A radar imaging method and apparatus based on triangular waves

Abstract

The application provides a radar imaging method and device based on a triangular wave, obtains original echo data of completely symmetrical up-chirp and down-chirp in a triangular wave period, and respectively extracts up-wave data sequence and down-wave data sequence; respectively performs dynamic imaging processing on the up-wave data sequence and the down-wave data sequence, and obtains corresponding up-wave images and down-wave images; establishes a phase relationship according to the up-wave images and the down-wave images, restores TDMA ambiguity, and obtains a real target speed; and performs phase alignment on the up-wave images and the down-wave images based on the real target speed, and obtains a final target image. The maximum non-ambiguous speed of a single channel due to polling is recovered first, and then the up-wave and down-wave phase relationship of the triangular wave is used to further expand the speed range; meanwhile, the ambiguity is resolved according to the fixed phase relationship between the up-wave and the down-wave, and the single chirp is no longer excessively dependent on being designed to be as short as possible, and is more suitable for use of an engineering system under constraints of ranging resolution, signal-to-noise ratio, sampling rate and hardware resources.

Description

Technical Field

[0001] This invention relates to the field of radar signal processing technology, and in particular to a radar imaging method and apparatus based on triangular waves. Background Technology

[0002] Vehicle-mounted millimeter-wave radar is widely used in scenarios such as intelligent driving assistance, automatic parking, road environment perception, target detection, and moving target tracking. As the requirements for perception accuracy continue to increase, radar systems not only need to output the target's distance, speed, and angle information, but also need to further recover the target's scattering structure and spatial distribution for target recognition, dynamic scene understanding, and multi-target separation. Therefore, moving target imaging has become an important development direction for vehicle-mounted millimeter-wave radar.

[0003] Currently, vehicle-mounted 4D millimeter-wave radar typically employs a MIMO (Multiple In-Process Array) system, constructing a virtual array through multiple transmit and receive channels to improve angular resolution and spatial dimensional information recovery capabilities. In engineering implementation, the transmitter often uses TDMA (Time-Digital-Depth Array) polling, where multiple transmit channels sequentially transmit chirp signals, and the receiver collects the corresponding echoes from each transmit channel to reconstruct the virtual array data.

[0004] However, under the TDMA-MIMO system, for moving targets, the signal acquisition times for different transmission channels are different, and the target's position has changed at different transmission times. This not only introduces array phase errors but also directly affects the velocity ambiguity characteristics. For the same transmission channel, the time interval between two adjacent effective transmissions will increase due to TDMA polling, thus the maximum unambiguous velocity will be significantly reduced compared to the single-channel condition.

[0005] On the other hand, triangular waves are a common type of operating waveform for vehicle-mounted millimeter-wave radar. A complete triangular wave cycle typically consists of an uphill chirp and a downhill chirp, with the uphill and downhill chirps having the same bandwidth, duration, and absolute slope, only with opposite slope signs. Triangular waves are often used to separate range and velocity terms, but in current moving target imaging processing, the frequency relationship between the uphill and downhill beat frequencies is usually utilized more, while the "complex phase relationship of the same range Doppler cell after imaging the uphill and downhill sections separately" is still not fully utilized.

[0006] Especially under TDMA-MIMO conditions, if the upwave and downwave within the same transmission channel can be imaged separately and their phase relationship established in the same target and the same distance Doppler cell, then this phase relationship can not only be used for velocity ambiguity resolution of the triangular wave itself, but also can prioritize solving the maximum unambiguous velocity compression problem caused by TDMA polling, thereby realizing integrated processing of moving target imaging and velocity deambiguity suitable for vehicle-mounted 4D millimeter-wave radar.

[0007] The existing technology mainly has the following problems:

[0008] (1) Under the TDMA-MIMO system, the equivalent slow time sampling interval of the same transmission channel increases, and the maximum unambiguous speed decreases significantly;

[0009] (2) Existing defuzzification methods usually rely on the short chirp duration itself. When the chirp is long and the number of transmission channels is large, the velocity fuzziness problem becomes more prominent.

[0010] (3) Although the triangular wave system has a natural time pairing relationship between upslope and downslope, the existing technology does not make full use of the phase relationship of the same unit after the upper and lower waves are imaged separately;

[0011] (4) There is a lack of a complete method for TDMA-MIMO vehicle-mounted millimeter-wave radar that can utilize the phase relationship between the upper and lower waves to first recover the velocity ambiguity compression caused by TDMA, and then further realize the maximum unambiguous velocity extension.

[0012] Therefore, there is an urgent need for a radar imaging method and device based on triangular waves to improve the above problems. Summary of the Invention

[0013] The purpose of this invention is to provide a radar imaging method and apparatus based on triangular waves, which can achieve target velocity ambiguity resolution and imaging enhancement under TDMA-MIMO system by utilizing the phase relationship of the same unit after imaging the upper and lower waves of a completely symmetrical triangular wave.

[0014] In a first aspect, the present invention provides a radar imaging method based on triangular waves, comprising the steps of: acquiring raw echo data of a completely symmetrical uphill chirp and downhill chirp within a triangular wave period, and extracting an upper wave data sequence and a lower wave data sequence respectively; performing dynamic imaging processing on the upper wave data sequence and the lower wave data sequence respectively to obtain corresponding upper wave images and lower wave images; establishing a phase relationship based on the upper wave images and the lower wave images to recover TDMA blur and obtain the true velocity of the target; and performing phase alignment on the upper wave images and the lower wave images based on the true velocity of the target to obtain a final target image.

[0015] Optionally, before obtaining the original echo data of the completely symmetrical uphill chirp and downhill chirp within the triangular wave period, the steps include: constructing a completely symmetrical triangular wave, which consists of an uphill chirp and a downhill chirp, both with the same duration, bandwidth, and absolute value of the frequency modulation slope, but opposite slope signs, and being symmetrical about the carrier frequency center; establishing a target echo model, obtaining the intermediate frequency beat frequencies of the uphill and downhill chirps respectively, and solving for the distance term and Doppler term.

[0016] Optionally, acquiring the raw echo data of the completely symmetrical uphill chirp and downhill chirp within the triangular wave period, and extracting the uphill data sequence and downhill data sequence respectively, includes: acquiring the raw echo data of each transmitting channel and each receiving channel at the uphill chirp and downhill chirp; and extracting the uphill data sequence and downhill data sequence for each transmitting channel.

[0017] Optionally, performing dynamic imaging processing on the upper and lower wave data sequences to obtain corresponding upper and lower wave images includes: performing range compression, range alignment, target focusing, and slow-time imaging on the upper and lower wave data sequences of each transmission channel to obtain corresponding upper and lower wave images.

[0018] Optionally, establishing a phase relationship based on the upper and lower wave images to recover TDMA ambiguity and obtain the true target velocity includes: for the same target, extracting the complex response of the corresponding Doppler unit in the upper and lower wave images within the same transmission channel; establishing a phase relationship between the same unit in the upper and lower waves based on the phase difference of the complex response; using the phase relationship and the ambiguity velocity obtained from the individual upper or lower wave images as joint constraints, first recovering the velocity ambiguity compression caused by TDMA polling to obtain compressed data; and expanding a higher-order velocity ambiguity interval based on the compressed data to obtain the true target velocity.

[0019] Optionally, performing phase alignment between the upper and lower wave images based on the target's true velocity to obtain the final target image includes: performing phase alignment between the upper and lower wave images based on the target's true velocity, and completing multi-emission channel fusion imaging processing to obtain the final target image.

[0020] Secondly, the present invention provides a radar imaging device based on triangular waves, the device comprising modules / units that execute any of the possible design methods described in the first aspect above. These modules / units can be implemented in hardware or by hardware executing corresponding software.

[0021] Thirdly, the present invention provides an electronic device including a memory and a processor, wherein the memory stores a program executable on the processor, and when the program is executed by the processor, the electronic device implements a method for performing any of the possible designs described above.

[0022] Fourthly, the present invention provides a readable storage medium storing a program, which, when executed, implements a method of any possible design of any of the above aspects.

[0023] Fifthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0024] The beneficial effects of the method of this invention are as follows: It acquires the original echo data of completely symmetrical uphill and downhill chirps within a triangular wave period, and extracts the uphill and downhill data sequences respectively; it performs dynamic imaging processing on the uphill and downhill data sequences respectively to obtain corresponding uphill and downhill images; it establishes a phase relationship based on the uphill and downhill images to recover TDMA ambiguity and obtain the true target velocity; and it performs phase alignment on the uphill and downhill images based on the true target velocity to obtain the final target image. It first recovers the maximum unambiguous velocity of a single channel that decreases due to polling, and then further expands the velocity range using the phase relationship between the uphill and downhill waves of the triangular wave; simultaneously, it performs deambiguity based on the fixed phase relationship between the uphill and downhill waves, no longer overly relying on designing individual chirps to be as short as possible, making it more suitable for use in engineering systems under constraints of ranging resolution, signal-to-noise ratio, sampling rate, and hardware resources. Attached Figure Description

[0025] Figure 1 A schematic flowchart of a radar imaging method based on triangular waves provided in an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the structure of a radar imaging device based on triangular waves provided in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.

[0029] The technical solutions of the embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the embodiments of the present invention, the terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to limit the present invention. The singular expressions “a,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise. It should also be understood that in the following embodiments of the present invention, “at least one” and “one or more” refer to one or more (including two). The term “and / or” is used to describe the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character “ / ” generally indicates that the preceding and following related objects are in an “or” relationship.

[0030] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the invention. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," and "in still other embodiments" appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless otherwise specifically emphasized. The term "connection" includes both direct and indirect connections, unless otherwise stated. "First" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0031] In embodiments of the present invention, "exemplarily" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design described as "exemplarily" or "for example" in embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or design solutions. Rather, the use of "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0032] like Figure 1 As shown, this invention provides a radar imaging method based on triangular waves, including the following steps:

[0033] S101, acquire the raw echo data of the uphill chirp and downhill chirp that are completely symmetrical within the triangular wave period, and extract the uphill data sequence and downhill data sequence respectively.

[0034] In some embodiments, before acquiring the raw echo data of the completely symmetrical uphill chirp and downhill chirp within the triangular wave period, the method further includes: constructing a completely symmetrical triangular wave, which consists of an uphill chirp and a downhill chirp, both having the same duration, bandwidth, and absolute value of the frequency modulation slope, but with opposite slope signs, and being symmetrical about the carrier frequency center; establishing a target echo model, obtaining the intermediate frequency beat frequencies of the uphill and downhill chirps respectively, and solving for the distance term and the Doppler term.

[0035] In other embodiments, acquiring raw echo data of the completely symmetrical uphill chirp and downhill chirp within the triangular wave period, and extracting the upwave data sequence and downwave data sequence respectively, includes: acquiring raw echo data of each transmitting channel and each receiving channel at the uphill chirp and downhill chirp; and extracting the upwave data sequence and downwave data sequence for each transmitting channel.

[0036] S102, perform dynamic imaging processing on the upper wave data sequence and the lower wave data sequence respectively to obtain the corresponding upper wave image and lower wave image.

[0037] In some embodiments, performing dynamic imaging processing on the upper and lower wave data sequences to obtain corresponding upper and lower wave images includes: performing range compression, range alignment, target focusing, and slow-time imaging on the upper and lower wave data sequences of each transmission channel to obtain corresponding upper and lower wave images.

[0038] S103, establish a phase relationship based on the upper and lower wave images, restore the TDMA blur, and obtain the true velocity of the target.

[0039] In some embodiments, establishing a phase relationship based on the upper and lower wave images to recover TDMA ambiguity and obtain the true velocity of the target includes: for the same target, extracting the complex response of the corresponding Doppler unit in the upper and lower wave images within the same transmission channel; establishing a phase relationship between the same unit in the upper and lower waves based on the phase difference of the complex response; using the phase relationship and the ambiguity velocity obtained from the individual upper or lower wave images as joint constraints, first recovering the velocity ambiguity compression caused by TDMA polling to obtain compressed data; and expanding a higher-order velocity ambiguity interval based on the compressed data to obtain the true velocity of the target.

[0040] S104, perform phase alignment on the upper and lower wave images based on the target's true velocity to obtain the final target image.

[0041] In some embodiments, phase alignment of the upper and lower wave images based on the target's true velocity to obtain the final target image includes: phase alignment of the upper and lower wave images based on the target's true velocity, and completion of multi-emission channel fusion imaging processing to obtain the final target image.

[0042] The advantage of this invention is that, in a TDMA-MIMO millimeter-wave radar with N transmission channels, a completely symmetrical triangular wave system is designed, so that each transmission channel transmits a set of symmetrical waveforms composed of an uphill chirp and a downhill chirp within its respective polling time slot; then, the upwave data sequence and downwave data sequence are extracted for each transmission channel, and range processing and target imaging are performed independently to obtain the upwave image and downwave image corresponding to each transmission channel; further, at the same range Doppler unit of the same target, the complex response of the upwave and downwave is extracted, and the correspondence between their phase difference and the true velocity of the target is established; using the phase relationship, the velocity ambiguity compression caused by TDMA polling is first determined and eliminated, and then the higher-order velocity ambiguity is further expanded to finally obtain the true velocity and complete the coherent fusion imaging of the upwave, downwave, and multiple transmission channels. Under TDMA-MIMO conditions, the maximum unambiguous velocity of a single channel that has decreased due to polling can be recovered first, and then the velocity range can be further extended by utilizing the phase relationship between the upper and lower waves of the triangular wave. At the same time, the method mainly relies on the fixed phase relationship between the upper and lower waves for deambiguation, and no longer depends excessively on designing a single chirp to be as short as possible. It is more suitable for use in engineering systems under the constraints of ranging resolution, signal-to-noise ratio, sampling rate and hardware resources.

[0043] To facilitate understanding, this embodiment further elaborates on the specific implementation process of the above method in conjunction with a specific application scenario. Taking vehicle-mounted radar detection of moving targets as an example, the specific steps include:

[0044] Step 1: Construct a fully symmetric triangular wave for TDMA-MIMO

[0045] Assume that the vehicle-mounted millimeter-wave radar has One launch channel and There are one receiving channel, and the transmitting end uses TDMA polling. and is a positive integer. Each transmission channel transmits a set of triangular wave signals within its polling time slot. Each set of triangular wave signals consists of an uphill chirp and a downhill chirp:

[0046] set up:

[0047] carrier frequency is ;

[0048] The duration of a single chirp is ;

[0049] FM bandwidth is ;

[0050] The absolute value of the frequency modulation slope is:

[0051]

[0052] The instantaneous frequency of the uphill chirp can then be expressed as:

[0053]

[0054] The instantaneous frequency of the downhill chirp can be expressed as:

[0055]

[0056] Therefore, uphill and downhill have the following relationship:

[0057] (1) The duration (i.e., length) is the same;

[0058] (2) Same bandwidth;

[0059] (3) The absolute values ​​of the frequency modulation slopes are the same;

[0060] (4) Only the slope signs are opposite;

[0061] (5) Regarding the center frequency Perfectly symmetrical.

[0062] For a given fixed transmission channel, the time interval between its uphill chirp and its downhill chirp is:

[0063]

[0064] Under TDMA polling conditions, the time interval between two consecutive chirps on the same transmit channel is:

[0065]

[0066] Similarly, the time interval between two adjacent downhill chirps is also:

[0067]

[0068] The purpose of this step is to clarify the two fundamental time scales under the TDMA-MIMO triangular wave system: the interval between the upslope and downslope within the same transmission channel. and the slow-time resampling interval of the same transmission channel Subsequent velocity fuzzy analysis is based on these two time scales.

[0069] Step 2: Establish a moving target echo model under TDMA-MIMO conditions

[0070] Let the radial distance to the target be:

[0071]

[0072] in, For reference time distance; The target radial velocity.

[0073] The two-way propagation delay of the target is:

[0074]

[0075] The corresponding Doppler frequency is:

[0076]

[0077] in:

[0078]

[0079] The carrier wavelength.

[0080] For an uphill chirp, after demodulation of the transmitted and echo signals, the intermediate frequency beat frequency can be expressed as:

[0081]

[0082] For downhill chirp, the mid-frequency beat frequency can be expressed as:

[0083]

[0084] Therefore, we can conclude that:

[0085]

[0086] as well as:

[0087]

[0088] The above relationship illustrates that uphill and downhill slopes differ in distance. The signs are reversed in the Doppler terms. The symbols are the same. Therefore, the same target should correspond to the same distance position in the upper and lower waves, and its complex phase difference is mainly caused by the target motion at the two launch times.

[0089] Step 3: Construct the upwave data sequence and downwave data sequence according to the transmission channel and perform imaging processing.

[0090] Regarding the first Each transmission channel is used to extract all its uphill chirps, forming the upwave slow time series (i.e., the upwave data series):

[0091]

[0092] Extract all downhill chirps to construct the next wave slow time series (i.e., the next wave data series):

[0093]

[0094] The upwave data sequence and the downwave data sequence are respectively subjected to range compression, range alignment, target focusing, and slow-time imaging processing to obtain the upwave imaging result (i.e., upwave image) corresponding to the transmission channel:

[0095]

[0096] And the next-wave imaging results (i.e., the next-wave image):

[0097]

[0098] For the same target, the same distance Doppler cell is represented in both the upper and lower frame images. Then, extract its complex response:

[0099]

[0100]

[0101] The purpose of this step is to form two independent imaging results for the upwave and downwave of each transmit channel under TDMA-MIMO conditions, providing input for subsequent velocity discrimination using the complex phase difference of the same unit.

[0102] Step 4: Establish the phase relationship between the upper and lower waves within the same transmission channel.

[0103] For the For the same target in multiple launch channels, the launch times differ between the uphill and downhill chirps:

[0104]

[0105] During this period, the target distance changes as follows:

[0106]

[0107] The phase change of the echo during two-way propagation is as follows:

[0108]

[0109] And because:

[0110]

[0111] Therefore, the above formula can be written as:

[0112]

[0113] Therefore, the complex responses of the upper-wave imaging results and the lower-wave imaging results in the same range Doppler cell satisfy:

[0114]

[0115] in This is a constant complex factor formed by the inconsistency between the uplink and downlink links, hardware amplitude and phase errors, and calibration errors within the transmission channel. After system calibration, it can be approximated as follows:

[0116]

[0117] Therefore:

[0118]

[0119] Right now:

[0120]

[0121] Further substitution ,get:

[0122]

[0123] This is the core phase relationship utilized in this invention.

[0124] This phase relationship indicates that, although TDMA polling causes the slow time repetition interval of the same transmit channel to become However, the time difference between the upstream and downstream waves within the same transmission channel is always only [missing information]. Therefore, the phase difference between the upper and lower waves still only corresponds to Target movement within a time period, regardless of the number of launch channels. The situation has deteriorated proportionally.

[0125] Step 5: Restore speed ambiguity compression caused by TDMA

[0126] For a single-channel, single-transmission condition, if the radar continuously transmits the same chirp, the time interval between two adjacent slow-time samples is: If only the uphill sequence or only the downhill sequence is taken, the corresponding interval is... Therefore, under single-channel conditions, the slow-time spectral processing frequency for a single upwave data sequence or a single downwave data sequence is:

[0127]

[0128] By the sampling theorem, the maximum unambiguous range of Doppler frequencies satisfies:

[0129]

[0130] Therefore, the corresponding maximum unambiguous speed is:

[0131]

[0132] The maximum unambiguous speed under single-channel conditions is defined as:

[0133]

[0134] Now considering The transmit channel uses a TDMA-MIMO system. For a fixed transmit channel, it transmits only one uphill and one downhill in each round of TDMA polling. Therefore, the time interval between two adjacent uphill chirps is different from that of a single channel. Increase to:

[0135]

[0136] Therefore, the slow-time sampling frequency corresponding to the upper or lower wave data sequence of this transmission channel is:

[0137]

[0138] The corresponding maximum unambiguous Doppler frequency is:

[0139]

[0140] Furthermore, the maximum unambiguous speed can be obtained as:

[0141]

[0142] Right now:

[0143]

[0144] Substitution ,have:

[0145]

[0146] This indicates that, under TDMA-MIMO conditions, for any fixed transmit channel, when imaging is performed using only its upwave or downwave data sequence, the maximum unambiguous velocity will be compressed to the level under single-channel conditions due to the polling mechanism. .

[0147] As shown in step four, the phase difference between the upper and lower waves satisfies:

[0148]

[0149] Therefore, the velocity obtained by inverting the phase difference between the upper and lower waves can be written as:

[0150]

[0151] in The fuzzy order is an integer.

[0152] If only the principal value interval of the phase is considered Then, the unambiguous velocity range corresponding to the phase difference between the upper and lower waves is:

[0153]

[0154] This range and Irrelevant.

[0155] Therefore, the blur rate obtained for either the upwave or downwave image under TDMA-MIMO conditions Its actual speed satisfies:

[0156]

[0157] in, The order of speed ambiguity caused by TDMA.

[0158] On the other hand, the velocities corresponding to the phase difference between the upper and lower waves satisfy:

[0159]

[0160] in:

[0161]

[0162] Therefore, combining the two equations, we have:

[0163]

[0164] This can be achieved by searching for integers that satisfy the expression. and Determine the range of the actual speed.

[0165] When the target's true velocity is near the unambiguous range of a single channel before TDMA compression, the priority is to address the following: The problem is to first determine how many iterations the TDMA polling has traversed.

[0166]

[0167] The fuzzy interval. Once If correctly determined, the actual speed can first recover to a wider range unaffected by TDMA compression.

[0168] In other words, under TDMA-MIMO conditions, the primary function of the phase relationship between the upper and lower waves in this invention is to restore the maximum unambiguous velocity compression caused by TDMA, rather than directly discussing the doubling of velocity in the sense of a single channel.

[0169] Step Six: Further Expand the Maximum Unambiguous Speed

[0170] After completing the TDMA fuzzy order After the determination, the periodicity of the phase relationship between the upper and lower waves can be further utilized to expand the higher-order ambiguity range.

[0171] Depend on

[0172]

[0173] It can be seen that the velocity period corresponding to the phase difference between the upper and lower waves is:

[0174]

[0175] This means that after restoring the TDMA blur, the position of the target's true velocity within a larger velocity range can be determined based on the upper and lower wave imaging results and phase difference constraints.

[0176] If only the upper or lower data sequence is used under single-channel conditions, the maximum unambiguous speed is:

[0177]

[0178] The velocity range of the principal phase interval directly corresponding to the phase relationship between the upper and lower waves is:

[0179]

[0180] It is evident that this range doubles the unambiguous speed of a single channel compared to either a single upwave or a single downwave.

[0181] Therefore, under TDMA-MIMO conditions, the speed extension process of this invention can be divided into two levels:

[0182] The first level utilizes the phase relationship between upper and lower waves to eliminate the maximum unambiguous velocity compression caused by TDMA polling, thus expanding the velocity range from...

[0183]

[0184] Restored to no longer follow A larger range reduced proportionally;

[0185] The second level involves further expanding the velocity range using the phase relationship between the upper and lower waves after restoring the TDMA ambiguity, thereby extending it beyond the results of single-channel upper or lower wave processing:

[0186]

[0187] The purpose of this step is to divide the speed defuzzification logic under TDMA-MIMO conditions into two stages: "first recovery, then expansion," which better meets the engineering implementation requirements of vehicle-mounted 4D millimeter-wave radar.

[0188] In this invention, although the phase relationship between the upper and lower waves still includes ,Right now:

[0189]

[0190] However, this invention does not simply rely on reducing To expand the unambiguous speed, but through a given Under certain conditions, a deterministic phase relationship is established between the upper and lower waves, and this phase relationship is used to complete TDMA fuzzy recovery and further velocity unfolding.

[0191] In other words, the core of this invention is not "the chirp must be very short," but rather "within the existing chirp length, extracting the previously unused phase information between the upper and lower waves for velocity determination." Therefore, this invention is less overly dependent on the chirp duration itself, making it more suitable for use in practical vehicle radar systems under conditions of compromise among multiple performance indicators.

[0192] Step 7: Phase alignment and multi-channel fusion imaging after deblurring

[0193] After obtaining the target's true speed Then, phase compensation is performed on the downwave image within each transmission channel to make it have the same phase reference as the upwave image.

[0194] Let the compensation item be:

[0195]

[0196] The compensated image of the next wave is as follows:

[0197]

[0198] Then, coherent fusion of the upper and lower waves within the channel is performed to obtain:

[0199]

[0200] Then, MIMO virtual array fusion is performed on all transmission channels to form the final moving target imaging result.

[0201] The purpose of this step is to further achieve phase consistency between upper and lower waves and between multiple transmission channels, based on the completion of velocity blur resolution, thereby improving the focusing quality and fusion effect of moving target images.

[0202] The processing flow of this invention is as follows:

[0203] Step 1: Design a fully symmetrical triangular wave TDMA-MIMO system.

[0204] Step 2: Collect raw echo data for each transmit channel and each receive channel under uphill and downhill chirps.

[0205] Step 3: Extract the upwave data sequence and downwave data sequence for each transmission channel.

[0206] Step 4: Perform range processing and moving target imaging on the upwave data sequence and downwave data sequence of each transmission channel to obtain the corresponding upwave image and downwave image.

[0207] Step 5: For the same target, extract the complex response of the corresponding Doppler unit in the upper and lower wave images within the same transmission channel.

[0208] Step 6: Establish the phase relationship between the upper and lower waves of the same element based on the phase difference of the complex response.

[0209] Step 7: Using the phase relationship and the fuzzy velocity joint constraint obtained from the individual upwave or downwave images, first recover the velocity fuzzy compression caused by TDMA polling.

[0210] Step 8: Based on the recovery of TDMA ambiguity, further expand the higher-order velocity ambiguity range to obtain the true velocity of the target.

[0211] Step 9: Use the real velocity to perform phase alignment on the upper and lower wave images and complete multi-emission channel fusion imaging.

[0212] Step 10: Output the target's true velocity and the final moving target image.

[0213] The key to the embodiments of the present invention lies in:

[0214] 1. Incorporating the velocity ambiguity problem under TDMA-MIMO conditions into the framework of triangular wave target imaging. This invention does not only discuss the velocity measurement relationship of triangular waves under single-channel conditions, but also considers the velocity ambiguity problem caused by transmission polling and moving target imaging in a unified manner, starting from the TDMA-MIMO system commonly used in vehicle-mounted 4D millimeter-wave radar. Under this system, the effective slow-time sampling interval of the same transmission channel increases, and the maximum unambiguous velocity decreases. Therefore, this invention first takes "unambiguous velocity compression caused by TDMA" as one of the core problems to be solved, rather than simply staying at the level of conventional triangular wave ranging and velocities.

[0215] 2. Establish a deterministic phase relationship between the complex responses of the same range Doppler element in the upper and lower waves within the same transmission channel. This invention explicitly states that for the same target in the same transmission channel, there exists a phase difference between its complex responses in the same range Doppler element of the upper and lower wave images, determined by a fixed time interval between the upper and lower waves. This phase difference essentially corresponds to the two-way propagation phase change caused by the target's displacement between the two transmissions, and is therefore directly related to the target's true velocity. This relationship is the core basis for velocity fuzzy recovery and extension in this invention.

[0216] 3. Recovering and expanding the maximum unambiguous velocity using the phase relationship between upper and lower waves. The key to this invention is not merely using triangular waves for velocity expansion, but rather first utilizing the phase relationship between upper and lower waves to recover the maximum unambiguous velocity compression caused by TDMA-MIMO polling. After completing the TDMA ambiguity recovery, this invention continues to utilize the periodicity of the phase relationship between upper and lower waves to expand higher-order velocity ambiguity ranges. Therefore, the velocity deambiguity of this invention is not a single step, but includes two consecutive stages: "first recovering the TDMA ambiguity, then further expanding the velocity range," making the technical approach more suitable for MIMO moving target scenarios.

[0217] 4. Independent of chirp duration. Some existing deblurring methods rely heavily on sufficiently short chirp durations; otherwise, velocity ambiguity pressure increases significantly. While this invention also involves chirp duration parameters, its core lies in utilizing the fixed phase relationship between upper and lower waves for velocity discrimination, rather than simply relying on shortening the chirp to improve unambiguous velocity. Therefore, it still has good applicability under given chirp length conditions.

[0218] The advantages of the embodiments of the present invention are as follows:

[0219] 1. Solving the problem of reduced maximum unambiguous velocity under TDMA-MIMO system. This invention addresses the problem of reduced maximum unambiguous velocity caused by TDMA transmit polling in vehicle-mounted 4D millimeter-wave radar, enabling the system to maintain good moving target velocity discrimination capability even with an increased number of transmit channels.

[0220] 2. Achieving a "recover first, then expand" speed deblurring effect. This invention can not only recover the speed ambiguity compression caused by TDMA polling, but also continue to expand higher-order speed ambiguity intervals after recovery, thereby expanding the final discernible true speed range.

[0221] 3. Improve the utilization efficiency of triangular wave ups and downslope information. This invention no longer only uses the beat frequency relationship between ups and downslopes for conventional distance and velocity processing, but further utilizes the complex phase relationship of the same unit after the ups and downslopes are imaged separately, so that the information in the triangular wave can be more fully utilized.

[0222] 4. Reduced reliance on extremely short chirp design. Compared to solutions that primarily rely on shortening chirp duration to improve unambiguous speed, this invention can still recover and extend the speed range through the phase relationship between upper and lower waves within a given chirp length, making it more suitable for engineering environments where actual vehicle system parameters are limited.

[0223] 5. Improve the fusion quality of upper and lower wave images and multi-emission channel images. After completing velocity deblurring, this invention can further perform phase consistency compensation and fusion on upper and lower wave images and multi-emission channel images, thereby improving the focusing quality and energy accumulation effect of the target image.

[0224] 6. Improved adaptability to complex dynamic road scenarios. For complex dynamic scenarios such as high-speed oncoming vehicles, rapid incursions, and crossovers, this invention can maintain good target discrimination and imaging capabilities over a wider speed range, reducing misjudgments and mismatches caused by speed folding.

[0225] 7. Possesses favorable engineering implementation conditions. This invention is based on the existing TDMA-MIMO vehicle-mounted millimeter-wave radar architecture and triangular wave system, without requiring changes to the basic hardware structure of the system, making it easy to implement on existing DSP, FPGA, GPU, or SoC platforms.

[0226] 8. This invention provides a foundation for subsequent higher-order motion compensation and dynamic scene processing. The actual velocity results output by this invention can be further used for subsequent processing such as distance migration correction, higher-order motion compensation, multi-target association, and trajectory prediction, demonstrating good scalability.

[0227] like Figure 2As shown, based on the above method, the present invention provides a radar imaging device based on triangular waves, comprising: an acquisition unit 201, used to acquire raw echo data of a completely symmetrical uphill chirp and downhill chirp within the triangular wave period, and extract an upwave data sequence and a downwave data sequence respectively; an imaging unit 202, used to perform dynamic imaging processing on the upwave data sequence and the downwave data sequence respectively to obtain corresponding upwave images and downwave images; a calculation unit 203, used to establish a phase relationship based on the upwave image and the downwave image, recover TDMA ambiguity, and obtain the true velocity of the target; and a processing unit 204, used to perform phase alignment on the upwave image and the downwave image based on the true velocity of the target to obtain a final target image.

[0228] It should be understood that all relevant content of each step involved in the above method embodiments can be referenced to the functional description of the corresponding functional module, and will not be repeated here. Furthermore, the use of suffixes such as "module," "component," or "unit" to represent elements is merely for the purpose of illustrative purposes and has no specific meaning in itself. Therefore, "module," "component," or "unit" can be used interchangeably. Terminals can be implemented in various forms. For example, the terminals described in this invention may include mobile terminals such as mobile phones, tablets, laptops, handheld computers, personal digital assistants (PDAs), portable media players (PMPs), navigation devices, wearable devices, smart bracelets, pedometers, etc., as well as fixed terminals such as digital TVs and desktop computers. The following description will use mobile terminals as examples; those skilled in the art will understand that, in addition to elements specifically designed for mobile purposes, the construction according to embodiments of the present invention can also be applied to fixed-type terminals.

[0229] In other embodiments of the present invention, an electronic device 300 is disclosed, such as... Figure 3 As shown, the device may include: one or more processors 301; memory 302; display 303; one or more application programs (not shown); and one or more computer programs 304. These devices can be connected via one or more communication buses 305. The one or more computer programs 304 are stored in the memory 302 and configured to be executed by the one or more processors 301. The one or more computer programs 304 include instructions that can be used to perform actions such as... Figure 1 Each step in the corresponding embodiment.

[0230] Processor 301 can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0231] The memory 302 can be an internal storage unit of the electronic device 300, such as a hard disk or RAM of the electronic device 300. The memory 302 can also be an external storage device of the electronic device 300, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or FlashCard equipped on the electronic device 300. Furthermore, the memory 302 can include both internal and external storage units of the electronic device 300. The memory 302 is used to store computer programs and other programs and data required by the electronic device. The memory 302 can also be used to temporarily store data that has been output or will be output.

[0232] The computer program 304 can be divided into one or more modules / units. The one or more modules / units can be a series of computer program instruction segments that can perform a specific function. The instruction segments are used to describe the execution process of the computer program 304 in the electronic device 300.

[0233] In addition to the above-described structure, those skilled in the art will understand that Figure 3 This is merely an example of electronic device 300 and does not constitute a limitation on electronic device 300. Electronic device 300 may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device may also include input / output devices, network access devices, buses, etc.

[0234] Those skilled in the art will understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the functions described above can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this invention. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0235] Based on the above embodiments, the present invention also discloses a computer-readable storage medium having at least one computer program stored thereon, wherein the computer program, when executed by a processor, implements the methods described in the foregoing embodiments.

[0236] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing a processor. The program can be stored in a computer-readable storage medium, which is a non-transitory medium, such as random access memory, read-only memory, flash memory, hard disk, solid-state drive, magnetic tape, floppy disk, optical disk, and any combination thereof. The storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. This available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., digital video disc (DVD)), or a semiconductor medium (e.g., solid-state drive (SSD)).

[0237] The descriptions of the processes or structures corresponding to the above figures each have their own emphasis. For parts of a process or structure that are not described in detail, please refer to the relevant descriptions of other processes or structures.

[0238] Although the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. The above descriptions are merely embodiments of the present invention and do not limit the patent scope of the present invention. However, it should be understood that such modifications and variations fall within the scope and spirit of the present invention. Moreover, the present invention described herein may have other embodiments and can be implemented or realized in various ways. All equivalent transformations made based on the content of this specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of this invention.

Claims

1. A radar imaging method based on triangular waves, characterized in that, Including the following steps: The raw echo data of the uphill chirp and downhill chirp that are completely symmetrical within the triangular wave period are obtained, and the uphill data sequence and downhill data sequence are extracted respectively. The upper and lower wave data sequences are subjected to motion imaging processing respectively to obtain the corresponding upper and lower wave images; Establish the phase relationship based on the upper and lower wave images, recover the TDMA blur, and obtain the true velocity of the target. The upper and lower wave images are phase-aligned based on the target's true velocity to obtain the final target image.

2. The method according to claim 1, characterized in that, Before obtaining the raw echo data of the perfectly symmetrical uphill and downhill chirps within the triangular wave period, the following steps are also included: Construct a fully symmetrical triangular wave, which consists of an uphill chirp and a downhill chirp. The two chirps have the same duration, bandwidth, and absolute value of frequency modulation slope, but opposite signs of slope, and are symmetrical about the carrier frequency center. Establish a target echo model, obtain the mid-frequency beat frequencies for uphill and downhill sections respectively, and solve for the distance and Doppler terms.

3. The method according to claim 1, characterized in that, The raw echo data of the upslope and downslope chirps, which are completely symmetrical within the triangular wave period, are obtained, and the upslope and downslope data sequences are extracted respectively, including: Collect raw echo data of each transmitting channel and each receiving channel on the uphill chirp and downhill chirp; For each transmission channel, the upwave data sequence and the downwave data sequence are extracted separately.

4. The method according to claim 3, characterized in that, The upper and lower data sequences are subjected to motion imaging processing respectively to obtain corresponding upper and lower images, including: The upwave and downwave data sequences of each transmission channel are subjected to range compression, range alignment, target focusing, and slow-time imaging to obtain the corresponding upwave and downwave images.

5. The method according to claim 4, characterized in that, Based on the phase relationship established between the upper and lower wave images, the TDMA blur is recovered, and the true velocity of the target is obtained, including: For the same target, extract the complex response of the corresponding Doppler cell in the upper and lower wave images within the same transmission channel; Based on the phase difference of the complex response, establish the phase relationship between the upper and lower waves of the same element; Using the phase relationship and the fuzzy velocity joint constraint obtained from the individual upwave or downwave image, the velocity fuzzy compression caused by TDMA polling is first recovered to obtain the compressed data; Based on the compressed data, a higher-order velocity fuzzy interval is expanded to obtain the true velocity of the target.

6. The method according to claim 5, characterized in that, Based on the target's true velocity, the upper and lower wave images are phase-aligned to obtain the final target image, which includes: Based on the target's true velocity, the upper and lower wave images are phase-aligned to complete the multi-emission channel fusion imaging process and obtain the final target image.

7. A radar imaging device based on triangular waves, used in the method according to any one of claims 1-6, characterized in that, include: The acquisition unit is used to acquire the raw echo data of the uphill chirp and downhill chirp that are completely symmetrical within the triangular wave period, and to extract the uphill data sequence and downhill data sequence respectively. An imaging unit is used to perform dynamic imaging processing on the upper wave data sequence and the lower wave data sequence respectively to obtain the corresponding upper wave image and lower wave image; The calculation unit is used to establish a phase relationship based on the upper and lower wave images, recover the TDMA blur, and obtain the true velocity of the target. The processing unit is used to perform phase alignment on the upper and lower wave images based on the true velocity of the target to obtain the final target image.

8. An electronic device, characterized in that, The device includes a memory and a processor, wherein the memory stores a program that can run on the processor, and when the program is executed by the processor, causes the electronic device to perform the method of any one of claims 1-6.

9. A readable storage medium storing a program, characterized in that, When the program is executed, it implements the method of any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1-6.

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