Breathing and heartbeat detection method, storage medium, program product and equipment

Abstract

The invention belongs to the field of vital sign detection equipment, and particularly relates to a breath and heartbeat detection method, a storage medium, a program product and equipment. According to the method, two-stage detection is carried out on a target through a Doppler radar, in the first stage, only an intrinsic signal is emitted, and the respiratory frequency of a respiratory frequency band in an echo signal is positioned and recognized; in the second stage, an elimination signal capable of eliminating the breathing signal is modulated according to the known breathing frequency, the elimination effect is evaluated by combining the analysis of the echo signal, and the amplitude and the phase of the elimination signal are dynamically adjusted; and after the breathing elimination effect reaches the expectation, positioning and identifying the heartbeat frequency of the echo signal center frequency hopping band. In addition, a delay module and a data processing module are introduced into the existing Doppler radar, and then respiration and heartbeat detection equipment applying the method is obtained. According to the invention, the problems of narrow working frequency band, high computing power requirement and insufficient precision and real-time performance in the existing scheme are solved.

Description

Technical Field

[0001] This invention belongs to the field of vital sign detection equipment, specifically relating to a respiratory and heartbeat detection method based on Doppler radar active cancellation, and its corresponding storage medium, computer program product, and respiratory and heartbeat detection equipment. Background Technology

[0002] Respiratory and heart rate are key indicators for assessing human vital signs and are of great value in disease diagnosis, health monitoring, and emergency rescue. Non-contact vital sign detection technologies (such as radar detection) are gaining increasing attention due to their immunity to environmental factors and strong penetration capabilities. Doppler radar extracts respiratory and heart rate information by detecting phase changes in the echo signal caused by chest wall movement. Compared to other technologies, radar detection offers high stability and is suitable for non-contact scenarios such as burn monitoring and earthquake rescue.

[0003] The amplitude of chest wall vibration caused by respiration is greater than that of the heartbeat, but the frequency of respiration is lower than that of the heartbeat. This means that the amplitude of respiratory harmonics in the spectrum may be comparable to or even greater than that of the heartbeat, and respiration and heartbeat produce mutual harmonics. The amplitude of these mutual harmonics is similar to that of the heartbeat, further increasing the difficulty of heartbeat extraction. To address this problem, existing solutions mainly rely on algorithmic processing to extract heartbeats, including data length transformation techniques, supervised machine learning algorithms, and respiratory harmonic suppression techniques based on matched filters. However, existing algorithmic processing strategies mainly target the problem of respiratory harmonic suppression at a certain operating frequency. When the system operating frequency changes, fixed algorithms may not be able to cope with the changing spectrum, especially when the system frequency increases, respiratory harmonics are no longer the sole factor affecting heartbeat extraction, and the mutual harmonics between respiration and heartbeat become a significant interference. In addition, this strategy of extracting heartbeat frequency through algorithmic correction also suffers from complex data processing, high computational requirements, insufficient real-time performance, and unsuitability for embedded applications. Summary of the Invention

[0004] To address the problems of narrow operating bandwidth, high computing power requirements, and insufficient accuracy and real-time performance in existing algorithm-based respiratory and heartbeat extraction strategies, this invention provides a respiratory and heartbeat detection method based on Doppler radar active cancellation, along with its corresponding storage medium, computer program product, and respiratory and heartbeat detection device.

[0005] This invention is achieved using the following technical solution: A method for detecting respiratory and heartbeats based on Doppler radar active cancellation, comprising: First, a detection signal containing only the local oscillator signal is sent via a Doppler radar system for initial detection. The received echo signal is then subjected to Fast Fourier Transform and filtering to obtain a spectrum. The frequency corresponding to the signal peak in the breathing band is extracted from the spectrum and used as the breathing frequency f. res .

[0006] The detection signal, after superposition cancellation, is then transmitted via a Doppler radar system for multiple rounds of repeated detection; the received echo signal is then subjected to Fast Fourier Transform and filtering to obtain a spectrum. The frequency of the cancellation signal is f. res The phase and amplitude are dynamically adjusted in each round of detection based on the judgment that the elimination signal can cancel out the respiratory signal.

[0007] When the cancellation of the respiratory signal meets the requirements, the frequency corresponding to the peak value of the center hopping frequency band in the spectrum of the echo signal at this time is taken as the heart rate f. hb .

[0008] Whether the cancellation signal cancels out the respiratory signal or the degree of cancellation meets the requirements is evaluated by one or more of the following indicators: signal strength of the echo signal, signal peak value of the respiratory frequency band, and signal change of the heart rate band.

[0009] As a further improvement of the present invention, the criteria for determining whether the elimination signal can cancel the respiratory signal and whether the degree of cancellation between the two meets the requirements include any of the following: (i) If the signal strength of the current echo signal decreases relative to the previous one, it means that the two can cancel each other out; if the signal strength of the current echo signal decreases to 1 / of the signal strength of the echo signal at the time of the initial detection. α If the two cancel each other out, it means that the degree of cancellation meets the requirements.

[0010] in, α The reference value is the ratio of the signal intensity of the echo signal U1, which is the superposition of the heartbeat and respiratory signals, to the signal intensity of the echo signal U2, which only includes the heartbeat signal.

[0011] (ii) If the peak value of the mid-respiratory frequency band in the current echo signal decreases, it indicates that the two can cancel each other out; if the peak value of the mid-respiratory frequency band in the current echo signal decreases to 1 / of the peak value of the respiratory frequency band in the echo signal at the time of the initial detection, it indicates that the two can cancel each other out. β If the two cancel each other out, it means that the degree of cancellation meets the requirements.

[0012] in, β This is a reference value for the ratio of the peak value of the respiratory frequency band in the echo signal U1, which is the superposition of the heartbeat and respiratory signals, to the peak value of the respiratory frequency band in the echo signal U2, which only includes the heartbeat signal.

[0013] (iii) If only one peak in the current heartbeat frequency band has a flat or rising amplitude, while the amplitudes of the other peaks decrease, it means that the two can cancel each other out; if the rate of decrease of these peaks with decreasing amplitudes is reduced to the preset minimum threshold, it means that the degree of cancellation between the two meets the requirements.

[0014] As a further improvement of the present invention, the preset frequency band of the respiratory signal is 0.083~0.42Hz; the preset frequency band of the heartbeat signal is 0.75~2.50Hz.

[0015] As a further improvement of the present invention, the amplitude range of the respiratory signal is 4~12mm; the amplitude range of the heartbeat signal is 0.2~0.5mm.

[0016] As a further improvement of this invention, in the repeated detection stage, a data processing module first performs Fast Fourier Transform and filtering on the echo signal of each round to obtain a spectrum; then, it extracts the corresponding window signal according to the preset frequency bands of the respiratory and heartbeat signals; finally, it analyzes the window signal, and when the peak value of the respiratory frequency band in the echo signal of this round decreases to 1 / of the peak value of the respiratory frequency band in the echo signal during the initial detection... β At this time, it is determined whether the degree of cancellation between the elimination signal and the respiratory signal meets the requirements, and the frequency of the heartbeat signal is output.

[0017] As a further improvement of the present invention, in the repeated detection stage, a data processing module extracts the signal strength value of each round of echo signal. When the signal strength of the current round of echo signal decreases to 1 / 3 of the signal strength of the echo signal at the initial detection, the signal strength is calculated. α At this time, it is determined whether the degree of cancellation between the elimination signal and the respiratory signal meets the requirements, and the frequency of the heartbeat signal is output.

[0018] As a further improvement of the present invention, in the repeated detection stage, a data processing module first performs a fast Fourier transform and filtering on the echo signal of each round to obtain a spectrum; then, according to the preset frequency bands of the respiratory signal and heartbeat signal, the corresponding window signal is extracted; then, the amplitude change rate of each peak in the heartbeat signal window signal relative to the previous round is calculated. If only one peak has a positive amplitude change rate and the rest are negative, it means that the elimination signal can cancel the heartbeat signal. At this time, the peak with a positive change rate is recorded as the heartbeat peak; in subsequent detection, when the amplitude change rate of the other peaks besides the heartbeat peak is less than a preset minimum threshold, it is determined that the degree of cancellation between the elimination signal and the heartbeat signal meets the requirements, and the frequency of the heartbeat signal is output.

[0019] As a further improvement of the present invention, in the repeated detection stage, a data processing module first performs fast Fourier transform and filtering on the echo signal of each round to obtain a spectrum; then, according to the preset frequency bands of the respiratory signal and heartbeat signal, the corresponding window signal is extracted; then, a display module visualizes the window signal, and the user judges whether the cancellation signal cancels the respiratory signal according to the signal change of the heartbeat frequency band, and outputs the frequency of the heartbeat signal after the cancellation criterion is met.

[0020] The present invention also includes a storage medium storing a computer program, which, when executed by a processor, implements the aforementioned respiratory and heartbeat detection method based on Doppler radar active cancellation, and then generates detection results of the user's heart rate and respiratory rate based on the echo signals after multiple rounds of detection.

[0021] The present invention also includes a computer program product comprising a computer program that, when executed by a processor, implements the aforementioned respiratory and heartbeat detection method based on Doppler radar active cancellation, and then generates detection results of the user's heart rate and respiratory rate based on the echo signals after multiple rounds of detection.

[0022] The present invention also includes a respiratory and heart rate detection device, which includes a Doppler radar and a data processing module.

[0023] The Doppler radar includes a modulation module, a delay module, a signal generator, a transmitting antenna, a receiving antenna, a signal receiver, and a demodulation module. The modulation module sends modulation commands for the local oscillator signal to the signal generator; the signal generator generates a corresponding detection signal based on the received commands; the transmitting antenna transmits the detection signal generated by the signal generator; the delay module sends modulation commands to the signal generator to cancel the signal; the signal receiver collects the echo signal through the receiving antenna; and the demodulation module demodulates the echo signal collected by the signal receiver.

[0024] The data processing module is electrically connected to the demodulation module and the delay module. It is used to analyze the echo signal output by the demodulation module using the Doppler radar active cancellation-based respiratory and heartbeat detection method described in section 1, and to perform negative feedback control on the delay module based on the analysis results. This allows for the generation of user heart rate and respiratory rate detection results based on the echo signals after multiple rounds of detection.

[0025] The technical solution provided by this invention has the following beneficial effects: The solution provided by this invention uses Doppler radar to extract the target's breathing frequency and heart rate in two stages. In the heart rate extraction stage, this invention actively eliminates breathing signals by actively transmitting carrier waves through the radar system, thereby eliminating interference from breathing signals and significantly improving the extraction accuracy of heart rate.

[0026] The solution of this invention directly addresses the modulation waves generated by human respiration, thus disregarding the system's operating frequency and exhibiting good performance in various scenarios. Therefore, radar systems with different operating frequencies can be used, resulting in better compatibility with the operating frequencies of different devices.

[0027] The solution of this invention can achieve high-precision extraction of heartbeat frequency without relying on complex back-end signal processing, thus reducing the system's computing power requirements, helping to improve the real-time performance of the solution, and enabling the deployment of the solution by using embedded modules to improve existing equipment, which can significantly reduce the application cost of related solutions. Attached Figure Description

[0028] Figure 1 This is a spectrum diagram of a typical echo signal in Doppler radar-based respiratory and heartbeat detection.

[0029] Figure 2 This is a flowchart of the steps of the breathing and heartbeat detection method based on Doppler radar active cancellation provided in Embodiment 1 of the present invention.

[0030] Figure 3 This is the spectrum of the echo signal after the breath elimination process of this invention.

[0031] Figure 4 This is a schematic diagram of the respiratory and heart rate detection device provided in Embodiment 2 of the present invention.

[0032] Figure 5 To compare the spectral density of echo signals before and after respiratory signal elimination in the test experiment.

[0033] Figure 6 To test the spectrum comparison of echo signals obtained by the scheme of the present invention at different operating frequency bands in the experiment. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] Example 1

[0036] In this embodiment, the technicians discovered that when using continuous-wave Doppler radar to monitor vital signs, the chest cavity movement caused by breathing and heartbeat modulates the phase of the transmitted signal. At this time, the echo signal received by the continuous-wave Doppler radar can be considered as a wave superimposed on the transmitted signal, consisting of breathing and heartbeat signals. K The wave can be represented as: K = d r sin w r t+ d h sin w h t In the above formula, d r and d h These represent the amplitudes of the respiratory signal and the heartbeat signal, respectively. w r and w h These represent the frequencies of the respiratory and heartbeat signals, respectively.

[0037] Among them, statistical analysis of the differentiated vital sign signals of a massive number of users revealed that, at the signal frequency level, the frequency of respiratory signals... w r The frequency of heartbeat signals is typically distributed within the 0.083–0.42 Hz band, while the frequency of heartbeat signals... w h These frequencies typically fall within the 0.75–2.50 Hz band; therefore, in the spectrum of the superimposed wave K, the frequency bands of the respiratory and heartbeat signals do not overlap. Correspondingly, at the signal amplitude level, the amplitude of the respiratory signal… d r The range is 4~12mm; while the amplitude of the heartbeat signal d h The range is 0.2~0.5mm. The amplitude of the respiratory signal is tens of times greater than that of the heartbeat signal; therefore, if... Figure 1 As shown, when extracting respiratory and heartbeat signals from the superimposed signals, the harmonic signals of the respiratory signal and the mutual harmonic signals of the respiratory and heartbeat signals will inevitably cause significant interference to the extraction of the heartbeat signal.

[0038] To address this issue, the engineers in this embodiment propose a two-stage signal extraction strategy. In the first stage, the echo signal of the Doppler radar's transmitted signal is directly subjected to spectral analysis, and the frequency of the breathing signal is identified from the breathing frequency band. Since the amplitude of the heartbeat signal is much smaller than that of the breathing signal, the heartbeat signal hardly interferes with the identification and localization of the breathing signal in this stage.

[0039] In the second stage, addressing the impact of respiratory signal harmonics and environmental noise on heartbeat signal extraction, this embodiment employs an active compensation technique similar to active noise cancellation in headphones to identify the heartbeat signal. Specifically, based on the aforementioned principle of Doppler radar-based vital sign detection technology, when the transmitted signal itself carries a carrier wave containing respiratory information, and this carrier wave happens to have the same frequency, amplitude, and opposite phase as the modulation wave (i.e., the respiratory signal) caused by human respiration, the respiratory signal in the received echo signal can be canceled out. d r sin w r At this point, when performing signal demodulation and spectrum analysis on the echo signal, only the spectrum of the heartbeat signal will remain within the heartbeat frequency band of the echo signal; while the harmonic signals of the respiratory signal that interfere with the extraction of the heartbeat signal and the mutual harmonic signals of the respiratory and heartbeat signals will no longer exist.

[0040] To achieve the goal of eliminating the respiratory signal by modulating a carrier wave with the same frequency, amplitude, and opposite phase as the respiratory signal in the second stage, this embodiment superimposes a carrier wave of the corresponding frequency onto the Doppler radar's transmitted signal based on the known respiratory signal frequency. The amplitude and phase of the carrier wave are then adjusted in a step-by-step manner. The superimposed carrier wave is then evaluated based on the signal changes in the acquired echo signal to determine if it meets the requirements. This step-by-step feedback adjustment strategy allows the superimposed carrier wave to gradually approach the respiratory signal, ultimately extracting the frequency of the heartbeat signal that eliminates respiratory signal interference, thus achieving more accurate detection of both respiratory and signal frequencies.

[0041] Specifically, such as Figure 2 As shown, the breathing and heartbeat detection method based on Doppler radar active cancellation provided in this embodiment includes the following steps: I. Respiratory Rate Recognition First, a detection signal containing only the local oscillator signal is sent via a Doppler radar system for initial detection. The received echo signal is then subjected to Fast Fourier Transform and filtering to obtain a spectrum. The frequency corresponding to the signal peak in the breathing band is extracted from the spectrum and used as the breathing frequency f. res .

[0042] In detail, in practical applications, the demodulated echo signal output by the demodulation module of a Doppler radar system undergoes preliminary filtering and signal sampling. Following this, a Fast Fourier Transform (FFT) is performed on the sampled signal, and the signal is then split in the frequency domain using a bandpass or low-pass filter to locate the breathing frequency within the lower breathing band (0.083Hz-0.42Hz). The center frequency of the wave with the highest signal peak within the breathing band (which can be denoted as the "breathing peak") is the desired breathing frequency f. res .

[0043] II. Elimination of respiratory signals The detection signal, after superposition cancellation, is then transmitted via a Doppler radar system for multiple rounds of repeated detection; the received echo signal is then subjected to Fast Fourier Transform and filtering to obtain a spectrum. The frequency of the cancellation signal is f. res The phase and amplitude are dynamically adjusted in each round of detection based on the judgment that the elimination signal can cancel out the respiratory signal.

[0044] In this embodiment, the modulated cancellation signal included in the Doppler radar's transmitted signal during this stage is the carrier wave used to cancel the breathing signal, as described above. To achieve the best cancellation effect, both signals need to have the same frequency, the same amplitude, and opposite phase. Considering the breathing signal frequency is known, this embodiment only needs to continuously adjust the amplitude and phase of the cancellation signal included in the transmitted signal in subsequent processes.

[0045] In practical applications, in order to improve efficiency, this embodiment sets the control range of amplitude parameters in signal adjustment according to the known distribution range of the amplitude of respiratory signals of different users, and discretizes them according to preset accuracy requirements. The phase range of the signal is also discretized according to accuracy requirements. Finally, the two parameters are dynamically adjusted within the corresponding discrete range, so that the elimination signal that can achieve the best elimination effect can be quickly searched.

[0046] During the dynamic adjustment of the amplitude and phase of the signal elimination process, technicians can first fix the phase to find the optimal amplitude, and then fix the optimal amplitude to find the optimal phase. Alternatively, they can first fix the amplitude to find the optimal phase, and then fix the optimal phase to find the optimal amplitude. Furthermore, during the iterative optimization of the phase and amplitude parameters of the eliminated signal, technicians can use a step-by-step strategy to adjust the parameters within a discrete interval, or they can use a binary search method or other methods to adjust the parameters within a discrete interval, thereby reducing the number of adjustments and improving detection efficiency.

[0047] In the process of adjusting the amplitude and phase of the cancellation signal, the direction of parameter adjustment needs to be adjusted in conjunction with the cancellation effect. Based on the principle of signal superposition, the signal strength of the echo signal can be used to evaluate whether the cancellation signal cancels the respiratory signal or whether the degree of cancellation meets the requirements. Specifically, if the cancellation signal can weaken the respiratory signal, the respiratory signal within the echo signal will gradually disappear, leading to a gradual decrease in the signal strength of the echo signal. Conversely, if the two cannot cancel each other out, the cancellation signal will actually strengthen the respiratory signal, causing the signal strength of the echo signal to gradually increase. Therefore, observing the changes in the signal strength of the echo signal can assess the cancellation effect of the cancellation signal.

[0048] The effectiveness of the cancellation signal in cancelling the respiratory signal, or the degree of cancellation, can also be assessed by observing the peak value of the respiratory frequency band in the echo signal. According to signal principles, if the cancellation signal weakens the respiratory signal, the peak value of the respiratory peak within the respiratory frequency band of the echo signal will gradually decrease. Conversely, if the two cannot cancel each other out, the cancellation signal will actually strengthen the respiratory signal, causing the peak value of the respiratory peak within the respiratory frequency band of the echo signal to gradually increase. Therefore, observing changes in the peak value of the respiratory peak can evaluate the cancellation effect of the cancellation signal.

[0049] The effectiveness of the cancellation signal in cancelling the respiratory signal, and the degree of cancellation, can be assessed by observing signal changes in the heartbeat frequency band of the echo signal. As mentioned earlier, the signal components within the heartbeat frequency band include the heartbeat signal, harmonics of the respiratory signal, the mutual harmonics between the respiratory and heartbeat signals, and environmental noise. Therefore, if the cancellation signal can weaken the respiratory signal, the respiratory signal, its harmonics, and respiration harmonics within the heartbeat frequency band of the echo signal will decrease, while the heartbeat signal will remain unchanged. Thus, the visualization result within the heartbeat frequency band is that the peak value of the wave corresponding to the heartbeat will remain unchanged or slightly increase, while the waves of other signals will gradually decrease, thereby gradually "standing out" of the heartbeat signal from the background noise. Conversely, if the cancellation signal cannot weaken the respiratory signal, it will lead to the enhancement of other signals, causing the lower-amplitude heartbeat signal to be completely "submerged" and undetectable.

[0050] In summary, based on the above principles, this embodiment establishes three independent criteria for evaluating the cancellation signal: (i) If the signal strength of the current echo signal decreases relative to the previous one, it means that the two can cancel each other out; if the signal strength of the current echo signal decreases to 1 / of the signal strength of the echo signal at the time of the initial detection. α If , it means that the two are basically offset.

[0051] in, αThe reference value is the ratio of the signal intensity of the echo signal U1, which is the superposition of the heartbeat and respiratory signals, to the signal intensity of the echo signal U2, which only includes the heartbeat signal.

[0052] (ii) If the peak value of the mid-respiratory frequency band in the current echo signal decreases, it indicates that the two can cancel each other out; if the peak value of the mid-respiratory frequency band in the current echo signal decreases to 1 / of the peak value of the respiratory frequency band in the echo signal at the time of the initial detection, it indicates that the two can cancel each other out. β If the two are basically offset, it means that the requirement is met.

[0053] in, β This is a reference value for the ratio of the peak value of the respiratory frequency band in the echo signal U1, which is the superposition of the heartbeat and respiratory signals, to the peak value of the respiratory frequency band in the echo signal U2, which only includes the heartbeat signal.

[0054] (iii) If only one peak in the current heartbeat frequency band has a flat or rising amplitude, while the amplitudes of the other peaks decrease, it means that the two can cancel each other out; if the rate of decrease of these peaks with decreasing amplitudes is reduced to the preset minimum threshold, it means that the degree of basic cancellation between the two meets the requirements.

[0055] In practical applications, technicians can combine one of the above criteria to judge the cancellation effect of the modulated cancellation signal, or they can combine multiple criteria for a comprehensive judgment to avoid misjudgment caused by accidental factors (such as a sudden increase in environmental noise). α and β The specific value can be scientifically set after statistical analysis of massive experimental data from different users.

[0056] (III) Heart rate recognition When the degree of cancellation between the elimination signal and the respiratory signal meets the requirements, such as Figure 3 As shown, the peak corresponding to the heartbeat signal will be highlighted in the heartbeat frequency band. The frequency corresponding to the signal peak in the heartbeat frequency band of the echo signal spectrum at this time is taken as the heartbeat frequency f. hb .

[0057] It should be noted that the technical problem to be solved by the present invention is to extract the frequency of respiratory and heartbeat signals. Therefore, when eliminating respiratory signals in the second stage, it is not necessary to achieve the ideal state of complete elimination of respiratory signals. It is sufficient to highlight the heartbeat signal for easy identification and positioning.

[0058] In practical applications, the process of judging whether the technical effect of eliminating respiratory signals has been achieved, and adjusting the modulation parameters of the amplitude and phase of the eliminated signals, can be completed automatically by a computer, or it can be manually adjusted by the user after analysis and judgment.

[0059] For example, in the repeated detection phase, a data processing module first performs Fast Fourier Transform and filtering on the echo signal of each round to obtain a spectrum; then, it extracts the corresponding window signal according to the preset frequency bands of the respiratory and heartbeat signals; finally, it analyzes the window signal, and when the peak value of the respiratory frequency band in the echo signal of this round decreases to 1 / 3 of the peak value of the respiratory frequency band in the echo signal during the initial detection... β At this time, it is determined whether the degree of cancellation between the elimination signal and the respiratory signal meets the requirements, and the frequency of the heartbeat signal is output.

[0060] Alternatively, during the repeated detection phase, a data processing module can extract the signal strength value of each round of echo signals. When the signal strength of the current round of echo signals decreases to 1 / 3 of the signal strength of the echo signal at the initial detection, the signal strength is calculated. α At this time, it is determined whether the degree of cancellation between the elimination signal and the respiratory signal meets the requirements, and the frequency of the heartbeat signal is output.

[0061] Alternatively, during the repeated detection phase, a data processing module first performs a Fast Fourier Transform and filtering on the echo signal of each round to obtain a spectrum. Then, based on the preset frequency bands of the respiratory and heartbeat signals, the corresponding window signals are extracted. Next, the amplitude change rate of each peak in the heartbeat signal window relative to the previous round is calculated. If only one peak has a positive amplitude change rate and the rest are negative, it means that the cancellation signal can cancel the heartbeat signal. In this case, the peak with a positive change rate is recorded as the heartbeat peak. In subsequent detection, when the amplitude change rate of the peaks other than the heartbeat peak is less than a preset minimum threshold, it is determined that the degree of cancellation between the cancellation signal and the heartbeat signal meets the requirements, and the frequency of the heartbeat signal is output.

[0062] Alternatively, during the repeated detection phase, a data processing module first performs a fast Fourier transform and filtering on the echo signal of each round to obtain a spectrum; then, according to the preset frequency bands of the respiratory signal and heartbeat signal, the corresponding window signal is extracted; then, a display module visualizes the window signal, and the user judges whether the cancellation signal cancels the respiratory signal based on the signal change of the heartbeat frequency band, and outputs the frequency of the heartbeat signal after the cancellation criterion is met.

[0063] Example 2

[0064] The breathing and heartbeat detection method based on Doppler radar active cancellation provided in Example 1 is essentially a data processing method. In order to better apply this method, this example further provides a storage medium, a computer program product, and a breathing and heartbeat detection device.

[0065] Specifically, the storage medium provided in this embodiment stores a computer program. When the computer program is executed by the processor, it implements the breathing and heartbeat detection method based on Doppler radar active cancellation as in Embodiment 1, and then generates the detection results of the user's heartbeat frequency and breathing frequency based on the echo signals after multiple rounds of detection.

[0066] The computer program product provided in this embodiment includes a computer program. When the computer program is executed by a processor, it implements the breathing and heartbeat detection method based on Doppler radar active cancellation as in Embodiment 1, and then generates the detection results of the user's heart rate and breathing rate based on the echo signals after multiple rounds of detection.

[0067] like Figure 4 As shown, the respiratory and heartbeat detection device provided in this embodiment includes a Doppler radar and a data processing module. The Doppler radar includes a modulation module, a delay module, a signal generator, a transmitting antenna, a receiving antenna, a signal receiver, and a demodulation module. The modulation module sends a modulation command for the local oscillator signal to the signal generator; the signal generator generates a corresponding detection signal based on the received command; the transmitting antenna transmits the detection signal generated by the signal generator; the delay module sends a modulation command to the signal generator to cancel the signal; the signal receiver collects the echo signal through the receiving antenna; and the demodulation module demodulates the echo signal collected by the signal receiver.

[0068] The data processing module is electrically connected to the demodulation module and the delay module. In this embodiment, the data processing module is used to analyze the echo signal output by the demodulation module using the Doppler radar active cancellation-based respiratory and heartbeat detection method as described in Embodiment 1. Based on the analysis results, the delay module is subjected to negative feedback control, and after multiple rounds of detection, the detection results of the user's heart rate and respiratory rate are generated based on the echo signal.

[0069] In the respiratory and heartbeat detection device of this embodiment, during the first stage of detection, the Doppler radar generates a transmission signal containing only intrinsic signals based on the modulation module, and completes detection and signal analysis. In the subsequent second stage of detection, a transmission signal containing both intrinsic and cancellation signals is generated simultaneously based on the adjustment and delay modules, and detection and signal analysis are completed. In the second stage, the data processing module forms a feedback loop with the delay unit to dynamically adjust the delay module.

[0070] During the signal modulation cancellation process, the data processing module adjusts the delay unit based on information about both frequency and amplitude, regulating the amplitude and speed of the delay change. This superimposes a carrier wave with a breathing frequency and amplitude onto the intrinsic signal output by the transmitter. It is worth noting that the static delay of the delay unit represents the initial phase of this carrier wave. Dynamic adjustment of the delay unit achieves signal phase modulation, ultimately resulting in a carrier wave with a phase opposite to the wave generated by the chest cavity vibration caused by actual human respiration.

[0071] In practical applications, the data processing module in the respiratory and heartbeat detection device provided in this embodiment is essentially a computer device. In actual applications, it adopts an embedded computer device and is integrated into the Doppler radar used for vital sign detection. Alternatively, a standalone computer device can be used, such as a laptop, tablet, desktop computer, or a rack server, blade server, tower server, or cabinet server (including standalone servers or server clusters composed of multiple servers), which can execute computer programs, and serve as an external device for the existing Doppler radar.

[0072] The computer device in this embodiment includes, but is not limited to, a memory and a processor that can be interconnected via a system bus. In this embodiment, the memory (i.e., the readable storage medium) includes flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, optical disk, etc. In some embodiments, the memory can be an internal storage unit of the computer device, such as the hard disk or RAM of the computer device. In other embodiments, the memory can also be an external storage device of the computer device, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc. Of course, the memory can also include both internal storage units and external storage devices of the computer device. In this embodiment, the memory is typically used to store the operating system and various application software installed on the computer device. Furthermore, the memory can also be used to temporarily store various types of data that have been output or will be output.

[0073] In some embodiments, the processor may be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip. The processor is typically used to control the overall operation of a computer device.

[0074] Simulation test To verify the performance of the respiratory and heartbeat detection method based on Doppler radar active cancellation provided by this invention, this embodiment uses a laptop computer and a Doppler radar-based vital signs detector to build a corresponding test system and test the relevant scheme.

[0075] 1. Detection performance This experiment first uses a constructed testing system to extract the user's respiratory rate and heart rate using a two-step method. The echo signal in the first stage is as follows: Figure 5 As shown in part (a), after the respiration elimination following iterative optimization in the second stage, the resulting echo signal is as follows: Figure 5 As shown in part (b) of the document.

[0076] Observing the data in the figure, it can be seen that before respiratory elimination, the frequency acquisition of respiratory signals is stable and efficient. However, after respiratory elimination, the peak value of the respiratory peak in the respiratory frequency band decreases significantly. The respiratory harmonics and interharmonic signals within the heart rate are significantly weakened, making the corresponding peaks of the heart rate signal more prominent, which helps to improve the accuracy of heart rate recognition.

[0077] 2. Operating frequency This experiment further tested the performance of the relevant schemes of the present invention at operating frequencies of 18GHz and 20GHz, and obtained the following results: Figure 6 The signal spectrum diagram is shown above. Observing the data in the diagram, it can be seen that this scheme can obtain consistent signal characteristics at different operating frequencies, which proves that the scheme of the present invention can be applied to a wider range of operating frequencies.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A respiratory and heartbeat detection method based on Doppler radar active cancellation, characterized in that, It includes: First, a detection signal containing only the local oscillator signal is sent via a Doppler radar system for initial detection. The received echo signal is then subjected to Fast Fourier Transform and filtering to obtain a spectrum. The signal peak value of the breathing frequency band and its corresponding frequency are extracted from the spectrum and used as the breathing frequency f. res ; The detection signal, after superposition cancellation, is then transmitted via a Doppler radar system for multiple rounds of repeated detection; the received echo signal is then subjected to Fast Fourier Transform and filtering to obtain a spectrum; where the frequency of the cancellation signal is f. res The phase and amplitude are dynamically adjusted in each round of detection based on whether the cancellation signal can cancel out the respiratory signal. When the cancellation signal and respiratory signal cancel out to the required degree, the frequency corresponding to the peak value of the center hopping frequency band in the echo signal spectrum at this time is taken as the heart rate f. hb .

2. The respiratory and heartbeat detection method based on Doppler radar active cancellation as described in claim 1, characterized in that, Criteria for determining whether the elimination signal can cancel out the respiratory signal and whether the degree of cancellation meets the requirements include any of the following: (i) If the signal strength of the current echo signal decreases relative to the previous one, it means that the two can cancel each other out; if the signal strength of the current echo signal decreases to 1 / of the signal strength of the echo signal at the time of the initial detection. α If the two cancel each other out, it means that the degree of cancellation meets the requirements; in, α A reference value for the ratio of the signal intensity of the echo signal U1, which is the superposition of the heartbeat and respiratory signals, to the signal intensity of the echo signal U2, which only includes the heartbeat signal; (ii) If the peak value of the mid-respiratory frequency band in the current echo signal decreases, it indicates that the two can cancel each other out; if the peak value of the mid-respiratory frequency band in the current echo signal decreases to 1 / of the peak value of the respiratory frequency band in the echo signal at the time of the initial detection, it indicates that the two can cancel each other out. β If the two cancel each other out, it means that the degree of cancellation meets the requirements; in, β A reference value for the ratio of the peak value of the respiratory frequency band in the echo signal U1, which is the superposition of the heartbeat and respiratory signals, to the peak value of the respiratory frequency band in the echo signal U2, which only includes the heartbeat signal; (iii) If only one peak in the current heartbeat frequency band has a flat or rising amplitude, while the amplitudes of the other peaks decrease, it means that the two can cancel each other out; if the rate of decrease of these peaks with decreasing amplitudes is reduced to the preset minimum threshold, it means that the degree of cancellation between the two meets the requirements.

3. The respiratory and heartbeat detection method based on Doppler radar active cancellation as described in claim 2, characterized in that: The preset frequency range for the respiratory signal is 0.083~0.42Hz; the preset frequency range for the heartbeat signal is 0.75~2.50Hz.

4. The respiratory and heartbeat detection method based on Doppler radar active cancellation as described in claim 3, characterized in that: The amplitude range of the respiratory signal is 4~12mm; the amplitude range of the heartbeat signal is 0.2~0.5mm.

5. The respiratory and heartbeat detection method based on Doppler radar active cancellation as described in claim 4, characterized in that: During the repeated detection phase, a data processing module first performs Fast Fourier Transform and filtering on the echo signals of each round to obtain a spectrum. Then, it extracts the corresponding window signals based on the preset frequency bands of the respiratory and heartbeat signals. Finally, it analyzes the window signals, determining when the peak value of the respiratory frequency band in the current round of echo signals decreases to 1 / 3 of the peak value of the respiratory frequency band in the echo signals during the initial detection. β At this time, it is determined whether the degree of cancellation between the elimination signal and the respiratory signal meets the requirements, and the frequency of the heartbeat signal is output.

6. The respiratory and heartbeat detection method based on Doppler radar active cancellation as described in claim 4, characterized in that: During the repeated detection phase, a data processing module extracts the signal strength value of each round of echo signals. When the signal strength of the current round of echo signals decreases to 1 / 3 of the signal strength of the echo signal at the initial detection, the signal strength is calculated. α At this time, it is determined whether the degree of cancellation between the elimination signal and the respiratory signal meets the requirements, and the frequency of the heartbeat signal is output.

7. The respiratory and heartbeat detection method based on Doppler radar active cancellation as described in claim 4, characterized in that: During the repeated detection phase, a data processing module first performs Fast Fourier Transform and filtering on the echo signal of each round to obtain a spectrum. Then, it extracts the corresponding window signals according to the preset frequency bands of the respiratory and heartbeat signals. Next, it calculates the amplitude change rate of each peak in the heartbeat signal window relative to the previous round. If only one peak has a positive amplitude change rate and the rest are negative, it means that the elimination signal can cancel the heartbeat signal. In this case, the peak with a positive change rate is recorded as the heartbeat peak. In subsequent detection, when the amplitude change rate of the peaks other than the heartbeat peak is less than a preset minimum threshold, it is determined that the degree of cancellation between the elimination signal and the heartbeat signal meets the requirements, and the frequency of the heartbeat signal is output. Alternatively, during the repeated detection phase, a data processing module first performs a fast Fourier transform and filtering on the echo signal of each round to obtain a spectrum; then, it extracts the corresponding window signal according to the preset frequency bands of the respiratory signal and heartbeat signal; then, a display module visualizes the window signal, and the user judges whether the cancellation signal cancels the respiratory signal based on the signal change of the heartbeat frequency band, and outputs the frequency of the heartbeat signal after the cancellation criterion is met.

8. A storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, it implements the breathing and heartbeat detection method based on Doppler radar active cancellation as described in any one of claims 1-7, and then generates the detection results of the user's heart rate and breathing rate based on the echo signals after multiple rounds of detection.

9. A computer program product comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the breathing and heartbeat detection method based on Doppler radar active cancellation as described in any one of claims 1-7, and then generates the detection results of the user's heart rate and breathing rate based on the echo signals after multiple rounds of detection.

10. A respiratory and heart rate detection device, characterized in that: It includes: A Doppler radar includes a modulation module, a delay module, a signal generator, a transmitting antenna, a receiving antenna, a signal receiver, and a demodulation module. The modulation module is used to send modulation instructions for the local oscillator signal to the signal generator; the signal generator is used to generate the corresponding detection signal according to the received instructions; the transmitting antenna is used to transmit the detection signal generated by the signal generator. The delay module is used to send modulation commands to the signal generator to cancel the signal; the signal receiver collects the echo signal through the receiving antenna; the demodulation module is used to demodulate the echo signal collected by the signal receiver. The data processing module is electrically connected to the demodulation module and the delay module, and is used to analyze the echo signal output by the demodulation module using the Doppler radar active cancellation breathing and heartbeat detection method as described in any one of claims 1-7, and to perform negative feedback control on the delay module based on the analysis results, thereby generating the detection results of the user's heart rate and breathing rate based on the echo signal after multiple rounds of detection.

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