Inter-frame phase compensation and target detection methods, apparatuses, devices, and integrated circuits

Abstract

An inter-frame phase compensation and target detection method, device, component and integrated circuit, which can be applied to the field of radar signal processing, can reduce the inter-frame phase difference, reduce the false alarm rate, improve the performance of target detection, and make special targets or weak targets such as infants in the cabin can also be accurately detected, which can be applied to scenes such as child forgetting detection systems, safety belt reminding devices and the like.

Description

[0001] Cross-references to related applications

[0002] This disclosure claims priority to Chinese Patent Application No. 202411740580.8, filed with the China National Intellectual Property Administration on November 28, 2024, entitled “Signal Processing Method and Apparatus for Antenna Array, Integrated Circuit, Radio Device and Equipment”, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to, but is not limited to, radar signal processing technology, and more specifically, to an inter-frame phase compensation and target detection method, apparatus, device, and integrated circuit. Background Technology

[0004] Radar technology has been applied to intelligent cabins in automobiles, for example, to achieve target detection inside the cabin based on inter-frame accumulation, and to achieve target detection inside the cabin based on inter-frame phase of 1D-FFT data, but the performance of these solutions still needs to be improved. Summary of the Invention

[0005] To address the aforementioned technical problems, this disclosure provides an inter-frame phase compensation method, a target detection method, a device, an integrated circuit, an electromagnetic wave sensor, and an equipment, which can be applied to radar systems. By compensating for the inter-frame phase of 1D-FTT data (i.e., range-dimensional FFT data), the inter-frame phase difference can be reduced, the false alarm rate can be lowered, and the target detection performance can be improved. This enables the accurate detection of special or weak targets such as infants and young children inside the cabin. It can be applied to scenarios such as Child Presence Detection (CPD) and Safety Belt Reminder (SBR).

[0006] One embodiment of this disclosure provides an inter-frame phase compensation method, comprising: performing the following inter-frame phase compensation processing on at least one channel of a radar system: for each frame to be compensated in N frames, determining the phase compensation coefficient of the channel in the frame based on the phase information of the channel and the reference phase information in the frame, and performing phase compensation on the 1D-FFT data of the channel in the frame based on the phase compensation coefficient; wherein, the phase information of the channel in the frame is determined based on the 1D-FFT data of the channel in the frame on the first range cell, and N is a positive integer greater than or equal to 2.

[0007] It should be noted that the radar system in this embodiment can be an electromagnetic wave radar device such as a millimeter-wave radar, or an electromagnetic wave device such as an ultra-wideband (UWB) device operating in radar mode. In other embodiments, the radar system in this embodiment can also be an electromagnetic wave device operating in scenarios such as positioning mode and requiring inter-frame phase alignment.

[0008] Optionally, the inter-frame phase compensation method in this embodiment can be applied to scenarios where inter-frame phase difference is caused by non-distance factors, such as inter-frame phase difference caused by sampling time jitter.

[0009] An embodiment of this disclosure also provides an inter-frame phase compensation device applied to a radar system, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it can implement the inter-frame phase compensation method described in any embodiment of this disclosure.

[0010] An embodiment of this disclosure also provides a target detection method, comprising: performing inter-frame phase compensation on N frames of 1D-FFT data with M channels obtained based on electromagnetic wave signals received by a radar system, where M≥1 and N≥2, according to the inter-frame phase compensation method described in any embodiment of this disclosure; and performing target detection based on the N frames of 1D-FFT data with M channels after inter-frame phase compensation.

[0011] An embodiment of this disclosure also provides another target detection method, including: acquiring 1D-FFT data; performing inter-frame phase compensation based on a single coefficient on at least two frames of acquired 1D-FFT data, using the same phase compensation coefficient for 1D-FFT data of the same channel in the same frame at different distance units; and estimating vital signs based on at least two frames of 1D-FFT data after inter-frame phase compensation to achieve target detection.

[0012] An embodiment of this disclosure also provides another target detection method, comprising: acquiring an echo signal; the echo signal comprising at least two signal groups, each signal group comprising multiple signal units, and the time interval between adjacent signal units in the same signal group being less than the time interval between adjacent signal groups; performing intra-unit FFT processing on the signal units in the echo signal to obtain 1D-FFT data; performing phase compensation on the 1D-FFT data between different signal groups based on Doppler data, and then removing zero Doppler; and performing inter-group FFT processing on the 1D-FFT data after removing zero Doppler to obtain 2D-FFT data; wherein the 2D-FFT data is configured for target detection.

[0013] An embodiment of this disclosure also provides a target detection device applied to a radar system, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it can implement the target detection method described in any embodiment of this disclosure.

[0014] An embodiment of this disclosure also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it can implement the inter-frame phase compensation method described in any embodiment of this disclosure, or the target detection method described in any embodiment of this disclosure.

[0015] One embodiment of this disclosure also provides an integrated circuit, including a radio frequency module, an analog signal processing module, and a digital signal processing module connected in sequence; the radio frequency module is configured to generate and transmit electromagnetic wave signals, and receive electromagnetic wave signals; the analog signal processing module is configured to down-convert the received electromagnetic wave signals to obtain an intermediate frequency signal; the digital signal processing module is configured to perform analog-to-digital conversion on the intermediate frequency signals to obtain a digital signal; wherein, the digital signal processing module is further configured to perform inter-frame phase compensation based on the inter-frame phase compensation method described in any embodiment of this disclosure, or to perform target detection based on the target detection method described in any embodiment of this disclosure.

[0016] An embodiment of this disclosure also provides an electromagnetic wave device, comprising: a carrier; an integrated circuit as described in any embodiment of this disclosure, disposed on the carrier; and an antenna, disposed on the carrier, integrated with the integrated circuit as a single device or disposed separately; wherein the integrated circuit is connected to the antenna and is used to transmit the electromagnetic wave signal and / or receive the electromagnetic wave signal.

[0017] An embodiment of this disclosure also provides a terminal device, including: a device body; and an electromagnetic wave device disposed on the device body as described in any embodiment of this disclosure; wherein the electromagnetic wave device is configured to perform target detection and / or communication to provide reference information to the operation of the device body.

[0018] Other features and advantages of this disclosure will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the disclosure. Other advantages of this disclosure may be realized and obtained by means of the embodiments described in the description, claims, and drawings. Attached Figure Description

[0019] The accompanying drawings are provided to illustrate the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure. The shapes and sizes of the components in the drawings do not reflect actual proportions and are only intended to illustrate the content of this disclosure.

[0020] Figure 1 This is a schematic diagram of an exemplary radar system according to one embodiment;

[0021] Figure 2 This is a structural diagram of an exemplary radar system according to one embodiment;

[0022] Figure 3 This is a schematic diagram of electromagnetic waves emitted by a radar system in one embodiment;

[0023] Figure 4 This is a schematic diagram of the processing flow of an in-cabin detection scheme based on inter-frame accumulation according to an embodiment of this disclosure;

[0024] Figure 5 This is a schematic diagram of multi-frame 1D-FFT data according to an embodiment of this disclosure;

[0025] Figure 6A This is a schematic diagram of inter-frame phase change according to an embodiment of the present disclosure. Figure 6B yes Figure 6A A schematic diagram illustrating the relationship between inter-frame phase difference and frame number;

[0026] Figures 7A to 7D These are the execution steps when there is an inter-frame phase difference. Figure 4 A schematic diagram of the RD patterns on the four channels obtained by the scheme shown;

[0027] Figure 8 This is a flowchart of an embodiment of the inter-frame phase compensation method disclosed herein;

[0028] Figure 9 This is a flowchart of a target detection method according to an embodiment of the present disclosure;

[0029] Figure 10 This is a schematic diagram of an inter-frame phase detection device according to an embodiment of the present disclosure;

[0030] Figure 11 This is a block diagram of an integrated circuit according to an embodiment of the present disclosure;

[0031] Figure 12 This is a schematic diagram of an electromagnetic wave device according to an embodiment of the present disclosure;

[0032] Figure 13 This is a flowchart of another embodiment of the target detection method disclosed herein;

[0033] Figure 14This is a flowchart of another embodiment of the target detection method disclosed herein. Detailed Implementation

[0034] This disclosure describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that more embodiments and implementations are possible within the scope of the embodiments described herein.

[0035] In the description of this disclosure, words such as "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment described as "exemplary" or "for example" in this disclosure should not be construed as being more preferred or advantageous than other embodiments. The word "and / or" in this document describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. "Multiple" refers to two or more. Furthermore, to facilitate a clear description of the technical solutions of the embodiments of this disclosure, the terms "first" and "second" are used to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that "first" and "second" do not necessarily imply differences.

[0036] In describing representative exemplary embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Furthermore, the claims relating to the method and / or process should not be limited to the steps performed in the order written, and those skilled in the art will readily understand that these orders may be varied and still remain within the spirit and scope of the embodiments disclosed herein.

[0037] With the popularization of the concept of intelligent cockpits in automobiles, many related applications have emerged, such as CPD (Car Safety Device). CPD is a vehicle safety technology designed to prevent children (including infants and toddlers) from being trapped in vehicles and dying from heatstroke. It can determine the presence of living beings inside the vehicle by detecting heartbeat, breathing, movement, or other vital signs. CPD can be implemented based on onboard millimeter-wave radar.

[0038] Figure 1A radar system 100 applicable to embodiments of this disclosure is illustrated, taking a frequency-modulated continuous wave (FMCW) millimeter-wave radar as an example. The radar system 100 includes a radio frequency (RF) chip 110, a transmitting antenna 120, a receiving antenna 130, and a main processing chip 140. The RF chip 110 is configured to generate a detection signal and transmit it through the transmitting antenna array 120. The detection signal can be an FMCW electromagnetic wave signal. Multiple transmitting antennas 120 are connected to the RF chip 110 and can form a transmitting antenna array, configured to transmit the detection signal. Multiple receiving antennas 130 are configured to receive the echo signal formed by the detection signal reflected by a target (i.e., the object being detected, the target object, hereinafter referred to as the target). The main processing chip 140 is connected to the receiving antenna array 130 and the RF chip 110, configured to process the echo signal obtained by the receiving antenna array 130 to obtain information such as the target's distance, velocity, and angle. In one example, the transmitting antenna 121 and the receiving antenna 131 can be integrated with the RF chip 110 to form an RF transceiver chip, which, together with the main processing chip 140, constitutes a radar signal transceiver processing system. In another example, the RF chip 110 and the main processing chip 140 can be integrated into a single SoC chip, enabling the transmission, reception, and processing of RF signals through a single chip. The transmitting and receiving antennas can also be integrated with this SoC chip to form an AiP chip or AoC chip structure, etc.

[0039] The integrated or separate radio frequency chip 110 and main processing chip 140 constitute the integrated circuit in the radar system. This integrated circuit, transmitting antenna, and receiving antenna can be mounted on a carrier, together forming an electromagnetic wave sensor. This electromagnetic wave sensor can be installed inside a vehicle cabin, for example, one or more on the roof. Each electromagnetic wave sensor can be used to detect one or two rows of seats within the cabin. When using the electromagnetic wave sensor for CPD detection, the region of interest can be set to the area where the person is most likely to be seated and the floor area. A distance range can be preset based on the distance from the seat and floor to the electromagnetic wave sensor. The distance cells within the preset distance range in 1D-FFT data, 2D-FFT data, or range-Doppler images are used as the distance cells of interest and processed accordingly.

[0040] Figure 2The radar system shown here, which can be used in this embodiment, includes a transmitting antenna 11, a power amplifier 21, a signal generator 23, a receiving antenna 13, a low-noise amplifier 31, a mixer 33, an analog-to-digital converter (ADC) module 41, and a digital signal processing module 51. The signal generator 23 can be a millimeter-wave generator implemented with an oscillator. The detection signal generated by the signal generator 23 is amplified by the power amplifier 21 and then transmitted through one or more transmitting antennas 11. The radar system typically transmits a series of chirps in frames. The detection signal transmitted by the FMCW-based radar system can use... Figure 3 The sawtooth waveform shown includes multiple chirp signals per frame. Each chirp signal includes an up-modulation band, a down-modulation band, and a frequency hold band. The period of the chirp signal is Tc. The signal transmission channel of the radar system consists of devices such as a signal generator 23 and a power amplifier 21.

[0041] The detection signal is reflected and / or refracted by the target to form an echo signal. The receiving antenna 13 amplifies the received echo signal through a low-noise amplifier 31, and then mixes it with the corresponding local oscillator signal in a mixer 33 to obtain an intermediate frequency (IF) signal. There are usually multiple receiving antennas 13. The signal channel of the radar system is composed of components such as the low-noise amplifier 31 and the mixer 33. The IF signal is sent to the analog-to-digital converter (ADC) 41 for sampling, and the resulting digital signal is further processed in the digital signal processing module 51. This includes performing range-dimensional FFT and Doppler-dimensional (i.e., velocity-dimensional) FFT to obtain the range-Doppler spectrum, or RD spectrum, of the digital signal. Based on the RD spectrum, the target's range, velocity, and direction of arrival are detected to achieve target judgment, location, and identification. Digital signal processing can also include windowing, clustering, digital beamforming (DBF), etc.

[0042] One embodiment provides an in-cabin detection scheme (hereinafter referred to as Scheme A) based on inter-frame accumulation for detecting personnel inside the cabin. Figure 4 As shown, the digital signals from multiple channels sampled by the ADC are processed using 1D. The resulting 1D-FFT data is buffered and accumulated to a predetermined number of frames, such as 128 frames, of distance-dimensional FFT data. Then, multi-frame correlation 2D processing is performed. This 2D processing includes inter-frame FFT performed after accumulating multiple frames of 1D-FFT data. The multi-frame 1D-FFT data can be found in [reference needed]. Figure 5The example in the figure has multiple channels, with the 1D-FFT data from each channel arranged into a matrix. In the figure, the horizontal axis of this matrix represents the frame arrangement direction, corresponding to the Doppler dimension; the vertical axis represents the range bin arrangement direction, corresponding to the range dimension. The figure shows 128 frames of 1D-FFT data, with each small square representing a single 1D-FFT data point, which is complex data with phase information. This scheme detects targets within a specified range, i.e., the region of interest, which can be defined based on the distance between the target's likely location and the radar system. The figure only shows a portion of the range bins within the specified range on the range dimension; these are referred to as the specified partial range bins in the text. This example uses range bins with indices from 5 to 20.

[0043] like Figure 4 As shown, this embodiment obtains the RD map through inter-frame FFT, and then has two processing branches. The detection branch sequentially performs single-input single-output fusion (SISO-combine), constant false alarm rate (CFAR) detection with peak selection, deep breathing force (DBF), and post-processing (such as target judgment, localization, and identification) on the RD map to obtain the detection result, such as the detection result of CPD. The classification branch performs 6-point DBF on the RD map and then feeds it into a convolutional neural network (CNN) model for target classification, such as distinguishing between adults and children, and outputs the classification result. This embodiment takes into account the characteristics of target movement in CPD or similar scenarios (such as the low-speed and repetitive nature of human breathing movements) and uses inter-frame FFT instead of traditional chirp-to-interval FFT, which can more effectively accumulate personnel breathing signals and improve the detection capability of targets inside the cabin.

[0044] Another embodiment provides an in-cabin detection scheme based on inter-frame phase of 1D-FFT data (hereinafter referred to as Scheme B). This scheme extracts the phase of 1D-FFT data on the distance cell where the suspected target is located, and detects and identifies key features of personnel based on the extracted feature data.

[0045] Figure 6AThis diagram illustrates the inter-frame phase variation of radar received data in the target detection scheme based on inter-frame range dimension data, when using software timing. The horizontal axis represents the frame index, and the vertical axis represents the inter-frame phase difference in degrees. Points in the diagram indicate the difference between the initial phase of the corresponding frame and the initial phase of the first frame. Since the phase measurement for each frame is performed in reverse relative to the stationary angle in the anechoic chamber, ideally, the initial phases of different frames should be the same, with an inter-frame phase difference of 0. However, tests show that using software timing for transmission and reception causes the initial phase of the received data to continuously change. Figure 6B As shown in the figure, the horizontal axis represents the phase difference in degrees, and the vertical axis represents the number of frames. It can be seen from the figure that the phase change between frames can reach approximately ±10 degrees.

[0046] The difference in initial phase between different frames will introduce unwanted phase differences into the FFT data sampled from different frames. These phase differences will affect the judgment, localization, and identification of targets. For example... Figures 7A to 7D As shown, in the presence of inter-frame phase difference, radar collects data in an empty vehicle scenario and executes Scheme A above. After completing the inter-frame FFT, the resulting RD map is obtained. The horizontal axis represents the frame doppler bin number, and the vertical axis represents the range cell number. Lighter-colored dots indicate strong points with higher energy. It can be seen that strong points appear in the high-frequency portion of the RD map, which will increase the false alarm rate and make false alarms more likely. Furthermore, the existence of inter-frame phase difference will also lead to inaccurate phase in the 1D-FFT data extracted when executing Scheme B, affecting the accuracy of detecting and identifying key human vital signs.

[0047] Therefore, detection schemes based on inter-frame data have relatively strict requirements on the initial phase of each received frame signal. Although inter-frame phase changes can be mitigated through high-precision counters and circuit design, this often requires more complex designs, thus increasing costs.

[0048] Therefore, one embodiment of this disclosure provides an inter-frame phase compensation method, such as... Figure 8 As shown, this includes performing the following inter-frame phase compensation processing on at least one channel of the radar system:

[0049] Step 210: For each frame to be compensated in N frames, determine the phase compensation coefficient of the channel in the frame based on the phase information of the channel and the reference phase information in the frame, where N is a positive integer greater than or equal to 2.

[0050] Step 220: Perform phase compensation on the 1D-FFT data of the channel in the frame based on the phase compensation coefficient; wherein, the phase information of the channel in the frame is determined based on the 1D-FFT data of the channel in the first distance unit in the frame.

[0051] The inter-frame phase compensation processing in this embodiment can be performed periodically in units of N frames.

[0052] In this embodiment, when performing target detection based on inter-frame data in a software timing mode, inter-frame phase compensation reduces the inter-frame phase difference, which can largely avoid the problems of increased false alarm rate and easy false alarms caused by the inter-frame phase difference, thus improving the performance of target detection, especially the accuracy of indoor and cabin target detection. At the same time, this embodiment does not require the use of high-precision counters and corresponding circuits, reducing the complexity and cost of the radar system.

[0053] When a moving object is present, the phase of 1D-FFT data is affected by the Doppler effect and changes. The inter-frame phase difference to be compensated in this embodiment is the difference in the initial phase of each frame. To minimize the influence of the Doppler effect, the phase of at least one channel in each frame and its difference from the reference phase are calculated based on the echo signal generated by a stationary object (corresponding to zero-Doppler data). Therefore, unless otherwise explicitly defined, 1D-FFT data without inter-frame phase compensation in this document refers to 1D-FFT data that has not undergone zero-Doppler removal, i.e., 1D-FFT data retaining the DC component.

[0054] In one example of this embodiment, when the transmitter transmits a probe signal, there is only one chirp per frame for each channel. In another example, when the transmitter transmits a probe signal, there are multiple chirs per frame for each channel, but the receiver processes (at least including inter-frame phase compensation processing) only one chirp's 1D-FFT data per channel. In yet another example, when the transmitter transmits a probe signal, there are multiple chirs per frame for each channel, and the receiver, during processing (at least including inter-frame phase compensation processing), first performs a complex summation calculation on the 1D-FFT data of multiple chirs for each channel, meaning that the size of the 1D-FFT data per channel per frame during inter-frame phase compensation is the same as the size of the 1D-FFT data of one chirp. In these examples of this embodiment, a channel in a frame may have only one 1D-FFT data in a distance unit. However, this disclosure is not limited to this. In the case that a channel in a frame has multiple 1D-FFT data in a distance unit, when determining the phase compensation coefficient of a channel in a frame, only one of the 1D-FFT data can be used for calculation.

[0055] In one exemplary embodiment of this disclosure, when the radar system has multiple channels, for each frame to be compensated, the inter-frame phase compensation processing is performed on each channel. In another exemplary embodiment of this disclosure, when the radar system has multiple channels, for each frame to be compensated, the inter-frame phase compensation processing is performed on the first channel; then, phase compensation is performed on the 1D-FFT data of the other channels in the frame according to the phase compensation coefficient of the first channel in that frame. In the radar system of this disclosure embodiment, the number of range cells in each channel in each frame is the same. Multiple range cells of a channel in a frame can use the same phase compensation coefficient or different phase compensation coefficients. If different phase compensation coefficients are used, when the phase compensation coefficient of the first channel in that frame is used for other channels in that frame, the phase compensation coefficient used by the first channel in that frame on the range cell with index r will be used as the phase compensation coefficient used by the other channels in that frame on the range cell with index r.

[0056] Considering the potential differences in inter-frame phase differences across multiple channels in a radar system, performing inter-frame phase compensation processing on each channel separately can more effectively reduce these differences and achieve the best target detection performance. Furthermore, the inter-frame phase differences across multiple channels in a radar system are correlated. Using the phase compensation coefficients calculated for one channel for the corresponding frames in other channels can reduce computational load and, to some extent, reduce the inter-frame phase differences in other channels, thereby lowering the false alarm rate.

[0057] In an exemplary embodiment of this disclosure, the radar system employs a software timing method, and the position corresponding to the first distance unit is the location of a stationary object. Therefore, the phase information of the frame determined based on the 1D-FFT data of the frame on the first distance unit will not include phase changes caused by the Doppler effect of object motion, accurately reflecting the initial phase of the frame, and thus effectively ensuring the effectiveness of phase compensation. Here, "stationary object" refers to an object that is relatively stationary or approximately stationary relative to the radar. When the radar is fixedly installed inside a car cabin, "stationary object" refers to an object that is "immobile" inside the car cabin. For example, in the scenario of detecting children inside the cabin, the location of the floor is the location of the stationary object. Taking a top-mounted radar as an example, within the detection range, the reflected signal from the floor is the strongest. In this case, the distance unit with the strongest power or amplitude can be used as the first distance unit, making the location corresponding to the first distance unit the location of the stationary object.

[0058] In this embodiment, the first distance unit is determined as follows: Energy information of the multiple distance units is obtained based on the 1D-FFT data of the channel across multiple distance units in the N frames; and one of the multiple distance units is determined as the first distance unit based on the energy information. In this embodiment, the first distance unit is determined based on the 1D-FFT data of N frames. For the same channel, the first distance unit is the same in each of the N frames; for different channels, the determined first distance unit can be the same or different.

[0059] This embodiment uses real-time calculation to determine the first distance unit, which can more accurately identify the first distance unit that meets the conditions and improve the accuracy of phase compensation. However, this disclosure is not limited to this. In another embodiment, the first distance unit is a preset value. For example, the preset value can be a pre-set value, which can be preset based on the distance between the target object's predetermined position (such as the floor) and the radar system in a basically fixed environment such as inside a car cabin. Alternatively, the preset value can be obtained by performing one or more calculations to obtain a distance unit with the largest power or amplitude, and then set as the first distance unit and used in the phase compensation of subsequent frames.

[0060] In an exemplary embodiment of this disclosure, obtaining the energy information of the plurality of distance units based on the 1D-FFT data of the channel in the N frames at the plurality of distance units includes: for each of the plurality of distance units, calculating the summation or averaging of the plurality of 1D-FFT data of the channel in the N frames at the distance unit, and then taking the modulus of the calculation result to obtain the power corresponding to the distance unit, or taking the modulus of the calculation result to obtain the amplitude corresponding to the distance unit; wherein, the plurality of distance units are all the distance units of the channel in the N frames or a specified portion of the distance units.

[0061] If a moving object exists at a certain distance, the amplitude or power of the 1D-FFT data in the Doppler dimension of the corresponding distance cell will change periodically due to the Doppler effect. In this embodiment, by summing or averaging the 1D-FFT data of N frames in a distance cell, the influence of amplitude changes caused by the Doppler effect can be eliminated, so that the calculated power or amplitude can reflect the energy information of the zero-Doppler data (i.e., the 1D-FFT data generated by reflection from a stationary object) in that distance cell (which can be represented by parameters such as power and amplitude). The first distance cell selected based on this energy information, such as the distance cell with the highest energy, is the distance cell with the highest energy of the zero-Doppler data.

[0062] In one example of this embodiment, when calculating the energy information of a range cell, the energy information of all range cells in the channel across N frames can be calculated, and then the first range cell can be selected from them. In another example, a subset of range cells can be specified based on a preset range, and the energy information of only the specified subset of range cells in the channel across N frames can be calculated, from which the first range cell can be selected. The preset range may be a known range between the target and the radar system, but this disclosure is not limited thereto.

[0063] In one example of this embodiment, determining one of the plurality of distance units as the first distance unit based on the energy information includes: determining the distance unit with the largest corresponding power or amplitude among the plurality of distance units as the first distance unit. Generally, the higher the power or amplitude of the signal, the less interference the signal is subject to. Therefore, in this embodiment, the distance unit with the largest corresponding power or amplitude among the plurality of distance units is used as the first distance unit, making the phase of the frame calculated based on the 1D-FFT data on the first distance unit more reliable. However, in other embodiments, the distance unit with the second largest corresponding power or amplitude among the plurality of distance units can also be used as the first distance unit, or the distance units can be sorted from largest to smallest power or amplitude, and one of the first few distance units can be used as the first distance unit.

[0064] In an exemplary embodiment of this disclosure, determining the phase compensation coefficient for each of the N frames to be compensated, based on the phase information of the channel in that frame and the reference phase information, includes:

[0065] For each of the N frames, based on a 1D-FFT data of that channel on the first distance unit in that frame. Calculate the phase of this channel in this frame. And according to Phase with reference difference Determine the phase compensation coefficient k used by this channel in the range cell with index r in this frame. i,r ;

[0066]

[0067] in, yes The real part, yes The imaginary part of is given by , where i is the index of the frame, i = 0, 1, 2, ..., N-1, and r0 is the index of the first distance cell. Similar to the usual representation, exp() is an exponential function with base e. The letter 'j' in the number represents the imaginary unit, meaning the real part is 0 and the imaginary part is 0.

[0068] In another exemplary embodiment of this disclosure, it has been found that when the radar system adopts a software timing method, the inter-frame phase difference is mainly caused by the misalignment between the frequency modulated continuous wave (FMCW) clock and the ADC sampling clock. Therefore, this embodiment introduces a phase compensation coefficient (also known as a compensation factor) that is linearly related to the range unit to improve the accuracy of phase compensation.

[0069] Assuming the time difference of the misalignment is Δt, the resulting inter-frame phase difference Δφ at distance D is:

[0070]

[0071] Where f0 is the intermediate frequency corresponding to distance D, BW (Band Width) is the effective sweep bandwidth, and r max For the maximum distance. In the application of a given waveform, BW and r max All are constants.

[0072] Since the inter-frame phase difference is linearly related to the distance D, and the distance D is equal to the index r of the range bin multiplied by the value corresponding to the range bin (which is the product's range resolution when not exceeding resolution, and the actual range resolution achieved by the algorithm when exceeding resolution), the inter-frame phase difference is also linearly related to the index r of the range bin.

[0073] This embodiment considers the influence of distance on inter-frame phase difference, and obtains... Phase with reference difference Then, the phase compensation coefficient k used by this channel in the frame at the distance cell with index r is calculated according to the following formula. i,r

[0074]

[0075] Where r0 is the index (also called the sequence number) of the first distance unit, r∈Hr, and Hr is the set of indexes of the distance units to be compensated in the channel of the frame. The distance units to be compensated in the channel of the frame can be all the distance units or a specified part of the distance units. Usually, the distance units to be compensated in different frames and different channels can be the same.

[0076] In one of the aforementioned embodiments, the inter-frame phase difference used to calculate the phase compensation coefficient is linearly related to the distance. Different phase compensation coefficients are used for different distance units within a single channel in a frame. This method yields more accurate phase compensation coefficients and achieves better phase compensation results. In the other embodiment, the same phase compensation coefficient is used for all distance units of a single channel within a frame (hereinafter referred to as single-coefficient inter-frame phase compensation). In scenarios such as CPD, where the distance unit containing the 1D-FFT data to be compensated is similar to the first distance unit, this approximation algorithm can also achieve good performance and reduce computational load. In both embodiments, the phase compensation coefficients used in the same distance unit for different frames are calculated separately based on the 1D-FTT data from different frames. For different channels within the same frame, the phase compensation coefficients can be the same (e.g., all using the phase compensation coefficient of the first channel) or different (calculated separately).

[0077] In one example of this embodiment, The phase of this channel in the first frame of the N frames. At this point, the inter-frame phase difference of the first frame in the N frames is 0, and the inter-frame phase difference of the frame with index i is equal to...

[0078] In another example of this embodiment, The phase of this channel in the first frame after the radar system is powered on. At this point, the inter-frame phase difference of that channel in the frame with index i It can be calculated using the following formula:

[0079]

[0080]

[0081] in, This refers to the phase of the channel in the previous frame. This represents the inter-frame phase difference of this channel in the previous frame, which has already been calculated.

[0082] To calculate the inter-frame phase difference of this channel in the frame with index i using the method described in this example, it is only necessary to compare the inter-frame phase difference of this channel between the current frame and the previous frame. Add the inter-frame phase difference of this channel in the stored previous frame. This can be obtained, and the inter-frame phase difference can then be used to update the storage, which is relatively simple to implement. Specifically, the phase of the first frame after power-on can be calculated from the 1D-FFT data of the distance unit with the largest amplitude or power selected during the first processing, but there is no need to calculate the phase difference; it can be used as the reference phase itself.

[0083] In another example of this embodiment, if phase compensation of the 1D-FFT data of the channel in the previous frame has been completed before calculating the phase compensation coefficient of the channel in the current frame, when calculating the phase compensation coefficient of the channel in the other N frames excluding the first frame, the phase of the channel after phase compensation in the cached previous frame or any frame is used as... It is simple to implement. As for the first frame of the N frames, the inter-frame phase difference can be directly set to 0, that is, the phase of this channel in the frame is the reference phase by default.

[0084] In yet another example of this embodiment, the reference phase Set a value, such as an empirical value or a statistical value, or directly set a reference phase.

[0085] In this embodiment of the present disclosure, the phase of a channel in a frame is obtained based on the 1D-FFT data (complex data) of that channel on the first distance unit in that frame. The phase of a channel in a frame after phase compensation can be obtained based on the 1D-FFT data of that channel on the first distance unit after phase compensation in that frame.

[0086] In an exemplary embodiment of this disclosure, determining the phase compensation coefficient for each of the N frames to be compensated, based on the phase information of the channel in that frame and the reference phase information, includes:

[0087] For each of the N frames, based on a 1D-FFT data of that channel on the first distance unit in that frame. and 1D-FFT data a containing reference phase information ref Calculate the phase compensation coefficient k used by this channel in all range cells to be compensated in this frame. i ;

[0088]

[0089] Where i is the index of the frame, i = 0, 1, 2, ..., N-1, j m It is the index of the first distance cell.

[0090] Unlike the previous embodiments that calculated the phase compensation coefficient by the difference between the current frame phase and the reference phase, this embodiment directly uses 1D-FFT data containing the current frame phase and 1D-FFT data containing reference phase information to calculate the phase compensation coefficient, achieving the same inter-frame phase compensation effect with a simpler calculation. In addition to supplementing the inter-frame phase, this embodiment can also compensate for amplitude fluctuations caused by imperfections in the transmitting and receiving units across multiple frames, achieving better inter-frame accumulation.

[0091] In one example of this embodiment, a refThis is a 1D-FFT data of this channel on the first distance unit in the first frame of the N frames. At this time, the phase compensation coefficient of this channel in the first frame of the N frames is 1, and the phase compensation coefficient of this channel in the frame with index i is k. i equal

[0092] In another example of this embodiment, a ref This refers to a 1D-FFT data point for this channel in the first frame after the radar system is powered on. The phase compensation coefficient k for this channel in the frame with index i is also included. i The following formula can be used for calculation:

[0093]

[0094] in, k is the 1D-FFT data of this channel in the first distance unit in the previous frame. i-1 The phase compensation coefficients for this channel have already been calculated in the previous frame. This example uses the phase compensation coefficients calculated in the previous frame for iterative calculation, which is relatively simple to implement. Specifically, the 1D-FFT data for this channel in the first frame after power-on can use the 1D-FFT data from the distance unit with the largest amplitude or power selected during the first processing.

[0095] In another example of this embodiment, if phase compensation of the 1D-FFT data of the channel in the previous frame has been completed before calculating the phase compensation coefficient of the channel in the current frame, when calculating the phase compensation coefficient of the channel in the other frames of the N frames excluding the first frame, the phase-compensated 1D-FFT data of the channel in the previous frame or any frame is used as a. ref This example is simple to implement. In the first frame of the N frames, the phase compensation system of this channel can be directly set to 1, that is, by default, the 1D-FFT data of this channel in the first distance unit in the first frame is 1D-FFT data containing reference phase information.

[0096] In another example of this embodiment, 1D-FFT data a containing reference phase information ref Set a value, such as an empirical value or a statistical value, or directly set a 1D-FFT data.

[0097] In an exemplary embodiment of this disclosure, the step of performing phase compensation on the 1D-FFT data of that channel in the frame based on the phase compensation coefficient includes:

[0098] Phase compensation is performed on the 1D-FFT data of this channel in the frame at the distance cell to be compensated using the following formula:

[0099] a′ i,r=a i,r ·k i,r

[0100] Among them, a i,r It is the 1D-FFT data of this channel in the frame at the distance cell with index r, a' i,r It is the phase-compensated 1D-FFT data of this channel in the frame at the distance cell with index r, k i,r Let i be the phase compensation coefficient used by the channel in the frame at the distance cell with index r, where i is the index of the frame, i = 0, 1, 2, ..., N-1, r ∈ Hr, and Hr is the set of indices of the distance cells to be compensated for the channel in the frame.

[0101] This disclosure also provides a target detection method in one embodiment, such as... Figure 9 As shown, the method includes:

[0102] Step 310: Perform inter-frame phase compensation on N frames of 1D-FFT data with M channels obtained based on the electromagnetic wave signals received by the radar system, according to the inter-frame phase compensation method described in any embodiment of this disclosure, where M≥1 and N≥2.

[0103] In this embodiment, inter-frame phase compensation is performed periodically in units of N frames. The N frames of 1D-FFT data from the M channels mentioned in this step can be obtained by mixing, analog-to-digital conversion, and 1D-FFT of the electromagnetic wave signals (such as radar echo signals) received by the radar system.

[0104] Step 320: Target detection is performed based on the N frames of 1D-FFT data from the M channels after inter-frame phase compensation.

[0105] In this embodiment, inter-frame phase compensation based on N frames of 1D-FFT data is performed during target detection, which can reduce the false alarm rate and improve target detection performance. This enables the accurate detection of special or weak targets such as children inside the cabin, and can be applied to scenarios such as CPD and SBR. Therefore, the exemplary target detection method of this disclosure can be applied to car cabins or interiors, and the detected targets may include children.

[0106] The electromagnetic wave signal in this embodiment can be a radar echo signal, but is not limited to this. For example, it can also be the electromagnetic wave signal received by a UWB chip operating in radar mode, or other electromagnetic wave devices operating in scenarios such as positioning mode and requiring inter-frame phase alignment.

[0107] In an exemplary embodiment of this disclosure, before performing inter-frame phase compensation on N frames of 1D-FFT data with M channels obtained based on electromagnetic wave signals, the inter-frame phase compensation method according to any embodiment of this disclosure further includes:

[0108] Inter-frame phase compensation is performed on the N frames of 1D-FFT data in the M channels according to any of the following conditions:

[0109] Condition 1: Based on the N frames of 1D-FFT data from the M channels, perform adult detection to determine that no adults are present;

[0110] Condition 2: Perform multi-person detection based on N frames of 1D-FFT data from the M channels to determine that there are no multiple people.

[0111] As previously mentioned, this embodiment utilizes the zero-Doppler data to calculate the frame phase for inter-frame phase compensation. Children have a smaller radar cross section (RCS). Research shows that in a car cabin where only children are present, the clutter intensity reflected by stationary objects dominates, with energy exceeding that of the echo reflected by the child. The first range unit is selected based on energy; for example, choosing the range unit with the highest energy ensures that the data in that unit is zero-Doppler data (data obtained from processing the received signal reflected by a stationary object). For instance, in a car cabin detection scenario, if children are present, the clutter intensity reflected by the floor and seats is still stronger than the echo reflected by the child. The first range unit selected based on energy will be the range unit corresponding to the floor or seat. The 1D-FFT data in this range unit is zero-Doppler data, which can then be used to calculate the frame phase, avoiding the influence of moving targets on the phase. In a car cabin, both adults and children have breathing difficulties, so both are considered moving targets.

[0112] However, when adults are present in the car cabin (especially multiple adults), the conclusion that clutter reflected from stationary objects dominates may not hold true. In this case, the distance cell with the highest energy might be the distance cell containing the echo reflected from an adult. Using the distance cell with the highest energy as the first distance cell to calculate the frame phase may be affected by the Doppler effect, leading to inaccurate phase calculations and affecting compensation. The first distance cell found in this situation might be the distance cell containing an adult, and phase compensation would compensate for phase changes caused by adult breathing and the system's inter-frame error, resulting in the failure to detect adults. Children, on the other hand, have lower energy than stationary objects at zero Doppler, so the highest power distance cell found is the stationary object. Phase compensation only compensates for the system's inter-frame error and does not affect the detection of children. Therefore, this embodiment first detects adults, and only when no adults are found does it perform inter-frame phase compensation on N frames of 1D-FFT data from M channels.

[0113] In an exemplary embodiment of this disclosure, the target detection based on N frames of 1D-FFT data from the M channels after inter-frame phase compensation includes:

[0114] Multi-frame joint processing is performed on N frames of 1D-FFT data from the M channels after inter-frame phase compensation to achieve target detection in the region of interest; or

[0115] Perform at least one of deep learning-based target detection, target localization, and target recognition on N frames of 1D-FFT data from the M channels after inter-frame phase compensation, to achieve at least one of the judgment, localization, and recognition of targets in the region of interest; or

[0116] After performing two-dimensional digital beamforming on N frames of 1D-FFT data from the M channels after inter-frame phase compensation, the frame data is accumulated to a preset number, and then inter-frame FFT processing is performed to obtain the RD map of the M channels; and, based on the RD map of the M channels, at least one of deep learning-based target detection, target localization, and target recognition is performed to achieve at least one of the judgment, localization, and recognition of targets in the region of interest.

[0117] In one example of this embodiment, the multi-frame joint processing of N frames of 1D-FFT data from the M channels after inter-frame phase compensation to achieve target detection in the region of interest includes:

[0118] Inter-frame FFT is performed on N frames of 1D-FFT data from the M channels after inter-frame phase compensation to obtain the RD maps of the M channels; and, target detection of the region of interest is achieved based on the RD maps of the M channels.

[0119] The target detection of the region of interest is achieved based on the RD map of the M channels, including:

[0120] When M>1, after incoherently accumulating the RD maps of the M channels, continue with constant false alarm rate (CFAR) processing based on noise estimation, direction-of-arrival (DOA) estimation, and target judgment, localization, and identification operations based on deep learning; or

[0121] When M>1, after performing constant false alarm rate (CFAR) processing on the RD maps of the M channels, binary integration processing of the channel domain, direction-of-arrival (DOA) estimation, and target judgment, localization, and recognition operations based on deep learning are performed; or

[0122] When M≥1, after performing two-dimensional digital beamforming on the RD spectra of the M channels, target classification processing based on deep learning is continued to achieve target judgment, localization and recognition operations.

[0123] In an exemplary embodiment of this disclosure, performing at least one of deep learning-based target detection, target localization, and target recognition on N frames of 1D-FFT data from the M channels after inter-frame phase compensation, to achieve at least one of the judgment, localization, and recognition of targets in the region of interest, includes:

[0124] Target point cloud data is obtained based on N frames of 1D-FFT data from the M channels after inter-frame phase compensation.

[0125] The target point cloud data is processed by at least one of machine learning-based false alarm suppression, clustering, and machine learning-based target classification to achieve at least one of the judgment, localization, and identification of targets in the region of interest.

[0126] The inter-frame phase compensation method of any embodiment of this disclosure can also be used in the cabin detection method based on inter-frame phase of 1D-FFT data in the foregoing embodiments, i.e., Scheme B. This scheme enables the extraction of the phase of the 1D-FFT data at the distance cell where the suspected target is located based on the compensated phase, and the detection and identification of key personnel features based on the extracted feature data. This improves the detection and identification performance of the scheme.

[0127] This disclosure also provides a target detection method in one embodiment, such as... Figure 13 As shown, the method includes:

[0128] Step 410: Obtain 1D-FFT data;

[0129] Step 420: Perform single-coefficient inter-frame phase compensation on at least two frames of acquired 1D-FFT data, using the same phase compensation coefficient on different distance units for the same channel within the same frame; and

[0130] Step 430: Estimate the vital signs based on at least two frames of 1D-FFT data after inter-frame phase compensation to achieve target detection.

[0131] The 1D-FFT data obtained in step 410 above can be obtained by mixing, analog-to-digital conversion, and 1D-FFT of the electromagnetic wave signal (such as radar echo signal) received by the radar system, but is not limited to this. In step 420 above, inter-frame phase compensation based on a single coefficient is performed, that is, the same phase compensation coefficient is used on the same channel in different range cells in the same frame. Since only one phase compensation coefficient needs to be calculated for each channel in a frame, it simplifies the calculation in engineering practice, has low computational complexity, and is suitable for real-time processing. This approximation can still improve the accuracy of target detection and parameter estimation by eliminating inter-frame phase inconsistency, and is applicable to various millimeter-wave radar coefficients, such as FMCW radar and pulse radar. In this embodiment, each channel can use the phase compensation coefficient calculated by a certain channel, or each channel can calculate the phase compensation coefficient independently, that is, perform inter-frame phase compensation separately. The method of this embodiment can be applied to a car cabin or interior, and the target detected in step 430 above can include children, but is not limited to this.

[0132] The method in this embodiment can compensate for inter-frame phase errors caused by non-distance factors (such as sampling time jitter), without the need for high-precision counters and corresponding circuits. It can reduce inter-frame phase differences caused by non-distance factors, and to a certain extent avoid the problems of increased false alarm rate and easy false alarm caused by inter-frame phase differences, thereby improving the performance of target detection, especially the accuracy of target detection inside the cabin and indoors.

[0133] In one example of this embodiment, the target detection method can be applied to an electromagnetic wave device with radar functionality. The electromagnetic wave device does not have a device for recording inter-frame phase changes, or although it does have a device for recording inter-frame phase changes, it does not function during target detection. This embodiment implements inter-frame phase compensation through software rather than hardware, eliminating the need for a device to record inter-frame phase changes. The electromagnetic wave device design is simple, and the hardware design does not have special requirements for inter-frame phase differences. Furthermore, by not setting up or activating a device (such as a counter) for recording inter-frame phase changes, low complexity and low cost can be achieved, along with low power consumption.

[0134] In an exemplary embodiment of this disclosure, the step of performing inter-frame phase compensation based on a single coefficient on at least two frames of acquired 1D-FFT data includes: performing inter-frame phase compensation based on a single coefficient on at least two frames of acquired 1D-FFT data using a zero-Doppler signal; that is, this embodiment can perform inter-frame phase compensation based on zero Doppler. As mentioned above, when a moving object is present, the phase of the 1D-FFT data will change due to the Doppler effect. This embodiment performs inter-frame phase compensation on the 1D-FFT data based on a zero-Doppler signal (e.g., the echo signal generated by an object stationary relative to the radar, which can also be called zero-Doppler data), thus avoiding the influence of the Doppler effect.

[0135] In an exemplary embodiment of this disclosure, the estimation of vital signs parameters based on at least two frames of 1D-FFT data after inter-frame phase compensation includes: removing zero Doppler from the at least two frames of 1D-FFT data after inter-frame phase compensation before estimating the vital signs parameters. When estimating some characteristic parameters such as respiratory rate, it is necessary to capture motion parameters. In this case, the 1D-FFT data after inter-frame phase compensation can be first subjected to zero Doppler (i.e., removal of DC component) before estimation.

[0136] In an exemplary embodiment of this disclosure, the estimation of vital signs based on at least two frames of 1D-FFT data after inter-frame phase compensation includes:

[0137] Respiratory rate estimation is performed using at least two frames of 1D-FFT data after inter-frame phase compensation, employing inter-frame accumulation. This can be used to optimize the aforementioned in-cabin detection scheme (Scheme A) based on inter-frame accumulation, performing inter-frame phase compensation on the obtained 1D-FFT data, followed by multi-frame correlation 2D processing; or...

[0138] Based on the phase information of the 1D-FFT data corresponding to the range cell where the suspected target is located in at least two frames of 1D-FFT data after inter-frame phase compensation, vital signs parameters can be estimated. This can be used to optimize the aforementioned cabin detection scheme (Scheme B) based on the inter-frame phase of 1D-FFT data. After inter-frame phase compensation of the obtained 1D-FFT data, the phase of the 1D-FFT data at the range cell where the suspected target is located is extracted, and the key features of personnel (such as respiratory rate) are detected and identified based on the extracted feature data.

[0139] In an exemplary embodiment of this disclosure, the target detection method is applied to a child detection in-vehicle (CPD) scenario; the step of estimating vital signs based on at least two frames of 1D-FFT data after inter-frame phase compensation to achieve the target detection method includes:

[0140] Determine whether an adult exists in the current scene based on at least two frames of acquired 1D-FFT data;

[0141] If no adult is present, perform single-coefficient inter-frame phase compensation on at least two frames of 1D-FFT data, and estimate the vital signs parameters based on at least two frames of 1D-FFT data after inter-frame phase compensation to achieve target detection.

[0142] If an adult is present, inter-frame phase compensation is not performed; instead, vital signs parameters are estimated directly based on at least two frames of acquired 1D-FFT data to achieve target detection.

[0143] This embodiment only initiates precise detection of infants and toddlers in the cabin when no adults are present (including minors with a certain level of behavioral capacity who are identified as adults due to the high energy of reflected electromagnetic waves), i.e., active child presence detection. As mentioned earlier, when an adult is present in the car cabin, the distance cell with the highest energy may be the distance cell where the echo reflected by the adult is located. Due to the Doppler effect, the phase calculation and compensation may be inaccurate, and phase compensation may result in the failure to detect adults. Therefore, this embodiment first performs adult detection. If no adult is found, inter-frame phase compensation is then performed. If an adult is found, the vital signs are directly estimated based on at least two frames of 1D-FFT data to achieve target detection. When the target detection of this embodiment is applied in a CPD, it can achieve in-vehicle child detection in accordance with the provisions of Euro NCAP (European New Car Assessment Programme), C-NCAP (China New Car Assessment Programme), Hot Cars Act (a US law), etc., and can trigger the required alarm operations accordingly.

[0144] In an exemplary embodiment of this disclosure, the inter-frame phase compensation method as described in any embodiment of this disclosure is used to perform single-coefficient inter-frame phase compensation on at least two frames of acquired 1D-FFT data.

[0145] Another embodiment of this disclosure also provides a target detection method, such as Figure 14 As shown, it includes:

[0146] Step 510: Acquire the echo signal, which includes at least two signal groups, each signal group including multiple signal units, and the time interval between adjacent signal units in the same signal group is less than the time interval between adjacent signal groups.

[0147] Step 520: Perform FFT processing on the signal units in the echo signal to obtain 1D-FFT data, and perform phase compensation on the 1D-FFT data between different groups of signals based on Doppler data;

[0148] This means that phase compensation is performed on the distance-group data plane. For example, if the signal group is a single frame signal, then single-coefficient phase compensation is performed on the distance-frame data plane.

[0149] Step 530: Remove zero Doppler. Perform inter-group FFT processing on the 1D-FFT data after removing zero Doppler to obtain 2D-FFT data, wherein the 2D-FFT data is configured for target detection.

[0150] Compared to conventional phase compensation, which typically involves removing zero Doppler, this embodiment, based on the dominance of stationary clutter intensity, utilizes energy accumulation to compensate for phase differences using zero Doppler. This method effectively reduces the adverse effects of phase difference variations between signal groups (or frames) without requiring high-precision counters or corresponding circuit designs, thereby lowering design complexity and cost. Subsequently, inter-group FFT processing is performed on the 1D-FFT data after removing zero Doppler to obtain 2D-FFT data; this 2D-FFT data is configured for target detection; for example, CPD detection can be performed based on signal group or inter-frame accumulation.

[0151] In some optional embodiments of this example, the echo signal may include at least two signal groups, each signal group may include multiple signal units, and the time interval between adjacent signal units in the same signal group is less than the time interval between adjacent signal groups; wherein, the signal group may be a frame signal or a long frame signal containing multiple groups, the signal unit may be the chirp signal of millimeter-wave radar in FMCW or the preamble sequence pulse in UWB sensor, and the corresponding echo signal may be the channel impulse response (CIR), etc.

[0152] In some optional embodiments of this example, the phase compensation of the 1D-FFT data between different groups of signals based on Doppler data may include: obtaining the energy of each range bin in the Doppler dimension based on the 1D-FFT data, and obtaining the range bin with the largest Doppler energy; for example, based on the 1D-FFT data, the sum of complex data of the Doppler dimension data of each range bin can be calculated (the calculation result can also be obtained by averaging, medianing, etc.), and the energy (such as power or amplitude) corresponding to each range bin can be obtained by taking the modulus (or taking the modulus) of the calculation result, and then candidate range bins can be determined by selecting extreme values, maximum values, or second largest values ​​according to preset rules. Subsequently, the phase difference between each signal group can be obtained based on the candidate range bins determined above. For example, the phase difference between each signal group relative to a preset signal group can be obtained based on the 1D-FFT data corresponding to the range bin with the largest energy; if the signal group is a frame signal, the phase difference of other frames relative to the first frame can be obtained by using the first logical frame of the buffer as a reference. Finally, phase compensation can be performed on the 1D-FFT data between different groups of signals on at least some range cells (such as the range cell of interest) based on the phase difference before performing 2D-FFT. That is, the phase compensation operation described above can effectively reduce the inter-frame phase instability of the 1D-FFT data caused by the system, and based on the compensated 1D-FFT data, inter-frame FFT or phase extraction based on the suspected target on the range cell can continue to be performed, realizing the detection of key human vital signs (such as breathing) parameters in relatively enclosed space areas (such as inside a car cabin or indoors).

[0153] Based on the target detection method implemented in the above embodiments, by using phase compensation for 1D-FFT data based on inter-frame or inter-signal group containing zero Doppler signals, it can effectively reduce the initial phase changes between system frames or between signal groups, improve the quality of coherent accumulation signals between frames or between signal groups, and thus effectively control the subsequent false alarm rate and improve the performance of target detection.

[0154] One embodiment of this disclosure also provides an inter-frame phase compensation device, applied to a radar system, such as... Figure 10 As shown, the device includes a memory 50 and a processor 60. The memory 50 stores a computer program, and the processor 60, when executing the computer program, can implement the inter-frame phase compensation method described in any embodiment of this disclosure. This device can be used... Figure 1 The main processing chip shown is used to implement this.

[0155] The processor in this and other embodiments can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), a microprocessor, etc., or other conventional processors; the processor can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA), discrete logic or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components; or a combination of the above devices. That is, the processor in the above embodiments can be any processing device or combination of devices that implements the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. If the embodiments of this disclosure are implemented in part in software, then instructions for software can be stored in a suitable non-volatile computer-readable storage medium, and one or more processors can be used to execute the instructions in hardware to implement the methods of the embodiments of this disclosure.

[0156] This disclosure also provides a target detection device in an embodiment of a radar system, see [link to relevant documentation]. Figure 10 It includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the target detection method described in any embodiment of this disclosure.

[0157] An embodiment of this disclosure also provides a non-transient computer-readable storage medium storing a computer program that, when executed by a processor, can implement the inter-frame phase compensation method described in any embodiment of this disclosure, or can implement the target detection method described in any embodiment of this disclosure.

[0158] One embodiment of this disclosure also provides an integrated circuit, such as... Figure 11 As shown, the integrated circuit includes a radio frequency module 2011, an analog signal processing module 2012, and a digital signal processing module 2013 connected in sequence, wherein:

[0159] The radio frequency module 2011 is configured to generate and transmit electromagnetic wave signals, and to receive electromagnetic wave signals (such as radar echo signals).

[0160] The analog signal processing module 2012 is configured to down-frequency the received electromagnetic wave signal to obtain an intermediate frequency signal; and

[0161] The digital signal processing module 2013 is configured to perform analog-to-digital conversion on the intermediate frequency signal to obtain a digital signal; wherein, the digital signal processing module is further configured to perform inter-frame phase compensation according to the inter-frame phase compensation method according to any embodiment of the present disclosure, or to perform target detection according to the target detection method according to any embodiment of the present disclosure.

[0162] In one example of this embodiment, the integrated circuit is an electromagnetic wave transceiver chip, such as a millimeter-wave radar chip or a UWB chip.

[0163] One embodiment of this disclosure also provides an electromagnetic wave device (such as an electromagnetic wave sensor), such as... Figure 12 As shown, it includes: a carrier 4; an integrated circuit 5 according to any embodiment of this disclosure, disposed on the carrier 4; and an antenna 6 disposed on the carrier 4, either integrated with the integrated circuit 5 as a single device or disposed separately; wherein the integrated circuit 5 is connected to the antenna 6 and is used to transmit the electromagnetic wave signal and / or receive the electromagnetic wave signal.

[0164] An embodiment of this disclosure also provides a terminal device (such as a car), including: a device body; and an electromagnetic wave device as described in any embodiment of this disclosure, disposed on the device body; wherein the electromagnetic wave device is configured to perform target detection and / or communication to provide reference information to the operation of the device body.

[0165] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. An inter-frame phase compensation method, comprising: Perform the following inter-frame phase compensation process on at least one channel of the radar system: For each frame to be compensated in N frames, the phase compensation coefficient of the channel in the frame is determined according to the phase information of the channel and the reference phase information in the frame. The phase compensation is then performed on the 1D-FFT data of the channel in the frame based on the phase compensation coefficient. The phase information of the channel in the frame is determined according to the 1D-FFT data of the channel in the first distance unit in the frame, and N is a positive integer greater than or equal to 2.

2. The inter-frame phase compensation method as described in claim 1, characterized in that: In the case that the radar system has multiple channels, for each frame to be compensated, the inter-frame phase compensation processing is performed on each channel separately; or In the case that the radar system has multiple channels, for each frame to be compensated, the inter-frame phase compensation processing is performed on the first channel; then, phase compensation is performed on the 1D-FFT data of the other channels in the frame according to the phase compensation coefficient of the first channel in the frame.

3. The inter-frame phase compensation method as described in claim 1, characterized in that: The radar system uses a software timing method, and the position corresponding to the first distance unit is the position of the stationary object. The first distance unit is a set value; or, the first distance unit is determined by the following method: obtaining the energy information of the multiple distance units based on the 1D-FFT data of the channel in the N frames on multiple distance units respectively, and determining one of the multiple distance units as the first distance unit based on the energy information.

4. The inter-frame phase compensation method as described in claim 3, characterized in that: The step of obtaining the energy information of the multiple range cells based on the 1D-FFT data of the channel in the N frames at multiple range cells includes: For each of the plurality of distance units, the summation or averaging of the plurality of 1D-FFT data of the channel in the N frames on the distance unit is calculated, and the power corresponding to the distance unit is obtained by taking the modulus of the calculation result, or the amplitude corresponding to the distance unit is obtained by taking the modulus of the calculation result. The plurality of distance units are all the distance units of the channel in the N frames or a specified portion of the distance units.

5. The inter-frame phase compensation method as described in claim 4, characterized in that: The step of determining one of the plurality of distance units as the first distance unit based on the energy information includes: determining the distance unit with the largest corresponding power or amplitude among the plurality of distance units as the first distance unit.

6. The inter-frame phase compensation method as described in claim 1, characterized in that: For each frame to be compensated in N frames, the phase compensation coefficient for that channel in that frame is determined based on the phase information and reference phase information of that channel in that frame, including: For each of the N frames, based on a 1D-FFT data a of that channel in the first distance unit in that frame. i,r0 Calculate the phase of this channel in this frame. And according to Phase with reference difference Determine the phase compensation coefficient k of this channel in the distance cell with index r in this frame. i,r As shown in the following formula: or in, yes The real part, yes The imaginary part of the , i is the index of the frame, i = 0, 1, 2, ..., N-1, r0 is the index of the first distance unit, r ∈ Hr, Hr is the set of indices of the distance units to be compensated in the channel of the frame.

7. The inter-frame phase compensation method as described in claim 6, characterized in that: The phase of this channel in the first frame of the N frames. or The phase of this channel in the first frame after the radar system is powered on. or If phase compensation for the 1D-FFT data of the channel in the previous frame has been completed before calculating the phase compensation coefficient of the channel in the current frame, then when calculating the phase compensation coefficient of the channel in the other N frames excluding the first frame, the phase of the channel after phase compensation in the buffered previous frame or any frame is used as... or This is the set value.

8. The inter-frame phase compensation method as described in claim 1, characterized in that: For each frame to be compensated in N frames, the phase compensation coefficient for that channel in that frame is determined based on the phase information and reference phase information of that channel in that frame, including: For each of the N frames, based on a 1D-FFT data of that channel on the first distance unit in that frame. and 1D-FFT data a containing reference phase information ref Calculate the phase compensation coefficient k used by this channel in all range cells to be compensated in this frame. i ; Where i is the index of the frame, i = 0, 1, 2, ..., N-1, and r0 is the index of the first distance cell.

9. The inter-frame phase compensation method as described in claim 8, characterized in that: a ref For the first frame of the N frames, it is a 1D-FFT data of that channel on the first distance unit; or a ref This refers to a 1D-FFT data point for this channel in the first frame after the radar system is powered on. or If phase compensation for the 1D-FFT data of the same channel in the previous frame has been completed before calculating the phase compensation coefficients for the current frame, then when calculating the phase compensation coefficients for the channels in the N frames other than the first frame, a 1D-FFT data of the previous frame or any frame after phase compensation on the first distance unit is used as a. ref ; a ref This is the set value.

10. The inter-frame phase compensation method as described in claim 1, characterized in that: The step of performing phase compensation on the 1D-FFT data of that channel in the frame based on the phase compensation coefficient includes: performing phase compensation on the 1D-FFT data of that channel in the frame at the distance unit to be compensated using the following formula: a‘ i,r =a i,r ·k i,r Among them, a i,r It is the 1D-FFT data of this channel in the frame at the distance cell with index r, a' i,r It is the phase-compensated 1D-FFT data of this channel in the frame at the distance cell with index r, k i,r Let i be the phase compensation coefficient used by the channel in the frame at the distance cell with index r, where i is the index of the frame, i = 0, 1, 2, ..., N-1, r ∈ Hr, and Hr is the set of indices of the distance cells to be compensated for the channel in the frame.

11. An inter-frame phase compensation device, applied in a radar system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the inter-frame phase compensation method as described in any one of claims 1 to 10.

12. A target detection method, comprising: According to any one of claims 1 to 10, inter-frame phase compensation is performed on N frames of 1D-FFT data with M channels obtained based on electromagnetic wave signals received by the radar system, where M≥1 and N≥2. Target detection is performed based on N frames of 1D-FFT data from the M channels after inter-frame phase compensation.

13. The target detection method as described in claim 12, characterized in that: The method is applied to the cabin or interior of a car, and the targets for detection include children; the electromagnetic wave signal is a radar echo signal.

14. The target detection method as described in claim 12, characterized in that: Before performing inter-frame phase compensation on the N frames of 1D-FFT data with M channels obtained based on electromagnetic wave signals, the method further includes: performing inter-frame phase compensation on the N frames of 1D-FFT data with M channels according to any one of the following conditions only when at least one of the following conditions is met: Condition 1: Based on the N frames of 1D-FFT data from the M channels, perform adult detection to determine that no adults are present; Condition 2: Perform multi-person detection based on N frames of 1D-FFT data from the M channels to determine that there are no multiple people.

15. The target detection method as described in claim 12, characterized in that: The target detection based on the N frames of 1D-FFT data from the M channels after inter-frame phase compensation includes: Multi-frame joint processing is performed on N frames of 1D-FFT data from the M channels after inter-frame phase compensation to achieve target detection in the region of interest; or Perform at least one of deep learning-based target detection, target localization, and target recognition on N frames of 1D-FFT data from the M channels after inter-frame phase compensation, to achieve at least one of the judgment, localization, and recognition of targets in the region of interest; or After performing two-dimensional digital beamforming on N frames of 1D-FFT data from the M channels after inter-frame phase compensation, the frame data is accumulated to a preset number, and then inter-frame FFT processing is performed to obtain the RD map of the M channels; and, based on the RD map of the M channels, at least one of deep learning-based target detection, target localization, and target recognition is performed to achieve at least one of the judgment, localization, and recognition of targets in the region of interest.

16. The target detection method as described in claim 15, characterized in that: The step of performing multi-frame joint processing on N frames of 1D-FFT data from the M channels after inter-frame phase compensation to achieve target detection in the region of interest includes: Inter-frame FFT is performed on N frames of 1D-FFT data from the M channels after inter-frame phase compensation to obtain the RD maps of the M channels; and, target detection of the region of interest is achieved based on the RD maps of the M channels. The target detection of the region of interest is achieved based on the RD map of the M channels, including: When M>1, after incoherently accumulating the RD maps of the M channels, continue with constant false alarm rate (CFAR) processing based on noise estimation, direction-of-arrival (DOA) estimation, and target judgment, localization, and identification operations based on deep learning; or When M>1, after performing constant false alarm rate (CFAR) processing on the RD maps of the M channels, binary integration processing of the channel domain, direction-of-arrival (DOA) estimation, and target judgment, localization, and recognition operations based on deep learning are performed; or When M≥1, after performing two-dimensional digital beamforming on the RD spectra of the M channels, target classification processing based on deep learning is continued to achieve target judgment, localization and recognition operations.

17. The target detection method as described in claim 14, characterized in that: The step of performing at least one of deep learning-based target detection, target localization, and target recognition on N frames of 1D-FFT data from the M channels after inter-frame phase compensation, to achieve at least one of the judgment, localization, and recognition of targets in the region of interest, includes: Target point cloud data is obtained based on N frames of 1D-FFT data from the M channels after inter-frame phase compensation. The target point cloud data is processed by at least one of machine learning-based false alarm suppression, clustering, and machine learning-based target classification to achieve at least one of the judgment, localization, and identification of targets in the region of interest.

18. A target detection method, characterized in that, The method includes: Acquire 1D-FFT data; At least two frames of acquired 1D-FFT data are subjected to inter-frame phase compensation based on a single coefficient, with the same phase compensation coefficient used on different distance cells for the same channel within the same frame; and Vital parameter estimation is performed based on at least two frames of 1D-FFT data after inter-frame phase compensation to achieve target detection.

19. The target detection method as described in claim 18, characterized in that: The step of performing single-coefficient inter-frame phase compensation on at least two frames of acquired 1D-FFT data includes: performing single-coefficient inter-frame phase compensation on at least two frames of acquired 1D-FFT data using a zero-Doppler signal; and / or The estimation of vital signs based on at least two frames of 1D-FFT data after inter-frame phase compensation includes: removing zero Doppler from at least two frames of 1D-FFT data after inter-frame phase compensation and then estimating the vital signs.

20. The target detection method as described in claim 18, characterized in that, The estimation of vital signs based on at least two frames of 1D-FFT data after inter-frame phase compensation includes: Respiratory rate estimation is performed using inter-frame accumulation based on at least two frames of 1D-FFT data after inter-frame phase compensation; or Based on the phase information of the 1D-FFT data corresponding to the range cell where the suspected target is located in at least two frames of 1D-FFT data after inter-frame phase compensation, the vital signs parameters are estimated.

21. The target detection method as described in claim 18, characterized in that, It is applied to electromagnetic wave devices with radar functionality; wherein the electromagnetic wave device is not equipped with a device for recording inter-frame phase changes, or although the electromagnetic wave device is equipped with a device for recording inter-frame phase changes, it does not work when performing target detection.

22. The target detection method according to any one of claims 18-21, characterized in that, In scenarios involving in-vehicle child detection, before performing single-coefficient inter-frame phase compensation on at least two frames of acquired 1D-FFT data, the method further includes: Determine whether an adult exists in the current scene based on at least two frames of acquired 1D-FFT data; If no adult is present, perform single-coefficient inter-frame phase compensation on at least two frames of 1D-FFT data, and estimate the vital signs parameters based on at least two frames of 1D-FFT data after inter-frame phase compensation to achieve target detection. If an adult is present, inter-frame phase compensation is not performed; instead, vital signs parameters are estimated directly based on at least two frames of acquired 1D-FFT data to achieve target detection.

23. The target detection method according to any one of claims 18-22, characterized in that, The inter-frame phase compensation method as described in any one of claims 1-10 is used to perform single-coefficient inter-frame phase compensation on at least two frames of acquired 1D-FFT data.

24. A target detection method, the method comprising: Acquire echo signals; the echo signals include at least two signal groups, each signal group includes multiple signal units, and the time interval between adjacent signal units in the same signal group is less than the time interval between adjacent signal groups; The signal units in the echo signal are subjected to FFT processing within the signal unit to obtain 1D-FFT data; After performing phase compensation on the 1D-FFT data between different groups of signals based on Doppler data, zero Doppler is removed; as well as 2D-FFT data are obtained by performing inter-group FFT processing on the 1D-FFT data after removing zero Doppler. The 2D-FFT data is configured for target detection.

25. The target detection method as described in claim 24, characterized in that, The phase compensation of the 1D-FFT data between different groups of signals based on Doppler data includes: Based on the 1D-FFT data, the energy of each distance cell in the Doppler dimension is obtained, and the distance cell with the largest Doppler energy is obtained; Based on the distance unit with the highest energy and the corresponding 1D-FFT data, the phase difference between each signal group and the preset signal group is obtained; and Phase compensation is performed on the 1D-FFT data between different groups of signals on the range cell of interest based on the phase difference.

26. A target detection device, applied to a radar system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the target detection method as described in any one of claims 12 to 25.

27. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the inter-frame phase compensation method as described in any one of claims 1 to 10, or the target detection method as described in any one of claims 12 to 25.

28. An integrated circuit, characterized in that, It includes a radio frequency module, an analog signal processing module, and a digital signal processing module connected in sequence; The radio frequency module is configured to generate and transmit electromagnetic wave signals, and to receive electromagnetic wave signals. The analog signal processing module is configured to down-frequency the received electromagnetic wave signal to obtain an intermediate frequency signal. The digital signal processing module is configured to perform analog-to-digital conversion on the intermediate frequency signal to obtain a digital signal; The digital signal processing module is further configured to perform inter-frame phase compensation according to any one of the methods described in claims 1-10, or to perform target detection according to any one of the methods described in claims 12 to 25.

29. The integrated circuit according to claim 28, characterized in that, The integrated circuit is an electromagnetic wave transceiver chip.

30. An electromagnetic wave device, characterized in that, include: Carrier; The integrated circuit as described in claim 28 or 29 is disposed on the carrier; The antenna is mounted on the carrier and can be integrated with the integrated circuit as a single device or disposed separately. The integrated circuit is connected to the antenna and is used to transmit the electromagnetic wave signal and / or receive the electromagnetic wave signal.

31. A terminal device, characterized in that, include: Equipment body; And, the electromagnetic wave device as described in claim 30, disposed on the device body; The electromagnetic wave device is configured to perform target detection and / or communication to provide reference information for the operation of the device body.

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