Multi-target vital sign detector and its detection method

Abstract

The present invention is a multi-target vital sign detector and its detection method. The multi-target vital sign detector includes a self-injection locked oscillator, a chirp up / down frequency converter, a frequency demodulation unit, and a multi-target vital sign processing unit. The chirp up / down frequency converter converts the oscillation signal of the self-injection locked oscillator into a frequency-modulated continuous wave signal to detect an area, and converts the received frequency-modulated continuous wave signal reflected by the area into an injection signal. The injection signal is injected into the self-injection locked oscillator to make it in a self-injection locked state. Finally, the positions and vital signs of multiple organisms are obtained from the oscillation signal through the frequency demodulation unit and the multi-target vital sign processing unit. The purpose of using the self-injection locked oscillator is to improve the sensitivity of the frequency-modulated continuous wave detector, and effectively distinguish the vital signs of multiple organisms located at different positions.

Description

Technical Field

[0001] The present invention relates to a vital sign detector, and more particularly to a multi-target vital sign detector and a detection method thereof. Background Art

[0002] Generally speaking, a non-contact vital sign detector detects the vital signs of a living body by transmitting a wireless signal to the living body and receiving the wireless signal reflected by the living body, so as to detect the Doppler effect caused by the displacement of the living body. However, a non-contact vital sign detector generally can only be used to detect the vital signs of a single target, and the detection of the vital signs of multiple living bodies will be unidentifiable due to the mutual interference between the wireless signals reflected by each living body.

[0003] A Frequency-Modulated Continuous Wave Radar (FMCW radar) transmits a transmitted signal whose frequency changes with time to an object, and receives a reflected signal from the object, so as to obtain the distance between the object and the radar by the frequency difference between the transmitted signal and the reflected signal at the same time point. However, due to the low sensitivity of the Frequency-Modulated Continuous Wave Radar, it is not suitable for detecting the tiny displacement caused by the vital signs of a living body. Summary of the Invention

[0004] The present invention discloses a multi-target vital sign detector, which greatly improves the detection sensitivity of the vital signs of living bodies at different distances by using a self-injection locked oscillator in a Frequency-Modulated Continuous Wave Radar.

[0005] A multi-target vital sign detector of the present invention includes a self-injection locked oscillator, a chirp up / down frequency converter, a frequency demodulation unit, and a multi-target vital sign processing unit. The self-injection locked oscillator generates an oscillation signal. The chirp up / down frequency converter has an up-conversion mixer, a transceiver antenna, and a down-conversion mixer. The up-conversion mixer is electrically connected to the self-injection locked oscillator to convert the oscillation signal into a frequency-modulated continuous wave signal. The transceiver antenna is electrically connected to the up-conversion mixer to transmit the frequency-modulated continuous wave signal as a transmitted signal to an area. Then, the transceiver antenna receives the reflected signal reflected by the area as a frequency-modulated continuous wave received signal. The down-conversion mixer is electrically connected to the transceiver antenna to convert the frequency-modulated continuous wave received signal into an injection signal. The self-injection locked oscillator is electrically connected to the down-conversion mixer and receives the injection signal to be in a self-injection locked state. The frequency demodulation unit is electrically connected to the self-injection locked oscillator to frequency-demodulate the oscillation signal into a frequency-demodulated signal. The multi-target vital sign processing unit is electrically connected to the frequency demodulation unit to sample and process the frequency-demodulated signal to construct a distance-vs-vital-sign Doppler image.

[0006] Preferably, the chirp up / down converter has a chirp signal generator for outputting a chirp signal. The upconverter is electrically connected to the chirp signal generator to mix the oscillation signal and the chirp signal, thereby converting the oscillation signal into the frequency-modulated continuous wave signal. The downconverter is electrically connected to the chirp signal generator to mix the frequency-modulated continuous wave received signal and the chirp signal, thereby converting the frequency-modulated continuous wave received signal into the injection signal.

[0007] Preferably, it includes a first power divider. The first power divider is electrically connected to the self-injection-locked oscillator and is configured to divide the oscillation signal into two paths. One path of the oscillation signal is transmitted to the upconverter, and the other path of the oscillation signal is transmitted to the frequency demodulation unit.

[0008] Preferably, the chirp up / down converter has a second power divider. The second power divider is electrically connected to the chirp signal generator to receive the chirp signal. The second power divider is configured to divide the chirp signal into two paths. One path of the chirp signal is transmitted to the upconverter, and the other path of the chirp signal is transmitted to the downconverter.

[0009] Preferably, the multi-target vital sign processing unit has a range-Doppler image module for sampling and processing the frequency demodulated signal to output a range-Doppler image.

[0010] Preferably, the multi-target vital sign processing unit further has a background removal module, an amplitude normalization module, and a peak search module. The background removal module is configured to remove the background of the range-Doppler image and output a background-removed range-Doppler image. The amplitude normalization module is configured to perform amplitude normalization on the background-removed range-Doppler image and output a normalized range-Doppler image. The peak search module is configured to search for a plurality of peaks higher than a threshold value in the normalized range-Doppler image to construct a range-versus-vital-sign Doppler image, which simultaneously shows the range and the frequency information of the vital signs.

[0011] Preferably, the transceiver antenna has a transmitting antenna and a receiving antenna. The transmitting antenna is electrically connected to the upconverter to transmit the frequency-modulated continuous wave signal as the transmitted signal to the area. The receiving antenna is electrically connected to the downconverter to receive the reflected signal reflected from the area as the frequency-modulated continuous wave received signal and transmit it to the downconverter.

[0012] Preferably, the receiving antenna is a switched antenna array, which has a switch and a plurality of receiving antenna array units. The receiving antenna array units are used to receive the reflected signal reflected by the area as the frequency-modulated continuous wave receiving signal. The switch is electrically connected to the down-conversion mixer and the receiving antenna array units and is used to switch the receiving antenna array units therein to be coupled to the down-conversion mixer. The down-conversion mixer is used to convert the frequency-modulated continuous wave receiving signal into the injection signal. The phase shifter is electrically connected to the down-conversion mixer and the self-injection locking oscillator and is used to phase-shift the injection signal by 0 degrees or 90 degrees to generate an orthogonal phase-shifted injection signal. The orthogonal phase-shifted injection signal is used to inject into the self-injection locking oscillator to make the self-injection locking oscillator enter the self-injection locking state.

[0013] Preferably, the self-injection locking oscillator is used to operate in the self-injection locking state to generate an orthogonal phase-shifted oscillation signal. The first power divider is used to divide the orthogonal phase-shifted oscillation signal into two paths. One path of the orthogonal phase-shifted oscillation signal is used to be transmitted to the up-conversion mixer and is converted into the frequency-modulated continuous wave signal. The other path of the orthogonal phase-shifted oscillation signal is transmitted to the frequency demodulation unit, and the frequency demodulation unit is used to frequency-demodulate the orthogonal phase-shifted oscillation signal into an orthogonal frequency demodulation signal.

[0014] Preferably, the multi-target vital sign processing unit has a range-Doppler image module and an azimuth digital beamforming module. The range-Doppler image module is used to sample and process the orthogonal frequency demodulation signal to generate a plurality of range-Doppler images corresponding to the receiving antenna array units. The azimuth digital beamforming module is coupled to the range-Doppler image module and is used to extract the range-azimuth image from the plurality of range-Doppler images corresponding to the receiving antenna array units.

[0015] A detection method of a multi-target vital sign detector according to the present invention includes: a self-injection locking oscillator generates an oscillation signal; a chirp up / down converter converts the oscillation signal into a frequency-modulated continuous wave signal for detecting an area, and the chirp up / down converter converts the reflected signal reflected by the area into an injection signal, and the injection signal injects into the self-injection locking oscillator to make the self-injection locking oscillator in the self-injection locking state; a frequency demodulation unit frequency-demodulates the oscillation signal to generate a frequency demodulation signal; and a multi-target vital sign processing unit samples and processes the frequency demodulation signal to construct a range-vital sign Doppler image.

[0016] Preferably, the multi-target vital sign processing unit includes a range-Doppler image module, a background removal module, an amplitude normalization module, and a peak search module. The range-Doppler image module is configured to sample and process the frequency-demodulated signal of the frequency demodulation unit to output a range-Doppler image. The background removal module is configured to remove the background of the range-Doppler image and output a background-removed range-Doppler image. The amplitude normalization module is configured to perform amplitude normalization on the background-removed range-Doppler image and output a normalized range-Doppler image. The peak search module is configured to search for a plurality of peaks higher than a threshold value in the normalized range-Doppler image to construct a range-versus-vital-sign Doppler image, which simultaneously displays range and frequency information of vital signs.

[0017] Preferably, the transceiver antenna includes a transmitting antenna and a receiving antenna. The transmitting antenna is electrically connected to the up-conversion mixer to transmit the frequency-modulated continuous wave signal as the transmitted signal to the area. The receiving antenna is electrically connected to the down-conversion mixer to receive the reflected signal reflected from the area as the frequency-modulated continuous wave received signal and transmit it to the down-conversion mixer.

[0018] Preferably, the receiving antenna is a switched antenna array. The switched antenna array includes a switch and a plurality of receiving antenna array units. The receiving antenna array units are configured to receive the reflected signal reflected from the area as the frequency-modulated continuous wave received signal. The switch is electrically connected to the down-conversion mixer and the receiving antenna array units and is configured to switch the receiving antenna array units coupled to the down-conversion mixer. The down-conversion mixer is configured to convert the frequency-modulated continuous wave received signal into the injection signal. The phase shifter is electrically connected to the down-conversion mixer and the self-injection-locked oscillator and is configured to phase-shift the injection signal by 0 degrees or 90 degrees to generate an orthogonally phase-shifted injection signal, which is used to inject into the self-injection-locked oscillator to make the self-injection-locked oscillator enter the self-injection-locked state.

[0019] Preferably, the self-injection-locked oscillator is configured to operate in the self-injection-locked state to generate an orthogonally phase-shifted oscillation signal. The orthogonally phase-shifted oscillation signal is divided into two paths. One path of the orthogonally phase-shifted oscillation signal is transmitted to the up-conversion mixer and converted into the frequency-modulated continuous wave signal. The other path of the orthogonally phase-shifted oscillation signal is transmitted to the frequency demodulation unit, which is configured to frequency-demodulate the orthogonally phase-shifted oscillation signal into an orthogonally frequency-demodulated signal.

[0020] Preferably, the multi-target vital sign processing unit has a range-Doppler image module and an azimuth digital beamforming module. The range-Doppler image module is used to sample and process the quadrature frequency demodulation signal to generate a plurality of range-Doppler images corresponding to the receiving antenna array unit. The azimuth digital beamforming module is coupled to the range-Doppler image module and is used to extract the range-azimuth images from the plurality of range-Doppler images corresponding to the receiving antenna array unit.

[0021] The multi-target vital sign detector of the present invention uses a self-injection locked oscillator to provide high-sensitivity vital sign monitoring. In addition, the multi-target vital sign detector is based on frequency modulated continuous wave radar technology and can use the distance information of organisms to distinguish the vital signs of each organism. Description of the Drawings

[0022] Figure 1 : Circuit diagram of the multi-target vital sign detector according to the first embodiment of the present invention.

[0023] Figure 2 : Functional block diagram of the multi-target vital sign processing unit according to the first embodiment of the present invention.

[0024] Figure 3 : Schematic diagram of signal processing by the range-Doppler image module according to the first embodiment of the present invention.

[0025] Figure 4 : Flowchart of the detection method of the multi-target vital sign detector according to the first embodiment of the present invention.

[0026] Figure 5 : Flowchart of the processing method of the multi-target vital sign processing unit according to the first embodiment of the present invention.

[0027] Figure 6 : Circuit diagram of the multi-target vital sign detector according to the second embodiment of the present invention.

[0028] Figure 7 : Functional block diagram of the multi-target vital sign processing unit according to the second embodiment of the present invention.

[0029] Figure 8 : Range spectrogram measured and generated by the multi-target vital sign detector according to the first embodiment of the present invention.

[0030] Figures 9A to 9C : Doppler spectrogram measured and generated by the multi-target vital sign detector according to the first embodiment of the present invention.

[0031] Figure 10: Distance-versus-vital-sign Doppler image constructed by the multi-target vital sign detector according to the first embodiment of the present invention.

[0032] Figure 11 : Distance-versus-azimuth angle image constructed by the multi-target vital sign detector according to the second embodiment of the present invention.

[0033] Figures 12A to 12C : Doppler spectrogram generated by the multi-target vital sign detector according to the second embodiment of the present invention.

[0034]

Description of Main Element Symbols

[0035] 100: Multi-target vital sign detector 110: Self-injection locking oscillator

[0036] 120: Chirp up / down frequency converter 121: Up-conversion mixer

[0037] 122: Transceiving antenna 122a: Transmitting antenna

[0038] 122b: Receiving antenna 122c: Switch

[0039] 122d: Receiving antenna array unit 123: Down-conversion mixer

[0040] 124: Chirp signal generator 125: Second power divider

[0041] 126: Phase shifter 130: Frequency demodulation unit

[0042] 140: Multi-target vital sign processing unit 141: Distance-Doppler image module

[0043] 142: Background removal module 143: Amplitude normalization module

[0044] 144: Peak search module 145: Azimuth digital beamforming module

[0045] 150: First power divider 10: Multi-target vital sign detection method

[0046] 11: Conversion of continuous wave signal to frequency-modulated continuous wave signal 12: Detection of area

[0047] 13: Self-injection locking 14: Frequency demodulation

[0048] 15: Multi-target vital sign processing 15a: Generation of distance-Doppler image

[0049] 15b: Background removal 15c: Amplitude normalization

[0050] 15d: Peak search S O : Oscillation signal

[0051] S FCO : Frequency - modulated continuous - wave signal S FCR : Frequency - modulated continuous - wave received signal

[0052] S I : Injection signal S DM : Frequency - demodulated signal

[0053] S CH : Chirp signal S T : Transmitted signal

[0054] S R : Reflected signal F: Filter

[0055] PA: Power amplifier LNA: Low - noise amplifier

[0056] BPF: Band - pass filter Amp: Amplifier

[0057] A: Area Detailed implementation manner

[0058] Please refer to Figure 1 , which is an embodiment of the present invention, a circuit diagram of a multi - target vital sign detector 100. The multi - target vital sign detector 100 has a self - injection - locked oscillator 110, a chirp up - down converter 120, a frequency - demodulation unit 130, a multi - target vital sign processing unit 140, and a first power divider 150.

[0059] The self - injection - locked oscillator 110 is a voltage - controlled oscillator, which receives a control voltage (not shown in the figure) and generates an oscillation signal S O , and the first power divider 150 is electrically connected to the self - injection - locked oscillator 110 to divide the oscillation signal S O into two paths.

[0060] Please refer to Figure 1 , the chirp up - down converter 120 has an up - conversion mixer 121, a transceiver antenna 122, a down - conversion mixer 123, a chirp signal generator 124, and a second power divider 125. Among them, the chirp signal generator 124 generates a chirp signal S CH , and the second power divider 125 is electrically connected to the chirp signal generator 124 to divide the chirp signal S CH into two paths. The up - conversion mixer 121 is electrically connected to the first power divider 150 and the second power divider 125 to receive one path of the oscillation signal S from the first power divider 150 O , and receive one path of the chirp signal S from the second power divider 125 CH , and the up - conversion mixer 121 mixes the chirp signal S CHand the oscillation signal S O The mixing wave is a frequency-modulated continuous wave signal S FCO . Among them, if the chirp signal generator 124 generates a stepped chirp signal, the frequency-modulated continuous wave signal S FCO can become a stepped-frequency continuous wave signal.

[0061] Please refer to Figure 1 , the transceiver antenna 122 is coupled to the up-conversion unit 121 via the filter F and the power amplifier PA to transmit the frequency-modulated continuous wave signal S FCO as the transmission signal S T to area A. The filter F is used to filter out the redundant components of the frequency-modulated continuous wave signal S FCO , and the power amplifier PA is used to amplify the frequency-modulated continuous wave signal S FCO . The transceiver antenna 122 receives the reflected signal S R reflected from area A as the frequency-modulated continuous wave received signal S FCR . The down-conversion mixer 123 is electrically connected to the transceiver antenna 122 via the low-noise amplifier LNA to receive the frequency-modulated continuous wave received signal S FCR , and the second power divider 125 receives another path of the chirp signal S CH . After the frequency-modulated continuous wave received signal S FCR is amplified by the low-noise amplifier LNA, the down-conversion mixer 123 mixes it with the chirp signal S CH to convert it into the injection signal S I . In this embodiment, the transmitting antenna 122a and the receiving antenna 122b of the transceiver antenna 122 are respectively electrically connected to the up-conversion mixer 121 and the down-conversion mixer 123. The transmitting antenna 122a transmits the frequency-modulated continuous wave signal S FCO as the transmission signal S T to area A, and the receiving antenna 122b receives the reflected signal S R reflected from area A as the frequency-modulated continuous wave received signal S FCR and transmits it to the down-conversion mixer 123.

[0062] Please refer to Figure 1 , the self-injection locking oscillator 110 is coupled to the down-conversion unit 123 via the band-pass filter BPF and the amplifier Amp and receives the injection signal S I, to put the self-injection-locked oscillator 110 in a self-injection-locked state. The band-pass filter BPF and the amplifier Amp are used to amplify the injection signal S within a narrow bandwidth. I .

[0063] When there is at least one living body in the area A, the relative displacement between the living body and the transceiver antenna 122 will affect the transmitted signal S. T Generate a Doppler effect, so that the reflected signal S R Contains a Doppler phase shift component caused by the relative displacement. Since the transmitted signal S T Is a linear chirp wave whose frequency changes linearly with time. Therefore, if there are multiple living bodies in the area A, the living bodies at different distances will cause the transmitted signal S T And the reflected signal S R Generate different frequency differences between them. Thus, the frequency-modulated continuous wave received signal S FCR And the injection signal S I Both contain the distance and displacement information of the living bodies located in the area A. After the injection signal S I Is injected into the self-injection-locked oscillator 110, the frequency modulation generated on the oscillation signal S O Of the self-injection-locked oscillator 110 will also contain the distance and displacement information of the living bodies.

[0064] Please refer to Figure 1 , the frequency demodulation unit 130 is electrically connected to the self-injection-locked oscillator 110 through the first power divider 150 to receive another path of the oscillation signal S O , and the frequency demodulation unit 130 performs frequency demodulation on the oscillation signal S O And outputs a frequency demodulation signal S DM , where the frequency demodulation unit 130 can be a delay line frequency demodulation unit or a phase-locked loop frequency demodulation unit.

[0065] Please refer to Figure 1 And Figure 2 , the multi-target vital sign processing unit 140 has a Range-Doppler map module 141, a background removal module 142, an amplitude normalization module 143, and a peak search module 144. In this embodiment, the multi-target vital sign processing unit 140 is a data acquisition and calculation system. In other embodiments, the multi-target vital sign processing unit 140 can be other calculation devices.

[0066] Please refer to Figure 2, the range-Doppler image module 141 samples and processes the frequency demodulation signal S of the frequency demodulation unit 130 DM and outputs a range-Doppler map. Please refer to Figure 3 the upper left figure, which is the J×N raw data matrix (time vs. scan frequency) initially constructed by the range-Doppler image module 141 for processing the frequency demodulation signal S DM . Here, J is the total number of frequency scan cycles at different time points, and N is the total number of scan frequency points. Then, a first fast Fourier transform is performed on each horizontal-axis raw data matrix in the upper left figure to obtain the J×M range data matrix (time vs. distance axis) in the upper right figure, where M is the total number of distance points. Finally, a second fast Fourier transform is performed on each vertical-axis data in the upper right figure to obtain the L×M range-Doppler matrix (frequency vs. distance axis) in the lower right figure, where L is the total number of Doppler spectrum points. The range-Doppler image is constructed by using the range-Doppler matrix to represent the Doppler spectra of organisms at different distances.

[0067] However, in any case, due to the interference of stationary objects, it is quite difficult to interpret the vital signs of each organism from the range-Doppler image. Therefore, in this embodiment, the background removal module 142, the amplitude normalization module 143, and the peak search module 144 are further used to process the range-Doppler image. Among them, the background removal module 142 receives the range-Doppler image from the range-Doppler image module 141, and the background removal module 142 removes the background of the range-Doppler image by using the range-Doppler images at different times and outputs a background-removed range-Doppler image. Since the Doppler spectra caused by vital signs change over time, different from the Doppler spectra caused by stationary objects that do not change over time, using the background-removed range-Doppler image can eliminate the interference of stationary objects and make it easier to interpret the vital signs of each organism.

[0068] The amplitude normalization module 143 receives the background-removed range-Doppler image and performs amplitude normalization on the background-removed range-Doppler image to output a normalized range-Doppler image. By amplitude normalization, regardless of the distance of the organism, the maximum amplitude of the vital sign signals of each organism is the same, which is beneficial for displaying the respiration and heartbeat frequencies of each organism. The peak search module 144 searches for multiple peaks higher than the threshold value in the normalized range-Doppler image to construct a distance vs. vital sign Doppler image, so as to simultaneously display the distance of each organism and the frequency information of the vital signs.

[0069] The multi-target vital sign detector 100 of the present invention uses the self-injection locked oscillator 110 to improve the sensitivity of the frequency-modulated continuous wave detection process, enabling the multi-target vital sign detector 100 to distinguish the vital signs of organisms at different distances.

[0070] Please refer to Figure 4 , which is an embodiment of the detection method 10 of the multi-target vital sign detector 100 of the present invention. The detection method 10 includes: "converting the continuous wave signal into a frequency-modulated continuous wave signal 11", "detecting the area 12", "self-injection locking 13", "frequency demodulation 14", and "processing multi-target vital signs 15".

[0071] First, please refer to Figure 1 and Figure 4 , in step 11, the self-injection locked oscillator 110 outputs the oscillation signal S O , and the oscillation signal S O is a continuous wave signal. The chirp up / down frequency converter 120 receives the oscillation signal S O and converts the oscillation signal S O into the frequency-modulated continuous wave signal S FCO . Then, in step 12, the chirp up / down frequency converter 120 transmits the frequency-modulated continuous wave signal S FCO as the transmission signal S T to the area A for vital sign detection. Among them, please refer to Figure 1 , the up-conversion mixer 121 of the chirp up / down frequency converter 120 receives the oscillation signal S of the self-injection locked oscillator 110 from the first power divider 150 O , and receives the chirp signal S of the chirp signal generator 124 via the second power divider 125 CH to convert the oscillation signal S O into the frequency-modulated continuous wave signal S FCO . The transmitting antenna 122a receives the frequency-modulated continuous wave signal S from the up-conversion mixer 121 FCO and transmits it as the transmission signal S T to the area A. The receiving antenna 122b receives the reflected signal S reflected by the area A R as the frequency-modulated continuous wave received signal S FCR . The down-conversion mixer 123 receives the frequency-modulated continuous wave received signal S FCR and receives the chirp signal S of the chirp signal generator 124 via the second power divider 125 CH , and the down-conversion unit 123 converts the frequency-modulated continuous wave received signal S FCR into the injection signal SI 。

[0072] Please refer to Figure 1 and Figure 4 , in step 13, the injection signal S I is injected into the self-injection-locked oscillator 110 to make the self-injection-locked oscillator 110 in the self-injection-locked state. Among them, if there is at least one living body in the area A, the oscillation signal S O of the self-injection-locked oscillator 110 will generate a frequency modulation related to the distance and displacement information of the living body. In step 14, the frequency demodulation unit 130 receives the oscillation signal S O of the self-injection-locked oscillator 110 from the first power divider 150, and the frequency demodulation unit 130 performs frequency demodulation on the oscillation signal S O to generate the frequency demodulation signal S DM . Finally, in step 15, the multi-target vital sign processing unit 140 samples and processes the frequency demodulation signal S DM to construct the distance-to-vital-sign Doppler image.

[0073] Please refer to Figure 2 and Figure 5 , in this embodiment, step 15 performed by the multi-target vital sign processing unit 140 includes "generating a distance Doppler image 15a", "background removal 15b", "amplitude normalization 15c", and "peak search 15d". In step 15a, the distance Doppler image module 141 samples and processes the frequency demodulation signal S DM to generate the distance Doppler image. In step 15b, the background removal module 142 removes the background of the distance Doppler image to generate the background-removed distance Doppler image. In step 15c, the amplitude normalization module 143 receives the background-removed distance Doppler image and performs amplitude normalization on the background-removed distance Doppler image to generate the normalized distance Doppler image. Finally, in step 15d, the peak search module 144 searches for multiple peaks higher than the threshold value in the normalized distance Doppler image to construct the distance-to-vital-sign Doppler image to simultaneously display the distance of each living body and the frequency information of the vital signs. Since the detailed operations of each step in the detection method 10 of the multi-target vital sign detector have been disclosed in the description of the multi-target vital sign detector 100, they will not be elaborated here.

[0074] Please refer to Figure 6, is the circuit diagram of the multi-target vital sign detector 100 according to the second embodiment of the present invention. In the second embodiment, the chirp up / down converter 120 further includes a phase shifter 126. In addition, the receiving antenna 122b is a switched antenna array, which has a switch 122c and a plurality of receiving antenna array units 122d. Each of the receiving antenna array units 122d is used to receive the reflected signal S reflected by the area A R For each of the frequency-modulated continuous wave received signals S FCR , and the position information of the organism can be further obtained.

[0075] The switch 122c is electrically connected to the down-conversion mixer 123 and the antenna receiving array unit 122d. Therefore, the frequency-modulated continuous wave signal S received by each of the antenna receiving array units 122d FCR Is transmitted to the down-conversion mixer 123 via the switch 122c. Then, the down-conversion mixer 123 receives the chirp signal S of the chirp signal generator 124 from the second power divider 150 CH And mix it with the frequency-modulated continuous wave received signal S FCR To perform mixing and convert it into the injection signal S I .

[0076] The phase shifter 126 is electrically connected to the down-conversion mixer 123 and the self-injection-locked oscillator 110, and provides a phase shift of 0 degrees or 90 degrees for the injection signal S I To generate an orthogonally phase-shifted injection signal S I,QUAD , the orthogonally phase-shifted injection signal S I,QUAD Injects and locks the self-injection-locked oscillator 110 to make it enter the self-injection-locked state. Thus, the self-injection-locked oscillator 110 in the self-injection-locked state generates an orthogonally phase-shifted oscillation signal S O,QUAD . In the transmission path, the orthogonally phase-shifted oscillation signal S O,QUAD Is transmitted to the up-conversion mixer 121 via the first power divider and mixed with the chirp signal S generated by the chirp signal generator 124 CH To obtain the frequency-modulated continuous wave signal S FCO .

[0077] The frequency demodulation unit 130 receives the orthogonally phase-shifted oscillation signal S of the self-injection-locked oscillator 110 via the first power divider 150 O,QUAD And performs frequency demodulation to obtain an orthogonally frequency-demodulated signal S DM,QUAD . The orthogonally frequency-demodulated signal S DM,QUAD Can use digital beamforming technology by the multi-target vital sign processing unit 140 to calculate the phase difference between each of the antenna array units 122d, and then extract the azimuth angle of the organism in the area A.

[0078] Please refer to Figure 7 , the multi-target vital sign processing unit 140 of this second embodiment includes the range-Doppler image module 141 and the azimuth digital beamforming module 145. The range-Doppler image module 141 samples and processes the quadrature frequency demodulation signal S of the frequency demodulation unit 130 DM,QUAD to generate the plurality of range-Doppler images corresponding to the receiving antenna array unit 122d. The azimuth beamforming module 154 is coupled to the range-Doppler image module 141 and extracts the range-azimuth images from the plurality of range-Doppler images corresponding to the antenna array unit 122d by digital beamforming technology.

[0079] The purpose of the second embodiment is not only to enable the multi-target vital sign detector 100 to distinguish the vital signs of the organisms at different distances by the self-injection locked oscillator 110 and the chirp up / down converter 120, but also to enable the multi-target vital sign detector 100 to distinguish the vital signs of the organisms at different azimuth angles by the newly added switch 122c, the receiving antenna array unit 122d and the phase shifter 126 in the chirp up / down converter 120.

[0080] Please refer to Figures 8 to 10 , which are the measured data of the multi-target vital sign detector 100 of the first embodiment of the present invention. In this measurement, there are three human organisms at different distances relative to the multi-target vital sign detector 100, and the organisms are all within the beam width coverage range of the transmitting antenna 122a of the chirp up / down converter 120. Among them, the 1st to 3rd organisms are sitting at positions 135, 210, and 285 centimeters away from the multi-target vital sign detector 100 respectively. Figure 8 For the frequency demodulation signal S DM after the first fast Fourier transform, the resulting range spectrum signal. In the range spectrum signal, the frequencies of the components with the maximum peaks are the frequencies 160, 210, and 260 Hz corresponding to the distances between the 1st to 3rd organisms and the multi-target vital sign detector respectively. Figures 9A to 9C Shows the Doppler spectrum obtained by performing the second fast Fourier transform on the components at frequencies 160, 210, and 260 Hz in the range spectrum signal through multiple scan cycle changes, and Figures 9A to 9C the frequency on the horizontal axis is converted to velocity. The respiration rate and heart rate of the 1st to 3rd organisms can be identified from the components with the maximum peaks in the ranges of 10 to 30 times / minute and 60 to 120 times / minute of velocity in each Doppler spectrum respectively.

[0081] Figure 10 For the distance-versus-vital-sign Doppler image generated by the multi-target vital-sign processing unit 140, the distance-versus-vital-sign Doppler image simultaneously shows the distances and vital-sign frequencies of the first to third organisms. Among them, the vital-sign frequencies of the first to third organisms at the same distance are caused by respiration, respiratory harmonic, and heartbeat in ascending order.

[0082] Figure 11 and Figures 12A to 12C are the measured data of the multi-target vital-sign detector 100 according to the second embodiment of the present invention. In this measurement, the first to third organisms are respectively located at three polar coordinate positions (135 cm, 70 degrees), (210 cm, 110 degrees), and (285 cm, 90 degrees) relative to the multi-target vital-sign detector 100. Figure 11 is the distance-versus-azimuth image constructed by the azimuth digital beamforming module 145 of the multi-target vital-sign processing unit 140. The figure shows good consistency between the actual positions and the detected positions of the first to third organisms. The measurement result proves that the multi-target vital-sign detector 100 according to the second embodiment can measure the distances and azimuth angles of the organisms relative to the multi-target vital-sign detector 100. Figures 12A to 12C shows that by Figure 11 The Doppler spectra at the positions of the first to third organisms in the distance-versus-azimuth image of. The respiration and heartbeat frequencies of the first to third organisms can be clearly identified from Figures 12A to 12C the Doppler spectra of, indicating that the multi-target vital-sign detector 100 according to the second embodiment can simultaneously measure the vital signs of the organisms located at different positions.

[0083] The above is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as the content does not depart from the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A multi - target vital sign detector, characterized in that, it comprises: A self - injection - locked oscillator for outputting an oscillation signal; A chirp up - down frequency converter having an up - frequency mixer, a transceiver antenna, and a down - frequency mixer. The up - frequency mixer is electrically connected to the self - injection - locked oscillator to convert the oscillation signal into a frequency - modulated continuous - wave signal. The transceiver antenna is electrically connected to the up - frequency mixer to receive the frequency - modulated continuous - wave signal and transmit it as a transmitted signal to the area. The transceiver antenna is also used to receive the reflected signal reflected from the area as a frequency - modulated continuous - wave received signal. The down - frequency mixer is electrically connected to the transceiver antenna and converts the frequency - modulated continuous - wave received signal into an injection signal. Among them, the self - injection - locked oscillator is electrically connected to the down - frequency mixer and receives the injection signal to be in a self - injection - locked state; A frequency demodulation unit electrically connected to the self - injection - locked oscillator to perform frequency demodulation on the oscillation signal and output a frequency - demodulated signal; and A multi - target vital sign processing unit electrically connected to the frequency demodulation unit to sample and process the frequency - demodulated signal and construct a distance - versus - vital - sign Doppler image.

2. The multi - target vital sign detector according to claim 1, characterized in that, the chirp up - down frequency converter has a chirp signal generator for outputting a chirp signal. The up - frequency mixer is electrically connected to the chirp signal generator to mix the oscillation signal and the chirp signal to convert the oscillation signal into the frequency - modulated continuous - wave signal. The down - frequency mixer is electrically connected to the chirp signal generator to mix the frequency - modulated continuous - wave received signal and the chirp signal to convert the frequency - modulated continuous - wave received signal into the injection signal.

3. The multi - target vital sign detector according to claim 1, characterized in that, it includes a first power divider electrically connected to the self - injection - locked oscillator and used to divide the oscillation signal into two paths. One path of the oscillation signal is transmitted to the up - frequency mixer, and the other path of the oscillation signal is transmitted to the frequency demodulation unit.

4. The multi - target vital sign detector according to claim 2, characterized in that, the chirp up - down frequency converter has a second power divider electrically connected to the chirp signal generator to receive the chirp signal. The second power divider is used to divide the chirp signal into two paths. One path of the chirp signal is transmitted to the up - frequency mixer, and the other path of the chirp signal is transmitted to the down - frequency mixer.

5. The multi - target vital sign detector according to claim 1, characterized in that, the multi - target vital sign processing unit has a distance - Doppler image module for sampling and processing the frequency - demodulated signal and outputting a distance - Doppler image.

6. The multi - target vital sign detector according to claim 5, characterized in that, The multi-target vital sign processing unit further includes a background removal module, an amplitude normalization module, and a peak search module. The background removal module is used to remove the background of the range-Doppler image and output a background-removed range-Doppler image. The amplitude normalization module is used to perform amplitude normalization on the background-removed range-Doppler image and output a normalized range-Doppler image. The peak search module is used to search for a plurality of peaks higher than a threshold value in the normalized range-Doppler image to construct a range-vs-vital-sign Doppler image, which simultaneously shows the range and the frequency information of the vital signs.

7. The multi-target vital sign detector according to claim 1, wherein, the transceiver antenna has a transmitting antenna and a receiving antenna. The transmitting antenna is electrically connected to the up-conversion mixer to transmit the frequency-modulated continuous wave signal as the transmitted signal to the area. The receiving antenna is electrically connected to the down-conversion mixer to receive the reflected signal reflected from the area as the frequency-modulated continuous wave received signal and transmit it to the down-conversion mixer.

8. The multi-target vital sign detector according to claim 7, wherein, the receiving antenna is a switched antenna array. The switched antenna array has a switch and a plurality of receiving antenna array units. The receiving antenna array units are used to receive the reflected signal reflected from the area as the frequency-modulated continuous wave received signal. The switch is electrically connected to the down-conversion mixer and the receiving antenna array units and is used to switch the receiving antenna array unit therein to be coupled to the down-conversion mixer. The down-conversion mixer is used to convert the frequency-modulated continuous wave received signal into the injection signal. The phase shifter is electrically connected to the down-conversion mixer and the self-injection locking oscillator and is used to phase-shift the injection signal by 0 degrees or 90 degrees to generate an orthogonally phase-shifted injection signal. The orthogonally phase-shifted injection signal is used to inject into the self-injection locking oscillator to make the self-injection locking oscillator enter the self-injection locking state.

9. The multi-target vital sign detector according to claim 8, wherein, the self-injection locking oscillator is used to operate in the self-injection locking state to generate an orthogonally phase-shifted oscillation signal. The first power divider is used to divide the orthogonally phase-shifted oscillation signal into two paths. One path of the orthogonally phase-shifted oscillation signal is used to be transmitted to the up-conversion mixer and is converted into the frequency-modulated continuous wave signal. The other path of the orthogonally phase-shifted oscillation signal is transmitted to the frequency demodulation unit, and the frequency demodulation unit is used to frequency-demodulate the orthogonally phase-shifted oscillation signal into an orthogonally frequency-demodulated signal.

10. The multi-target vital sign detector according to claim 9, wherein, the multi-target vital sign processing unit has a range-Doppler image module and an azimuth digital beamforming module. The range-Doppler image module is used to sample and process the orthogonally frequency-demodulated signal to generate a plurality of range-Doppler images corresponding to the receiving antenna array units. The azimuth digital beamforming module is coupled to the range-Doppler image module and is used to extract a range-vs-azimuth image from the plurality of range-Doppler images corresponding to the receiving antenna array units.

11. Detection method of a multi-target vital sign detector, characterized in that, it includes: The self-injection locked oscillator outputs an oscillation signal; The chirp up / down frequency converter converts the oscillation signal into a frequency modulated continuous wave signal to detect a region. The chirp up / down frequency converter also converts the frequency modulated continuous wave received signal into an injection signal. The chirp up / down frequency converter includes an up-conversion mixer, a transceiver antenna, and a down-conversion mixer. The up-conversion mixer is electrically connected to the self-injection locked oscillator to convert the oscillation signal into the frequency modulated continuous wave signal. The transceiver antenna is electrically connected to the up-conversion mixer to transmit the frequency modulated continuous wave signal as a transmitted signal to the region and receive the reflected signal reflected by the region as the frequency modulated continuous wave received signal. The down-conversion mixer is electrically connected to the transceiver antenna to convert the frequency modulated continuous wave received signal into the injection signal; The injection signal is injected into the self-injection locked oscillator to make the self-injection locked oscillator in a self-injection locked state; The frequency demodulation unit performs frequency demodulation on the oscillation signal and outputs a frequency demodulation signal; and The multi-target vital sign processing unit samples and processes the frequency demodulation signal to construct a distance-versus-vital-sign Doppler image.

12. The detection method of the multi-target vital sign detector according to claim 11, characterized in that, The multi-target vital sign processing unit has a distance Doppler image module, a background removal module, an amplitude normalization module, and a peak search module. The distance Doppler image module is used to sample and process the frequency demodulation signal of the frequency demodulation unit and output a distance Doppler image. The background removal module is used to remove the background of the distance Doppler image and output a background-removed distance Doppler image. The amplitude normalization module is used to perform amplitude normalization on the background-removed distance Doppler image and output a normalized distance Doppler image. The peak search module is used to search for multiple peaks higher than a threshold value in the normalized distance Doppler image to construct a distance-versus-vital-sign Doppler image. The distance-versus-vital-sign Doppler image simultaneously displays the distance and the frequency information of the vital signs.

13. The detection method of the multi-target vital sign detector according to claim 11, characterized in that, The transceiver antenna has a transmitting antenna and a receiving antenna. The transmitting antenna is electrically connected to the up-conversion mixer to transmit the frequency modulated continuous wave signal as the transmitted signal to the region. The receiving antenna is electrically connected to the down-conversion mixer to receive the reflected signal reflected by the region as the frequency modulated continuous wave received signal and transmit it to the down-conversion mixer.

14. The detection method of the multi-target vital sign detector according to claim 13, characterized in that, The receiving antenna is a switched antenna array. The switched antenna array has a switch and a plurality of receiving antenna array units. The receiving antenna array units are used to receive the reflected signal reflected in the area as the frequency-modulated continuous wave receiving signal. The switch is electrically connected to the down-conversion mixer and the receiving antenna array units and is used to switch the receiving antenna array units therein to be coupled to the down-conversion mixer. The down-conversion mixer is used to convert the frequency-modulated continuous wave receiving signal into the injection signal. The phase shifter is electrically connected to the down-conversion mixer and the self-injection locking oscillator and is used to phase-shift the injection signal by 0 degrees or 90 degrees to generate an orthogonal phase-shifted injection signal. The orthogonal phase-shifted injection signal is used to inject into the self-injection locking oscillator to make the self-injection locking oscillator enter the self-injection locking state.

15. The detection method of the multi-target vital sign detector according to claim 14, characterized in that, the self-injection locking oscillator is used to operate in the self-injection locking state to generate an orthogonal phase-shifted oscillation signal. The orthogonal phase-shifted oscillation signal is divided into two paths. One path of the orthogonal phase-shifted oscillation signal is transmitted to the up-conversion mixer and is converted into the frequency-modulated continuous wave signal. The other path of the orthogonal phase-shifted oscillation signal is transmitted to the frequency demodulation unit. The frequency demodulation unit is used to frequency-demodulate the orthogonal phase-shifted oscillation signal into an orthogonal frequency-demodulated signal.

16. The detection method of the multi-target vital sign detector according to claim 15, characterized in that, the multi-target vital sign processing unit has a range-Doppler image module and an azimuth digital beamforming module. The range-Doppler image module is used to sample and process the orthogonal frequency-demodulated signal to generate a plurality of range-Doppler images corresponding to the receiving antenna array units. The azimuth digital beamforming module is coupled to the range-Doppler image module and is used to extract the range-azimuth image from the plurality of range-Doppler images corresponding to the receiving antenna array units.

Images