CN117908021A

CN117908021A - Radar imaging method and device

Info

Publication number: CN117908021A
Application number: CN202211233311.3A
Authority: CN
Inventors: 张慧; 马莎; 宋思达
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-10-10
Filing date: 2022-10-10
Publication date: 2024-04-19

Abstract

The application provides a radar imaging method and a radar imaging device, wherein the method comprises the following steps: transmitting at least one first signal, the at least one first signal being a signal wave front modulated in a horizontal and/or vertical direction; receiving at least one echo signal reflected by the target object on the at least one first signal; the target object is imaged from the at least one echo signal. By implementing the embodiment of the application, the angular resolution can be improved. Furthermore, the method improves the ADAS capability of an advanced driving assistance system of the terminal in automatic driving or assisted driving, and can be applied to the Internet of vehicles, such as vehicle external connection V2X, workshop communication long-term evolution technology LTE-V, vehicle-vehicle V2V and the like.

Description

Radar imaging method and device

Technical Field

The application relates to the technical field of radars, in particular to a radar imaging method and device.

Background

With the high-speed development of modern economy, intelligent terminals such as intelligent transportation equipment, intelligent household equipment, robots and the like are gradually entering into daily life of people. In order to improve user experience, comfort and safety of a user in using the intelligent terminal are effectively improved, and various sensors such as millimeter wave radar, laser radar, cameras, ultrasonic radar and the like are often installed on the intelligent terminal.

Taking an intelligent terminal as an intelligent transportation device as an example, the millimeter wave radar becomes a main force sensor of the unmanned system and the auxiliary driving system due to lower cost and more mature technology. Advanced driving assistance systems (ADVANCED DRIVER ASSISTANCE SYSTEMS, ADAS) have now developed ten more functions, in which adaptive cruise control (Adaptive Cruise Control, ACC), automatic emergency braking (Autonomous Emergency Braking, AEB), lane change assistance (LANCE CHANGE ASSIST, LCA), blind spot monitoring (Blind Spot Monitoring, BSD) are all independent of millimeter wave radar. Millimeter waves generally refer to electromagnetic waves having wavelengths between 1 and 10mm, and correspond to frequencies ranging from 30 to 300GHz. In this frequency band, the millimeter wave-related characteristics are well suited for application in the vehicle-mounted field. However, the angular resolution of the point cloud data obtained by the millimeter wave radar is limited by the length of the antenna aperture (or virtual aperture), the point cloud is sparse, and the detection or recognition capability of the point cloud to a stationary target is low. Multiple transmit multiple receive (multiple input multiple output, MIMO) radar technology can be used to improve angular resolution. MIMO radar technology is limited in the size of radar mounted on a vehicle, resulting in no further improvement in angular resolution.

Therefore, a technical means for improving the angular resolution is urgently needed.

Disclosure of Invention

The application provides a radar imaging method and a radar imaging device, which can improve the angular resolution.

In a first aspect, there is provided a radar imaging method, the method comprising: transmitting at least one first signal, the at least one first signal being a signal wave front modulated in a horizontal and/or vertical direction; receiving at least one echo signal reflected by the target object on the at least one first signal; the target object is imaged from the at least one echo signal. It can be seen that the at least one first signal is a signal which is wavefront-modulated in the horizontal and/or vertical direction such that the at least one first signal is similar to the azimuth signal of the synthetic aperture radar (SYNTHETIC APERTURE RADAR, SAR), i.e. a synthetic aperture similar to SAR can be equivalently obtained by wavefront modulation. Therefore, when at least one echo signal reflected by at least one first signal is imaged based on the target object, the imaging angular resolution of the target object can be improved. Meanwhile, the problem that SAR imaging cannot perform forward-looking imaging is solved.

In the application, the range of the horizontal direction is the range of the angle of view of the radar horizontal direction, such as-80 degrees to 80 degrees, -60 degrees to 60 degrees or-15 degrees to 15 degrees, etc. The vertical range is the range of the angle of view of the radar in the vertical direction, such as-9 DEG to 9 DEG or-5 DEG to 5 deg. The horizontal direction and the vertical direction may be in a coordinate system centered on the radar, or may be in a coordinate system centered on another position.

In the present application, the wavefront modulation may include phase modulation and/or amplitude modulation.

In the present application, the number of target objects may be one or more. For example, in an autopilot scenario, the target object may be one or more of a traveling car, a moving pedestrian, a stationary vehicle, an obstacle, a guardrail, and the like.

In the present application, the wavefront-modulated signal in the horizontal and/or vertical directions is similar to the SAR azimuth signal. The operating mode of the SAR may be a stripe mode, a bunching (spotlight) mode, a sliding bunching mode, or the like. Thus, the signal after wavefront modulation in the horizontal and/or vertical directions may be similar to the azimuth signal of the stripe-mode SAR, the azimuth signal of the beamformed mode SAR, or the azimuth signal of the sliding beamformed mode SAR, etc. It will be appreciated that in the swath mode, different imaging widgets can be obtained by varying the angle of incidence; in the beam focusing mode, the imaging area can be always in the coverage of the antenna beam by adjusting the beam direction; in the slip beamforming mode, directional resolution may be controlled by controlling the speed of movement of the antenna illumination area across the ground.

In addition, in the present application, imaging can be understood as 4D imaging.

In a second aspect, there is provided a radar imaging method, the method comprising: transmitting at least one first signal; receiving at least one echo signal reflected by the target object on the at least one first signal; performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction; the target object is imaged. It can be seen that by receiving at least one echo signal reflected by the target object on at least one first signal and performing a wavefront modulation on the at least one echo signal in a horizontal and/or vertical direction, the at least one echo signal after the wavefront modulation is similar to the azimuth signal of the SAR, that is to say, a synthetic aperture similar to the SAR can be equivalently obtained by the wavefront modulation, so that the imaging angular resolution of the target object can be improved when the target object is imaged. Meanwhile, the problem that SAR imaging cannot perform forward-looking imaging is solved.

In a third aspect, there is provided a radar imaging method, the method comprising: transmitting at least one first signal, the at least one first signal being a signal wave front modulated in a horizontal and/or vertical direction; receiving at least one echo signal reflected by the target object on the at least one first signal; performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction; the target object is imaged. It can be seen that the at least one first signal is a signal which is wavefront-modulated in the horizontal and/or vertical direction such that the at least one first signal is similar to the azimuth signal of the SAR, i.e. a synthetic aperture similar to the SAR can be equivalently obtained by the wavefront modulation. At the same time, the at least one echo signal is wavefront-modulated in the horizontal and/or vertical direction, so that the wavefront-modulated at least one echo signal resembles the azimuth signal of the SAR, which further increases the synthetic aperture. Therefore, when the target object is imaged, the imaging angular resolution of the target object can be further improved. Meanwhile, the problem that SAR imaging cannot perform forward-looking imaging is solved.

Optionally, with reference to the first aspect or the third aspect, the at least one first signal includes a plurality of first signals, where the plurality of first signals are sent at different times, and the plurality of first signals have different wavefront modulation coefficients corresponding to the same direction, where one wavefront modulation coefficient is used to perform wavefront modulation on one first signal in one direction, and where one first signal has different wavefront modulation coefficients corresponding to different directions. It can be seen that the wavefront modulation coefficients corresponding to the first signals transmitted at different times in the same direction are different, that is, the wavefronts of the first signals transmitted at different times in the same direction are different. Meanwhile, the wavefront modulation coefficients of one first signal corresponding to different directions are different, that is, the wavefront of one first signal in different directions is different. This can equivalently obtain a synthetic aperture similar to SAR.

In the present application, the same direction may be understood as the same pointing angle corresponding to the horizontal direction and/or the vertical direction. Conversely, different directions can be understood as at least one of the following: the horizontal direction pointing angle is different, and the vertical direction pointing angle is different. Of course, one direction may include a pointing angle in a horizontal and/or vertical direction.

In the present application, when wavefront modulation is performed in the horizontal direction, the same direction may be understood as the same pointing angle corresponding to the horizontal direction, different directions may be understood as different pointing angles in the horizontal direction, and one direction may be understood as the pointing angle in the horizontal direction. When wavefront modulation is performed in the vertical direction, the same direction may be understood as the same pointing angle corresponding to the vertical direction, different directions may be understood as different pointing angles in the vertical direction, and one direction may be understood as the pointing angle in the vertical direction. In wavefront modulation in the horizontal and vertical directions, the same direction may be understood as the same pointing angle corresponding to the horizontal direction and the same pointing angle corresponding to the vertical direction, and different directions may be understood as different pointing angles in the horizontal direction and/or different pointing angles in the vertical direction, and one direction includes the pointing angle in the horizontal direction and the pointing angle in the vertical direction.

Optionally, with reference to the first aspect or the third aspect, the at least one first signal is a signal that is wavefront modulated in a horizontal direction and/or a vertical direction according to a wavefront modulation matrix; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients in different directions at one moment in time, a column of the wavefront modulation matrix represents the wavefront modulation coefficients in the same direction at different moments in time, and a first signal is determined from a row vector of the wavefront modulation matrix. It can be seen that one row of the wavefront modulation matrix represents the wavefront modulation coefficients in different directions at one instant, and one first signal is determined from one row vector of the wavefront modulation matrix, so that at one instant the wavefront modulation coefficients of one first signal in different directions are different, i.e. the wavefronts of the first signal in different directions are different. Meanwhile, the list of the wavefront modulation matrices indicates the wavefront modulation coefficients of the same direction at different moments in time, so that the wavefront modulation coefficients corresponding to different first signals transmitted at different moments in time in the same direction are different, that is, the wavefronts of different first signals transmitted at different moments in time in the same direction are different. This can equivalently obtain a synthetic aperture similar to SAR.

It should be noted that, in the present application, the number of the wavefront modulation matrices may be one or more. Illustratively, one wavefront modulation matrix is used for wavefront modulation in both the horizontal and vertical directions. Also exemplary, one wavefront modulation matrix is used for wavefront modulation in the horizontal direction and another wavefront modulation matrix is used for wavefront modulation in the vertical direction.

Optionally, with reference to the second aspect or the third aspect, performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction includes: wave front modulation is performed on different wave front modulation coefficients of at least one echo signal in the same direction, and wave front modulation is performed on each echo signal of the at least one echo signal in different directions based on different wave front modulation coefficients. It can be seen that, by performing wavefront modulation on different echo signals in at least one echo signal based on different wavefront modulation coefficients in the same direction and performing wavefront modulation on each echo signal in at least one echo signal based on different wavefront modulation coefficients in different directions, the wavefront of the modulated different echo signals in the same direction is different, and the wavefront of each modulated echo signal in different directions is also different, so that a synthetic aperture similar to the SAR can be equivalently obtained.

Optionally, with reference to the second aspect or the third aspect, wavefront modulating different echo signals in at least one echo signal in a same direction based on different wavefront modulation coefficients, and wavefront modulating each echo signal in at least one echo signal in a different direction based on different wavefront modulation coefficients, includes: according to the wave front modulation matrix, wave front modulation is carried out on different wave front modulation coefficients of different wave front signals in at least one wave back signal in the same direction, and wave front modulation is carried out on each wave back signal of the at least one wave back signal in different directions on the basis of different wave front modulation coefficients; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients of one moment in different directions, a column of the wavefront modulation matrix represents the wavefront modulation coefficients of the same direction in different moments, and an echo signal is determined according to a row vector of the wavefront modulation matrix. It can be seen that the first column of the wavefront modulation matrix represents the wavefront modulation coefficients of the same direction at different moments, so that, according to the wavefront modulation matrix, the wavefront modulation is performed on different echo signals in at least one echo signal in the same direction based on different wavefront modulation coefficients, so that the wavefronts of the modulated different echo signals in the same direction are different. Meanwhile, one row of the wave front modulation matrix represents wave front modulation coefficients of one moment in different directions, and one echo signal is determined according to one row vector of the wave front modulation matrix, so that each echo signal in at least one echo signal is subjected to wave front modulation in different directions based on different wave front modulation coefficients according to the wave front modulation matrix, and the wave front of each modulated echo signal in different directions can be made to be different. This can equivalently obtain a synthetic aperture similar to SAR.

Optionally, with reference to the first aspect, the second aspect, or the third aspect, a row vector of the wavefront modulation matrix includes a non-zero element and a zero element, and a phase of the non-zero element includes a quadratic term. It can be seen that because the phase of the non-zero element includes a quadratic term, the phase of the wavefront modulated signal can be made to have a quadratic term, i.e. the wavefront modulated signal is made to resemble the azimuth signal of the SAR.

In the present application, the quadratic term can be understood as a square term.

Optionally, with reference to the first aspect, the second aspect or the third aspect, positions of non-zero elements in different row vectors of the wavefront modulation matrix are different. This may mimic the range of illumination of the beam in the stripmode SAR, which in turn may make the wavefront modulated signal similar to the azimuth signal of the stripmode SAR.

Optionally, with reference to the first aspect, the second aspect or the third aspect, the wavefront modulation matrix includes a first row vector and a second row vector that are adjacent to each other, and elements in the first row vector are cyclically shifted according to elements in the second row vector. This can simulate the imaging process of the forward motion of the strippattern SAR beam, thereby achieving high resolution capabilities similar to strippattern SAR.

Optionally, with reference to the first aspect, the second aspect, or the third aspect, the wavefront modulation matrix satisfies the following formula:

Where j is an imaginary unit, β is a direction-modulating frequency, λ is a wavelength of the first signal, and L is a number of non-zero elements in one row vector of the wavefront modulation matrix.

In the present application, the directional modulation frequency may refer to a modulation slope of echo signals that are different along a slow time dimension. exp represents an exponential function based on e.

Optionally, with reference to the first aspect, the second aspect or the third aspect, the phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix includes a first term and a second term. This makes the wavefront modulated signal similar to the azimuth signal of the beamformed SAR.

Optionally, with reference to the first aspect, the second aspect, or the third aspect, phases of different wavefront modulation coefficients in one row vector of the wavefront modulation matrix include different first order coefficients. It can be seen that the first order coefficients comprise a horizontal or vertical pointing angle, and that the first order coefficients are different, i.e. the horizontal or vertical pointing angle is different, and different pointing angles may represent different beam center orientations, so that the wavefront modulated signal may be similar to the azimuth signal of the beamformed SAR.

Where j is an imaginary unit, α is a first order coefficient included in the phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix, γ is a second order coefficient included in the phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix, λ is the wavelength of the first signal, x _i is the i-th pointing angle in the horizontal direction or the vertical direction, i is an integer greater than or equal to 1 and less than or equal to N, t _ah is the transmission time of the h pulse, and h is an integer greater than or equal to 1 and less than or equal to K.

In one possible embodiment, α and γ may be set to be constant. In a further possible embodiment of the present invention, V is the motion direction of the radar in the SAR, and R ₀ is the nearest slant distance between the target object in the SAR and the radar.

In a fourth aspect, a radar imaging apparatus is provided, the apparatus comprising a transceiver unit and a processing unit, the transceiver unit being configured to transmit at least one first signal, the at least one first signal being a signal modulated in a wavefront in a horizontal direction and/or a vertical direction; the receiving and transmitting unit is also used for receiving at least one echo signal reflected by the target object on at least one first signal; and the processing unit is used for imaging the target object according to the at least one echo signal.

In a fifth aspect, a radar imaging apparatus is provided, the apparatus comprising a transceiver unit and a processing unit, the transceiver unit being configured to transmit at least one first signal; the receiving and transmitting unit is also used for receiving at least one echo signal reflected by the target object on at least one first signal; a processing unit for performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction; and the processing unit is also used for imaging the target object.

In a sixth aspect, a radar imaging apparatus is provided, the apparatus comprising a transceiver unit and a processing unit, the transceiver unit being configured to transmit at least one first signal, the at least one first signal being a signal modulated in a wavefront in a horizontal and/or vertical direction; the receiving and transmitting unit is also used for receiving at least one echo signal reflected by the target object on at least one first signal; a processing unit for performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction; and the processing unit is also used for imaging the target object.

Optionally, with reference to the fourth aspect or the sixth aspect, at least one first signal includes a plurality of first signals, the plurality of first signals are transmitted at different times, the plurality of first signals have different wavefront modulation coefficients corresponding to the same direction, one wavefront modulation coefficient is used for performing wavefront modulation on one first signal in one direction, and one first signal has different wavefront modulation coefficients corresponding to different directions.

Optionally, with reference to the fourth or sixth aspect, the at least one first signal is a signal that is wavefront modulated in a horizontal direction and/or a vertical direction according to a wavefront modulation matrix; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients in different directions at one moment in time, a column of the wavefront modulation matrix represents the wavefront modulation coefficients in the same direction at different moments in time, and a first signal is determined from a row vector of the wavefront modulation matrix.

Optionally, with reference to the fifth aspect or the sixth aspect, when the at least one echo signal is wavefront-modulated in a horizontal direction and/or a vertical direction, the processing module is configured to perform wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction, and perform wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions.

Optionally, with reference to the fifth aspect or the sixth aspect, when performing wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction and performing wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions, the processing module is configured to perform wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction according to the wavefront modulation matrix and performing wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients of one moment in different directions, a column of the wavefront modulation matrix represents the wavefront modulation coefficients of the same direction in different moments, and an echo signal is determined according to a row vector of the wavefront modulation matrix.

Optionally, with reference to the fourth aspect, the fifth aspect or the sixth aspect, a row vector of the wavefront modulation matrix includes a non-zero element and a zero element, and a phase of the non-zero element includes a quadratic term.

Optionally, with reference to the fourth aspect, the fifth aspect or the sixth aspect, positions of non-zero elements in different row vectors of the wavefront modulation matrix are different.

Optionally, with reference to the fourth aspect, the fifth aspect or the sixth aspect, the wavefront modulation matrix includes a first row vector and a second row vector that are adjacent to each other, and elements in the first row vector are cyclically shifted according to elements in the second row vector.

Optionally, with reference to the fourth aspect, the fifth aspect or the sixth aspect, the wavefront modulation matrix satisfies the following formula:

Optionally, with reference to the fourth aspect, the fifth aspect or the sixth aspect, the phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix includes a first term and a second term.

Optionally, with reference to the fourth aspect, the fifth aspect or the sixth aspect, phases of different wavefront modulation coefficients in one row vector of the wavefront modulation matrix include different coefficients of the order terms.

A seventh aspect provides a radar imaging apparatus, comprising a wavefront modulation device, a transmit antenna, a receive antenna and a processor, the radar imaging apparatus being arranged to implement the method of any of the first, second or third aspects.

In an eighth aspect, there is provided a computer storage medium having a computer program stored thereon, which when run on a computer causes the computer to perform the method according to any of the first, second or third aspects.

A ninth aspect provides a vehicle comprising the apparatus of the fourth, fifth or sixth aspect.

In a tenth aspect, there is provided a chip comprising a processor and a communications interface, the processor being operable to invoke and execute instructions from the communications interface, the processor, when executing the instructions, implementing the method of any of the first, second or third aspects.

An eleventh aspect provides a radar imaging apparatus including: a processor and a memory; the memory is used to store one or more programs, the one or more programs comprising computer-executable instructions, which when executed by the apparatus, cause the apparatus to perform the method of any of the first, second or third aspects.

In a twelfth aspect, there is provided a computer program product comprising a computer program which, when run on a computer, causes the computer to perform the method of any of the first, second or third aspects.

Drawings

Fig. 1 is a schematic diagram of a radar system according to an embodiment of the present application;

fig. 2 is a schematic diagram of the internal structure of a radar according to an embodiment of the present application;

fig. 3 is a schematic flow chart of a radar imaging method according to an embodiment of the present application;

FIG. 4 is a schematic diagram of an inversion process for an imaged scene according to an embodiment of the present application;

FIG. 5 is a schematic flow chart of another radar imaging method according to an embodiment of the present application;

FIG. 6 is a schematic flow chart of another radar imaging method according to an embodiment of the present application;

fig. 7 is a schematic structural view of a radar imaging device 70 according to an embodiment of the present application;

Fig. 8 is a schematic structural view of a vehicle 80 according to an embodiment of the present application;

fig. 9 is a schematic structural diagram of a radar imaging device 90 according to an embodiment of the present application.

Detailed Description

For ease of understanding, the following description of some of the concepts related to the embodiments of the application are given by way of example for reference. The following is described:

1. Radar device

The radar may also be referred to as radar device, detector, radar detection device, detection device or radar signal transmission device. It should be understood that the radar in the embodiments of the present application may be a vehicle-mounted radar, an airborne radar, a satellite-borne radar, a ship-borne radar, a missile-borne radar, a ground-based radar, a radar station, or the like.

The radar in the embodiment of the application can be applied to various fields such as intelligent transportation, automatic driving, atmospheric environment monitoring, geographical mapping, unmanned aerial vehicle and the like, and can complete one or more functions such as target detection, distance measurement, speed measurement, target tracking, imaging identification and the like. For example, it may be applied to adaptive cruise control (adaptive cruisecontrol, ACC), automatic emergency braking (autonomous emergency braking, AEB), lane change assist (LANECHANGE ASSIST, LCA), blind spot detection (blind spot monitoring, BSM), parking assist (PARKINGASSISTANCE, PA), pedestrian detection (PEDESTRIAN DETECTION, PD), and the like. The application is not limited to the function of the radar application.

As shown in fig. 1, the radar according to the embodiment of the present application may be mounted on a motor vehicle, an intersection camera, an unmanned aerial vehicle, a rail car, a bicycle, a signal lamp, a speed measuring device, or a network device (such as a base station and a terminal device in various systems), etc. The application is suitable for radar systems between vehicles, radar systems of other devices such as vehicles and unmanned aerial vehicles, or radar systems between other devices. For example, the radar may be mounted on an intelligent transportation device, an intelligent home device, a robot, or the like. For example, the intelligent home equipment obtains indoor high-resolution point cloud patterns through radar, and is used for health monitoring (such as falling detection), intrusion detection and the like. The application does not limit the type of terminal equipment for installing the radar and the installation position of the radar.

The radar in the embodiment of the application can also be applied to scenes such as industrial remote control and the like.

It should be noted that the technical solution of the embodiment of the present application is not limited to millimeter wave radars, but may be applied to radars of other wavebands, such as microwave wavebands, terahertz wavebands, and radars that may even be extended to other electromagnetic wave (including light waves, such as infrared, etc.) bands. The application does not limit the attribute of the electromagnetic wave emitted by the radar.

2. Slow time dimension (also referred to as azimuth dimension)

The slow time dimension may refer to the dimension along the pulse repetition period. For example, where a radar periodically transmits a pulse signal (or pulse) as multiple pulses are processed, the slow time may be used to mark the time between different pulses, and one pulse may be considered a sample of the slow time.

3. Fast time dimension (also referred to as distance dimension)

A fast time dimension may refer to a dimension along one pulse sample, which may reflect the time within the pulse. For example, the radar transmits a pulse, and acquires an echo signal corresponding to the pulse, where the pulse is sampled in a fast time. Wherein the fast time may reflect the distance.

4. Fast fourier transform (fast fourier transform, FFT): a method of fast computing the discrete fourier transform (discrete fourier transform, DFT) of a sequence or its inverse. Fourier analysis converts a signal from the original domain (typically time or space) to a representation of the frequency domain or vice versa.

5. Distance unit

Each sampling point is a distance unit (also called a distance gate) after the echo signal is subjected to matched filtering or mixing processing. The range bin of the radar corresponds to the resolved range of the radar, the range being continuous and the range bin being discrete.

The following describes a system architecture to which the embodiments of the present application are applied. It should be noted that, the system architecture and the service scenario described in the present application are for more clearly describing the technical solution of the present application, and do not constitute a limitation on the technical solution provided by the present application. It should be understood that, with the evolution of the system architecture and the appearance of new service scenarios, the technical solution provided by the present application is equally applicable to similar technical problems.

The radar provided by the embodiment of the application can comprise a transmitting antenna, a receiving antenna, a wave front modulation device, a signal processing unit and the like, wherein:

(1) The transmitting antenna is used for transmitting at least one first signal. The first signal may be, for example, a frequency modulated continuous wave (frequency modulated continuous wave, FMCW), a Continuous Wave (CW), a wavefront modulated continuous wave (phasemodulation continuous wave, PMCW), or an orthogonal frequency division multiplexing (orthogonal frequency division multiplexing, OFDM), etc.

Wherein the number of transmit antennas may be one or more. It will be appreciated that the greater the number of transmit antennas, the greater the antenna aperture of the radar, and the greater the angular resolution.

(2) The receiving antenna is used for receiving at least one echo signal reflected by the target object on at least one first signal.

Wherein the number of receiving antennas may be one or more. It will be appreciated that the greater the number of receive antennas, the greater the antenna aperture of the radar, and the greater the angular resolution.

(3) The wavefront modulation device may also be referred to as an antenna aperture coding device. The wave front modulation device is used for carrying out wave front modulation on at least one first signal in the horizontal direction and/or the vertical direction; and/or the wavefront modulation device is used for performing wavefront modulation on at least one echo signal in the horizontal direction and/or the vertical direction.

It will be appreciated that performing wavefront modulation in the horizontal direction may increase the synthetic aperture of the radar in the horizontal dimension, which in turn may increase the horizontal dimension angular resolution of the radar. The wave front modulation is carried out in the vertical direction, so that the synthetic aperture of the radar in the vertical dimension can be improved, and the vertical dimension angle resolution of the radar can be improved. Thus, in one possible implementation, the horizontal dimension angular resolution may be achieved by wavefront modulation in the horizontal direction and the vertical dimension angular resolution may be achieved by multiple transceiver antennas. In another possible embodiment, the horizontal dimension angular resolution may be achieved by a plurality of transceiver antennas and the vertical dimension angular resolution may be achieved by wavefront modulation in the vertical direction. In yet another possible embodiment, the horizontal dimension angular resolution may be achieved by wavefront modulation in the horizontal direction and the vertical dimension angular resolution may be achieved by wavefront modulation in the vertical direction.

In the present application, the wavefront-modulated signal in the horizontal and/or vertical directions is similar to the SAR azimuth signal. The operating mode of the SAR may be a stripe mode, a beaming (spotlight) mode, a sliding beaming mode, or the like, and thus the signal after wavefront modulation in the horizontal and/or vertical directions may be similar to the azimuth signal of the stripe mode SAR, the azimuth signal of the beaming mode SAR, or the azimuth signal of the sliding beaming mode SAR, or the like. It will be appreciated that in the swath mode, different imaging widgets can be obtained by varying the angle of incidence; in the beam focusing mode, the imaging area can be always in the coverage of the antenna beam by adjusting the beam direction; in the slip beamforming mode, directional resolution may be controlled by controlling the speed of movement of the antenna illumination area across the ground.

Alternatively, the wavefront modulation device may be integrated with the transmit antenna and/or the receive antenna, or may be disposed on the transmit antenna and/or the receive antenna separately, such as at the front end of the transmit antenna and/or the receive antenna.

In a possible embodiment, when the number of transmit antennas is one or more and the number of receive antennas is one or more, the wavefront modulation device is integrated on only part or all of the one or more transmit antennas or is deployed on only part or all of the one or more transmit antennas individually.

In a further possible embodiment, when the number of transmit antennas is one or more and the number of receive antennas is one or more, the wavefront modulation device is integrated on only part or all of the one or more receive antennas or is deployed solely on only part or all of the one or more receive antennas.

In another possible embodiment, when the number of transmitting antennas is one or more and the number of receiving antennas is one or more, the wavefront modulation device may be integrated on or separately deployed on some or all of the one or more transmitting antennas. The wavefront modulation device may also be integrated on or separately deployed on some or all of the one or more receive antennas.

The wavefront modulation device may include, for example, one or more of a metamaterial, a plasma, a liquid crystal, and the like.

(4) The signal processing unit is used for imaging the target object.

The processing and transmitting process of radar signals will be described below with reference to fig. 2 by taking an FMCW system radar, in which a wavefront modulation device is disposed at the front end of a transmitting antenna and/or a receiving antenna, as an example.

The oscillator may generate a signal whose frequency increases linearly with time, which may be, for example, a voltage-controlled oscillator (VCO), or it may be understood that the voltage-controlled oscillator and a phase-locked loop (PLL) may generate a signal whose frequency increases linearly with time. The signal may be referred to as a chirped continuous wave (linear frequency modulated continuous wave, LFMCW) or a local oscillator signal, which is passed through a Power Amplifier (PA) and then into a transmitting antenna.

In fig. 2-1, only the front end of the transmitting antenna is provided with a wave front modulation device, and the signal entering the transmitting antenna is transmitted out after being wave front modulated in the horizontal direction and/or the vertical direction by the wave front modulation device at the front end of the transmitting antenna, and the signal reflected by the target object is received by the receiving antenna. The signal is processed by a low noise amplifier (low noise amplifier, LNA), mixed with a local oscillator signal in a mixer to obtain an intermediate frequency signal (which may also be referred to as a beat signal), and the intermediate frequency signal is processed by a low pass filter (low PASS FILTER, LPF) and then converted into a digital signal by an analog-to-digital converter (ADC). Of course, the intermediate frequency signal may also be processed by a high pass filter (HIGH PASS FILTER, HPF) before being processed by the LPF. The digital signals are supplied to a signal processing unit which processes the digital signals to image the target object.

In fig. 2-2, only the front end of the receiving antenna is provided with a wavefront modulation device, and a signal entering the transmitting antenna is transmitted through the transmitting antenna and received by the receiving antenna as a signal reflected back by the target object. Because the front end of the receiving antenna is provided with the wave front modulation device, the wave front modulation device can perform wave front modulation on the signal reflected by the target object in the horizontal direction and/or the vertical direction. The wave front modulated signal is processed by a low noise amplifier, mixed with a local oscillation signal in a mixer to obtain an intermediate frequency signal, and the intermediate frequency signal is converted into a digital signal by an ADC after being processed by an LPF. Of course, the intermediate frequency signal may also be processed by the HPF before being processed by the LPF. The digital signals are supplied to a signal processing unit which processes the digital signals to image the target object.

In fig. 2-3, front ends of the transmitting antenna and the receiving antenna are respectively provided with a wavefront modulation device, and specific processes may be combined with fig. 2-1 and 2-2, which are not described herein.

A radar imaging method is described below with reference to the accompanying drawings, it being understood that the method may be applied to a radar or a chip in a radar or a circuit in a radar, without limitation. Hereinafter, radar will be described as an execution subject.

Referring to fig. 3, fig. 3 is a schematic flow chart of a radar imaging method according to an embodiment of the present application. The method comprises the following steps:

301. at least one first signal is transmitted, the at least one first signal being a signal wave front modulated in the horizontal and/or vertical direction.

Step 301 may include, for example: at least one first signal is transmitted through a transmit antenna.

Optionally, the at least one first signal includes a plurality of first signals, the plurality of first signals are transmitted at different times, the plurality of first signals have different wavefront modulation coefficients corresponding to the same direction, one wavefront modulation coefficient is used for performing wavefront modulation on one first signal in one direction, and one first signal has different wavefront modulation coefficients corresponding to different directions. This can equivalently obtain a synthetic aperture similar to SAR.

In the present application, the same direction may be understood as the same pointing angle corresponding to the horizontal direction and/or the vertical direction, whereas different directions may be understood as at least one of the following: the horizontal direction pointing angle is different, and the vertical direction pointing angle is different. Of course, one direction may include a pointing angle in a horizontal and/or vertical direction.

Alternatively, the at least one first signal being a signal wavefront modulated in the horizontal and/or vertical direction may be understood as: the at least one first signal is a signal which is wavefront modulated in a horizontal and/or vertical direction according to a wavefront modulation matrix. Wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients in different directions at one moment in time, a column of the wavefront modulation matrix represents the wavefront modulation coefficients in the same direction at different moments in time, and a first signal is determined from a row vector of the wavefront modulation matrix. This can equivalently obtain a synthetic aperture similar to SAR.

It should be appreciated that in the present application, the wavefront modulation matrix may be a matrix of K rows and N columns, where K is an integer greater than or equal to 1 and N is an integer greater than or equal to 1. The wavefront modulation matrix may be implemented in any of the following ways.

A mode one,

One row vector of the wave front modulation matrix comprises non-zero elements and zero elements, and the phases of the non-zero elements comprise quadratic terms. In the present application, the quadratic term can be understood as a square term. It can be seen that because the phase of the non-zero element includes a quadratic term, the phase of the wavefront modulated signal can be made to have a quadratic term, i.e. the wavefront modulated signal is made to resemble the azimuth signal of the SAR.

Illustratively, in the case where a wavefront modulation matrix is used for wavefront modulation in the horizontal direction or the vertical direction, the wavefront modulation matrix satisfies the following formula (1):

Wherein L is the number of non-zero elements in a row vector of the wavefront modulation matrix, and β is the directional modulation frequency, which in the present application may refer to the modulation slope of different echo signals along the slow time dimension. It should be understood that in the present application, j is an imaginary unit, λ is the wavelength of the first signal, exp represents an exponential function based on e. It can be seen that one row vector in equation (1) includes non-zero elements and zero elements, e.g., the non-zero elements of the first row in the wavefront modulation matrix are respectively Etc., the remaining elements being 0. And/> The phase of the etc. includes a quadratic term, i.e. a square term.

Note that, the formula (1) shows only the phase of the wavefront modulation coefficient. In addition, equation (1) may also be expressed asWherein K is an integer greater than or equal to 1 and less than or equal to K, and N is an integer greater than or equal to 1 and less than or equal to N. It should be understood that, in the present application, rect represents a rectangular function.

Optionally, the positions of non-zero elements in different row vectors of the wavefront modulation matrix are different. The positions of the non-zero elements of the first row and the second row are different as in equation (1). This may mimic the range of illumination of the beam in the stripmode SAR, which in turn may make the wavefront modulated signal similar to the azimuth signal of the stripmode SAR.

Optionally, the wavefront modulation matrix includes adjacent first row vectors and second row vectors, and elements in the first row vectors are cyclically shifted according to elements in the second row vectors. The elements of the second row as in equation (1) may be cyclically shifted from the elements of the first row. Specifically, in the formula (1), the element of the first column of the second row is the element of the last column of the first row, the element of the second column of the second row is the element of the first column of the first row, the element of the third column of the second row is the element of the second column of the first row, and so on. This can simulate the imaging process of the forward motion of the strippattern SAR beam, thereby achieving high resolution capabilities similar to strippattern SAR.

A second mode,

The phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix includes a primary term and a secondary term. This makes the wavefront modulated signal similar to the azimuth signal of the beamformed SAR.

Illustratively, in the case where a wavefront modulation matrix is used for wavefront modulation in the horizontal direction or the vertical direction, the wavefront modulation matrix satisfies the following formula (2):

Wherein equation (2) shows only the phase of the wavefront modulation coefficient. Alpha is a first order coefficient included in the phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix. Gamma is a quadratic term coefficient included in the phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix. Of course, in the present application, γ may also be referred to as a steering frequency. In one possible embodiment, α and γ may be set to be constant. In a further possible embodiment of the present application, V is the motion direction of the radar in the SAR, and R ₀ is the nearest slant distance between the target object in the SAR and the radar.

Wherein x _i is the i-th pointing angle in the horizontal direction or the vertical direction, i is an integer greater than or equal to 1 and less than or equal to N, t _ah is the transmission time of the h-th pulse, and h is an integer greater than or equal to 1 and less than or equal to K.

It can be seen that for the first row and first column in equation (2), the phase of the wavefront modulation coefficient includes a first term and a second term.

It should be noted that any one element in the formula (2) may be expressed asOr,/>Wherein K is an integer greater than or equal to 1 and less than or equal to K, and N is an integer greater than or equal to 1 and less than or equal to N.

Optionally, the phases of different wavefront modulation coefficients in one row vector of the wavefront modulation matrix comprise different first order coefficients. It can be seen that the first order coefficients comprise a horizontal or vertical pointing angle, and that the first order coefficients are different, i.e. the horizontal or vertical pointing angle is different, and different pointing angles may represent different beam center orientations, so that the wavefront modulated signal may be similar to the azimuth signal of the beamformed SAR.

Illustratively, for the first row and first column in equation (2), the phase of the wavefront modulation coefficient includes a first order coefficient of pi alpha x ₁t_a1, and for the second row and second column in equation (2), the phase of the wavefront modulation coefficient includes a first order coefficient of pi alpha x ₂t_a1,πax₁t_a1 that is different from pi alpha x ₂t_a1, i.e., x ₁ and x ₂. x ₁ may be, for example, the 1 st pointing angle in the horizontal direction, x ₂ may be, for example, the 2 nd pointing angle in the horizontal direction, or x ₁ may be, for example, the 1 st pointing angle in the vertical direction, and x ₂ may be, for example, the 2 nd pointing angle in the vertical direction, which indicates that the corresponding pointing angles of x ₁ and x ₂ are different, and thus may indicate different beam center orientations.

Optionally, the method may further comprise step 302.

302. At least one echo signal reflected by the target object on the at least one first signal is received.

Step 302 may include, for example: at least one echo signal reflected by the target object on the at least one first signal is received by the receiving antenna.

Illustratively, the echo signal s ^R(t)＝A·w·s^T (t- τ) is taken as an example where the target object is a point target and the number of wavefront modulation matrices is one. Wherein A is a wave front modulation matrix, w is radar back scattering sectional area corresponding to a target object, tau is time delay generated by the first signal to the target object and then reflected by the target object and received by the radar,R ₀ may be the distance of the target object relative to the radar and c is the speed of light.

S ^T (t) may be the original radar signal and a·s ^T (t) may be the first signal. Taking an FMCW regime radar as an example,F ₀ is carrier frequency, T _r is pulse width of FMCW signal, and K _r is linear modulation frequency of FMCW signal; p represents the pulse number, T _c is the transmit pulse period, T _a＝p·T_c,t_r＝t-p·T_c, which may be referred to herein as T _r being the fast time, T _a being the slow time, t=t _r+t_a.

Optionally, the method may further comprise step 303.

303. The target object is imaged from the at least one echo signal.

Alternatively, the echo signal in step 303 may be understood as an echo signal processed by an ADC. For example, after the receiving antenna of the radar receives the echo signal, the echo signal may be processed by the LNA, and then mixed with the local oscillation signal in the mixer, to obtain an intermediate frequency signal, where the intermediate frequency signal is processed by the LPF, and then converted into a digital signal by the converter. Of course, the intermediate frequency signal may also be processed by the HPF before being processed by the LPF.

In one possible implementation, step 303 may include: performing a fast fourier transform (fast fourier transform, FFT) on the one or more echo signals in a fast time dimension to obtain a second signal; the second signal is matched filtered in the slow time dimension to generate an imaging result of the target object. It can be seen that by performing FFT on one or more echo signals in the fast time dimension and matched filtering on the post-FFT signal in the slow time dimension, the linear equation set solution problem can be converted into a matched filtering problem, reducing the computational complexity.

It will be appreciated that by performing an FFT on one or more echo signals in the fast time dimension, the target object may be compressed to a corresponding range bin. And formulating the second signal may be, for example F _r is a value after FFT on fast time t _r, λ=c/f ₀.

In the present application, the matched filtering may be frequency domain matched filtering or time domain matched filtering.

Optionally, the matched filtering of the second signal in the slow time dimension to generate an imaging result of the target object may include, for example: performing FFT on the second signal in a slow time dimension to obtain a third signal; processing the third signal by adopting a matched filtering reference function to obtain a fourth signal; an inverse fast fourier transform (invert fastfourier transformation, IFFT) is performed on the fourth signal in the slow time dimension to generate an imaging result of the target object. The processing of the third signal by using the matched filtering reference function to obtain the fourth signal can be understood as: and carrying out complex multiplication on the matched filtering reference function and the third signal to obtain a fourth signal. It can be seen that the imaging of the target object is realized through one FFT, one complex multiplication and one IFFT, so that the computational complexity can be reduced.

It should be appreciated that the FFT in the slow time dimension needs to be performed in the same range gate, but because of the range migration existing in the overall motion of the target object, the FFT cannot be performed directly on a certain range gate of the target object, so that the range migration correction (RANGE CELL migration correction, RCMC) may also be performed on the second signal before the FFT is performed on the second signal in the slow time dimension, so as to reduce the range migration.

The matched filter reference function may be determined according to a wavefront modulation matrix (the wavefront modulation matrix is implemented in the first manner), may be determined according to a phase of the third signal, and may be determined according to a preset chirp characteristic in a frequency domain. Specifically, for example, the third signal after time-deconvolution is complex conjugated to calculate a zero-padding discrete fourier transform (discrete fourier transform, DFT), so as to obtain a matched filter reference function. Or performing DFT on the third signal after zero padding, and performing complex conjugate, thereby obtaining the matched filter reference function.

In another possible embodiment, step 303 may include: performing FFT on one or more echo signals in a fast time dimension to obtain a second signal; performing frequency modulation removal processing on the second signal to obtain a fifth signal; the fifth signal is IFFT in the slow time dimension to generate an imaging result of the target object. It can be seen that the amount of IFFT computation can be reduced by performing FFT on one or more echo signals in the fast time dimension and performing de-fm processing on the post-FFT signals.

Optionally, performing a frequency-removing process on the second signal to obtain a fifth signal may include: and processing the second signal by adopting the frequency-removing reference function to obtain a fifth signal. The processing of the second signal by the de-fm reference function to obtain the fifth signal may be understood as: and carrying out complex multiplication on the frequency-removed reference function and the second signal to obtain a fifth signal.

In the present application, the de-modulation reference function may be determined according to a wavefront modulation matrix (the wavefront modulation matrix is implemented in the second manner described above), or may be determined according to the phase of the second signal.

Exemplary, de-FM reference functionOr de-frequency modulation reference function

In addition, in the present application, the wavefront modulation matrix a and the radar back-scatter matrix W of the imaging region in which the target object is located satisfy the following formula: aw=s. Wherein W is a matrix of N rows and M columns, M is an integer greater than or equal to 1. S is the distance compressed signal, S is the matrix of K rows and M columns. N represents the number of units of the imaging region divided in the direction dimension, and M represents the number of units of N divided in the distance dimension. Element W _nm in W represents a backscattering coefficient of a scattering point corresponding to an nth pointing angle and an mth distance unit in a horizontal direction, N is an integer greater than or equal to 1 and less than or equal to N, and M is an integer greater than or equal to 1 and less than or equal to M. Element S _km in S represents the signal of each pointing angle in the beam range received by the mth distance unit at the kth time.

Taking the implementation of the FMCW system radar and the wave front modulation matrix in the above manner as an example, Can also be expressed as: Wherein r _m is the distance size corresponding to the mth distance unit. Meanwhile, it can be seen that s (k, m) is similar to the azimuth signal of SAR after distance compression and distance migration correction.

It will be appreciated that from a and S, inversion of the imaged scene can be accomplished by estimating W. Referring to fig. 4, fig. 4 is a schematic diagram illustrating an inversion process of an imaged scene according to an embodiment of the present application. It can be seen that a is a matrix of 8 rows and 12 columns, W is a matrix of 12 rows and 7 columns, and S is a matrix of 8 rows and 7 columns. Wherein, the black part of a in fig. 4 is a non-zero element, and the white part is zero; the black part of W is the radar back scattering cross section area corresponding to the target object, and the white part is zero. Therefore, the black part corresponding to S obtained by multiplying the points A and W is data obtained by compressing the target object to the corresponding distance unit, and the white part is zero.

It can be seen that the at least one first signal is a signal which is wavefront-modulated in the horizontal and/or vertical direction such that the at least one first signal is similar to the azimuth signal of the SAR, i.e. a synthetic aperture similar to the SAR can be equivalently obtained by the wavefront modulation. Therefore, when at least one echo signal reflected by at least one first signal is imaged based on the target object, the imaging angular resolution of the target object can be improved. Meanwhile, the problem that SAR imaging cannot perform forward-looking imaging is solved.

Referring to fig. 5, fig. 5 is a schematic flow chart of another radar imaging method according to an embodiment of the present application. The method comprises the following steps:

501. At least one first signal is transmitted.

Step 501 may include, for example: at least one first signal is transmitted through a transmit antenna.

502. At least one echo signal reflected by the target object on the at least one first signal is received.

Step 502 may include, for example: at least one echo signal reflected by the target object on the at least one first signal is received by the receiving antenna.

503. The at least one echo signal is wavefront modulated in the horizontal and/or vertical direction.

Optionally, step 503 may include, for example: wave front modulation is performed on different wave front modulation coefficients of at least one echo signal in the same direction, and wave front modulation is performed on each echo signal of the at least one echo signal in different directions based on different wave front modulation coefficients. This can equivalently obtain a synthetic aperture similar to SAR.

Optionally, wavefront modulation is performed on different echo signals in the at least one echo signal in the same direction based on different wavefront modulation coefficients, including: according to the wave front modulation matrix, wave front modulation is carried out on different wave front modulation coefficients of different wave front signals in at least one wave back signal in the same direction, and wave front modulation is carried out on each wave back signal of the at least one wave back signal in different directions on the basis of different wave front modulation coefficients; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients of one moment in different directions, a column of the wavefront modulation matrix represents the wavefront modulation coefficients of the same direction in different moments, and an echo signal is determined according to a row vector of the wavefront modulation matrix. This can equivalently obtain a synthetic aperture similar to SAR.

It should be noted that, the wavefront modulation matrix may refer to the description of step 301 in fig. 3, which is not described herein.

Optionally, the method further comprises step 504.

504. The target object is imaged.

It should be appreciated that step 504 is similar to step 303 of fig. 3, with the difference that: the echo signals used in imaging the target object in step 303 are not wavefront modulated in the horizontal and/or vertical directions, whereas the echo signals used in imaging the target object in step 504 are signals wavefront modulated in the horizontal and/or vertical directions.

It can be seen that by receiving at least one echo signal reflected by the target object on at least one first signal and performing a wavefront modulation on the at least one echo signal in a horizontal and/or vertical direction, the at least one echo signal after the wavefront modulation is similar to the azimuth signal of the SAR, that is to say, a synthetic aperture similar to the SAR can be equivalently obtained by the wavefront modulation, so that the imaging angular resolution of the target object can be improved when the target object is imaged. Meanwhile, the problem that SAR imaging cannot perform forward-looking imaging is solved.

Referring to fig. 6, fig. 6 is a schematic flow chart of another radar imaging method according to an embodiment of the present application. The method comprises the following steps:

601. at least one first signal is transmitted, the at least one first signal being a signal wave front modulated in the horizontal and/or vertical direction.

Step 601 is similar to step 301 of fig. 3, and will not be described herein.

602. At least one echo signal reflected by the target object on the at least one first signal is received.

Step 602 is similar to step 502 in fig. 5, and is not described herein.

603. The at least one echo signal is wavefront modulated in the horizontal and/or vertical direction.

Step 603 is similar to step 503 of fig. 5, and is not described herein.

604. The target object is imaged.

Step 604 is similar to step 504 of fig. 5, and is not described herein.

It can be seen that the at least one first signal is a signal which is wavefront-modulated in the horizontal and/or vertical direction such that the at least one first signal is similar to the azimuth signal of the SAR, i.e. a synthetic aperture similar to the SAR can be equivalently obtained by the wavefront modulation. At the same time, the at least one echo signal is wavefront-modulated in the horizontal and/or vertical direction, so that the wavefront-modulated at least one echo signal resembles the azimuth signal of the SAR, which further increases the synthetic aperture. Therefore, when the target object is imaged, the imaging angular resolution of the target object can be further improved. Meanwhile, the problem that SAR imaging cannot perform forward-looking imaging is solved.

The foregoing details of the method according to the embodiments of the present application and the apparatus according to the embodiments of the present application are provided below.

The embodiment of the present application also provides an apparatus for implementing any one of the above methods, for example, a radar imaging apparatus including a unit (or means) to implement each step performed by the radar in any one of the above methods.

For example, referring to fig. 7, fig. 7 is a schematic structural diagram of a radar imaging device 70 according to an embodiment of the present application, where the radar imaging device 70 includes a processing unit 701 and a transceiver unit 702, for example, to implement the method of any one of the embodiments shown in fig. 3, fig. 5, or fig. 6.

It should be understood that the division of the units in the above apparatus is only a division of a logic function, and may be fully or partially integrated into one physical entity or may be physically separated when actually implemented. Furthermore, units in the apparatus may be implemented in the form of processor-invoked software; the device comprises, for example, a processor, the processor being connected to a memory, the memory having instructions stored therein, the processor invoking the instructions stored in the memory to perform any of the methods or to perform the functions of the units of the device, wherein the processor is, for example, a general purpose processor, such as a central processing unit (central processing unit, CPU) or microprocessor, and the memory is either internal to the device or external to the device. Or the units in the device may be implemented in the form of hardware circuits, where some or all of the functions of the units may be implemented by a design of hardware circuits, and where the hardware circuits may be understood as one or more processors; for example, in one implementation, the hardware circuit is an application-specific integrated circuit (ASIC), and the functions of some or all of the above units are implemented by designing the logic relationships of elements in the circuit; for another example, in another implementation, the hardware circuit may be implemented by a programmable logic device (programmable logic device, PLD), for example, a field programmable gate array (field programmable GATE ARRAY, FPGA), which may include a large number of logic gates, and the connection relationship between the logic gates is configured by a configuration file, so as to implement the functions of some or all of the above units. All units of the above device may be realized in the form of processor calling software, or in the form of hardware circuits, or in part in the form of processor calling software, and in the rest in the form of hardware circuits.

In an embodiment of the present application, the processor is a circuit with signal processing capability, and in one implementation, the processor may be a circuit with instruction reading and running capability, such as a central processing unit, a microprocessor, a graphics processor (graphics processing unit, GPU) (which may be understood as a microprocessor), or a digital signal processor (DIGITAL SINGNAL processor, DSP), etc.; in another implementation, the processor may perform a function through a logical relationship of hardware circuitry that is fixed or reconfigurable, e.g., a hardware circuit implemented by the processor as an ASIC or PLD, such as an FPGA. In the reconfigurable hardware circuit, the processor loads the configuration document, and the process of implementing the configuration of the hardware circuit may be understood as a process of loading instructions by the processor to implement the functions of some or all of the above units. Furthermore, a hardware circuit designed for artificial intelligence may be also be considered as an ASIC, such as a neural network processing unit (neural network processing unit, NPU) tensor processing unit (tensor processing unit, TPU), a deep learning processing unit (DEEP LEARNING processing unit, DPU), etc.

It will be seen that each of the units in the above apparatus may be one or more processors (or processing circuits) configured to implement the above method, for example: CPU, GPU, NPU, TPU, DPU, microprocessors, DSP, ASIC, FPGA, or a combination of at least two of these processor forms.

Furthermore, the units in the above apparatus may be integrated together in whole or in part, or may be implemented independently. In one implementation, these units are integrated together and implemented in the form of a system-on-a-chip (SOC). The SOC may include at least one processor for implementing any of the methods above or for implementing the functions of the units of the apparatus, where the at least one processor may be of different types, including, for example, a CPU and an FPGA, a CPU and an artificial intelligence processor, a CPU and a GPU, and the like.

The general flow performed by the apparatus 70 during the display is the same whether the functional blocks are subdivided or combined. For example, the transceiver unit 702 in the above-described apparatus 70 may also be referred to as a communication unit. Typically, each unit corresponds to a respective program code (or program instruction), which when executed on a processor causes the unit to perform a respective flow to thereby implement a respective function. It should be noted that the implementation of each unit described below may correspond to the corresponding description of the embodiment shown in fig. 3, 5 or 6.

In a possible implementation, the radar imaging device 70 may be a radar in the embodiment shown in fig. 3, or a module in a radar, such as a chip or an integrated circuit. The radar imaging apparatus includes a processing unit 701 and a transceiver unit 702, wherein the descriptions of the respective units are as follows:

A transceiver unit 702 for transmitting at least one first signal, where the at least one first signal is a signal modulated in a wavefront in a horizontal direction and/or a vertical direction; the transceiver unit 702 is further configured to receive at least one echo signal reflected by the target object on the at least one first signal; a processing unit 701 for imaging a target object from at least one echo signal.

Optionally, the at least one first signal includes a plurality of first signals, the plurality of first signals are transmitted at different times, the plurality of first signals have different wavefront modulation coefficients corresponding to the same direction, one wavefront modulation coefficient is used for performing wavefront modulation on one first signal in one direction, and one first signal has different wavefront modulation coefficients corresponding to different directions.

Optionally, the at least one first signal is a signal wavefront modulated in a horizontal direction and/or a vertical direction according to a wavefront modulation matrix; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients in different directions at one moment in time, a column of the wavefront modulation matrix represents the wavefront modulation coefficients in the same direction at different moments in time, and a first signal is determined from a row vector of the wavefront modulation matrix.

Optionally, a row vector of the wavefront modulation matrix includes a non-zero element and a zero element, and a phase of the non-zero element includes a quadratic term.

Optionally, the positions of non-zero elements in different row vectors of the wavefront modulation matrix are different.

Optionally, the wavefront modulation matrix includes adjacent first row vectors and second row vectors, and elements in the first row vectors are cyclically shifted according to elements in the second row vectors.

Optionally, the wavefront modulation matrix satisfies the following formula:

Optionally, the phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix includes a first term and a second term.

Optionally, the phases of different wavefront modulation coefficients in one row vector of the wavefront modulation matrix comprise different first order coefficients.

Optionally, the wavefront modulation matrix satisfies the following formula:

/>

In yet another possible implementation, the radar imaging device 70 may be a radar in the embodiment shown in fig. 5, or a module in a radar, such as a chip or an integrated circuit, etc. The radar imaging apparatus includes a processing unit 701 and a transceiver unit 702, wherein the descriptions of the respective units are as follows:

a transceiver unit 702 for transmitting at least one first signal; the transceiver unit 702 is further configured to receive at least one echo signal reflected by the target object on the at least one first signal; a processing unit 701 for performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction; the processing unit 701 is further configured to image a target object.

Optionally, when the at least one echo signal is wavefront-modulated in the horizontal direction and/or the vertical direction, the processing unit 701 is configured to perform wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction, and perform wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions.

Optionally, when performing wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction and performing wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions, the processing module is configured to perform wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction according to the wavefront modulation matrix and performing wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients of one moment in different directions, a column of the wavefront modulation matrix represents the wavefront modulation coefficients of the same direction in different moments, and an echo signal is determined according to a row vector of the wavefront modulation matrix.

Optionally, the wavefront modulation matrix satisfies the following formula:

In another possible implementation, the radar imaging device 70 may be the radar of the embodiment shown in fig. 6, or a module in the radar, such as a chip or an integrated circuit. The radar imaging apparatus includes a processing unit 701 and a transceiver unit 702, wherein the descriptions of the respective units are as follows:

A transceiver unit 702 for transmitting at least one first signal, where the at least one first signal is a signal modulated in a wavefront in a horizontal direction and/or a vertical direction; the transceiver unit 702 is further configured to receive at least one echo signal reflected by the target object on the at least one first signal; a processing unit 701 for performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction; the processing unit 701 is further configured to image a target object.

Optionally, the wavefront modulation matrix satisfies the following formula:

Referring to fig. 8, fig. 8 is a schematic structural diagram of a vehicle 80 according to an embodiment of the present application, where the vehicle 80 includes a radar 801.

In a possible implementation, a radar in the vehicle is configured to transmit at least one first signal, the at least one first signal being a signal that is wavefront modulated in a horizontal and/or vertical direction; a radar in the vehicle, further configured to receive at least one echo signal reflected by the target object on the at least one first signal; radar in a vehicle is also used to image a target object from at least one echo signal.

Optionally, the wavefront modulation matrix satisfies the following formula:

/>

Optionally, the wavefront modulation matrix satisfies the following formula:

In a further possible implementation, a radar in the vehicle is used to transmit at least one first signal; a radar in the vehicle, further configured to receive at least one echo signal reflected by the target object on the at least one first signal; radar in a vehicle, further for wavefront modulating at least one echo signal in a horizontal and/or vertical direction; radar in vehicles is also used to image target objects.

Optionally, when the at least one echo signal is wavefront-modulated in a horizontal direction and/or a vertical direction, the radar in the vehicle is configured to wavefront-modulate different echo signals of the at least one echo signal in a same direction based on different wavefront modulation coefficients, and wavefront-modulate each echo signal of the at least one echo signal in a different direction based on different wavefront modulation coefficients.

Optionally, when performing wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction and performing wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions, the radar in the vehicle is configured to perform wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction according to the wavefront modulation matrix and perform wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients of one moment in different directions, a column of the wavefront modulation matrix represents the wavefront modulation coefficients of the same direction in different moments, and an echo signal is determined according to a row vector of the wavefront modulation matrix.

Optionally, the wavefront modulation matrix satisfies the following formula:

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Optionally, the wavefront modulation matrix satisfies the following formula:

In another possible implementation, a radar in a vehicle is configured to transmit at least one first signal, the at least one first signal being a signal that is wavefront modulated in a horizontal and/or vertical direction; a radar in the vehicle, further configured to receive at least one echo signal reflected by the target object on the at least one first signal; radar in a vehicle, further for wavefront modulating at least one echo signal in a horizontal and/or vertical direction; radar in vehicles is also used to image target objects.

Optionally, the wavefront modulation matrix satisfies the following formula:

Referring to fig. 9, fig. 9 is a schematic structural diagram of a radar imaging device 90 according to an embodiment of the present application, where the device 90 may include at least one memory 901 and at least one processor 902. Optionally, a bus 903 may also be included. Further optionally, a communication interface 904 may be included, wherein the memory 901, the processor 902 and the communication interface 904 are connected via a bus 903.

The memory 901 is used to provide a storage space, and data such as an operating system and a computer program may be stored in the storage space. The memory 901 may be one or more of a random access memory (random access memory, RAM), a read-only memory (ROM), an erasable programmable read-only memory (erasable programmable read only memory, EPROM), or a portable read-only memory (compact disc read-only memory, CD-ROM), etc.

The processor 902 is a module for performing arithmetic operations and/or logic operations, and may specifically be one or more of processing modules such as a CPU, GPU, microprocessor (microprocessor unit, MPU), ASIC, FPGA, complex programmable logic device (Complex programmable logic device, CPLD), and the like.

The communication interface 904 is used to receive data transmitted from outside and/or transmit data to outside, and may be a wired link interface including an ethernet cable or the like, or may be a wireless link (Wi-Fi, bluetooth, general wireless transmission, or the like) interface. Optionally, the communication interface 904 may also include a transmitter (e.g., radio frequency transmitter, antenna, etc.) or a receiver, etc. coupled to the interface.

The processor 902 of the apparatus 90 is configured to read the computer program stored in the memory 901, and perform the display method described above, for example, the display method described in any one of the embodiments of fig. 3, 5 or 6.

In some possible implementations, the radar imaging device 90 may be a radar in the embodiment shown in fig. 3, or a module in a radar, such as a chip or an integrated circuit, etc. The processor 902 in the apparatus 90 is configured to read a computer program stored in the memory 901 to perform the following operations:

Transmitting at least one first signal through the communication interface 904, the at least one first signal being a signal wave front modulated in a horizontal and/or vertical direction; receiving at least one echo signal reflected by the target object on the at least one first signal through the communication interface 904; the target object is imaged from the at least one echo signal.

Optionally, the wavefront modulation matrix satisfies the following formula:

In some possible implementations, the radar imaging device 90 may be a radar in the embodiment shown in fig. 5, or a module in a radar, such as a chip or an integrated circuit, etc. The processor 902 in the apparatus 90 is configured to read a computer program stored in the memory 901 to perform the following operations:

Transmitting at least one first signal through the communication interface 904; receiving at least one echo signal reflected by the target object on the at least one first signal through the communication interface 904; performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction; the target object is imaged.

Optionally, the processor 902 is specifically configured to perform the following operations when performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction: wave front modulation is performed on different wave front modulation coefficients of at least one echo signal in the same direction, and wave front modulation is performed on each echo signal of the at least one echo signal in different directions based on different wave front modulation coefficients.

Optionally, when performing wavefront modulation on different echo signals of the at least one echo signal in the same direction based on different wavefront modulation coefficients, and performing wavefront modulation on each echo signal of the at least one echo signal in different directions based on different wavefront modulation coefficients, the processor 902 is specifically configured to perform the following operations: according to the wave front modulation matrix, wave front modulation is carried out on different wave front modulation coefficients of different wave front signals in at least one wave back signal in the same direction, and wave front modulation is carried out on each wave back signal of the at least one wave back signal in different directions on the basis of different wave front modulation coefficients; wherein a row of the wavefront modulation matrix represents the wavefront modulation coefficients of one moment in different directions, a column of the wavefront modulation matrix represents the wavefront modulation coefficients of the same direction in different moments, and an echo signal is determined according to a row vector of the wavefront modulation matrix.

Optionally, the wavefront modulation matrix satisfies the following formula:

In some possible implementations, the radar imaging device 90 may be a radar in the embodiment shown in fig. 6, or a module in a radar, such as a chip or an integrated circuit, etc. The processor 902 in the apparatus 90 is configured to read a computer program stored in the memory 901 to perform the following operations:

Transmitting at least one first signal through the communication interface 904, the at least one first signal being a signal wave front modulated in a horizontal and/or vertical direction; receiving at least one echo signal reflected by the target object on the at least one first signal through the communication interface 904; performing wavefront modulation on at least one echo signal in a horizontal direction and/or a vertical direction; the target object is imaged.

Optionally, the wavefront modulation matrix satisfies the following formula:

The embodiment of the application also provides a radar imaging device, which is characterized in that the radar imaging device comprises a wave front modulation device, a transmitting antenna, a receiving antenna and a processor, and is used for realizing the method according to any one of the embodiments shown in fig. 3, 5 or 6.

Embodiments of the present application also provide a computer storage medium having a computer program stored thereon, which when run on a computer causes the computer to perform a method according to any of the embodiments shown in fig. 3,5 or 6.

The embodiment of the application also provides a chip, which comprises a processor and a communication interface, wherein the processor is used for calling and running instructions from the communication interface, and when the processor executes the instructions, the method according to any one of the embodiments shown in fig. 3, 5 or 6 is realized.

The embodiment of the application also provides a radar imaging device, which comprises: a processor and a memory; the memory is used to store one or more programs, the one or more programs comprising computer-executable instructions that, when executed by the apparatus, cause the apparatus to perform the method of any of the embodiments shown in fig. 3, 5 or 6.

Embodiments of the present application also provide a computer program product comprising a computer program which, when run on a computer, causes the computer to perform the method according to any of the embodiments shown in fig. 3,5 or 6.

In the embodiment of the present application, unless otherwise indicated, "/" means that the related objects are in an "or" relationship, for example, a/B may represent a or B; the "and/or" in the present application is merely an association relationship describing the association object, and indicates that three relationships may exist, for example, a and/or B may indicate: there are three cases, a alone, a and B together, and B alone, wherein a, B may be singular or plural. Also, in the description of the present application, unless otherwise indicated, "a plurality" means two or more than two. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b, or c may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be one or more. In addition, in order to facilitate the clear description of the technical solution of the embodiments of the present application, in the embodiments of the present application, the words "first", "second", etc. are used to distinguish the network element from the same item or similar items having substantially the same effect. It will be appreciated by those of skill in the art that the words "first," "second," and the like do not limit the amount and order of execution, and that the words "first," "second," and the like do not necessarily differ.

Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.

The above embodiments are further described in detail for the purpose, technical solution and beneficial effects of the present application, and it should be understood that the above embodiments are only illustrative embodiments of the present application and are not intended to limit the scope of the present application, and any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solution of the present application should be included in the scope of the present application.

It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program for instructing relevant hardware, where the program may be stored in a computer readable storage medium, and the storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

Claims

1. A radar imaging method, the method comprising:

Transmitting at least one first signal, the at least one first signal being a signal wave front modulated in a horizontal and/or vertical direction;

receiving at least one echo signal reflected by the target object on the at least one first signal;

Imaging the target object according to the at least one echo signal.

2. A radar imaging method, the method comprising:

Transmitting at least one first signal;

performing wavefront modulation on the at least one echo signal in a horizontal direction and/or a vertical direction;

imaging the target object.

3. A radar imaging method, the method comprising:

imaging the target object.

4. A method according to claim 1 or 3, wherein the at least one first signal comprises a plurality of first signals transmitted at different times, the plurality of first signals having different wavefront modulation coefficients corresponding to the same direction, one wavefront modulation coefficient being used to wavefront modulate one first signal in one direction, one first signal having different wavefront modulation coefficients corresponding to different directions.

5. The method according to claim 1, 3 or 4, wherein the at least one first signal is a signal wave-front modulated in a horizontal and/or vertical direction according to a wave-front modulation matrix;

Wherein a row of the wavefront modulation matrix represents wavefront modulation coefficients in different directions at one moment, a column of the wavefront modulation matrix represents wavefront modulation coefficients in the same direction at different moments, and a first signal is determined according to a row vector of the wavefront modulation matrix.

6. A method according to claim 2 or 3, wherein said wavefront modulating said at least one echo signal in the horizontal and/or vertical direction comprises:

And performing wavefront modulation on different echo signals in the at least one echo signal based on different wavefront modulation coefficients in the same direction, and performing wavefront modulation on each echo signal in the at least one echo signal based on different wavefront modulation coefficients in different directions.

7. The method of claim 6, wherein wavefront modulating different ones of the at least one echo signal in the same direction based on different wavefront modulation coefficients, and wavefront modulating each of the at least one echo signal in different directions based on different wavefront modulation coefficients, comprises:

According to the wave front modulation matrix, wave front modulation is carried out on different wave front modulation coefficients of different wave front signals in the at least one wave back signal in the same direction, and wave front modulation is carried out on each wave back signal of the at least one wave back signal in different directions on the basis of different wave front modulation coefficients;

Wherein a row of the wavefront modulation matrix represents wavefront modulation coefficients in different directions at one moment, a column of the wavefront modulation matrix represents wavefront modulation coefficients in the same direction at different moments, and an echo signal is determined according to a row vector of the wavefront modulation matrix.

8. The method according to claim 5 or 7, characterized in that a row vector of the wavefront modulation matrix comprises non-zero elements and zero elements, the phase of which non-zero elements comprises quadratic terms.

9. The method of claim 8, wherein the positions of non-zero elements in different row vectors of the wavefront modulation matrix are different.

10. The method of claim 5, 7, 8 or 9, wherein the wavefront modulation matrix comprises adjacent first and second row vectors, the elements in the first row vector being cyclically shifted from the elements in the second row vector.

11. The method of claim 5, 7,8, 9 or 10, wherein the wavefront modulation matrix satisfies the following formula:

Wherein j is an imaginary unit, β is a direction-tuning frequency, λ is a wavelength of the first signal, and L is a number of non-zero elements in one row vector of the wavefront modulation matrix.

12. The method according to claim 5 or 7, wherein the phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix comprises a primary term and a secondary term.

13. The method of claim 12, wherein the phases of different wavefront modulation coefficients in a row vector of the wavefront modulation matrix comprise different order coefficients.

14. The method of claim 5, 7, 12 or 13, wherein the wavefront modulation matrix satisfies the following equation:

Wherein j is an imaginary unit, α is a first order coefficient included in a phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix, γ is a second order coefficient included in a phase of any one of the wavefront modulation coefficients in the wavefront modulation matrix, λ is a wavelength of the first signal, x _i is an i-th pointing angle in a horizontal direction or a vertical direction, i is an integer greater than or equal to 1 and less than or equal to N, t _ah is a transmission time of an h-th pulse, and h is an integer greater than or equal to 1 and less than or equal to K.

15. A radar imaging device is characterized in that the device comprises a receiving and transmitting unit and a processing unit,

The receiving and transmitting unit is used for transmitting at least one first signal, and the at least one first signal is a signal subjected to wave front modulation in the horizontal direction and/or the vertical direction;

The receiving and transmitting unit is further used for receiving at least one echo signal reflected by the target object on the at least one first signal;

the processing unit is used for imaging the target object according to the at least one echo signal.

16. A radar imaging device is characterized in that the device comprises a receiving and transmitting unit and a processing unit,

The receiving and transmitting unit is used for transmitting at least one first signal;

The processing unit is used for carrying out wave front modulation on the at least one echo signal in the horizontal direction and/or the vertical direction;

the processing unit is also used for imaging the target object.

17. A radar imaging device is characterized in that the device comprises a receiving and transmitting unit and a processing unit,

the processing unit is also used for imaging the target object.

18. A radar imaging device comprising a transmitting antenna, a receiving antenna and a processor, the radar imaging device being configured to implement the method of any of claims 1-14.

19. A computer storage medium having a computer program stored thereon, which when run on a computer causes the computer to perform the method of any of claims 1-14.

20. A vehicle comprising the apparatus of claim 15, 16 or 17.

21. A chip comprising a processor and a communication interface, the processor being configured to invoke and execute instructions from the communication interface, the processor, when executing the instructions, implementing the method of any of claims 1-14.