A multi-vital sign non-contact sensing radar system based on microwave photonic technology

Abstract

The present invention discloses a multi-vital sign non-contact sensing radar system based on microwave photonic technology. The optical domain manipulation module generates broadband optical signals and sends them to the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module respectively. One path is used as an optical radio frequency signal to detect one vital sign, and receives the echo sent by the front end of the optical antenna to obtain an intermediate frequency signal containing vital sign information; the other path generates a microwave ultra-wideband radio frequency signal to detect another vital sign, and receives the echo sent by the front end of the antenna to obtain an intermediate frequency signal containing vital sign information. The two intermediate frequency signals are converted from analog to digital and then digitally filtered, time-frequency analyzed, signal smoothed, and coordinate transformed by the data processing module, and finally the vital sign information is extracted. This system utilizes the ultra-wideband capability of the microwave photonic radar to simultaneously generate broadband optical signals and ultra-wideband radio frequency signals, thereby realizing simultaneous non-contact measurement of the respiration and pulse of living organisms.

Description

Technical Field

[0001] The present invention relates to the technical field of non-contact measurement radars for vital signs, and can be applied to medical treatment, battlefield rescue, and vital sign monitoring. In particular, the present invention relates to a multi-vital sign non-contact sensing radar system based on microwave photon technology. Background Art

[0002] Vital sign monitoring is crucial for assessing a person's health, providing timely and important information about their physiological status. Conventional vital sign tracking technologies require contact with the body, but most are invasive. Sensors that come into contact with the body can irritate or damage the skin, interfere with treatment or cause discomfort, provide a medium for infection and cross-infection, and hinder mobility. This has driven the need for effective, non-contact methods for monitoring vital signs. Summary of the Invention

[0003] The present invention achieves the technical effect of non-contact monitoring of vital signs by providing a multi-vital sign non-contact sensing radar system based on microwave photon technology.

[0004] The present invention provides a multi-vital sign non-contact perception radar system based on microwave photonic technology, comprising: an optical domain manipulation module, a laser signal transmitting and receiving module, a microwave signal transmitting and receiving module, an optical antenna front end, an antenna front end, an analog-to-digital converter and a data processing module; the optical signal output port of the optical domain manipulation module is respectively connected to the optical signal input ports of the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module; the optical signal communication port of the laser signal transmitting and receiving module is bidirectionally connected to the optical signal communication port of the optical antenna front end; the electrical signal communication port of the microwave signal transmitting and receiving module is bidirectionally connected to the electrical signal communication port of the antenna front end; the intermediate frequency signal output ports of the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module are both connected to the electrical signal input port of the analog-to-digital converter; the electrical signal output port of the analog-to-digital converter is connected to the electrical signal input port of the data processing module, and the data processing module performs digital filtering, time-frequency analysis, signal smoothing, and coordinate transformation on the received signal, and then extracts the vital sign signal.

[0005] Specifically, the data processing module includes:

[0006] The digital filtering unit is used to perform digital high-pass filtering on the received signal to filter out the intermediate frequency digital signal, and then perform digital band-pass filtering with different center frequencies to filter out different vital sign signals of different people;

[0007] The time-frequency analysis unit is used to perform short-time Fourier transform on the different vital sign signals of different people after filtering to obtain the signal time-frequency curve;

[0008] A signal smoothing unit, configured to smooth the signal time-frequency curve;

[0009] A coordinate transformation unit is used to perform coordinate transformation on the smoothed curve so that the smoothed curve corresponds to a distance-time curve and a speed-time curve;

[0010] The vital sign signal extraction unit is used to extract vital signs from the distance-time curve and the speed-time curve.

[0011] Specifically, the coordinate transformation unit is specifically used to first subtract the reference frequency value from the vertical coordinates of the smoothed signal time-frequency curve, and then substitute the vertical coordinates of the smoothed signal time-frequency curve into the formula D=T w fc / 2B and V=avg(ff m )c / f c The corresponding distance-time curve and speed-time curve are obtained; wherein D is the distance between the detected human body and the antenna, V is the micro-motion speed of the detected human body, Tw is the sweep frequency period of the detection signal, f is the ordinate of the signal time-frequency curve after the smoothing process, f m is the average frequency of the smoothed signal time-frequency curve at each moment, f c is the frequency of the optical carrier, c is the speed of light, B is the bandwidth of the transmitted signal, and avg is the arithmetic mean.

[0012] Specifically, the vital sign signal extraction unit is specifically used to derive the distance-time curve and speed-time curve or count the number of signal cycles, cycle changes and amplitude changes per unit time to obtain the frequency, speed and strength information of the corresponding vital signs.

[0013] Specifically, the data processing module further includes:

[0014] The data preprocessing unit is used to convert the data format output by the analog-to-digital converter, remove points exceeding the threshold by setting a threshold, remove outliers, and send the processed data to the digital filtering unit.

[0015] Specifically, the optical domain manipulation module includes: a laser, a phase modulator 1, a phase modulator 2, a microwave signal source 1, a microwave signal source 2, an optical filter 1, an optical filter 2 and a first-stage 1×2 optical splitter; the optical signal output port of the laser is connected to the optical signal input port of the phase modulator 1, the microwave signal output port of the microwave signal source 1 is connected to the microwave signal input port of the phase modulator 1, the optical signal output port of the phase modulator 1 is connected to the optical signal input port of the optical filter 1; the optical signal output port of the optical filter 1 is connected to the optical signal input port of the phase modulator 2 The microwave signal input port of the microwave signal source 2 is connected to the microwave signal input port of the phase modulator 2, and the optical signal output port of the phase modulator 2 is connected to the optical signal input port of the optical filter 2; the optical signal output port of the optical filter 2 is connected to the optical signal input port of the first-stage 1×2 optical splitter, the first optical signal output port of the first-stage 1×2 optical splitter is connected to the optical signal input port of the laser signal transmitting and receiving module, and the second optical signal output port of the first-stage 1×2 optical splitter is connected to the optical signal input port of the microwave signal transmitting and receiving module.

[0016] Specifically, the laser signal transmitting and receiving module includes: a second-stage 1×2 optical splitter 1, a circulator, a 2×1 optical coupler, a first-stage 1×N optical splitter, optical delay devices 1 to N and a photodetector 1; the optical signal input port of the second-stage 1×2 optical splitter 1 is connected to the optical signal output port of the optical domain control module, and the first optical signal output port of the second-stage 1×2 optical splitter 1 is connected to the optical signal communication port 1 of the circulator; the optical signal communication port 2 of the circulator is bidirectionally connected to the first optical signal communication port of the first-stage 1×N optical splitter; the second optical signal communication port of the first-stage 1×N optical splitter is respectively connected to the The first optical signal communication ports of the optical delay devices 1 to N are bidirectionally connected; the second optical signal communication ports of the optical delay devices 1 to N are bidirectionally connected to the optical signal communication port of the front end of the optical antenna; the optical signal communication port 3 of the circulator is connected to the first optical signal input port of the 2×1 optical coupler, the second optical signal input port of the 2×1 optical coupler is connected to the second optical signal output port of the second-stage 1×2 optical splitter 1, the optical signal output port of the 2×1 optical coupler is connected to the optical signal input port of the photodetector 1, and the electrical signal output port of the photodetector 1 is connected to the electrical signal input port of the analog-to-digital converter.

[0017] Specifically, the microwave signal transmitting and receiving module includes: a second-stage 1×2 optical splitter 2, a second-stage 1×N optical splitter, optical delay devices N+1 to 2N, photoelectric detectors 2 to N+2, power amplifiers 1 to N and an intensity modulator; the optical signal input port of the second-stage 1×2 optical splitter 2 is connected to the optical signal output port of the optical domain control module, and the first optical signal output port of the second-stage 1×2 optical splitter 2 is connected to the optical signal input port of the second-stage 1×N optical splitter; the optical signal output port of the second-stage 1×N optical splitter is respectively connected to each optical signal input port of the optical delay devices N+1 to 2N; each optical signal output port of the optical delay devices N+1 to 2N is connected one-to-one with the photoelectric detectors 2 to The optical signal input ports of the photodetectors 2 to N+1 are connected one by one; the electrical signal output ports of the photodetectors 2 to N+1 are connected one by one to the optical signal input ports of the power amplifiers 1 to N; the electrical signal output ports of the power amplifiers 1 to N are connected to the electrical signal input port of the antenna front end; the electrical signal output port of the antenna front end is connected to the first optical signal input port of the intensity modulator, the second optical signal output port of the second-stage 1×2 optical splitter 2 is connected to the second optical signal input port of the intensity modulator, the optical signal output port of the intensity modulator is connected to the optical signal input port of the photodetector N+2, and the electrical signal output port of the photodetector N+2 is connected to the electrical signal input port of the analog-to-digital converter.

[0018] Specifically, the laser antenna in the front end of the optical antenna is a fiber collimator.

[0019] Specifically, the microwave antenna in the antenna front end is a single element antenna or an array antenna.

[0020] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0021] 1. The optical domain manipulation module generates two broadband optical signals, which are divided into two paths and sent to the laser signal transmitter and receiver module and the microwave signal transmitter and receiver module, respectively. One path serves as the photon radar system's optical RF signal to detect one vital sign and receives the echo sent by the optical antenna front end, which is then de-skewed in the optical domain to obtain an intermediate frequency (IF) signal containing that vital sign information. The other path generates a microwave ultra-wideband RF signal to detect another vital sign and receives the echo sent by the antenna front end, which is de-skewed in the optical domain to obtain an IF signal containing that vital sign information. Both IF signals undergo analog-to-digital conversion via an analog-to-digital converter and then undergo digital filtering, time-frequency analysis, signal smoothing, and coordinate transformation in the data processing module to extract the vital sign information. This system leverages the ultra-wideband capabilities of microwave photon radar to simultaneously generate broadband optical and ultra-wideband RF signals. This enables simultaneous non-contact measurement of multiple / same vital signs (e.g., respiration and pulse), providing a non-contact, non-destructive, and more accurate measurement method for life and health monitoring.

[0022] 2. By increasing the number of transmitting and receiving branches for optical and microwave signals, adding a 1×N optical splitter, and adjusting the delay of the delay device, the information contained in multiple echo signals can be extracted simultaneously without interfering with each other, thereby realizing simultaneous non-contact measurement of the vital signs of single / multiple living organisms in the optical / electrical domain. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A module diagram of a multi-vital-sign non-contact sensing radar system based on microwave photonic technology provided by an embodiment of the present invention;

[0024] Figure 2 A diagram showing the working principle of a data processing module in a multi-vital sign non-contact sensing radar system based on microwave photonic technology according to an embodiment of the present invention;

[0025] Figure 3 A block diagram of the optical domain control module in a multi-vital sign non-contact sensing radar system based on microwave photonic technology provided by an embodiment of the present invention;

[0026] Figure 4 A block diagram of a laser signal transmitting and receiving module in a multi-vital sign non-contact sensing radar system based on microwave photonic technology provided by an embodiment of the present invention;

[0027] Figure 5 A block diagram of a microwave signal transmitting and receiving module in a multi-vital sign non-contact sensing radar system based on microwave photonic technology provided by an embodiment of the present invention;

[0028] Figure 6 This is a block diagram of a microwave signal transmission and reception expansion module in a multi-vital sign non-contact perception radar system based on microwave photonic technology provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The embodiment of the present invention achieves the technical effect of non-contact monitoring of vital signs by providing a multi-vital sign non-contact sensing radar system based on microwave photon technology.

[0030] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0031] like Figure 1 As shown, the multi-vital sign non-contact sensing radar system based on microwave photonic technology provided by an embodiment of the present invention includes: an optical domain manipulation module, a laser signal transmitting and receiving module, a microwave signal transmitting and receiving module, an optical antenna front end, an antenna front end, an analog-to-digital converter, and a data processing module. The optical signal output port of the optical domain manipulation module is connected to the optical signal input port of the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module respectively; the optical signal communication port of the laser signal transmitting and receiving module is bidirectionally connected to the optical signal communication port of the optical antenna front end; the electrical signal communication port of the microwave signal transmitting and receiving module is bidirectionally connected to the electrical signal communication port of the antenna front end; the intermediate frequency signal output ports of the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module are both connected to the electrical signal input port of the analog-to-digital converter; the electrical signal output port of the analog-to-digital converter is connected to the electrical signal input port of the data processing module. The data processing module performs digital filtering, time-frequency analysis, signal smoothing, and coordinate transformation on the received signal to extract the vital sign signal. At the optical antenna front end, the laser signal transmitting and receiving module outputs an optical signal and sends it to the optical antenna. The optical antenna transmits the optical signal. The target echo signal is received by the optical antenna and sent to the laser signal transmitting and receiving module. In the front end of the antenna, the radio frequency signal generated by the microwave signal transmitting and receiving module is sent to the antenna, the antenna transmits the electrical signal, and the target echo signal is received by the antenna and sent to the microwave signal transmitting and receiving module.

[0032] like Figure 2 As shown, the structure of the data processing module is specifically described. The data processing module includes:

[0033] The digital filtering unit is used to perform digital high-pass filtering on the received signal to filter out the intermediate frequency digital signal, divide it into N channels and then perform digital band-pass filtering with different center frequencies respectively to filter out different vital sign signals of N different people;

[0034] A time-frequency analysis unit is used to perform short-time Fourier transform on the filtered vital sign signals of N different people to obtain a signal time-frequency curve;

[0035] A signal smoothing unit is used to smooth the signal time-frequency curves of N people and filter out noise points;

[0036] A coordinate transformation unit is used to perform coordinate transformation on the smoothed curves of the N personnel so that the smoothed curves correspond to distance-time curves and speed-time curves;

[0037] Specifically, the coordinate transformation unit is specifically used to first subtract the reference frequency value from the vertical coordinates of the smoothed signal time-frequency curves of the N personnel, and then substitute the vertical coordinates of the smoothed signal time-frequency curves into the formula D=T w fc / 2B and V=avg(ff m )c / f c The corresponding distance-time curve and velocity-time curve are obtained; where D is the distance between the detected human body and the antenna, V is the micro-motion speed of the detected human body, Tw is the sweep frequency period of the detection signal, f is the vertical coordinate of the signal time-frequency curve after smoothing, and f m is the average frequency of the smoothed signal time-frequency curve at each moment, f c is the frequency of the optical carrier, c is the speed of light, B is the bandwidth of the transmitted signal, and avg is the arithmetic mean.

[0038] The vital sign signal extraction unit is used to extract vital signs from the distance-time curve and the speed-time curve.

[0039] Specifically, the vital sign signal extraction unit is specifically used to derive the distance-time curve and the speed-time curve or to count the number of signal cycles, cycle changes and amplitude changes in a unit time to obtain the frequency, speed and strength information of the corresponding vital signs. Specifically, the number of cycles of the time-distance curve or the time-speed curve and the time of each cycle in a unit time are calculated, and the oscillation frequency of the curve is obtained by dividing the vertical coordinate of the time-distance curve or the time-speed curve with the horizontal coordinate to obtain the time-amplitude change speed curve and the time-acceleration curve. Taking the chest rise and fall and pulse as an example, the frequency change, amplitude change and time of each rise and fall of the human chest or the frequency change, amplitude change and time of each pulse can be extracted, which can reflect the human breathing frequency and breathing strength or the human heartbeat frequency and heartbeat strength, that is, the human vital sign information is extracted.

[0040] In order to remove outliers in the echo signal and improve the accuracy of vital sign signal monitoring, the data processing module also includes:

[0041] The data preprocessing unit is used to convert the data format output by the analog-to-digital converter, remove points exceeding the threshold by setting a threshold, remove outliers, and send the processed data to the digital filtering unit.

[0042] like Figure 3 As shown, the structure of the optical domain manipulation module is specifically described. The optical domain manipulation module includes: a laser, a phase modulator 1, a phase modulator 2, a microwave signal source 1, a microwave signal source 2, an optical filter 1, an optical filter 2, and a first-stage 1×2 optical splitter; the optical signal output port of the laser is connected to the optical signal input port of the phase modulator 1, the microwave signal output port of the microwave signal source 1 is connected to the microwave signal input port of the phase modulator 1, and the optical signal output port of the phase modulator 1 is connected to the optical signal input port of the optical filter 1; the optical signal output port of the optical filter 1 is connected to the optical signal input port of the phase modulator 2, the microwave signal output port of the microwave signal source 2 is connected to the microwave signal input port of the phase modulator 2, and the optical signal output port of the phase modulator 2 is connected to the optical signal input port of the optical filter 2; the optical signal output port of the optical filter 2 is connected to the optical signal input port of the first-stage 1×2 optical splitter, the first optical signal output port of the first-stage 1×2 optical splitter is connected to the optical signal input port of the laser signal transmitting and receiving module, and the second optical signal output port of the first-stage 1×2 optical splitter is connected to the optical signal input port of the microwave signal transmitting and receiving module. In the optical domain manipulation module, a laser generates single-frequency continuous light as the carrier of the first-stage phase modulator. This light is phase-modulated by the microwave signal V1(t) generated by the first-stage signal source through the first-stage phase modulator. The modulated optical signal is sent to a dual-bandpass optical filter to filter out the required optical sideband pair. This optical sideband signal serves as the carrier of the second-stage phase modulator. It is phase-modulated by the microwave signal V2(t) generated by the second-stage signal source through the second-stage phase modulator. The modulated optical signal passes through a bandpass optical filter to filter out the required optical sidebands, which are then sent to the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module respectively through a 1×2 optical splitter.

[0043] In this embodiment, the laser is any one of a semiconductor laser, a fiber laser, or other single-frequency laser. The signal source is any one of a direct digital frequency synthesizer, a photogenerated microwave source, and an optoelectronic hybrid microwave source. The generated signal is any one of a single-frequency signal, a noise signal, a linear frequency modulation signal, or a phase-coded signal. Microwave signal source 1 and microwave signal source 2 can be implemented as independent signal sources or as a single multi-output signal source. The dual-bandpass optical filter and the bandpass optical filter are fiber Bragg gratings or programmable optical filters.

[0044] like Figure 4As shown, the structure of the laser signal transmitting and receiving module is specifically described. The laser signal transmitting and receiving module includes: a second-stage 1×2 optical splitter 1, a circulator, a 2×1 optical coupler, a first-stage 1×N optical splitter, optical delay devices 1 to N, and a photodetector 1; the optical signal input port of the second-stage 1×2 optical splitter 1 is connected to the optical signal output port of the optical domain control module, and the first optical signal output port of the second-stage 1×2 optical splitter 1 is connected to the optical signal communication port 1 of the circulator; the optical signal communication port 2 of the circulator is bidirectionally connected to the first optical signal communication port of the first-stage 1×N optical splitter; the first optical signal output port of the first-stage 1×N optical splitter is connected to the optical signal communication port of the first-stage 1×N optical splitter. The two optical signal communication ports are bidirectionally connected to the first optical signal communication ports of the optical delay devices 1 to N respectively; the second optical signal communication ports of the optical delay devices 1 to N are bidirectionally connected to the optical signal communication port of the front end of the optical antenna; the optical signal communication port 3 of the circulator is connected to the first optical signal input port of the 2×1 optical coupler, the second optical signal input port of the 2×1 optical coupler is connected to the second optical signal output port of the second-stage 1×2 optical splitter 1, the optical signal output port of the 2×1 optical coupler is connected to the optical signal input port of the photodetector 1, and the electrical signal output port of the photodetector 1 is connected to the electrical signal input port of the analog-to-digital converter. In the laser signal transmitting and receiving module, the optical signal is divided into two paths, one as a reference signal, and the other is output by a circulator to a 1×N optical splitter and then sent to N optical fiber delay devices. After passing through the N optical delay devices, the optical signal is emitted by the optical antenna front end to detect human vital signs. The echo is received by the optical antenna front end and then passes through N optical delay devices to the circulator and is sent to the optical coupler for coupling with the reference optical signal. The photoelectric detector then completes the de-skewing processing to generate an intermediate frequency signal, which is sent to the analog-to-digital converter for conversion. The data processing module then extracts the vital sign information.

[0045] like Figure 5As shown, the structure of the microwave signal transmitting and receiving module is specifically described. The microwave signal transmitting and receiving module includes: a second-stage 1×2 optical splitter 2, a second-stage 1×N optical splitter, optical delay devices N+1 to 2N, photoelectric detectors 2 to N+2, power amplifiers 1 to N, and an intensity modulator; the optical signal input port of the second-stage 1×2 optical splitter 2 is connected to the optical signal output port of the optical domain control module, and the first optical signal output port of the second-stage 1×2 optical splitter 2 is connected to the optical signal input port of the second-stage 1×N optical splitter; the optical signal output port of the second-stage 1×N optical splitter is respectively connected to each optical signal input port of the optical delay devices N+1 to 2N; each optical signal output port of the optical delay devices N+1 to 2N is connected to each optical signal input port of the optical domain control module. The optical signal input ports of the photodetectors 2 to N+1 are connected one by one; the electrical signal output ports of the photodetectors 2 to N+1 are connected one by one to the optical signal input ports of the power amplifiers 1 to N; the electrical signal output ports of the power amplifiers 1 to N are connected to the electrical signal input port of the antenna front end; the electrical signal output port of the antenna front end is connected to the first optical signal input port of the intensity modulator, the second optical signal output port of the second-stage 1×2 optical splitter 2 is connected to the second optical signal input port of the intensity modulator, the optical signal output port of the intensity modulator is connected to the optical signal input port of the photodetector N+2, and the electrical signal output port of the photodetector N+2 is connected to the electrical signal input port of the analog-to-digital converter. In the microwave signal transmission and reception module, the optical signal is split into two paths. One path is sent to the intensity modulator as an optical carrier, and the other path is sent to a 1×N optical splitter. N optical delay devices generate N radio frequency signals through the beat frequency of N photoelectric detectors. These signals are then amplified by N power amplifiers and sent to the antenna front end for transmission to detect human vital signs. The antenna front end receives the echo and uses it as the modulation signal of the intensity modulator to modulate the intensity of the optical carrier. The photoelectric detector beat frequency completes the de-skewing process to generate an intermediate frequency signal, which is sent to the analog-to-digital converter for conversion. The data processing module then extracts the vital sign information.

[0046] In order to prevent echo crosstalk and perform distributed detection of human vital signs, multiple antenna front ends are set in the microwave signal transmitting and receiving module to form a microwave signal transmitting and receiving extension module, such as Figure 6 As shown, the electrical signal output ports of power amplifiers 1 to N are connected to N antenna front ends in a one-to-one correspondence, and N RF signals are transmitted and received by the N antenna front ends.

[0047] In this embodiment, the laser antenna in the optical antenna front end is a fiber collimator. The microwave antenna in the antenna front end is a single element antenna or an array antenna. The optical delay device can be any of a programmable optical delay device, a manually adjustable optical delay device, or a delay fiber. The intensity modulator can be replaced by a phase modulator plus an optical filter combination. To optimize the signal-to-noise ratio and ensure detection performance, optical / electrical amplifiers can be added as appropriate in the specific system configuration.

[0048] In order to achieve system integration, by combining optoelectronic hybrid integration technology, lasers, electro-optical modulators, optical filters, optical delay devices, optical splitters, optical couplers, photodetectors, radio frequency amplifiers, and electrical signal sources can be partially or completely integrated into one module, making the system smaller.

[0049] The radar system according to the present invention operates as follows:

[0050] First, the optical domain manipulation module generates two frequency-symmetrical chirped optical signals, which are input into the optical input ports of the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module.

[0051] Next, the laser signal transmission and reception module completes the transmission and reception of optical signals, and the received optical signals undergo de-skew processing. The specific implementation process is as follows: the optical signal is transmitted by the optical delay device through the optical antenna front end to detect human vital signs. The echo is received by the optical antenna front end, passes through the delay device, and is separated from the transmitted optical signal by a circulator. The echo is output by the circulator to a 2×1 optical coupler, coupled with the reference optical signal, and then mixed by the photodetector beat frequency. The microwave signal transmission and reception module completes the transmission and reception of microwave signals. After passing through the optical delay device, the optical signal is beat frequency-generated into a broadband RF signal by the photodetector. After being amplified by the power amplifier, it is transmitted through the antenna front end to detect human vital signs. The echo is received by the antenna and sent to the intensity modulator as the modulation signal to modulate the optical signal. The output optical signal undergoes beat frequency de-skew processing by the photodetector beat frequency. The data generated by the laser signal transmission and reception module and the microwave signal transmission and reception module are sent to the data processing module to extract human vital sign information.

[0052] In order to facilitate public understanding, the technical solution of the present invention is further explained in detail theoretically by taking the optical domain manipulation module generating two symmetrical chirped optical signals as an example.

[0053] In the optical domain manipulation module, the microwave signal V1(t) generated by signal source 1 is a broadband signal, and the microwave signal V2(t) generated by signal source 2 is a single-frequency signal. The bandwidth and center frequency of the ultra-wideband RF signal output by the photodetector can be independently tuned.

[0054] The laser generates a single-frequency continuous optical signal, which can be expressed as:

[0055] E in (t) = E c exp(j2πf c t) (1)

[0056] Among them, E c and f c Respectively represent the amplitude and frequency of the laser output optical signal.

[0057] In the first-level phase modulation, the microwave signal V1(t) generated by the signal source 1 is a broadband linear frequency modulation signal, which can be expressed as

[0058] V1(t)=V1cos(2πf1t+πμ1t 2 ) (2)

[0059] Wherein, V1 and f1 represent the amplitude and frequency of the microwave signal V1(t), respectively. Assuming that the period is T1 and the bandwidth is B1, the tuning frequency μ1=B1 / T1.

[0060] The microwave signal V1(t) is loaded into the first-stage phase modulator. The optical signal output by the first-stage phase modulator can be expressed as:

[0061] E out1 (t) = E c exp[j2πf c t+jβ1cos(2πf1t+πμ1t 2 )] (3)

[0062] Where β1=πV1 / V π1 Indicates the modulation index of the signal, V π1 is the half-wave voltage of the first-stage phase modulator.

[0063] Using Bessel function expansion, we get

[0064]

[0065] J n () represents the nth-order Bessel function of the first kind.

[0066] The above optical signal is filtered through an optical dual-bandpass filter to select ±N-order optical sidebands. The ±N-order optical sideband signals can be expressed as:

[0067] E -N (t) = E c j -N J -N (β1)exp[j2πf c t-jN(2πf1t+πμ1t 2 )] (5)

[0068] E N (t) = E c j N J N (β1)exp[j2πf c t+jN(2πf1t+πμ1t 2 )2πf1t] (6)

[0069] The output optical signal of the dual-bandpass optical filter can be expressed as:

[0070] E out2 (t) = E -N (t)+E N (t) (7)

[0071] The output optical signal of the dual-bandpass optical filter is input to the optical signal input port of the second-stage phase modulator.

[0072] The microwave signal V2(t) generated by signal source 2 is a broadband signal and can be expressed as:

[0073] V2(t)=V2(t)cos(2πf2t) (8)

[0074] Wherein, V2 and f2 represent the amplitude and frequency of the microwave signal V2(t), respectively.

[0075] The microwave signal V2(t) is loaded into the RF input port of the second-stage phase modulator as the second-stage modulated signal. The optical signal output by the second-stage phase modulator can be expressed as:

[0076]

[0077] Where β2=πV2 / V π2 Represents the modulation index of the signal, V π2 is the half-wave voltage of the second-stage phase modulator.

[0078] Using Bessel function expansion, we get

[0079]

[0080] A bandpass optical filter is used to filter out the +M-order optical sideband of the -N-order signal and the -M-order optical sideband of the +N-order signal. This pair of optical sidebands is the pair of optical sidebands closest to the carrier signal frequency generated by the laser. The output optical signal of the bandpass optical filter can be expressed as:

[0081]

[0082] The optical signal output by the optical domain control module can be simplified as

[0083]

[0084] Wherein, E0' and E0" represent the amplitudes of the two optical sidebands output by the laser, respectively; f3 represents the frequency interval between the various center frequencies of the two optical signals and the symmetrical center frequency; μ is the frequency modulation slope of the two optical signals. The above optical signals are split into two paths by the first-stage 1×2 optical splitter and sent to the optical signal input ports of the laser signal transmitting and receiving module and the microwave signal transmitting and receiving / transmitting and receiving extension module, respectively.

[0085] In the laser signal transmission and reception module, the optical signal E0(t) is split into two paths by the first-stage 1×2 optical splitter. One path is sent to circulator port 1, and then to circulator port 2 to the first-stage 1×N optical splitter, where it is split into N paths. The paths are then sent to optical delay devices 1 to N, respectively. The optical antenna front end detects the vital signs of persons 1 to N. Taking the pulse as an example, assuming that the echo signal received from the kth (1≤k≤N) person is

[0086]

[0087] Among them, E e ' 1k and E e ” 1k are the amplitudes of the two chirped optical signals in the echo, τ e1k is the target echo delay, τ c1k is the corresponding compensation delay, f d1k is the Doppler frequency shift caused by human pulse, φ k is the echo phase change caused by reflection.

[0088] The echo signal is received by the front end of the optical antenna, passes through the optical delay devices 1 to N, enters from the circulator port 2 and exits from the 3 port, and is sent to the 2×1 optical coupler. The output optical signal is de-skewed by the photoelectric detector beat frequency and the compensation delay τ is adjusted. c1k The spurious signals generated by the beat frequency of the echo signals can be turned into low-frequency signals. The target intermediate frequency signal is filtered out through a high-pass filter, and the intermediate frequency signal V e1k (t)(1≤k≤N) can be expressed as

[0089]

[0090] Taking the kth intermediate frequency signal as an example, V' e1k and V″ e ” 1k are the amplitude of the microwave signal after receiving the echo beat frequency de-skewing, τ c1k is the compensation delay of the kth optical delay device for the kth echo signal. Adjust the compensation delay τ c1k The intermediate frequency signals can be made to correspond to the detected persons 1 to N. When the detected persons 1 to N breathe, the Doppler frequencies generated by the pulse micro-vibration are f d11 、f d12 …f d1N , the N intermediate frequency signals mentioned above generate symmetrical oscillation signals, and their frequency differences are 2f d11 、2f d12 …2f d1N , which is proportional to the pulse fluctuation speed of the measured persons 1 to N, and their frequencies are 2μ1(τ e11 +τ c11 )、2μ1(τ e12 +τc12 )…2μ1(τ e1N +τ c1N ), divided by 2μ and then subtracted from the corresponding compensation delay τ c11 , τ c12 …τ c1N , which is proportional to the distance between the pulse of the measured persons 1~N and the radar system, thereby reflecting the pulse conditions of the measured persons 1~N.

[0091] In the microwave signal transmitting and receiving module, the optical signal E0(t) is split into two paths by the first-stage 1×2 optical splitter. One path is sent to the intensity modulator as an optical carrier, and the other path is sent to the second-stage 1×N optical splitter and then to the optical delay devices N+1 to 2N respectively. The photoelectric detectors 2 to N+1 respectively beat the frequency to generate the radio frequency signal V RFk (t)(1≤k≤N), the kth (1≤k≤N) RF signal can be expressed as

[0092] V RFk (t) = V RFk cos[2πf RFk (t+τ c2k )+2πμ(t+τ c2k ) 2 ] (15)

[0093] Among them, V RFk is the amplitude of the N-channel transmitted microwave signal, τ c2k This is the compensation delay corresponding to N channels of transmitted microwave signals.

[0094] The front end of the antenna detects the vital signs of persons 1 to N respectively. Taking the chest rise and fall as an example, taking the kth (1≤k≤N) person under test as an example, it is assumed that the signal after de-skewing of the echo of the person under test received by the front end of the antenna is

[0095]

[0096] Where V RXk is the amplitude of the echo microwave signal, τ e2k is the target echo delay, τ c1k is the corresponding compensation delay, f d2k It is the Doppler frequency shift caused by the rise and fall of the human chest. is the echo phase change caused by reflection.

[0097] The echo signal is the modulation signal of the intensity modulator of the receiving branch, which controls the polarization current of the intensity modulator to make it work at the orthogonal bias point. The output signal of the intensity modulator can be expressed as

[0098]

[0099] in, A is the phase difference introduced by the two arms of the intensity modulator when the intensity modulator works at orthogonal polarization points. k is the amplification factor of power amplifier k. Let is the modulation coefficient of the intensity modulator. At the same time, since the echo signal is weak, the above formula can be expanded using the first-kind Bessel function

[0100]

[0101] Adjust the compensation delay τ c2k The spurious signals generated by the beat frequency of the echo signals can be turned into low-frequency signals. The echoes are de-skewing after being beat by the low-frequency photoelectric detector to generate electrical signals. After passing through a high-pass filter, they are filtered out through N different band-pass filters to obtain N target intermediate frequency signals. Taking the kth (1≤k≤N) intermediate frequency signal as an example, it can be expressed as

[0102]

[0103] Adjust the compensation delay τ c2k The echo can be de-skewed to contain N intermediate frequency signals corresponding to the detected persons 1 to N. When the detected persons 1 to N breathe, the chest fluctuations generate Doppler frequencies f d21 、f d22 …f d2N The intermediate frequency signal generated by the detected person changes accordingly. By extracting its frequency change envelope, the chest fluctuation of persons 1 to N can be reflected.

[0104] In the data processing module, the echo signal The analog signal is converted into a digital signal by an analog-to-digital converter. The data storage form is based on actual conditions. The data processing flow is: data preprocessing, digital filtering, time-frequency analysis, signal smoothing, coordinate transformation, and finally extraction of vital signs signals. The following is the specific implementation method.

[0105] First, data preprocessing is required. The digital signal output from the analog-to-digital converter (ADC) must be converted to the input format required by the data processor, for example, converting a TDMS file to a BIN or CSV file. The converted data is then filtered, with points greater than a threshold (either in absolute value or by other definition) replaced with the average of the preceding and following points (either the arithmetic mean or by other definition), thereby eliminating outliers. The digital signal is then digitally filtered, using either an FIR (finite impulse response) or an IIR (infinite impulse response) filter. High-pass digital filtering is performed, followed by N signal paths. Each path is then bandpass filtered to extract the target intermediate frequency (IF) signal. Each path is then bandpass filtered M times to extract the M digital vital sign signals. Short-time Fourier transforms are then performed on each of the N IF signals to obtain the time-frequency curves of the M vital sign signals for the N subjects. Smoothing is performed on N·M time-frequency curves. The specific operation can be regarded as a high-pass digital filter (the filter parameters are changed in real time) to obtain a digital signal with noise and DC components eliminated. The frequency values ​​of the N·M time-frequency curves are subtracted from the corresponding reference frequency f rv1 、f rv2 …f rvN·M (1≤k≤N·M), and then substitute into the conversion formula D=T w fc / 2B and V=avg(ff m )c / f c , we can get the actual-distance curve and speed-distance curve. By taking the derivative of the converted curve or counting the number of signal cycles, cycle changes and amplitude changes per unit time, we can reflect the frequency, speed and strength information of the vital signs corresponding to the curve (such as changes in chest rise and fall and pulse), thereby completing the extraction of M types of vital signs information of N measured persons.

[0106] In summary, the embodiments of the present invention provide a multi-vital sign non-contact sensing radar system based on microwave photonic technology, which realizes the simultaneous non-contact measurement of the breathing and pulse of a living organism, providing a non-contact, non-destructive and more accurate measurement method for life and health monitoring.

[0107] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0108] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0109] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0110] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0111] Any details not described in the embodiments of the present invention are well-known to those skilled in the art. Finally, it should be noted that the above embodiments are only intended to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or equivalents should be included in the scope of the claims of the present invention.

Claims

1. A multi-vital sign non-contact sensing radar system based on microwave photon technology, characterized in that: include: Optical domain control module, laser signal transmitting and receiving module, microwave signal transmitting and receiving module, optical antenna front end, antenna front end, analog-to-digital converter and data processing module; The optical signal output port of the optical domain manipulation module is connected to the optical signal input ports of the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module respectively; the optical signal communication port of the laser signal transmitting and receiving module is bidirectionally connected to the optical signal communication port of the front end of the optical antenna; the electrical signal communication port of the microwave signal transmitting and receiving module is bidirectionally connected to the electrical signal communication port of the front end of the antenna; the intermediate frequency signal output ports of the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module are both connected to the electrical signal input port of the analog-to-digital converter; the electrical signal output port of the analog-to-digital converter is connected to the electrical signal input port of the data processing module, and the data processing module performs digital filtering, time-frequency analysis, signal smoothing, and coordinate transformation on the received signal, and then extracts the vital sign signal; the coordinate transformation unit is specifically used to first subtract the reference frequency value from the vertical coordinate of the smoothed signal time-frequency curve, and then substitute the vertical coordinate of the smoothed signal time-frequency curve into the formula D=T w fc / 2B and V=avg(ff m )c / f c The corresponding distance-time curve and speed-time curve are obtained; wherein D is the distance between the detected human body and the antenna, V is the micro-motion speed of the detected human body, Tw is the sweep frequency period of the detection signal, f is the ordinate of the signal time-frequency curve after the smoothing process, f m is the average frequency of the smoothed signal time-frequency curve at each moment, f c is the frequency of the optical carrier, c is the speed of light, B is the bandwidth of the transmitted signal, and avg is the arithmetic mean.

2. The multi-vital-sign non-contact sensing radar system based on microwave photon technology according to claim 1, characterized in that: The data processing module includes: The digital filtering unit is used to perform digital high-pass filtering on the received signal to filter out the intermediate frequency digital signal, and then perform digital band-pass filtering with different center frequencies to filter out different vital sign signals of different people; The time-frequency analysis unit is used to perform short-time Fourier transform on the different vital sign signals of different people after filtering to obtain the signal time-frequency curve; A signal smoothing unit, configured to smooth the signal time-frequency curve; A coordinate transformation unit is used to perform coordinate transformation on the smoothed curve so that the smoothed curve corresponds to a distance-time curve and a speed-time curve; The vital sign signal extraction unit is used to extract vital signs from the distance-time curve and the speed-time curve.

3. The multi-vital sign non-contact sensing radar system based on microwave photon technology as claimed in claim 2, characterized in that: The vital sign signal extraction unit is specifically used to derive the distance-time curve and the speed-time curve or to count the number of signal cycles, cycle changes and amplitude changes per unit time to obtain the frequency, speed and strength information of the corresponding vital sign.

4. The multi-vital-sign non-contact sensing radar system based on microwave photon technology as claimed in claim 2, characterized in that: The data processing module further includes: The data preprocessing unit is used to convert the data format output by the analog-to-digital converter, remove points exceeding the threshold by setting a threshold, remove outliers, and send the processed data to the digital filtering unit.

5. The multi-vital-sign non-contact sensing radar system based on microwave photon technology as claimed in claim 1, characterized in that: The optical domain manipulation module includes: a laser, a phase modulator 1, a phase modulator 2, a microwave signal source 1, a microwave signal source 2, an optical filter 1, an optical filter 2, and a first-stage 1×2 optical splitter; the optical signal output port of the laser is connected to the optical signal input port of the phase modulator 1, the microwave signal output port of the microwave signal source 1 is connected to the microwave signal input port of the phase modulator 1, the optical signal output port of the phase modulator 1 is connected to the optical signal input port of the optical filter 1; the optical signal output port of the optical filter 1 is connected to the optical signal input port of the phase modulator 2 The microwave signal output port of the microwave signal source 2 is connected to the microwave signal input port of the phase modulator 2, and the optical signal output port of the phase modulator 2 is connected to the optical signal input port of the optical filter 2; the optical signal output port of the optical filter 2 is connected to the optical signal input port of the first-stage 1×2 optical splitter, the first optical signal output port of the first-stage 1×2 optical splitter is connected to the optical signal input port of the laser signal transmitting and receiving module, and the second optical signal output port of the first-stage 1×2 optical splitter is connected to the optical signal input port of the microwave signal transmitting and receiving module.

6. The multi-vital-sign non-contact sensing radar system based on microwave photon technology as claimed in claim 1, characterized in that: The laser signal transmitting and receiving module includes: a second-stage 1×2 optical splitter 1, a circulator, a 2×1 optical coupler, a first-stage 1×N optical splitter, optical delay devices 1 to N, and a photodetector 1; the optical signal input port of the second-stage 1×2 optical splitter 1 is connected to the optical signal output port of the optical domain control module, the first optical signal output port of the second-stage 1×2 optical splitter 1 is connected to the optical signal communication port 1 of the circulator; the optical signal communication port 2 of the circulator is bidirectionally connected to the first optical signal communication port of the first-stage 1×N optical splitter; the second optical signal communication port of the first-stage 1×N optical splitter is respectively connected to the optical delay device. The first optical signal communication ports of the optical timers 1 to N are bidirectionally connected; the second optical signal communication ports of the optical delay devices 1 to N are bidirectionally connected to the optical signal communication port of the front end of the optical antenna; the optical signal communication port 3 of the circulator is connected to the first optical signal input port of the 2×1 optical coupler, the second optical signal input port of the 2×1 optical coupler is connected to the second optical signal output port of the second-stage 1×2 optical splitter 1, the optical signal output port of the 2×1 optical coupler is connected to the optical signal input port of the photodetector 1, and the electrical signal output port of the photodetector 1 is connected to the electrical signal input port of the analog-to-digital converter.

7. The multi-vital-sign non-contact sensing radar system based on microwave photon technology as claimed in claim 1, characterized in that: The microwave signal transmitting and receiving module includes: a second-stage 1×2 optical splitter 2, a second-stage 1×N optical splitter, optical delay devices N+1 to 2N, photoelectric detectors 2 to N+2, power amplifiers 1 to N, and an intensity modulator; the optical signal input port of the second-stage 1×2 optical splitter 2 is connected to the optical signal output port of the optical domain control module, the first optical signal output port of the second-stage 1×2 optical splitter 2 is connected to the optical signal input port of the second-stage 1×N optical splitter; the optical signal output port of the second-stage 1×N optical splitter is respectively connected to each optical signal input port of the optical delay devices N+1 to 2N; each optical signal output port of the optical delay devices N+1 to 2N is connected one-to-one to the photoelectric detectors 2 to N+1. The optical signal input ports of the photodetectors 2 to N+1 are connected one-to-one with the optical signal input ports of the power amplifiers 1 to N; the electrical signal output ports of the power amplifiers 1 to N are connected with the electrical signal input port of the antenna front end; the electrical signal output port of the antenna front end is connected with the first optical signal input port of the intensity modulator, the second optical signal output port of the second-stage 1×2 optical splitter 2 is connected with the second optical signal input port of the intensity modulator, the optical signal output port of the intensity modulator is connected with the optical signal input port of the photodetector N+2, and the electrical signal output port of the photodetector N+2 is connected with the electrical signal input port of the analog-to-digital converter.

8. The multi-vital-sign non-contact sensing radar system based on microwave photon technology as claimed in claim 1, characterized in that: The laser antenna in the front end of the optical antenna is a fiber collimator.

9. The multi-vital-sign non-contact sensing radar system based on microwave photon technology as claimed in claim 1, characterized in that: The microwave antenna in the antenna front end is a single element antenna or an array antenna.

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