Speed and distance decoupling method and device for step frequency radar signal and computer readable storage medium

Abstract

The invention relates to a speed and distance decoupling method and speed and distance decoupling equipment for a step frequency radar signal and a computer readable storage medium. The speed distance decoupling method comprises the following steps: S1, performing FFT (Fast Fourier Transform) processing on an echo intermediate frequency signal to obtain information of a one-dimensional FFT distance dimension; s2, extracting waveforms of a positive slope as a group A and waveforms of a negative slope as a group B from the information of the distance dimension of the one-dimensional FFT, and respectively performing two-dimensional FFT processing to obtain a complex matrix of the two-dimensional FFT; s3, extracting frequency information corresponding to an amplitude peak value from the complex matrix, taking a one-dimensional frequency as a fast change frequency, and taking a two-dimensional frequency as a slow change frequency; s4, calculating to obtain a frequency offset Fr; s5, calculating based on the frequency offset Fr to obtain a frequency offset Fd; and S6, solving the real speed and the real distance of the target. The distance and the speed of the target can be effectively obtained.

Description

Technical Field

[0001] The present invention relates to the field of radar signal processing technology, and in particular to a speed-distance decoupling method for a stepped frequency radar signal, a speed-distance decoupling device and a computer-readable storage medium. Background Art

[0002] At present, in many common FMCW (Frequency Modulated Continuous Wave) millimeter wave radars, the stepped frequency technology of single slope FMCW waveform is widely used to effectively improve the distance resolution. Figure 1 The waveform of the single slope frequency modulated continuous wave of the prior art is shown. As shown in the figure, this technology does bring certain advantages in practical applications, enabling the radar to more accurately determine the distance information of the target when detecting the target. However, the radar using this technology faces a more difficult problem during the detection process, that is, the frequency Fd originally used to characterize the speed (based on the Doppler effect) will be coupled with the distance frequency Fr brought by the step frequency waveform.

[0003] Specifically, when the radar signal is processed and detected, only the coupled frequency Fd+Fr can be obtained. This situation makes it impossible for the radar to accurately measure the speed and distance of the target separately. Because in this coupled state, it is difficult to directly separate the frequency Fd related to speed and the frequency Fr related to distance from the detected frequency. This is undoubtedly a major challenge for application scenarios that need to accurately obtain target speed and distance information at the same time.

[0004] To address this problem, existing technologies usually use two main solutions. The first is to estimate the target speed by using the correlation between different frames of data. By analyzing multiple frames of radar data collected at different time points, finding the rules and correlations therein, the target speed information can be inferred. The advantage of this method is that it can make full use of the data changes in the time dimension to improve the accuracy of speed estimation. The second method is to estimate the speed first, then use the estimated speed for motion compensation, and then calculate the distance. This method first makes a preliminary estimate of the speed through a specific algorithm and model, then adjusts the radar echo signal according to the estimated speed to eliminate the influence of the target motion on the distance measurement, and finally accurately calculates the distance of the target. The first method relies on the accuracy and stability of multiple frames of data. If some frames of data are wrong or biased due to environmental interference during the data acquisition process, then when performing correlation analysis based on these data, an erroneous speed estimate will be generated. And analyzing the correlation between different frames of data requires complex calculations. With the increase in the number of data frames and the increase in the amount of data, the amount of calculation will increase exponentially. This is a huge challenge for the real-time processing capability of the radar system. The second method may have errors in the first step of speed estimation. This error will propagate and amplify in the subsequent motion compensation and distance calculation process. In multi-target application scenarios or environments with dynamic interference, the effectiveness of this method will be limited. Summary of the invention

[0005] In view of the above problems in the prior art, the present invention proposes a speed-distance decoupling method, a speed-distance decoupling device and a computer-readable storage medium for a stepped frequency radar signal, which can quickly and effectively obtain the distance and speed of a target.

[0006] Specifically, the present invention proposes a speed-distance decoupling method for a stepped frequency radar signal, wherein N groups of frequency-modulated continuous waves with stepped frequencies are transmitted at the transmitting end of the radar, and each group sequentially transmits two frequency-modulated continuous waves with slopes of K and -K, with an initial center frequency of f1 and a frequency step of Δf; the speed-distance decoupling method at the receiving end of the radar comprises the following steps:

[0007] S1, perform FFT processing on the received echo intermediate frequency signal corresponding to each set of transmission waveforms to obtain one-dimensional FFT distance dimension information;

[0008] S2, extracting the waveforms with positive slopes from the information of the one-dimensional FFT distance dimension as group A, extracting the waveforms with negative slopes as group B, performing two-dimensional FFT processing on group A and group B respectively, and obtaining a two-dimensional FFT complex matrix;

[0009] S3, extracting frequency information corresponding to the amplitude peak from the complex matrix, and using the one-dimensional frequency as the fast-changing frequency and the two-dimensional frequency as the slow-changing frequency;

[0010] S4, based on the fast changing frequency and the slow changing frequency, the coupling frequency of group A is obtained as Fd+Fr, and the coupling frequency of group B is obtained as -Fd+Fr, where Fd is the frequency offset related to the distance, and Fr is the frequency offset related to the speed, and the frequency offset Fr is calculated;

[0011] S5, calculating a frequency offset Fd based on the frequency offset Fr;

[0012] S6, calculating the real speed and real distance of the target based on the frequency offset Fr and the frequency offset Fd.

[0013] According to one embodiment of the present invention, each group sequentially transmits two frequency modulated continuous waves with slopes of K and -K, which means that each group in the N groups of frequency modulated continuous waves first transmits a frequency modulated continuous wave with a slope of K and then transmits a frequency modulated continuous wave with a slope of -K, or each group in the N groups of frequency modulated continuous waves first transmits a frequency modulated continuous wave with a slope of -K and then transmits a frequency modulated continuous wave with a slope of K.

[0014] According to one embodiment of the present invention, in step S4, the frequency offset Fr is calculated as follows:

[0015] Fr=((Fd+Fr)+(-Fd+Fr)) / 2.

[0016] According to one embodiment of the present invention, in step S5, the frequency offset Fr obtained by calculation is substituted into the obtained coupling frequencies of group A or group B to obtain the frequency offset Fd.

[0017] According to one embodiment of the present invention, in step S6, the calculation formula for solving the real speed v of the target is:

[0018]

[0019] Where c is the speed of light and f1 is the initial center frequency.

[0020] According to one embodiment of the present invention, in step S6, the calculation formula for solving the real distance R of the target is:

[0021]

[0022] Where c is the speed of light and K is the slope of the FMCW.

[0023] The present invention also provides a speed-distance decoupling device for a stepped frequency radar, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the aforementioned speed-distance decoupling methods when executing the computer program.

[0024] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the speed-distance decoupling method as described in any one of the above items are implemented.

[0025] The present invention provides a speed-distance decoupling method, a speed-distance decoupling device and a computer-readable storage medium for a stepped frequency radar signal. Two sets of waveforms with the same slope absolute value and opposite signs are configured at the transmitting end, and their characteristics are used to perform frequency decoupling of speed and distance at the same one-dimensional frequency, thereby quickly calculating the distance and speed of the target.

[0026] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are included to provide further explanation of the present invention, and are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present invention and together with the description serve to explain the principle of the present invention.

[0028] In the attached figure:

[0029] Figure 1 The waveform diagram of the single slope frequency modulated continuous wave in the prior art is shown.

[0030] Figure 2 The waveform diagram of a positive and negative slope alternating frequency modulated continuous wave according to an embodiment of the present invention is shown.

[0031] Figure 3 A flowchart of a method for decoupling speed and distance of stepped frequency radar signals according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0032] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0036] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0037] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0038] Figure 2 The waveform diagram of a positive and negative slope alternating frequency modulated continuous wave according to an embodiment of the present invention is shown. Figure 3 The flowchart of the speed-distance decoupling method of the stepped frequency radar signal according to one embodiment of the present invention is shown. The present invention provides a speed-distance decoupling method of the stepped frequency radar signal. Figure 2 , the radar transmits N groups of frequency-stepped continuous frequency waves at the transmitting end, and each group sequentially transmits two frequency-modulated continuous waves with slopes of K and -K, with an initial center frequency of f1 and a frequency step of △f. As shown in the figure, the first group transmits a positive slope continuous frequency wave A1 with a center frequency f1 slope of K, followed by a negative slope continuous frequency wave B1 with a center frequency f1 slope of -K. The first group transmits a positive slope continuous frequency wave A2 with a center frequency f2 slope of K, followed by a negative slope continuous frequency wave B2 with a center frequency f2 slope of -K. According to this rule, the Nth group of transmitting ends transmits a positive slope continuous frequency wave An with a center frequency fn slope of K, followed by a negative slope continuous frequency wave Bn with a center frequency fn slope of -K.

[0039] The speed-distance decoupling method at the radar receiving end includes the following steps:

[0040] S1, perform FFT processing on the received echo intermediate frequency signal corresponding to each set of transmission waveforms to obtain one-dimensional FFT distance dimension information. Through FFT processing, the echo intermediate frequency signal in the time domain is converted into a frequency domain signal to obtain the distance dimension information.

[0041] S2, extract the waveform with positive slope from the information of the one-dimensional FFT distance dimension as group A, extract the waveform with negative slope as group B, perform two-dimensional FFT processing on group A and group B respectively, and obtain the complex matrix of two-dimensional FFT. In each group of frequency modulated continuous waves emitted by the radar transmitter, after the waveform with positive slope (slope is K) interacts with the target, the target information carried by its echo intermediate frequency signal has a unique expression in the frequency domain, and is significantly different from the waveform with negative slope. Therefore, it is necessary to perform two-dimensional FFT processing on group A and group B respectively.

[0042] S3, extract the frequency information corresponding to the amplitude peak from the complex matrix, and use the one-dimensional frequency as the fast-changing frequency and the two-dimensional frequency as the slow-changing frequency. Specifically, in the complex matrix obtained by the two-dimensional FFT, each element corresponds to a specific two-dimensional frequency component, and its amplitude value represents the relative strength of the frequency component in the entire signal. The frequency information corresponding to the position of the amplitude peak contains the most critical information about the target. After completing the extraction of the frequency information corresponding to the amplitude peak, the frequency should be classified into fast and slow changes. The one-dimensional frequency is defined as the fast-changing frequency, which is determined based on the actual characteristics of the radar signal during the processing process and the characteristics of the impact of the target movement on the signal. When the radar detects the target, some changes in the characteristics of the target, especially those related to the speed, often cause rapid changes in the echo signal in a short time, and this rapid change is more reflected in the one-dimensional frequency dimension in the frequency domain. The two-dimensional frequency is used as the slow-changing frequency because in the process of interaction between the target and the radar, some relatively stable or slowly changing target characteristics, such as the overall distance change of the target, some inherent scattering characteristics of the target, etc., these factors affect the echo signal in the frequency domain and are more reflected in the two-dimensional frequency dimension.

[0043] S4, based on the fast changing frequency and the slow changing frequency, the coupling frequency of group A is obtained as Fd+Fr, and the coupling frequency of group B is obtained as -Fd+Fr, where Fd is the frequency offset related to the distance, and Fr is the frequency offset related to the speed, and the frequency offset Fr is calculated. In other words, the frequency offset Fr is calculated based on the characteristics of the coupling frequency of group A and the coupling frequency of group B.

[0044] S5, calculating a frequency offset Fd based on the frequency offset Fr;

[0045] S6, calculating the real speed and real distance of the target based on the frequency offset Fr and the frequency offset Fd.

[0046] In some examples, each group sequentially transmits two FM continuous waves with slopes of K and -K, which means that each of the N groups of FM continuous waves first transmits a FM continuous wave with a slope of K and then transmits a FM continuous wave with a slope of -K, or each of the N groups of FM continuous waves first transmits a FM continuous wave with a slope of -K and then transmits a FM continuous wave with a slope of K.

[0047] In some examples, in step S4, the frequency offset Fr is calculated as:

[0048] Fr=((Fd+Fr)+(-Fd+Fr)) / 2.

[0049] Since Group B uses a transmission waveform with the opposite slope sign to Group A, the sign of the distance-related frequency offset Fd has changed, but the speed-related Fr remains the same, because the physical property of the target's movement speed itself will not change due to the change in the slope of the transmission waveform. When the coupling frequencies of Group A and Group B are added, the frequency offsets Fd and -Fd cancel each other out.

[0050] In some examples, in step S5, the frequency offset Fr obtained by calculation is substituted into the obtained coupling frequencies of group A or group B to obtain the frequency offset Fd.

[0051] In some examples, in step S6, the calculation formula for solving the actual speed v of the target is:

[0052]

[0053] Where c is the speed of light and f1 is the initial center frequency.

[0054] In some examples, in step S6, the calculation formula for solving the real distance R of the target is:

[0055]

[0056] Where c is the speed of light and K is the slope of the FMCW.

[0057] The present invention also provides a speed-distance decoupling device for a stepped frequency radar, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the aforementioned speed-distance decoupling methods when executing the computer program.

[0058] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above-mentioned speed-distance decoupling methods are implemented.

[0059] Among them, the specific implementation methods and technical effects of the speed distance decoupling device of the stepped frequency radar and the computer-readable storage medium can all be referred to the embodiments of the detection method provided by the above-mentioned present invention, and will not be repeated here.

[0060] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0061] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0062] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0063] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, a digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk often reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0064] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention covers modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A speed-distance decoupling method for a stepped frequency radar signal, wherein N groups of frequency-modulated continuous waves with stepped frequencies are transmitted at the transmitting end of the radar, and each group sequentially transmits two frequency-modulated continuous waves with slopes of K and -K, with an initial center frequency of f1 and a frequency step of Δf; the speed-distance decoupling method at the receiving end of the radar comprises the following steps: S1, perform FFT processing on the received echo intermediate frequency signal corresponding to each set of transmission waveforms to obtain one-dimensional FFT distance dimension information; S2, extracting the waveforms with positive slopes from the information of the one-dimensional FFT distance dimension as group A, extracting the waveforms with negative slopes as group B, performing two-dimensional FFT processing on group A and group B respectively, and obtaining a two-dimensional FFT complex matrix; S3, extracting frequency information corresponding to the amplitude peak from the complex matrix, and using the one-dimensional frequency as the fast-changing frequency and the two-dimensional frequency as the slow-changing frequency; S4, based on the fast changing frequency and the slow changing frequency, the coupling frequency of group A is obtained as Fd+Fr, and the coupling frequency of group B is obtained as -Fd+Fr, where Fd is the frequency offset related to the distance, and Fr is the frequency offset related to the speed, and the frequency offset Fr is calculated; S5, calculating a frequency offset Fd based on the frequency offset Fr; S6, calculating the real speed and real distance of the target based on the frequency offset Fr and the frequency offset Fd.

2. The speed-distance decoupling method for stepped frequency radar signals according to claim 1, characterized in that: Each group sequentially transmits two FM continuous waves with slopes of K and -K, which means that each group in the N groups of FM continuous waves first transmits an FM continuous wave with a slope of K and then transmits an FM continuous wave with a slope of -K, or each group in the N groups of FM continuous waves first transmits an FM continuous wave with a slope of -K and then transmits an FM continuous wave with a slope of K.

3. The speed-distance decoupling method for stepped frequency radar signals as claimed in claim 1, characterized in that: In step S4, the frequency offset Fr is calculated as: Fr=((Fd+Fr)+(-Fd+Fr)) / 2.

4. The speed-distance decoupling method for stepped frequency radar signals as claimed in claim 1, characterized in that: In step S5, the frequency offset Fr obtained by calculation is substituted into the obtained coupling frequencies of group A or group B to obtain the frequency offset Fd.

5. The speed-distance decoupling method for stepped frequency radar signals as claimed in claim 1, characterized in that: In step S6, the calculation formula for solving the target's true speed v is: Where c is the speed of light and f1 is the initial center frequency.

6. The speed-distance decoupling method for stepped frequency radar signals as claimed in claim 1, characterized in that: In step S6, the calculation formula for solving the real distance R of the target is: Where c is the speed of light and K is the slope of the FMCW.

7. A speed-distance decoupling device for a stepped frequency radar, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the speed-distance decoupling method according to any one of claims 1 to 6 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the speed-distance decoupling method according to any one of claims 1 to 6 are implemented.

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