Ranging method and apparatus, radar device, readable storage medium, and chip

Abstract

The present application relates to the technical field of radar devices. Provided are a ranging method and apparatus, a radar device, a readable storage medium, and a chip. The method can solve the problem in the prior art of the distance resolution being limited. The method is applied to a radar device, which has a first bandwidth. The method comprises: in a first bandwidth, sending a detection signal having a first waveform; receiving a first echo signal, wherein the first echo signal is a signal returned after the detection signal encounters an obstacle; performing sampling processing on the first echo signal, so as to obtain a second echo signal having a second waveform, wherein the sampling rate of the second echo signal is k times the first bandwidth, and k≥1; and using a filter bank to process the second echo signal, so as to obtain a ranging result, wherein the filter bank involves non-equal-length and non-matched filtering for the first waveform.

Description

A ranging method, apparatus, radar equipment, readable storage medium, and chip.

[0001] This application claims priority to Chinese Patent Application No. 202410681414.9, filed on May 28, 2024, entitled “A ranging method, apparatus, radar device, readable storage medium and chip”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of radar equipment technology, and in particular to a ranging method, device, radar equipment, readable storage medium, and chip. Background Technology

[0003] Currently, in indoor sensing technology, electronic devices can use radar to detect user behavior and physiological information in the indoor environment, and provide intelligent services based on this information. To obtain accurate user information, radar needs more precise distance detection capabilities, i.e., strong distance resolution. The radar's distance resolution is directly proportional to the transmitter bandwidth; the higher the bandwidth, the stronger the distance resolution. However, the transmitter bandwidth of radar equipment is usually limited (e.g., due to regulatory constraints), thus limiting the distance resolution. Therefore, there is an urgent need to provide a method to improve radar distance resolution without changing the transmitter bandwidth. Summary of the Invention

[0004] This application provides a ranging method, apparatus, radar equipment, readable storage medium, and chip, which solves the problem of limited range resolution in the prior art.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect, a ranging method is provided, applied to a radar device having a first bandwidth. The method includes: transmitting a detection signal having a first waveform within the first bandwidth; receiving a first echo signal, the first echo signal being a signal returned after the detection signal encounters an obstacle; sampling the first echo signal to obtain a second echo signal having a second waveform; the sampling rate of the second echo signal being k times the first bandwidth, where k ≥ 1; and processing the second echo signal using a filter bank to obtain a ranging result, wherein the filter bank is a non-uniform length unmatched filter of the first waveform.

[0007] In this embodiment, by processing the first echo signal returned by the detection signal at a sampling rate of k times, the sampling rate of the first echo signal is increased to a certain multiple of the first bandwidth, thereby obtaining a second echo signal with a second waveform. This completes the transfer of the distance resolution cost, that is, the distance resolution is changed from being limited by the first bandwidth to being determined by the sampling rate of the first echo signal. Based on the increase in the sampling rate, the distance resolution is improved. Then, a non-equal length unmatched filter corresponding to the first waveform is used to process the second echo signal of the second waveform. Compared with the use of a matched filter, the use of an unmatched filter can obtain a greater degree of freedom in signal processing, thereby making the ranging result have better local low sidelobe characteristics.

[0008] In some embodiments, sampling the first echo signal to obtain a second echo signal with a second waveform includes: sampling the first echo signal using a first sampling rate to obtain a second echo signal with a second waveform; the first sampling rate is k times the first bandwidth.

[0009] In this embodiment, when sampling the first echo signal, the sampling rate is directly k times the first bandwidth. This process does not require oversampling; it only requires adjusting the receiving sampling rate at the receiving end to the first sampling rate, and then sampling at the first sampling rate to obtain the sampled data at the target sampling rate. This process can be applied to a sampling mode where the receiving sampling rate is fixed and k times the first bandwidth, and sampling is performed directly at the fixed receiving sampling rate; it can also be applied to a sampling mode where the receiving sampling rate is adjustable, and the receiving sampling rate is adjusted to k times the first bandwidth, i.e., the first sampling rate, and then sampling is performed at the first sampling rate.

[0010] In other embodiments, sampling the first echo signal to obtain a second echo signal with a second waveform includes: sampling the first echo signal using a first sampling rate to obtain first sampled data, the first sampling rate being equal to a first bandwidth; and oversampling the first sampled data using a second sampling rate to obtain a second echo signal with a second waveform, the second sampling rate being k times the first sampling rate.

[0011] In this embodiment, when sampling the first echo signal, the first echo signal is first sampled at a first sampling rate equal to the first bandwidth to obtain first sampled data. Then, the first sampled data is oversampled at a second sampling rate that is k times the first sampling rate. The sampling process of the first echo signal is completed by combining the receiving sampling rate of the receiving end with oversampling. By introducing the oversampling mode, the workflow of the radar equipment can be further improved. Moreover, the oversampling method does not require adjustment of the receiving sampling rate, thereby reducing the pre-implementation working time of the algorithm.

[0012] In some embodiments, the first waveform includes N transmission sequences, each transmission sequence having a different phase code, and N being a positive integer.

[0013] The phase encoding is different from each other, which means that the phase and amplitude of each transmission sequence in the first waveform are adjustable parameters, so that the phase and amplitude of each transmission sequence have a certain degree of flexibility.

[0014] In some embodiments, the phase codes of each sequence in the transmission sequence are different, including: the phase and amplitude of each sequence in the transmission sequence are different, and each sequence includes W code elements, where W refers to the adjustable number of phase and amplitude respectively.

[0015] In the first waveform's detection signal, the phase of each transmission sequence can be any value between 0 and 2π, and the amplitude can be any value within a certain range. The specific settings can be adjusted according to actual conditions; this embodiment does not impose specific limitations.

[0016] In some embodiments, the second waveform includes ω*N received sequences, wherein the phase codes of each adjacent ω received sequences are the same, where ω≥2 and is a positive integer.

[0017] In some other embodiments, the value of ω can be set according to specific ranging requirements, but ω = βk must be satisfied.

[0018] In some embodiments, when oversampling the first echo signal, the oversampling factor β and the number of identical phase codes ω in the received sequence satisfy ω = βk, where k ≤ ω.

[0019] In some embodiments, the filtered waveform of the filter bank includes k*N filtered sequences.

[0020] In some embodiments, a filter bank is used to process the second echo signal to obtain a ranging result, including: performing convolution calculation using the filter bank and the second waveform to obtain the ranging result, wherein the ratio of the main lobe of the filter bank to the first waveform is d, and 0.6≤d≤1; under the main lobe ratio, the ranging result has the characteristic of local low sidelobes.

[0021] Among them, the local low sidelobe characteristic, compared with the global low sidelobe, can reduce the complexity of the data, making it possible to improve the resolution of the ranging results, and the current computational complexity and amount of computation can help to realize engineering.

[0022] In some embodiments, when the radar device executes the method in a first scenario, the generation of the detection signal and filter bank of the first waveform includes: determining algorithm-level parameters based on the scenario values ​​in the first scenario and the transmitting parameters of the radar device; running program code written according to the algorithm-level parameters, and using an optimization algorithm to generate the detection signal and filter bank of the first waveform for the objective function; wherein, the scenario values ​​include the farthest detection range and the maximum indoor speed; the transmitting parameters include the transmission carrier frequency, bandwidth, number of transmission antennas, and transmission sequence length; and the algorithm-level parameters include the filter sequence length, number of symbols, range low sidelobe range, velocity low sidelobe range, and main lobe ratio.

[0023] Optionally, the generation process of the first waveform detection signal and filter bank can be pre-generated by the server based on the waveform parameters in the application scenario of the radar equipment through a series of algorithms; or it can be generated by the radar equipment itself by a processor with large computing power through a series of algorithms. This embodiment does not impose specific restrictions on this.

[0024] In some embodiments, the transmitted signal of the first waveform and the filter bank are generated in advance by the server using an optimization algorithm based on program code written according to algorithm-level parameters, targeting an objective function, and then pre-set in the radar device.

[0025] In this embodiment, the process of generating the transmitted waveform from the radar device's transmitter and the filter bank from the processor on the server side—that is, generating the transmitted waveform and filter bank by running an algorithm on the server outside the radar device—occurs before the entire ranging process of the radar device and only requires one calculation. Normally, the entire process of generating the transmitted waveform and filter bank by running an algorithm requires significant computing power. By using a server with high computing power to generate the transmitted waveform and filter bank in advance, the radar device can directly use them during ranging. Compared to the traditional method of performing calculations in the radar device's processor, the computational load on the processor is greatly reduced in this embodiment.

[0026] In some embodiments, before transmitting a detection signal with a first waveform under a first bandwidth, the method further includes: determining receiver parameters based on scene values ​​in a first scene and transmitter parameters of the radar device, wherein the receiver parameters include a receiver sampling rate, an oversampling factor, a receiver sequence length, and a waveform encoding number.

[0027] In this embodiment, the receiving end parameters are determined based on the scene values ​​and the transmitting end parameters, so that when the first echo signal is sampled, the sampling results are more suitable for the scene and the ranging requirements of the radar equipment.

[0028] In some embodiments, sampling the first echo signal includes: sampling the first echo signal with receiver parameters so that the sampling rate of the second echo signal is k times the first bandwidth.

[0029] After the receiving parameters are determined, the radar equipment directly samples the first echo signal based on the determined receiving parameters during sampling. For example, it samples the first echo signal at a preset receiving sampling rate, or it samples the first echo signal by superimposing a preset receiving sampling rate with oversampling.

[0030] In some embodiments, the method further includes processing the ranging results by superimposed matrix feature space decomposition or a super-resolution algorithm of a neural network.

[0031] In this embodiment, in addition to improving the ranging capability of the radar equipment through this method, the ranging results can be further processed by superimposed matrix feature space decomposition or super-resolution algorithm of neural network, or other methods that can improve the ranging capability of the radar equipment, so as to make the ranging results more accurate.

[0032] In some embodiments, the radar device includes an ultra-wideband radar or a frequency-modulated continuous wave radar.

[0033] Optionally, the radar device can also be an ultra-wideband radar, millimeter-wave radar, or lidar, or a continuous wave radar, pulse radar, or frequency-modulated continuous wave radar, or a multiple-input multiple-output radar, a single-input multiple-output radar, or a single-input single-output radar.

[0034] Secondly, a ranging device is provided for use in radar equipment, the radar equipment having a first bandwidth. The device includes: a transmitting end for transmitting a detection signal having a first waveform within the first bandwidth; a receiving end for receiving a first echo signal, the first echo signal being the signal returned after the detection signal encounters an obstacle; a sampling module for sampling the first echo signal to obtain a second echo signal having a second waveform; the sampling rate of the second echo signal is k times the first bandwidth, where k≥1; and a processor for processing the second echo signal using a filter bank to obtain a ranging result, the filter bank being a non-uniform length unmatched filter of the first waveform.

[0035] Thirdly, a radar device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the ranging method as shown in the first aspect.

[0036] Fourthly, a computer-readable storage medium is provided that stores a computer program, which, when executed by a processor, implements the ranging method shown in the first aspect.

[0037] Fifthly, a chip is provided, the chip including a processor and a memory, the memory storing a computer program that, when executed by the processor, implements the ranging method as shown in the first aspect.

[0038] It is understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0039] Figure 1 is a schematic diagram of the application scenario of a radar device provided in an embodiment of this application in indoor sensing technology;

[0040] Figure 2 is a schematic diagram of the frame structure of a radar device provided in an embodiment of this application;

[0041] Figure 3 is a schematic diagram of the first waveform transmitted by a single transmitting antenna according to an embodiment of this application;

[0042] Figure 4 is a schematic flowchart of a ranging method provided in an embodiment of this application;

[0043] Figure 5 is a schematic diagram of a second waveform provided in an embodiment of this application;

[0044] Figure 6 is a schematic diagram of the characteristics of the second waveform and filter bank provided in an embodiment of this application;

[0045] Figure 7 is a schematic diagram of the receiving end sampling and processing the first echo signal according to an embodiment of this application;

[0046] Figure 8 is a schematic diagram illustrating the principle of distance resolution enhancement provided in an embodiment of this application;

[0047] Figure 9 is a schematic diagram of the distance measuring device provided in an embodiment of this application;

[0048] Figure 10 is a schematic diagram of the chip structure provided in the embodiment of this application. Detailed Implementation

[0049] The technical solutions provided in the embodiments of this application will be described below with reference to the accompanying drawings.

[0050] It should be understood that in the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in this document is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone.

[0051] In this embodiment, the terms "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 indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this embodiment, unless otherwise stated, "a plurality of" means two or more.

[0052] Indoor non-contact sensing technology (referred to as indoor sensing technology) refers to the use of technologies such as radar, infrared, ultrasound, and pyroelectric elements to detect objects or people in the indoor environment in a non-contact manner, thereby achieving the perception of the indoor environment. In addition, indoor sensing technology can also be used for indoor positioning, such as distinguishing floors and shops.

[0053] In recent years, with the increasing demand for personal health monitoring and higher requirements for living comfort, indoor sensing technology has received widespread attention and research in the health monitoring of indoor occupants. For example, as shown in Figure 1, electronic devices can acquire user information in the indoor environment through radar detection devices, enabling the perception of the dynamic and static vital signs of indoor occupants, understanding their behavior and physiological state, and thus providing intelligent services such as health monitoring services. This user information includes information on the user's behavior and physiology, such as the user's location, identity, movements, posture, breathing, heart rate, and sleep patterns.

[0054] The following describes the scenario of indoor sensing implemented by electronic devices. These electronic devices have built-in radar detection devices; for ease of explanation, the electronic devices will be referred to as radar devices. These radar detection devices can be ultra-wideband (UWB) radar, millimeter-wave radar, or lidar, etc.; they can also be continuous wave radar, pulse radar, or frequency-modulated continuous wave radar, etc.; and they can be multiple-input multiple-output (MIMO), single-input multiple-output (SIMO), or single-input single-output (SISO) radar, etc. Currently, electronic devices based on wireless MIMO radar for indoor occupant health monitoring have attracted attention due to their excellent privacy protection features.

[0055] Figure 1 is a schematic diagram of the application scenario of the radar device provided in an embodiment of this application in indoor sensing technology. As shown in Figure 1, the radar device is usually installed on the ceiling or wall of an indoor space. The radar device can detect people in a single room and is applicable to application scenarios such as home-based elderly care, nursing care and personal health monitoring.

[0056] During normal operation, the radar device transmits radar signals into the indoor scene, for example, a chirped signal (such as a linear chirped signal). The transmitted radar signals are reflected by objects in the indoor scene. The reflected echo signals are received by the radar device, and the processor in the radar device determines user information based on the time delay and / or frequency difference between the transmission of the radar signal and the reception of the echo signal, thereby detecting features such as the user's position, movement speed, and other characteristics in the indoor scene.

[0057] Figure 2 shows a schematic diagram of the frame structure of a radar device. As shown in Figure 2, the radar device includes a transmitter, a receiver, and a processor.

[0058] The transmitting end includes a transmitting antenna, which is used to transmit radar signals (also known as transmitted signals or detection signals) with a specific waveform. The transmitted waveform can be a standard uncoded waveform or a coded waveform. Additionally, the transmitting end also includes modulation circuitry, a clock, etc.

[0059] The receiving end includes a receiving antenna and a sampling module. The receiving antenna is used to receive the echo signal returned after the radar signal encounters an obstacle, and the sampling module is used to sample and process the echo signal to obtain an echo signal with a certain waveform.

[0060] The processor, including a microcontroller unit (MCU), a digital signal processing chip (DSP), and an analog-to-digital converter (ADC), is used to process the echo signal with a certain waveform obtained from the sampling device using a filter bank to determine user information. The filtered waveforms involved in the filter bank can be either matched or unmatched filters of the transmitted waveform.

[0061] The processor can be implemented as a general-purpose processor, a controller, or a digital signal processor, and includes, for example, combinational circuitry coupled to memory. In some embodiments, for example, the processor can be implemented using an ARM architecture.

[0062] In some embodiments, the processor may be implemented as a custom application-specific integrated circuit (ASIC).

[0063] In other embodiments, the processor includes a plurality of processors, each having one or more processing cores.

[0064] In other embodiments, the processor includes a single processor having one or more processing cores, or other types of processors. For example, it can be implemented using software running in a general-purpose MCU or DSP, which has a CPU, for example, coupled to memory and implemented using an ARM or x86 architecture. Alternatively, it can be implemented using a combination of a hardware accelerator and software running on a DSP or general-purpose MCU.

[0065] However, radar signals attenuate rapidly in the air, exhibit significant multipath effects indoors, and suffer substantial signal loss. Furthermore, indoor environments are subject to numerous interference factors, including both static and dynamic interference, which severely impact the identification accuracy of radar equipment. Therefore, to meet the high-accuracy detection requirements of radar equipment, it is necessary to improve its fundamental detection capabilities, such as ranging, velocity measurement, and angle measurement.

[0066] The ranging capability of radar equipment can also be referred to as range resolution. At different range resolutions, the smallest resolvable range cell (i.e., the minimum resolvable distance) varies, and the higher the range resolution, the smaller the smallest resolvable range cell. Furthermore, the range resolution of a radar equipment is directly proportional to the effective bandwidth (or simply bandwidth) of the radar transmitter; the higher the bandwidth, the smaller the resolvable range cell, the stronger the range resolution, and the better the ranging capability. For example, a radar signal with a bandwidth of 250MHz might have a range resolution of 0.6m; a radar signal with a bandwidth of 500MHz might have a range resolution of 0.3m.

[0067] In radar ranging, the correlation between the transmitted waveform of the detection signal and the filter bank of the received signal plays a crucial role in the target object detection effect. Furthermore, in communication systems, signal transmission may be affected by noise, interference, and distortion, causing differences between the received signal and the original signal. To mitigate these effects, filters are needed to extract the useful signal and remove noise. Therefore, ranging capabilities can be improved by designing the waveform of the detection signal at the transmitting end and applying a matched filter as the receiving filter for demodulation at the receiving end.

[0068] In some implementations, radar equipment uses standard uncoded waveforms at the transmitting end combined with matched filters at the receiving end for demodulation (such as linear frequency modulated waveforms and conjugate demodulation in frequency modulated continuous wave radar) to enhance radar ranging capabilities. Standard uncoded waveforms refer to typical waveforms without tuning (such as pulse signals, linear frequency modulated continuous waves, etc.), for example, x1, x2, x3…x m Matched filtering refers to filtering a waveform that is the conjugate and opposite in direction to the transmitted waveform itself. For example, matched filtering is applied to the x1, x2, x3…x segments of the transmitted waveform. m The inverse conjugate of . Radar equipment uses a standard uncoded waveform as the transmitted radar signal and a matched filter as the filtered waveform for the echo signal. Under this combination of transmitted waveform and demodulation filtering, the range resolution is calculated as follows: Where B is the transmitter bandwidth and c is the speed of light, taken as 3.00 × 10⁻⁶. 8 m / s. It can be seen that the range resolution of radar equipment is directly proportional to the transmitter bandwidth; the higher the bandwidth, the smaller the range resolution value (i.e., the smaller the smallest resolvable range unit), and the stronger the range resolution. However, under conditions of limited transmitter bandwidth (e.g., regulations restricting bandwidth), the range resolution is also limited, making it difficult to meet more stringent requirements for high range resolution.

[0069] In addition, although the method of using a standard uncoded waveform at the radar equipment transmitter and a matched filter for demodulation at the receiver has a better white noise background signal-to-noise ratio, the ranging results obtained by this method are not ideal in terms of sidelobe suppression and electromagnetic interference resistance because the uncoded waveform has weak anti-interference capability.

[0070] In another implementation, when the bandwidth of the radar equipment's transmitter needs to be kept within certain limits, a more accurate ranging capability can be achieved by using super-resolution algorithms to improve the radar equipment's range resolution. However, this method generally incurs significant computational costs, requiring the radar equipment's processor to possess substantial computing power to handle the computational demands of the super-resolution algorithm, thus placing extremely high demands on the radar equipment's processor's processing performance.

[0071] Based on this, the present application provides a ranging method that can transfer the range resolution cost by increasing the sampling rate of the radar device for the echo signal without changing the bandwidth of the radar device's transmitter. Then, the sampled echo signal is further processed by constructing a transmission waveform with good correlation and an unequal-length unmatched filter bank, thereby improving the range resolution of the radar device while making the ranging result have better local low sidelobe characteristics.

[0072] For ease of explanation, in this embodiment, the waveform of the detection signal transmitted by the radar device transmitter is called the first waveform (also known as the transmitted waveform), the waveform of the second echo signal obtained by the receiver after sampling the first echo signal returned by the detection signal is called the second waveform (also known as the echo waveform or the target waveform), and the waveform of the filtered signal involved in the filter bank is called the filtered waveform.

[0073] The ranging method provided in this embodiment consists of two processes: (i) the generation of the first waveform at the transmitting end of the radar equipment and the filter bank at the receiving end; and (ii) the ranging by the radar equipment based on the generated first waveform and the filter bank. These two processes will be described separately below.

[0074] (a) Generation of the first waveform at the transmitting end of the radar equipment and the filter bank at the receiving end.

[0075] The first waveform at the transmitting end of the radar equipment and the filter bank at the receiving end can be pre-generated by the server based on waveform parameters in the application scenario of the radar equipment through a series of algorithms. It should be noted that, in practical applications, depending on specific usage requirements, the first waveform at the transmitting end of the radar equipment and the filter bank at the receiving end can also be generated by the radar equipment's built-in processor with high computing power through a series of algorithms. This embodiment does not impose specific restrictions on this.

[0076] Among them, the waveform parameters include (1) scene values: the farthest detection distance, the maximum indoor speed, etc.; (2) transmitter parameters: the transmission carrier frequency, bandwidth, the number of transmission antennas and the length of the transmission sequence, etc.; (3) receiver parameters: the receiving sampling rate, the oversampling factor, the length of the receiving sequence and the number of identical waveform codes, etc.; (4) algorithm level parameters: the length of the filtering sequence and the number of symbols, the range of low sidelobes for distance, the range of low sidelobes for velocity and the ratio of the main lobe, etc.

[0077] The following explains the different types of parameters in the waveform parameters.

[0078] (1) Scene value:

[0079] The maximum detection range refers to the maximum distance that a radar device can detect, such as 20 meters; or, when the maximum detection range of a radar device is greater than the distance between the radar device and the farthest point in its application scenario, that distance is determined as the maximum detection range of the radar device.

[0080] The maximum indoor speed refers to the maximum speed of the target being sensed in the environment where the radar equipment is located. For example, the maximum speed of human movement indoors can be 5 m / s.

[0081] (2) Transmitter parameters:

[0082] The carrier frequency is a specific frequency of radio waves used to carry probe signals, measured in Hz. In wireless communication technology, carrier waves are typically used to transmit information. Digital signals are modulated onto a high-frequency carrier wave before being transmitted and received in the environment; the frequency of this carrier wave is called the carrier frequency.

[0083] Bandwidth refers to the difference between the highest and lowest frequencies of harmonics contained in a signal, that is, the frequency range of the signal. For example, the bandwidth B of a radar device is 250MHz. Typically, due to regulatory constraints, the bandwidth of the transmitting end of a radar device has an upper limit.

[0084] The number of transmitting antennas refers to the number of transmitting antennas on the radar equipment's transmitting end; it can be one or more. The number of transmitted waveforms generated on the server side can be determined based on the number of transmitting antennas.

[0085] When a radar device has a transmitting antenna, it can transmit a detection signal with a first waveform using that antenna. The first waveform transmitted by a single transmitting antenna is shown in Figure 3. As shown in Figure 3, the first waveform transmitted by transmitting antenna 1 is x1, x2, x3…x n The detection signal.

[0086] When a radar device has multiple transmitting antennas, it can transmit detection signals in a Multiple Input Multiple Output (MIMO) mode. For example, if the radar device includes four transmitting antennas, these four antennas can operate in a time division multiplexing (TDM) mode (TDM-MIMO), a frequency division multiplexing (FDM) mode (FDM-MIMO), or a code division multiplexing (CDM-MIMO) mode. The specific operating mode used can be set according to the actual application scenario; this embodiment does not impose specific limitations.

[0087] In some embodiments, when the transmitting antenna operates in TDM-MIMO mode to transmit a detection signal, the four transmitting antennas transmit detection signals of the same waveform, but at different times. For example, at the first time, the first transmitting antenna transmits a detection signal with waveform 1; at the second time, the second transmitting antenna transmits a detection signal with waveform 2; at the third time, the third transmitting antenna transmits a detection signal with waveform 3; and at the fourth time, the fourth transmitting antenna transmits a detection signal with waveform 4. The first, second, third, and fourth times are different times.

[0088] In other embodiments, when the transmitting antennas operate in CDM-MIMO or FDM-MIMO mode to transmit probe signals, the four transmitting antennas transmit probe signals with different waveforms simultaneously. For example, at the first moment, the first transmitting antenna transmits a probe signal with waveform 1, the second transmitting antenna transmits a probe signal with waveform 2, the third transmitting antenna transmits a probe signal with waveform 3, and the fourth transmitting antenna transmits a probe signal with waveform 4.

[0089] The transmission sequence length refers to the encoded length value of the transmission sequence in the first waveform involved by the transmitter. For example, the encoded length value of the first waveform is N, which means that the length of the transmission sequence in the first waveform is N, where N is a positive integer, for example, N can be 60 or 120.

[0090] (3) Receiver parameters:

[0091] The received sampling rate, also known as the receiver sampling rate, refers to the sampling frequency of the radar equipment's receiver. It should be understood that in this embodiment, the received sampling rate and the final sampling rate of the sampling module for the first echo signal (also known as the actual sampling rate), i.e., the sampling rate of the second echo signal, represent different things. When the receiver does not perform oversampling, the actual sampling rate is the same as the received sampling rate; however, when the receiver performs oversampling, the actual sampling rate is the received sampling rate plus the oversampling factor.

[0092] In this embodiment, k represents the ratio of the sampling rate of the second echo signal to the first bandwidth, which is the desired improvement factor in range resolution for the radar device. The value of k depends on the ratio of the filter sequence length of the filter bank to the transmission sequence length of the transmitted waveform. Once k is determined, the sampling rate of the second echo signal at the receiver can be determined as f. s =Bk, where B is the first bandwidth of the transmitter.

[0093] It should be noted that since the improvement factor k of distance resolution is related to the number of identical waveform codes ω in the algorithm-level parameters, and the improvement factor k of distance resolution should be less than or equal to the number of identical waveform codes ω, i.e., k ≤ ω, when determining the number of identical waveform codes in the algorithm-level parameters, one can first determine the resolution improvement factor k, and then determine the number of identical waveform codes ω in the algorithm-level parameters based on k and whether oversampling is performed.

[0094] The oversampling factor refers to the number of times the radar receiver performs oversampling. In this embodiment, β represents the oversampling factor, which is an integer greater than or equal to 1. When β = 1, it means that the receiver does not perform oversampling. The oversampling factor β, the range resolution enhancement factor k, and the waveform encoding similarity number ω satisfy the relationship ω = βk. Therefore, the waveform encoding similarity number ω in the algorithm-level parameters can be determined based on ω = βk. Furthermore, the oversampling factor is related to the operating mode of the radar receiver, which will be given in the following examples and will not be elaborated upon in this embodiment.

[0095] It should be noted that whether to perform oversampling and the oversampling factor are determined based on the radar equipment's desired range resolution improvement factor and the receiving sampling rate. For example, when the receiver is required to perform k times the number of sampling points, i.e., the ratio of the second echo signal's sampling rate to the first bandwidth is k, and k is proportional to the filter sequence length N... h The transmit sequence length N and the boost factor m of the receiver sampling rate satisfy the following relationship: k = N h / (m*N), when k=1, no oversampling is required, and when k>1, oversampling is performed at the corresponding multiple.

[0096] Furthermore, regarding the oversampling method, it is an operation performed by the receiving end through software, aiming to copy the sampled data in the received echo signal β times sequentially. This can be described using a matrix as follows: Where x represents the original data vector obtained by sampling, 1 represents a vector of all 1s with length β, and y represents the data vector obtained after oversampling.

[0097] The received sequence length refers to the encoded length value of the received sequence in the echo waveform involved at the receiving end. For example, the encoded length value of the echo waveform is M, which means that the length of the received sequence in the echo waveform is M, where M is ω*N, such as ω*60 or ω*120.

[0098] The number of identical waveform codes refers to the number of times the waveform codes are identical in the second echo signal of the second waveform obtained when the receiving end samples the first echo signal at the receiving sampling rate and the oversampling factor. This will be explained in detail in the following embodiments and will not be repeated here.

[0099] (4) Algorithm-level parameters

[0100] The algorithm-level parameters refer to the computational parameters involved at the algorithm level when the server generates the probe signal of the first waveform and the filter bank corresponding to the first waveform. These parameters are determined based on the transmitter parameters and scene values. Specifically, they include the filter sequence length, number of symbols, distance low-sidelobe range, velocity low-sidelobe range, and main lobe ratio.

[0101] The filter sequence length refers to the encoded length of the filter sequence in the filter waveform of the filter bank involved by the processor. For example, the encoded length P of the filter waveform indicates that the length of the filter sequence in the filter bank corresponding to the first waveform is P, where P and N are not equal. The length of this filter waveform is determined based on the specific sampling mode of the sampling module and the desired range resolution improvement factor of the radar equipment. For instance, in the first sampling mode, if the ratio of the sampling rate of the second echo signal to the first bandwidth is k1, and the desired range resolution improvement factor of the radar equipment is k1, then the filter waveform includes k1*N filter sequences; if the ratio of the sampling rate of the second echo signal to the first bandwidth is k2, and the desired range resolution improvement factor of the radar equipment is k2, then the filter waveform includes k2*N filter sequences.

[0102] The number of symbols refers to the adjustable number of amplitudes or phases in a waveform, which can be represented by W. For example, the phase of each sequence in the waveform can be any value from 0 to 2π, and the amplitude can be any value within a certain range.

[0103] The range low sidelobe range refers to the range of low sidelobe values ​​related to distance set based on the furthest detection distance when generating the first waveform and filter bank using the algorithm. It can be represented by 'a'. For example, if the furthest detection distance is 10m and the desired range resolution is 0.3, then the range low sidelobe range is -36 ≤ a ≤ 36.

[0104] The velocity low sidelobe range refers to the range of low sidelobe values ​​related to velocity set based on the maximum indoor velocity when generating the first waveform and filter bank using the algorithm. It can be represented by b. For example, if the maximum indoor velocity is 5 m / s, then the distance low sidelobe range is -1 ≤ b ≤ 1.

[0105] Main lobe ratio: This characterizes the correlation between the first waveform and the corresponding non-equal-length, non-matched filter bank. A higher value indicates a better correlation. It can be represented by the value 'd', where 0.6 ≤ d ≤ 1. For example, the main lobe ratio 'd' can be 0.7. At this ratio, the ranging result obtained after convolving the filter bank and the second waveform exhibits locally low sidelobes.

[0106] Based on the above waveform parameters, after determining the scene value and the transmitting parameters of the radar equipment, it is possible to determine, for example, f s The conversion relationship between ω=Bk or ω=βk yields the algorithm-level parameters and receiver parameters used to generate the first waveform and the corresponding filter bank. The server runs the code written according to the algorithm-level parameters. For the objective function, the optimization algorithm generates a probe signal with the first waveform and a non-equal-length, unmatched filter bank that is correlated with the first waveform. That is, the length of the transmitted sequence in the generated first waveform and the length of the filtered sequence in the filter bank are not equal, and the filtered waveform in the filter bank is unmatched with the first waveform.

[0107] For example, the server first utilizes the degrees of freedom of the radar equipment's transmitter and receiver to establish an objective function that minimizes the range sidelobe level of the first waveform and the corresponding non-equal-length unmatched filter group. Then, combining the constant-mode characteristics of the first waveform, the constant-energy characteristics of the non-equal-length unmatched filter sequence, and the signal-to-noise ratio loss, a template-free fractional optimization model is established. Finally, based on the alternating direction method of multipliers (ADMM) algorithm framework, variable decoupling is achieved, and the fractional optimization model is iteratively solved to obtain the first waveform sequence and the corresponding non-equal-length unmatched filter group sequence.

[0108] Among them, the non-equal-length non-matched filter bank is a special type of filter bank. Its characteristics are that the length of the filter bank and the first waveform are not equal, and the degree of matching between the filter bank and the first waveform is not high. This makes the non-equal-length non-matched filter bank more flexible and adaptable to dealing with different types of signals.

[0109] In this embodiment, the probe signal of the first waveform generated by the server includes N transmission sequences. These N transmission sequences have waveform characteristics where each transmission sequence has a different phase encoding. The different phase encodings mean that the phase and amplitude of each transmission sequence in the first waveform are adjustable parameters, allowing for a certain degree of flexibility in the phase and amplitude of each transmission sequence. For example, in the probe signal with the first waveform generated by the server, the phase of each transmission sequence can be any value from 0 to 2π, and the amplitude can be any value within a certain range. Specific settings can be made according to actual conditions, and this embodiment does not impose specific limitations.

[0110] The filter bank consists of filtered waveforms that are correlated with the first waveform. Correlation refers to the fact that the ranging result obtained after convolving the first waveform with the filter bank exhibits local low sidelobe characteristics. In other words, there is a relatively high peak value at the center of the main lobe, while other areas outside the center are suppressed, resulting in a relatively high signal-to-interference ratio.

[0111] It should be noted that if the radar equipment has multiple transmitting antennas (e.g., n transmitting antennas) operating in different frequency bands, then n detection signals with different waveforms need to be transmitted. In this case, the server generates a set of transmitted waveforms and a corresponding filter bank for each transmitted waveform, where the set of transmitted waveforms includes n transmitted waveforms. Alternatively, if the radar equipment's multiple transmitting antennas operate in other modes, such as orthogonal mode, then in this mode, the multiple transmitting antennas need to transmit detection signals with different waveforms. In this case, the server also needs to generate the corresponding set of transmitted waveforms and filter banks according to the specific operating mode. In other words, when generating transmitted waveforms and filter banks, the server adjusts the generation strategy of the corresponding transmitted waveforms and filter banks based on the frequency band or transmission mode of the transmitting antennas.

[0112] The embodiments in this section primarily consider the algorithm level, applying the concept of non-uniform length unmatched filter banks in waveform theory to construct a first waveform with excellent correlation and a non-uniform length unmatched filter bank. This process does not require increasing the transmitter bandwidth and is applicable not only to super-resolution ranging of phase-coded pulse radar but also to other radar equipment such as amplitude-phase co-coded radar.

[0113] Furthermore, by pre-generating the first waveform suitable for the radar equipment's transmitter and the filter bank for the receiver on the server, there are no limitations on the number of transmitting and receiving antennas and the transmission and reception modes of the radar equipment's transmitter and receiver. The radar equipment can operate in the traditional pulse radar mode or in the MIMO mode. The application standards of the radar equipment also include, but are not limited to, ultra-wideband (UWB) radar and frequency modulated continuous wave (FMCW) radar.

[0114] The first waveform and filter bank generated by the server can be pre-set in the radar equipment so that the radar equipment can use them directly in the subsequent ranging process.

[0115] (ii) The radar equipment performs ranging based on the generated first waveform and filter group.

[0116] Figure 4 is a schematic flowchart of a ranging method provided in an embodiment of this application. The method is applied to a radar device having a first bandwidth, under which the radar device has a first minimum resolution range. Referring to Figure 4, the method includes the following steps S401 to S404.

[0117] S401, the radar equipment transmits a detection signal with a first waveform within a first bandwidth.

[0118] Here, the first bandwidth refers to the signal bandwidth of the radar device's transmitting end; the first waveform is the transmission waveform generated by the server side in the above embodiment. For example, referring to the schematic diagram with transmission waveforms shown in Figure 3, the transmission waveform includes N transmission sequences, namely x1, x2, x3…x n In the N transmission sequences, the phase codes of each transmission sequence are different, including the amplitude and phase of each transmission sequence being different.

[0119] S402, the radar equipment receives the first echo signal.

[0120] The first echo signal refers to the signal that returns after the detection signal encounters an obstacle, and which is received without being sampled by the receiver.

[0121] S403, the radar equipment samples and processes the first echo signal to obtain a second echo signal with a second waveform.

[0122] The second echo signal, also known as the target echo signal, is the echo signal obtained by the radar equipment after sampling and processing the first echo signal. The ratio of the sampling rate of the second echo signal to the first bandwidth is k, meaning the sampling rate of the second echo signal is k times the first bandwidth, where k ≥ 1. The second waveform includes ω*N received sequences, where the phase encoding is the same for every ω adjacent received sequences, where ω is a positive integer and ω ≥ 2.

[0123] For example, if the number of identical phase codes ω in the received sequence is 2, as shown in Figure 5, then the second waveform includes 2N received sequences, namely x1, x1, x2, x2, x3, x3…x n x n In the 2N received sequences, the phase codes of two adjacent received sequences are the same, for example, x1, x1, x2. n x n .

[0124] After the radar equipment's transmitting end emits a detection signal with a first waveform, this detection signal encounters an obstacle in the field of view (FOV) and is reflected by the obstacle to form a first echo signal, which returns to the radar equipment's receiving end. The receiving end can sample and process the first echo signal using a preset sampling mode, such as a first sampling mode or a second sampling mode, to obtain a second echo signal with a second waveform. This preset sampling mode is determined based on the receiving end parameters determined in the aforementioned embodiments.

[0125] In some embodiments, the radar device samples the first echo signal to obtain a second echo signal with a second waveform, including: sampling the first echo signal using a first sampling rate to obtain a second echo signal with a second waveform; the first sampling rate is k times the first bandwidth.

[0126] For example, when the receiving sampling rate is fixed, the receiving sampling rate of the receiving end can be fixed to k times the first bandwidth. Alternatively, when the receiving sampling rate is adjustable, the receiving sampling rate can be adjusted to a first integer multiple of the first bandwidth, k1, where k1 = k; and no oversampling is performed, i.e., the oversampling factor β = 1. In this case, the actual sampling rate is the receiving sampling rate, i.e., the aforementioned first sampling rate. In this situation, the radar equipment samples and processes the first echo signal at the first sampling rate.

[0127] In other embodiments, the radar device samples the first echo signal to obtain a second echo signal with a second waveform, including: sampling the first echo signal using a first sampling rate to obtain first sampled data, where the first sampling rate is equal to a first bandwidth; and oversampling the first sampled data using a second sampling rate to obtain a second echo signal with a second waveform, where the second sampling rate is k times the first sampling rate. Oversampling the first echo signal, i.e., the oversampling factor β ≥ 2, means that the actual sampling rate is the received sampling rate plus the oversampling sampling rate. The radar device samples the first echo signal using the actual sampling rate.

[0128] For example, when the receiving sampling rate is fixed, it can be fixed to the first bandwidth. Alternatively, when the receiving sampling rate is adjustable, it can be adjusted to a second integer multiple of the first bandwidth, k2, where k2 < k. In this case, the first sampling rate is the receiving sampling rate. The first echo signal is sampled using the first sampling rate to obtain the first sampled data. Then, the first sampled data is oversampled using the second sampling rate, where the oversampling factor β ≥ 2. In this case, the actual sampling rate is the second sampling rate, which is the receiving sampling rate plus the oversampled sampling rate. In this scenario, the radar equipment samples the first echo signal using the second sampling rate.

[0129] It should be noted that in this embodiment, when the receiving sampling rate at the receiving end is adjustable, the specific adjustment factor of the receiving sampling rate and the corresponding sampling mode can be determined based on user operation. Adjusting the receiving end's sampling rate can determine whether an oversampling step is needed.

[0130] In this embodiment, when the receiving sampling rate is fixed or adjustable, the introduction of oversampling further improves the workflow of the radar equipment. Furthermore, oversampling eliminates the need to adjust the receiving sampling rate, thereby reducing the pre-implementation working time of the algorithm. It should be understood that when the receiving sampling rate meets the range resolution improvement requirement, whether or not oversampling is performed does not affect the range resolution improvement factor, but ω = βk must be satisfied.

[0131] When the receiver of a radar device needs to perform oversampling, it can be done at a preset receiver sampling rate or by using compressed sensing technology.

[0132] In some embodiments, the receiver uses a preset receiver sampling rate to copy the sampled data β times in sequence, thereby obtaining oversampled data with an oversampling factor of β.

[0133] In other embodiments, the receiver employs compressed sensing technology to compress the sampling rate to obtain oversampled data of the target. For example, the receiver uses compressed sensing technology to oversample 512M of data to achieve 1G of oversampled data. Compared to obtaining oversampled data of the target by copying the oversampled data using a preset receiving sampling rate, this method reduces the receiver's sampling rate requirements and further compresses the sampling rate on the receiver hardware while obtaining the oversampled data of the target.

[0134] S404, the radar equipment uses a filter bank to process the second echo signal to obtain the ranging result.

[0135] As described above, the filter bank is a non-uniform length, unmatched filter for the first waveform. This first waveform and the filter bank are correlated, and this correlation refers to the fact that the filter bank is a non-uniform length, unmatched filter for the first waveform. In other words, the filter bank is an unmatched filter for the second waveform. The ranging result obtained after convolving the second waveform with the filter bank exhibits local low sidelobe characteristics. It should be understood that, given the correlation between the first waveform and the filter bank, the second echo signal, obtained by sampling and processing the first echo signal returned by the first waveform's detection signal, also exhibits correlation with the filter bank.

[0136] The radar equipment uses a filter bank to process the second echo signal. Specifically, the radar equipment's processor uses the filter bank to perform convolution operations on the second waveform to obtain the ranging result.

[0137] For example, referring to Figure 6, the processor compares the second echo signal of the second waveform obtained after sampling processing at the receiving end with the filter group h1, h2, h3, h3…h… 2n h 2n-1 Convolution operations are performed to obtain the ranging result. In this ranging result, the radar device has a first minimum resolution range, and the value of the second minimum resolution range is smaller than the value of the first minimum resolution range. This achieves the ability to improve the range resolution of the radar device without changing the transmitter bandwidth. Furthermore, based on the correlation between the filter bank and the first and second waveforms, the ranging result exhibits a relatively high peak at the main lobe center 0, while other local regions at both ends of the main lobe center 0 are suppressed, as shown in the signal range of -100 to 100 in Figure 6, thus exhibiting local low sidelobe characteristics. Compared to global low sidelobe, local low sidelobe characteristics reduce data complexity, making it possible to improve the resolution of the ranging result, and the current computational complexity and amount of computation are conducive to engineering implementation.

[0138] In conjunction with the steps described above, after the radar device's receiver samples the first echo signal, the sampling rate of the receiver is improved. Under the corresponding receiver parameters, the second echo signal has a special waveform structure, namely, the phase codes of adjacent ω received sequences in the second waveform are the same. When the radar device's receiver includes multiple receiving antennas, such as m antennas, each receiving antenna receives the echo signal and samples it in its own independent receiving channel to obtain the second echo signal of the second waveform, as shown in Figure 7. At this time, the radar device's processor uses an unmatched, non-equal-length filter corresponding to the first waveform to process the second echo signal of the second waveform to obtain the ranging result. In this case, without considering carrier limitations, the sequence length based on the filter bank is determined according to the sampling rate corresponding to the specific sampling mode of the receiver. That is, the filter sequence of the filter bank is designed according to the actual sampling rate of the sampling mode. Therefore, the actual sampling rate of the receiver determines the range resolution rather than the first bandwidth of the transmitter. The formula for calculating the range resolution is: Among them, f s This represents the actual sampling rate.

[0139] Essentially, the phase codes of adjacent ω received sequences in the second waveform of the second echo signal are the same. Therefore, the degree of freedom of this second waveform is slightly low because every n phase codes are the same. The degree of freedom of both the second echo signal and the filter bank is mainly reflected in the unmatched filter. Under a certain degree of freedom, the ranging result can have the characteristic of local low sidelobes, and the degree of freedom of the unmatched filter can meet this requirement. In addition, the generalized ambiguity function of the second waveform and the unmatched filter has the characteristic of local low sidelobes. Compared with global low sidelobes, local low sidelobes usually achieve even lower sidelobes. Only this special waveform structure and the corresponding unmatched filter have the characteristic of local low sidelobes of the generalized ambiguity function. When the transmitter transmits detection signals with different waveforms, combined with oversampling at the receiver, the target echo has a special waveform form. The ranging result can not only meet the super-resolution requirements but also exhibit local low sidelobes, thereby improving the range resolution.

[0140] The ranging method provided in this embodiment is an algorithmic approach that, combined with the system framework of radar equipment, improves ranging resolution without requiring an increase in the transmitter bandwidth. It utilizes a detection signal with a first waveform generated by the server and a corresponding non-uniform, non-matched filter bank to achieve this resolution. The sampling rate at the receiver can be adjusted according to specific ranging requirements. By adjusting the receiver's operating mode, the sampling rate for the second echo signal is increased by a certain bandwidth multiple. This transforms the range resolution determination process from being based on the transmitter's bandwidth to being determined by the receiver's sampling rate for the second echo signal, thus transferring the cost of improved range resolution. The actual range resolution is improved through the correspondence between the first waveform and the non-uniform, non-matched filter bank.

[0141] The following specific examples will be used to explain in detail the generation of the first waveform at the transmitting end and the filter bank at the receiving end of the radar device provided in this embodiment, as well as the process of the radar device performing ranging based on the generated first waveform and filter bank.

[0142] Example 1

[0143] Taking the task of accurately locating indoor people in the first scenario as an example, this paper provides a detailed explanation of the ranging process of indoor people by radar equipment according to the ranging method provided in this embodiment.

[0144] (1) Determine the scene value and transmitter parameters of the first scene in the waveform parameters.

[0145] Scene value:

[0146] The maximum detection distance R is 10m; the maximum indoor speed v is 5m / s.

[0147] Transmitter parameters:

[0148] The transmission carrier frequency is 24GHz, the first bandwidth B is 250MHz, the number of transmission antennas is 4, and the transmission signal transmitted by each transmission antenna is a different waveform, that is, the number of waveforms is 4.

[0149] (2) Determine the algorithm-level parameters and receiver parameters based on the scenario values ​​and transmitter parameters.

[0150] In this embodiment, the receiver does not perform oversampling, i.e., the oversampling factor β = 1, and the expected improvement factor of the distance resolution k is 2, i.e., k = 2. Therefore, the sampling rate of the receiver can be fixed at f. s =Bk=2×250MHz=500MHz, that is, the actual sampling rate is 500MHz.

[0151] The number of identical waveform codes ω: According to the formula ω=βk, the number of identical waveform codes at the algorithm level can be determined, ω=2.

[0152] Transmit sequence length N: The length of the transmitted sequence in the transmitted waveform, i.e., the code length N of the transmitted waveform, where N = 60. The receiver filter sequence length, N, can be determined based on the transmitted sequence length and the actual sampling rate. h =kN=2N=120.

[0153] Based on the above parameters, the algorithm-level parameters in Table 1 below can be determined.

[0154] Table 1

[0155] Referring to Table 1 above, if we assume the length of the transmitted sequence in the transmitted waveform is N = 60, then the length of the filtered sequence in the filtered waveform of the filter bank is N. h =120; where, based on the farthest detection distance in the first scene, the improvement factor of distance resolution, and the maximum indoor velocity, the range of low sidelobe for distance is determined to be -36≤a≤36, and the range of low sidelobe for velocity is -1≤b≤1; the main lobe ratio d is set to 0.7.

[0156] (3) The server runs offline the program code written according to the algorithm level parameters to obtain the waveform set of the first waveform and the non-equal length unmatched filter group corresponding to each waveform.

[0157] Specifically, the server uses the algorithm-level parameters in Table 1 as input parameters, runs the program code written according to the algorithm-level parameters, and uses the optimization algorithm to generate the corresponding probe signal with the first waveform and the filter bank that is not of equal length and not matched with the first waveform for the target loss function.

[0158] It should be noted that in this example, the radar device has four transmitting antennas, and as shown in Table 1 above, the number of waveforms P is four. This means that the four transmitting antennas at the transmitting end need to transmit detection signals of different waveforms. Based on this, when generating the transmitted waveforms, the server generates a set of transmitted waveforms and a set of non-equal-length unmatched filter banks corresponding to each transmitted waveform in the set, as shown in Table 2 below.

[0159] Table 2

[0160] In this embodiment, the process of generating the transmission waveform at the radar device's transmitter and the filter bank at the processor side on the server side—that is, generating the transmission waveform and filter bank by running an algorithm on the server outside the radar device—occurs before the entire ranging process of the radar device and only requires one calculation. Normally, the entire process of generating the transmission waveform and filter bank by running an algorithm requires significant computing power. By using a server with high computing power to generate the transmission waveform and filter bank in advance, the radar device can directly use them during ranging. Compared to the traditional method of performing calculations in the radar device's processor, where each calculation is twenty to thirty times more computationally intensive, the computational load on the processor is significantly reduced in this embodiment.

[0161] It should be noted that if the frequency band of the transmitting antenna changes or the operating mode is adjusted, the transmitting waveform and filter bank need to be regenerated.

[0162] (4) The process of radar equipment performing ranging.

[0163] Transmitter: The first bandwidth B is 250MHz, the transmission carrier frequency is 24GHz, and the transmission server generates a detection signal with the first waveform.

[0164] As mentioned earlier, in this example, the number of transmitting antennas is 4, and the number of transmitted waveforms is 4, that is, each transmitting antenna transmits a detection signal with a different transmitted waveform.

[0165] At the receiving end: using a sampling rate of twice the first bandwidth, i.e., 500MHz, the first echo signal returned by the probe signal corresponding to the transmitted waveform is received in the receiving channel of each independent receiving antenna, resulting in four second echo signals with the second waveform.

[0166] It should be noted that the ranging method provided in this embodiment is applicable to the process of signal transmission and reception by the transmitting and receiving antennas of radar equipment in various operating modes, such as MIMO mode or general mode. Specific settings can be configured according to specific needs, and this embodiment does not impose any limitations. Assuming that the receiving antenna of the radar equipment transmits and receives signals in a single mode, that is, the receiving antenna only receives the detection signal transmitted by the corresponding transmitting antenna, then the receiving antenna receives the first echo signal and performs sampling processing as shown in Table 3 to obtain the corresponding second echo signal.

[0167] Table 3

[0168] Processor: The second echo signal is subjected to unmatched filtering using filter banks corresponding to each waveform to obtain the ranging result. Figure 8 shows the processing procedure for a set of second echo signals. As can be seen from Figure 8, after convolutional estimation of the second echo signal of the second waveform using unmatched filtering, the resulting ranging result has two distinct ranging peaks. The interval between these two ranging peaks is 0.3 cm, and there are local low sidelobes in the range of -36 to 36 on both sides of the two ranging peaks.

[0169] In this embodiment, the receiving end obtains a second echo signal with a special phase-coded signal format similar to that in Figure 8 after sampling the first echo signal. The second echo signal has a good correlation with the unmatched filter bank. Then, based on the excellent cross-correlation performance between the second echo signal and the unmatched filter bank, super-resolution ranging is achieved.

[0170] It should be noted that in this embodiment, the range resolution enhancement factor k depends on the ratio of the filter sequence length of the filter bank to the transmission sequence length of the probe signal, and can be an integer or a non-integer; while the oversampling factor needs to be set to an integer. If a non-integer super-resolution factor is required when β is an integer, it can be achieved by configuring the actual receiving sampling rate.

[0171] The ranging method provided in this embodiment enables super-resolution ranging of 0.3m within a test distance of up to 10m, even in a scenario with a first distance resolution of 0.6m. It should be understood that in the ranging process of radar equipment, velocity and angle measurement are independent of the ranging process. Furthermore, the entire ranging process provided in this embodiment does not require coupling with physical quantities related to velocity and angle measurement, thus having no substantial impact on other positioning operations such as velocity and angle measurement. Additionally, based on the simultaneous setting of a low-sidelobe velocity range in the waveform parameters, the ranging result can be further optimized for subsequent velocity measurement performance.

[0172] Meanwhile, for the ranging process itself, this ranging method does not require additional complex operations. It only performs convolution calculations (mismatch filtering) on ​​the processor side, relying on the design of the transmitted waveform and the filter waveform on the processor side to achieve super-resolution ranging, which can reduce the computational burden of ranging complexity for the radar equipment itself. In addition, calculations have shown that the traditional radar equipment's approach of using a pure algorithm on the processor to improve ranging capability based on the original waveform and matched filtering has very high requirements in terms of computing power and computational load. The computational load of a traditional ranging capability improvement is equivalent to performing three Fourier transforms of length 2N. The joint design scheme of the transmitted waveform and the corresponding non-equal-length unmatched filter bank proposed in this embodiment to achieve super-resolution ranging has significant advantages in terms of computational complexity and engineering feasibility.

[0173] Example 2

[0174] Similarly, taking the task of accurately locating indoor people in the first scenario as an example, specifically involving the oversampling process at the receiving end, the radar equipment measures the distance of indoor people according to the ranging method provided in this embodiment.

[0175] (1) Determine the scene value and transmitter parameters of the first scene in the waveform parameters.

[0176] Scene value:

[0177] The maximum detection distance R is 10m; the maximum indoor speed v is 5m / s.

[0178] Transmitter parameters:

[0179] The transmission carrier frequency is 24GHz, the first bandwidth B is 250MHz, the number of transmission antennas is 4, and the transmission signal transmitted by each transmission antenna is a different waveform, that is, the number of waveforms is 4.

[0180] (2) Determine the algorithm-level parameters and receiver parameters based on the scenario values ​​and transmitter parameters.

[0181] In this embodiment, oversampling is performed at the receiving end. The oversampling factor β can be a number greater than 1, and is set to a maximum of 2, meaning a maximum oversampling factor of 2. The desired improvement in distance resolution k is a super-resolution of 2-4 times, i.e., k=2 or k=4; and the receiving sampling rate at the receiving end is variable, divided into f s =Bk=2×250MHz=500MHz, and f s=Bk = 4 × 250MHz = 1GHz. When k = 2, the receiver uses a sampling rate of 500MHz with a 2x oversampling, resulting in an actual sampling rate of 1GHz. When k = 4, the receiver uses a sampling rate of 1GHz without oversampling, also resulting in an actual sampling rate of 1GHz. That is, as described above, when the sampling rate is sufficient to improve the distance resolution by a factor, whether or not oversampling is performed does not affect the improvement factor.

[0182] The number of identical waveform codes at the receiving end, ω: According to the formula ω=βk, since the waveform is generated only once, the number of identical waveform codes at the algorithm level can be determined to be ω=4.

[0183] Transmitted sequence waveform code length N: where N = 60. The receiver filter sequence length, N, can be determined based on the transmitted sequence length and the actual sampling rate. h =2N=120, or N h =4N=240. The following content uses N as the reference. h For example, 4N = 240.

[0184] Based on the above parameters, the algorithm-level parameters in Table 4 below can be determined.

[0185] Table 4

[0186] Referring to Table 1 above, if we assume the length of the transmitted sequence in the transmitted waveform is N = 60, then the length of the filtered sequence in the filtered waveform of the filter bank is N. h =240; where, based on the farthest detection distance in the first scene, the improvement factor of distance resolution, and the maximum indoor velocity, the range of low sidelobe for distance is determined to be -72≤a≤72, and the range of low sidelobe for velocity is -1≤b≤1; the main lobe ratio d is set to 0.7.

[0187] (3) The server runs offline the program code written according to the algorithm level parameters to obtain the waveform set of the first waveform and the non-equal length unmatched filter group corresponding to each waveform.

[0188] Specifically, the server uses the algorithm-level parameters in Table 4 as input parameters, runs the program code written according to the algorithm-level parameters, and uses the optimization algorithm to generate the corresponding detection signal with the first waveform and the result of the filter bank that is not of equal length and not matched with the first waveform for the target loss function.

[0189] (4) The process of radar equipment performing ranging.

[0190] Transmitter: The first bandwidth B is 250MHz, the transmission carrier frequency is 24GHz, and the transmission server generates a detection signal with the first waveform.

[0191] As mentioned earlier, in this example, the number of transmitting antennas is 4, and the number of transmitted waveforms is 4, that is, each transmitting antenna transmits a detection signal with a different transmitted waveform.

[0192] Receiver: Using 2 or 4 times (adjustable) the first bandwidth as the sampling rate, and combining 2 times oversampling and no oversampling respectively, the receiver channel of each independent receiving antenna receives the first echo signal returned by the probe signal with different transmitted waveforms, and obtains 4 second echo signals with second waveforms.

[0193] The processor uses filter banks corresponding to each waveform to perform unmatched filtering on the second echo signal to obtain the ranging result. After the processor performs convolution calculation on the second echo signal of the second waveform using unmatched filtering, the resulting ranging result has two obvious ranging peaks. The interval between the two ranging peaks is 0.3 or 0.15 cm, and there are local low sidelobes in the range of -72 to 72 on both sides of the two ranging peaks.

[0194] Similarly, using the ranging method provided in this embodiment, in a scenario with a first distance resolution of 0.6m, super-resolution ranging of 0.15m or 0.3m can be achieved within a test distance of up to 10m. Furthermore, it has no fundamental impact on other positioning tasks such as velocity and angle measurement; the main impact is on the increased complexity of the ranging process itself. Calculations show that the computational cost of performing one standard ranging operation is equivalent to performing three Fourier transforms of length 2N or 4N.

[0195] The ranging method provided in this embodiment reduces algorithm design costs. The entire process only requires the server to generate a set of waveforms and a non-uniform length unmatched filter bank offline. Combined with the variable sampling rate at the receiver, different ranging resolution requirements can be met without introducing additional ranging calculations. Furthermore, this method can be used on a single device in multiple scenarios. In scenarios where ultra-high distance resolution is not required, using a lower sampling rate (i.e., the same as the sampling rate in Example 1) combined with oversampling (2x oversampling) can reduce the workload on the device's processor. When ultra-high distance resolution is required, this can be achieved through mode switching, that is, switching the mode to the mode corresponding to a larger multiple of the receiver's sampling rate.

[0196] It should be noted that the method provided in this embodiment is an improvement process that satisfies the Rayleigh limit in hardware. Based on this improvement in distance resolution, super-resolution algorithms such as matrix feature space decomposition (multiple signal classification algorithm, MUSIC) and neural networks can be superimposed to further improve the distance resolution.

[0197] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0198] This application also provides a ranging device for use in radar equipment. The radar equipment has a first bandwidth. As shown in FIG9, the device includes a transmitter 901, a receiver 902, a sampling module 903, and a processor 904.

[0199] The transmitter 901 is used to transmit a probe signal with a first waveform within a first bandwidth.

[0200] The receiver 902 is used to receive the first echo signal, which is the signal returned after the detection signal encounters an obstacle.

[0201] The sampling module 903 is used to sample and process the first echo signal to obtain a second echo signal with a second waveform; the sampling rate of the second echo signal is k times the first bandwidth, where k≥1.

[0202] Processor 904 is used to process the second echo signal using a filter bank to obtain the ranging result. The filter bank is a non-equal length unmatched filter for the first waveform.

[0203] This application also provides a radar device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the ranging method shown in the above embodiments.

[0204] This application also provides a chip, as shown in FIG10, which includes a processor and a memory. The memory stores a computer program, which, when executed by the processor, implements the ranging methods in the above embodiments.

[0205] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the ranging methods provided in the above embodiments.

[0206] This application also provides a computer program product, which includes a computer program that, when run by an electronic device, enables the electronic device to implement the ranging methods provided in the above embodiments.

[0207] It should be understood that the processor mentioned in the embodiments of this application 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.

[0208] It should also be understood that the memory mentioned in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DRRAM).

[0209] In the embodiments provided in this application, the division of each framework or module is only a logical functional division. In actual implementation, there may be other division methods. For example, multiple frameworks or modules may be combined or integrated into another system, or some features may be ignored or not executed.

[0210] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0211] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0212] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., 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.

[0213] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A distance measurement method, characterized in that, Applied to a radar device having a first bandwidth, the method includes: A probe signal with a first waveform is transmitted within the first bandwidth; Receive the first echo signal, which is the signal returned by the detection signal after it encounters an obstacle; The first echo signal is sampled to obtain a second echo signal with a second waveform; the sampling rate of the second echo signal is k times the first bandwidth, where k≥1; The second echo signal is processed using a filter bank to obtain the ranging result. The filter bank is a non-equal length unmatched filter for the first waveform.

2. The method according to claim 1, characterized in that, The step of sampling the first echo signal to obtain a second echo signal with a second waveform includes: The first echo signal is sampled and processed using a first sampling rate to obtain a second echo signal with the second waveform; the first sampling rate is k times the first bandwidth.

3. The method according to claim 1, characterized in that, The step of sampling the first echo signal to obtain a second echo signal with a second waveform includes: The first echo signal is sampled and processed using a first sampling rate to obtain first sampled data, wherein the first sampling rate is equal to the first bandwidth. The first sampled data is oversampled using a second sampling rate to obtain a second echo signal with the second waveform. The second sampling rate is k times the first sampling rate.

4. The method according to any one of claims 1-3, characterized in that, The first waveform includes N transmission sequences, each of which has a different phase code, and N is a positive integer.

5. The method according to claim 4, characterized in that, The phase codes of each sequence in the transmission sequence are different, including: The phase and amplitude of each sequence in the transmission sequence are different, and each sequence includes W symbols, where W refers to the adjustable number of each phase and amplitude.

6. The method according to claim 4 or 5, characterized in that, The second waveform includes ω*N received sequences, wherein the phase codes of each adjacent ω received sequences are the same, where ω≥2 and is a positive integer.

7. The method according to claim 6, characterized in that, When oversampling the first echo signal, the oversampling factor β and the number of identical phase codes ω in the received sequence satisfy ω = βk, where k ≤ ω.

8. The method according to claim 7, characterized in that, The filtered waveforms of the filter bank include k*N filter sequences.

9. The method according to any one of claims 1-8, characterized in that, The process of using a filter bank to process the second echo signal to obtain the ranging result includes: The ranging result is obtained by convolution calculation using the filter bank and the second waveform, wherein the main lobe ratio of the filter bank to the first waveform is d, and 0.6≤d≤1; under the main lobe ratio, the ranging result has the characteristic of local low sidelobes.

10. The method according to any one of claims 1-9, characterized in that, When the radar device executes the method in the first scenario, the generation methods of the first waveform detection signal and the filter bank include: The algorithm-level parameters are determined based on the scene values ​​in the first scenario and the transmitting parameters of the radar device. Run the program code written according to the algorithm level parameters, and use the optimization algorithm to generate the probe signal of the first waveform and the filter bank for the objective function; The scenario values ​​include the farthest detection distance and the maximum indoor speed; the transmitter parameters include the transmission carrier frequency, bandwidth, number of transmission antennas, and transmission sequence length; the algorithm-level parameters include the filter sequence length, number of symbols, low-sidelobe range for distance, low-sidelobe range for velocity, and main lobe ratio.

11. The method according to claim 10, characterized in that, The first waveform transmission signal and the filter bank are generated by the server in advance by running program code written according to the algorithm level parameters, using an optimization algorithm for the objective function, and then preset in the radar device.

12. The method according to any one of claims 10-11, characterized in that, Before transmitting the probe signal with the first waveform under the first bandwidth, the method further includes: Based on the scene value in the first scenario and the transmitting parameters of the radar device, the receiving parameters are determined, wherein the receiving parameters include the receiving sampling rate, the oversampling factor, the receiving sequence length, and the number of waveform codes.

13. The method according to claim 12, characterized in that, The sampling process for the first echo signal includes: The first echo signal is sampled using the receiving end parameters so that the sampling rate of the second echo signal is k times the first bandwidth.

14. The method according to any one of claims 1-13, characterized in that, The method further includes: The ranging results are processed by superimposed matrix feature space decomposition or super-resolution algorithm of neural network.

15. The method according to any one of claims 1-14, characterized in that, The radar equipment includes ultra-wideband radar or frequency-modulated continuous wave radar.

16. A ranging device, characterized in that, Applied to radar equipment having a first bandwidth, the device includes: The transmitting end is used to transmit a probe signal having a first waveform within the first bandwidth; The receiving end is used to receive the first echo signal, which is the signal returned by the detection signal after it encounters an obstacle; The sampling module is used to sample the first echo signal to obtain a second echo signal with a second waveform; the sampling rate of the second echo signal is k times the first bandwidth, where k≥1; The processor is configured to process the second echo signal using a filter bank to obtain a ranging result, wherein the filter bank is a non-equal length unmatched filter for the first waveform.

17. A radar device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the ranging method as described in any one of claims 1-15.

18. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the ranging method as described in any one of claims 1-15.

19. A chip, characterized in that, The chip includes a processor and a memory, the memory storing a computer program that, when executed by the processor, implements the ranging method as described in any one of claims 1-15.

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