ground speed, resolution, mapping bandwidth, and working distance.

According to some embodiments of the present disclosure, the operating parameters of the strip mode include: signal bandwidth-narrowband, pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end oblique distance, far-end oblique distance distance, sampling start, number of sampling points and azimuth observation angle; and

The working parameters of the wide-area MTI mode include: signal bandwidth-broadband, pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end slant range, far-end slant range, sampling start, sampling Number of points, azimuth scan range, azimuth scan step, dwell pulse number and revisit time.

According to some embodiments of the present disclosure, the calculating the number of dwell pulses according to the requirement of the scanning range of the wide-area MTI mode and the working parameters of the wide-area MTI mode includes:

According to the requirements of the scanning range of the wide-area MTI mode and the pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end oblique distance, far-end viewing angle of the wave position selected by the wide-area MTI mode For the end slant distance and the start of sampling, an appropriate number of dwell pulses is selected, so that the action distance of the wide-area MTI mode is greater than or equal to the distal slant distance, so as to ensure that the targets within the illumination range meet the detection performance.

According to some embodiments of the present disclosure, calculating the revisit time required for scanning one cycle of the wide-area MTI mode according to the dwell pulse number includes:

The antenna azimuth 3dB beamwidth is

Among them, θ _3dB represents the beam width, λ represents, and _La represents the azimuth antenna length;

Taking half of the 3dB beam width θ _3dB as the step angle, the number of beam steps in a single scan is

where N _step represents the number of beam steps for a single scan, and Ψ represents half of the scan range; and

The revisit time T required to scan one cycle is calculated as

where T is the revisit time, n is the number of dwell pulses, and PRF _MTI is the pulse repetition frequency of the wide-area MTI mode.

Embodiments of the present disclosure also provide an apparatus for simultaneously implementing a strip mode and a wide-area MTI mode for an airborne SAR, including:

The working parameter obtaining module is used to obtain working parameters of strip mode and wide-area MTI mode;

a radar that simultaneously performs the strip mode and the wide-area MTI mode in a split-aperture manner;

The data processing module processes the received echo data of the stripe mode and the wide-area MTI mode to obtain stripe SAR images and spot trace information of the moving target, and associates the spot traces of the moving target to form track information of the moving target; and

Information fusion module, used to superimpose the track information to the corresponding position on the strip SAR image

Through the above-mentioned embodiments of the present disclosure, after the working parameters of the stripe mode and the wide-area MTI mode of the airborne SAR are designed by the device for simultaneously realizing the stripe mode and the wide-area MTI mode of the airborne SAR, the airborne SAR can simultaneously realize the stripe mode and the wide-area MTI mode of the airborne SAR. Execute the working parameters of strip mode and wide-area MTI mode; process the echo data working in strip mode and wide-area MTI mode respectively, and have the ability to obtain SAR high-resolution images and ground/sea surface moving target trajectory information at the same time, And the moving target trajectory information can be marked on the SAR image, which can improve the accuracy of moving target reconnaissance and surveillance, and can give full play to the advantages of multi-functional radar in all directions and multiple dimensions, providing radar users with efficient situational awareness.

Description of drawings

FIG. 1 schematically shows a flowchart of a method for simultaneously implementing a strip mode and a wide-area MTI mode in an airborne SAR according to an embodiment of the present disclosure;

FIG. 2 schematically shows a flow chart of the design of working parameters of the method for simultaneously realizing the strip mode and the wide-area MTI mode of the carrier SAR according to the embodiment of the present disclosure;

FIG. 3 schematically shows a working schematic diagram of a method for simultaneously implementing a stripe mode and a wide-area MTI mode on a carrier SAR according to an embodiment of the present disclosure;

FIG. 4 schematically shows a simulated wave position map and a schematic diagram of a PRF selection range according to a specific embodiment of the present disclosure;

FIG. 5 schematically shows a flow chart of calculating the re-entry time of the wide-area MTI mode according to a specific embodiment of the present disclosure; and

FIG. 6 schematically shows a schematic diagram of a stripe mode noise equivalent backscatter coefficient obtained by calculation according to a specific embodiment of the present disclosure.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure will be further described in detail below with reference to the specific embodiments and the accompanying drawings.

It should be understood, however, that these descriptions are exemplary only, and are not intended to limit the scope of the present disclosure. In the following detailed description, for convenience of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent, however, that one or more embodiments may be practiced without these specific details. Also, in the following description, descriptions of well-known technologies are omitted to avoid unnecessarily obscuring the concepts of the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. The term "comprising" as used herein indicates the presence of a feature, step, operation, but does not exclude the presence or addition of one or more other features.

All terms (including technical and scientific terms) used herein have the meaning as commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly rigid manner.

FIG. 1 schematically shows a flowchart of a method for simultaneously implementing a strip mode and a wide-area MTI mode in an airborne SAR according to an embodiment of the present disclosure.

In order to achieve the above objective, embodiments of the present disclosure provide a method for simultaneously implementing a stripe mode and a wide-area MTI mode for an airborne SAR, as shown in FIG. 1 , including operations S101 to S104 .

According to some embodiments of the present disclosure, operation S101 includes: acquiring working parameters of the stripe mode and the wide-area MTI mode.

According to some embodiments of the present disclosure, operation S102 includes operating to simultaneously perform the stripe mode and the wide-area MTI mode in a sub-aperture manner.

According to some embodiments of the present disclosure, operation S103 includes: processing the received echo data of the stripe mode and the wide-area MTI mode to obtain stripe SAR images and spot trace information of the moving target, and correlating the spot traces of the moving target to form the track information of the moving target.

Specifically, different dot traces are classified according to their respective target directions, and the dot traces in the same direction are associated to form the track information of the moving target.

According to some embodiments of the present disclosure, operation S101 includes: superimposing the track information on a corresponding position on the strip SAR image.

FIG. 2 schematically shows a flow chart of the design of working parameters of the method for simultaneously implementing the strip mode and the wide-area MTI mode in the on-board SAR according to an embodiment of the present disclosure.

According to some embodiments of the present disclosure, as shown in the figure, operation S101 includes sub-operations S201 to S205.

According to some embodiments of the present disclosure, sub-operation S201 includes: calculating a working parameter of the stripe mode according to a first preset index requirement or a first input condition.

According to some embodiments of the present disclosure, sub-operation S202 includes: calculating a working parameter of the wide-area MTI mode according to a second preset index requirement or a second input condition.

According to some embodiments of the present disclosure, sub-operation S203 includes: calculating the dwell pulse number of the wide-area MTI mode according to the requirement of the scanning range of the wide-area MTI mode and the working parameters of the wide-area MTI mode.

According to some embodiments of the present disclosure, sub-operation S204 includes: calculating a revisit time required for one cycle of scanning in the wide-area MTI mode according to the dwell pulse number.

According to some embodiments of the present disclosure, the sub-operation S205 includes: judging whether the revisit time meets the requirement for the target association tracking, if so, entering the sub-operation S206, and if not, returning to the sub-operation S201.

According to some embodiments of the present disclosure, the sub-operation S206 includes: outputting the working parameters of the stripe mode and the working parameters of the wide-area MTI mode.

Wherein, after returning to sub-operation S201, modifying the first preset index requirement or the first input condition and recalculating the working parameters of the stripe mode and the wide-area MTI mode.

FIG. 3 schematically shows a working schematic diagram of a method for simultaneously implementing a strip mode and a wide-area MTI mode on a carrier SAR according to an embodiment of the present disclosure.

According to some embodiments of the present disclosure, as shown in FIG. 3 , the pulse repetition frequency of the stripe mode and the wide-area MTI mode are the same, and both are the same as the pulse repetition frequency of the actual transmission, so as to realize the simultaneous execution of the stripe mode in a divided aperture manner. The strip mode and the wide-area MTI mode; and, the pulse repetition frequency of the strip mode is greater than or equal to α times the azimuth Doppler bandwidth, where the value of α ranges from 1.2 to 1.3.

According to some embodiments of the present disclosure, after determining the value range of the pulse repetition frequency of the stripe mode, the method further includes: calculating the spatial restriction condition of the wave position in combination with the first preset index requirement or the first input condition, and forming a wave position map, so as to form a wave position map. Ensure that the observation band echo corresponding to the wave position can be received completely and without interference; and, from the wave position map, select the signal pulse width and stripe mode pulse repetition frequency that satisfy the requirement that the echo interference of the off-camera point does not fall within the receiving window. .

According to some embodiments of the present disclosure, modifying the preset index requirements or input conditions to recalculate the working parameters of the strip mode and the wide-area MTI mode includes: reselecting from the wave bitmap to satisfy the requirement that the echo interference of the off-camera point does not fall within the receiving window within the signal pulse width and stripe mode pulse repetition frequency.

According to some embodiments of the present disclosure, the first preset index includes platform flight height, flight ground speed, resolution, mapping bandwidth, and working distance.

According to some embodiments of the present disclosure, the operating parameters of the strip mode include: signal bandwidth-narrowband, pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end slanting distance, far-end sloping distance, Sampling start, number of sampling points and azimuth observation angle; and, operating parameters of wide-area MTI mode include: signal bandwidth-broadband, pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end oblique angle Distance, far-end slope distance, sampling start, number of sampling points, azimuth scanning range, azimuth scanning step value, dwell pulse number and revisit time. Among them, in the strip mode operation, the azimuth observation angle is fixed, and the most commonly used is 0 degrees, that is, it works in the front side view state.

In this embodiment, the signal bandwidth-narrowband is a narrowband bandwidth suitable for the low-resolution stripe mode, and it is ensured that the noise equivalent backscatter coefficient (NEσ ₀ ) meets the requirements of the image signal-to-noise ratio.

In the selection of the bandwidth, the present disclosure designs two signal bandwidths for the _stripe mode and the wide-area _MTI mode. The signal bandwidth range is [f _MTI,L ,f _MTI,H ]. In order to ensure that the signals in the two operating modes do not interfere with each other, the two signal bandwidths generated by the design of the present disclosure satisfy f _MTI,H <f _strip,L .

According to some embodiments of the present disclosure, calculating the number of dwell pulses according to the scanning range requirement of the wide-area MTI mode and the working parameters of the wide-area MTI mode includes: according to the scanning range requirement of the wide-area MTI mode and the selection of the wide-area MTI mode The pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end sloping distance, far-end sloping distance and sampling start of the wave position, and select the appropriate number of dwell pulses to make the wide-area MTI The action distance of the mode is greater than or equal to the remote slant distance to ensure that the target within the illumination range meets the detection performance.

According to some embodiments of the present disclosure, calculating the revisit time required for one cycle of wide-area MTI mode scanning according to the dwell pulse number includes:

The antenna azimuth 3dB beamwidth is

Among them, θ _3dB represents the beam width, λ represents, and _La represents the azimuth antenna length;

Taking half of the 3dB beam width θ _3dB as the step angle, the number of beam steps in a single scan is

where N _step represents the number of beam steps for a single scan, and Ψ represents half of the scan range; and

The revisit time T required to scan one cycle is calculated as

where T is the revisit time, n is the number of dwell pulses, and PRF _MTI is the pulse repetition frequency of the wide-area MTI mode.

FIG. 5 schematically shows a flow chart of calculating the re-entry time of the wide-area MTI mode according to a specific embodiment of the present disclosure.

According to some embodiments of the present disclosure, it is judged whether the revisit time meets the requirement for target association tracking, and if so, output the working parameters of the stripe mode and the working parameters of the wide-area MTI mode, if not, output the working parameters of the strip mode and the wide-area MTI mode. Modifying the first preset index requires or recalculating the working parameters of the stripe mode and the wide-area MTI mode according to the first input condition. As shown in FIG. 5 , operations S301 to S30 are included.

According to some embodiments of the present disclosure, operation S301 includes: inputting the azimuth scanning angle and re-entry time requirement and inputting the near-end viewing angle, far-end viewing angle, and normal viewing angle calculated in operation S202.

According to some embodiments of the present disclosure, operation S302 includes: initializing the reentry time as 60s and initializing the PRF to be the PRF of operation S201.

According to some embodiments of the present disclosure, operation S303 includes: judging whether the re-entry time meets the requirements, if yes, proceed to operation S307 , if not, proceed to operation S304 .

According to some embodiments of the present disclosure, operation S304 includes: updating the PRF.

According to some embodiments of the present disclosure, operation S305 includes: calculating the number of beam steps.

According to some embodiments of the present disclosure, operation S306 includes: calculating the reentry time, and returning to operation S303 to re-determine.

According to some embodiments of the present disclosure, operation S307 includes: outputting the PRF.

Embodiments of the present disclosure also provide an apparatus for simultaneously implementing a strip mode and a wide-area MTI mode for an airborne SAR, including:

The working parameter acquisition module is used to obtain the working parameters of the strip mode and the wide-area MTI mode;

Radar, which performs both strip mode and wide-area MTI mode in a split-aperture manner;

The data processing module processes the received echo data in the strip mode and the wide-area MTI mode to obtain strip SAR images and the trace information of the moving target, and correlates the trace information of the moving target to form the track information of the moving target ;as well as

The information fusion module is used to superimpose the track information to the corresponding position on the strip SAR image.

The technical solution of the present disclosure is further described below through a specific embodiment.

In this embodiment, taking ground reconnaissance and monitoring as an example, the main index requirements and input conditions are as follows:

Flight altitude: 18000m;

Flight ground speed: 240m/s;

Antenna working bandwidth: 8～12GHz (X-band);

Antenna size: 1500mm (length) × 380mm (height);

Peak power: 23000W;

Strip mode resolution: 1m (azimuth) × 1m (distance);

Wide-area MTI mode resolution: 20m;

Strip mode mapping bandwidth: 20km;

Wide-area MTI mode mapping bandwidth: 20km;

Wide-area MTI azimuth scanning range: ±60°;

Wide-area MTI mode detection vehicle target RCS: 10m2; and

Action distance: 120km.

Step 1. According to the flight altitude, the operating distance, and the surveying and mapping bandwidth, the strip mode range can be determined to the surveying strip area: the near-end slant range is 110.1km, the far-end slant range is 129.9km, the near-end viewing angle is 80.1°, and the far-end viewing angle is 81.4°, The surveying and mapping bandwidth is 20km. According to the resolution requirement, the signal bandwidth of stripe mode can be determined as 200MHz.

Determine the value range of PRF. To avoid azimuth ambiguity, the azimuth sampling frequency PRF of the stripe mode should be greater than or equal to 1.3 times the azimuth Doppler bandwidth, namely:

In the distance direction, in order to prevent distance blurring, there is another limitation on PRF. For side-view radar, it is:

The present disclosure designs a working form that performs the strip mode and the wide-area MTI mode simultaneously in a split-aperture manner, that is, the PRFs used for the stripe imaging and the wide-area MTI mode are equal, and the value is the actual transmit PRF. Therefore, the value range of the actual transmitted PRF is:

737Hz≤PRF _system ≤7500Hz

After determining the selection range of PRF, it is necessary to combine the parameters such as near-end viewing angle, far-end viewing angle, and pulse width to determine the spatial constraints of the wave position, that is, the wave position map (also called the zebra diagram), so as to ensure that the observation corresponding to the wave position brings echoes. can be received intact and without interference. The wave bitmap is determined by the following constraints: Assuming that the echo is received after i PRFs, the condition for the transmitted pulse not to fall into the echo receiving window is:

Among them, T _p is the pulse width, T _pt is the pulse protection time, and R _n and R _f are the near-end and far-end slope distances, respectively.

Assuming that the echo delay time of the off-camera point is greater than or equal to j PRFs, the following conditions must be met to prevent the off-camera echo interference from falling within the receiving window:

Among them, H is the height of the carrier aircraft relative to the ground.

According to the above constraints, the appropriate signal pulse width and PRF _system can be selected from the wave position map. As shown in Figure 4, when the pulse width is 100us, the optional PRF within the viewing angle range is below the black dotted line. In this example, select PRF _system = 900 Hz, resulting in PRF _strip = 900 Hz, PRF _spot = 900 Hz.

It is calculated by the Noise Equivalent Backscattering Coefficient (NESZ) formula:

Among them, K is Boltzmann's constant (1.38×10- ²³ J/K), T ₀ is the receiver temperature (290K), F _n is the receiver noise figure, and R is the slant range (action distance) from the carrier to the target. ), L _s is the system loss, P _av is the average power of the transmitted signal, G _t is the transmit antenna gain, Gr is the receive antenna _{gain, ρ g is} the ground distance resolution, and V is the carrier speed.

FIG. 6 schematically shows a schematic diagram of a stripe mode noise equivalent backscatter coefficient obtained by calculation according to a specific embodiment of the present disclosure.

The obtained noise-equivalent backscatter coefficient is better than -38dB, as shown in Figure 6. The X-band noise equivalent backscatter coefficient is generally required to be better than -20 ~ -25dB, and the system design meets the requirements of the image signal-to-noise ratio.

Step 2. According to the flight altitude, the operating distance, and the surveying and mapping bandwidth, the wide-area MTI mode range direction surveying swath area can be determined: the near-end slant range is 110.1km, the far-end slant range is 129.9km, the near-end viewing angle is 80.1°, and the far-end viewing angle is 81.4°. , The surveying and mapping bandwidth is 20km. According to the resolution requirement, the signal bandwidth of the wide-area MTI mode can be determined to be 10MHz.

Step 3. According to the scanning range requirements (±60 degrees) and the pulse width of the wave position selected in step 2, 100us, PRF _MTI , near-end viewing angle, far-end viewing angle, normal viewing angle, near-end slanting distance, far-end slanting distance and sampling Initially, select the number of dwell pulses n=32, and calculate the range of MTI mode from the radar equation:

Among them, P _t is the peak transmit power, σ _t is the target radar cross-sectional area (RCS), D ₀ is the detection force factor, 14dB in this example, L _sys is the system loss (including atmospheric round-trip loss, radome loss, Antenna scanning loss, system amplitude and phase error loss, signal processing loss, etc.), take 12dB in this example.

Step 4: Calculate the revisit time T required for scanning one cycle (±60 degrees) in the wide-area MTI mode.

The antenna azimuth 3dB beamwidth is:

Taking half of the 3dB beam width θ _3dB as the step angle, the number of beam steps N _step in a single scan is:

The revisit time T required to scan one cycle (±ψ degrees) is calculated as:

The detection and revisit time of the wide-area MTI mode is 4.05s to meet the requirements of target association tracking, and the design is completed. Output the working parameters of stripe mode and wide-area MTI mode.

Through the above-mentioned embodiments of the present disclosure, after the working parameters of the stripe mode and the wide-area MTI mode of the airborne SAR are designed by the device for simultaneously realizing the stripe mode and the wide-area MTI mode of the airborne SAR, the airborne SAR can simultaneously realize the stripe mode and the wide-area MTI mode of the airborne SAR. Execute the working parameters of strip mode and wide-area MTI mode; process the echo data working in strip mode and wide-area MTI mode respectively, and have the ability to obtain SAR high-resolution images and ground/sea surface moving target trajectory information at the same time, And the moving target trajectory information can be marked on the SAR image, which can improve the accuracy of moving target reconnaissance and surveillance, and can give full play to the advantages of multi-functional radar in all directions and multiple dimensions, providing radar users with efficient situational awareness.

So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that, in the accompanying drawings or the text of the description, the implementations that are not shown or described are in the form known to those of ordinary skill in the technical field, and are not described in detail. In addition, the above definitions of various components are not limited to various specific structures, shapes or manners mentioned in the embodiments, and those of ordinary skill in the art can simply modify or replace them.

It should also be noted that, in the specific embodiments of the present disclosure, unless known to the contrary, the numerical parameters in the specification and the appended claims are approximations that can Characteristics change. In particular, all numbers used in the specification and claims to indicate compositional dimensions, range conditions, etc., should be understood to be modified by the word "about" in all instances. In general, the meaning expressed is meant to include a change of ±10% in some embodiments, a change of ±5% in some embodiments, a change of ±1% in some embodiments, and a change of ±1% in some embodiments. Example ±0.5% variation.

Those skilled in the art will appreciate that various combinations and/or combinations of features recited in various embodiments and/or claims of the present disclosure are possible, even if such combinations or combinations are not expressly recited in the present disclosure. In particular, various combinations and/or combinations of the features recited in the various embodiments of the present disclosure and/or in the claims may be made without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of this disclosure.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above are only specific embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure should be included within the protection scope of the present disclosure.

Claims (10)

1. a method for airborne SAR to realize strip mode and wide-area MTI mode simultaneously, is characterized in that, comprises: Get the working parameters of stripe mode and wide-area MTI mode; simultaneously executing the stripe mode and the wide-area MTI mode in a split-aperture manner; The received echo data of the stripe mode and the wide-area MTI mode are processed to obtain stripe SAR images and the spot trace information of the moving target, and the spot trace information of the moving target is correlated to form the moving target. the target's track information; and The track information is superimposed on the corresponding position on the strip SAR image. 2. The method according to claim 1, wherein the acquiring the operating parameters of the stripe mode and the wide-area MTI mode comprises: Calculate the operating parameters of the strip mode according to the first preset index requirement or the first input condition; Calculate the operating parameters of the wide-area MTI mode according to the second preset index requirement or the second input condition; Calculate the number of dwell pulses in the wide-area MTI mode according to the requirements of the scanning range of the wide-area MTI mode and the operating parameters of the wide-area MTI mode; calculating the revisit time required for one cycle of scanning of the wide-area MTI mode according to the dwell pulse number; and Judging whether the revisit time meets the requirements for target association tracking, if so, output the working parameters of the stripe mode and the working parameters of the wide-area MTI mode, if not, modify the first preset index A request or a first input condition recalculates the operating parameters of the stripe mode and the wide-area MTI mode. 3. The method of claim 2, wherein The pulse repetition frequency of the stripe mode and the wide-area MTI mode is the same, and both are the same as the pulse repetition frequency of the actual transmission, so as to realize the simultaneous execution of the stripe mode and the wide-area MTI in a sub-aperture manner mode; and The pulse repetition frequency of the stripe mode is greater than or equal to α times the azimuth Doppler bandwidth, where the value of α ranges from 1.2 to 1.3. 4. The method according to claim 3, further comprising: after determining the value range of the pulse repetition frequency of the stripe mode: Combining the first preset index requirement or the first input condition to calculate the spatial constraints of the wave position and form a wave position map, so as to ensure that the echoes in the observation band corresponding to the wave position can be received completely and without interference; and The signal pulse width and the pulse repetition frequency of the stripe mode are selected from the wave position map so that the off-camera point echo interference does not fall within the receiving window. 5. The method according to claim 4, wherein the modifying the preset index requirement or input condition and recalculating the working parameters of the stripe mode and the wide-area MTI mode comprises: The signal pulse width and the pulse repetition frequency of the stripe mode are reselected from the wave position map so that the off-camera point echo interference does not fall within the receiving window. 6 . The method according to claim 3 , wherein the first preset index comprises platform flight height, flight ground speed, resolution, surveying and mapping bandwidth, and working distance. 7 . 7. The method of claim 3, wherein The working parameters of the strip mode include: signal bandwidth-narrowband, pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end slanting distance, far-end slanting distance, sampling start, number of sampling points and azimuth observation angles; and The working parameters of the wide-area MTI mode include: signal bandwidth-broadband, pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end slant range, far-end slant range, sampling start, sampling Number of points, azimuth scan range, azimuth scan step, dwell pulse number and revisit time. 8. The method according to claim 7, wherein the calculating the number of dwell pulses according to the requirements of the scanning range of the wide-area MTI mode and the operating parameters of the wide-area MTI mode comprises: According to the requirements of the scanning range of the wide-area MTI mode and the pulse width, pulse repetition frequency, near-end viewing angle, far-end viewing angle, normal viewing angle, near-end oblique distance, far-end viewing angle of the wave position selected by the wide-area MTI mode For the end slant distance and the start of sampling, an appropriate number of dwell pulses is selected, so that the action distance of the wide-area MTI mode is greater than or equal to the distal slant distance, so as to ensure that the targets within the illumination range meet the detection performance. 9. The method according to claim 8, wherein calculating the revisit time required for scanning one cycle of the wide-area MTI mode according to the dwell pulse number comprises: The antenna azimuth 3dB beamwidth is

Among them, θ _3dB represents the beam width, λ represents, and _La represents the azimuth antenna length; Taking half of the 3dB beam width θ _3dB as the step angle, the number of beam steps in a single scan is

where N _step represents the number of beam steps for a single scan, and Ψ represents half of the scan range; and The revisit time T required to scan one cycle is calculated as

where T is the revisit time, n is the number of dwell pulses, and PRF _MTI is the pulse repetition frequency of the wide-area MTI mode. 10. A device for simultaneously realizing strip mode and wide-area MTI mode for an airborne SAR, comprising: The working parameter obtaining module is used to obtain working parameters of strip mode and wide-area MTI mode; a radar that simultaneously performs the strip mode and the wide-area MTI mode in a split-aperture manner; The data processing module processes the received echo data of the stripe mode and the wide-area MTI mode to obtain stripe SAR images and spot trace information of the moving target, and associates the spot traces of the moving target to form track information of the moving target; and The information fusion module is used for superimposing the track information to the corresponding position on the strip SAR image.

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