Multi-vital-sign non-contact perception radar system based on microwave photon technology

Abstract

The invention discloses a multi-vital-sign non-contact perception radar system based on a microwave photon technology. The optical domain control module generates broadband optical signals and sends the broadband optical signals to the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module respectively. One path serves as an optical radio frequency signal to detect a vital sign, and receives echoes sent by the front end of the optical antenna to obtain an intermediate frequency signal containing vital sign information; the other path of beat frequency generates a microwave ultra-wideband radio frequency signal to detect another vital sign, and receives an echo sent by the front end of the antenna to obtain an intermediate frequency signal containing vital sign information, and the two intermediate frequency signals are subjected to analog-to-digital conversion and then are subjected to digital filtering, time-frequency analysis, signal smoothing and coordinate transformation processing by the data processing module; and finally extracting vital sign information. According to the system, the ultra-wideband capability of the microwave photon radar is utilized, a wideband optical signal and an ultra-wideband radio-frequency signal are generated at the same time, and simultaneous non-contact measurement of respiration and pulse of a life body is achieved.

Description

Technical Field

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

[0002] Vital sign monitoring is essential for assessing a person's health status because it provides important information about physiological status in a timely manner. Conventional vital sign tracking technologies require contact with the human body, but most of these technologies are invasive. Body contact sensors can irritate or damage human skin, interfere with treatment or cause discomfort, provide a medium for infection and cross-infection, and hinder mobility. Therefore, this has prompted the need for effective non-contact methods to monitor 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 photon technology, comprising: an optical domain control 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 control module is respectively connected with 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 with 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 with 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 with the electrical signal input port of the analog-to-digital converter; the electrical signal output port of the analog-to-digital converter is connected with 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 processing on the received signal, and then extracts the vital sign signal.

[0005] Specifically, the data processing module includes:

[0006] A 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 transformation on the different vital sign signals of different persons after filtering to obtain the signal time-frequency curve;

[0008] A signal smoothing unit, used for smoothing the signal time-frequency curve;

[0009] A coordinate transformation unit, used for performing 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 the vital sign 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, 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.

[0012] Specifically, the vital sign signal extraction unit is 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 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 wild values ​​therein, 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 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.

[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 optical signal output port of the optical domain control module. 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+1~2N, photoelectric detectors 2~N+2, power amplifiers 1~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+1~2N; each optical signal output port of the optical delay devices N+1~2N is connected one-to-one with the photoelectric detectors 2~ The optical signal input ports of the photodetector N+1 are connected; the electrical signal output ports of the photodetectors 2 to N+1 are connected one by 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 front end of the antenna; the electrical signal output port of the front end of the antenna 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.

[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. Two broadband optical signals are generated by the optical domain control module and divided into two paths, which are sent to the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module respectively. One path is used as the optical radio frequency signal of the photon radar system to detect a vital sign, and the echo sent by the front end of the optical antenna is received and de-slanted in the optical domain 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 the echo sent by the front end of the antenna is received and de-slanted in the optical domain to obtain an intermediate frequency signal containing another vital sign information. The two intermediate frequency signals are converted by analog-to-digital converters 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 uses the ultra-wideband capability of microwave photon radar to simultaneously generate broadband optical signals and ultra-wideband radio frequency signals, which can realize simultaneous non-contact measurement of multiple / same life forms (such as breathing and pulse), and can provide non-contact, non-destructive and more accurate measurement methods for life and health monitoring.

[0022] 2. By increasing the number of transmitting and receiving branches of optical and microwave signals, a 1×N optical splitter is added, and the delay of the delay device is adjusted to achieve simultaneous extraction of information contained in multiple echo signals 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 photon technology provided by an embodiment of the present invention;

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

[0025] Figure 3 A module diagram of an 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 module diagram of a laser signal transmitting and receiving module in a multi-vital sign non-contact sensing radar system based on microwave photon technology provided by an embodiment of the present invention;

[0027] Figure 5 A module 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 A module diagram of a microwave signal transmitting and receiving extension module in a multi-vital sign non-contact sensing radar system based on microwave photonic technology provided in 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 in conjunction with 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 photon technology provided by the embodiment of the present invention includes: an optical domain control 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 control module is respectively connected to the optical signal input port 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 processing on the received signal, and then extracts the vital sign signal. At the front end of the optical antenna, the laser signal transmitting and receiving module outputs an optical signal to the optical antenna, and the optical antenna transmits the optical signal, and 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, and the data processing module includes:

[0033] A 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 transformation on the different vital sign signals of N different persons after filtering to obtain a signal time-frequency curve;

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

[0036] A coordinate transformation unit, used for performing 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 used to first subtract the reference frequency value from the vertical coordinates of the signal time-frequency curves of the N personnel after smoothing, and then substitute the vertical coordinates of the signal time-frequency curves after smoothing 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; 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 ordinate 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 the vital sign 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, and obtain the frequency, speed and strength information of the corresponding vital signs. Specifically, the maximum and minimum values ​​of the curve appear once as a cycle, and the number of cycles of the time-distance curve or the time-speed curve in a unit time and the time of each cycle 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 respect to the horizontal coordinate, and the time-amplitude change speed curve and the time-acceleration curve can be obtained. Taking the chest rise and fall and pulse as an example, the frequency change, amplitude change and each rise and fall time of the human chest rise and fall or the frequency change, amplitude change and each pulse time of the human 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 wild values ​​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 wild values, 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, the laser generates single-frequency continuous light as the carrier of the first-stage phase modulator, which 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. The optical sideband signal is used as the carrier of the second-stage phase modulator, which 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, filters out the required optical sideband, and is 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 lasers. The signal source is any one of a direct digital frequency synthesizer, a photogenerated microwave source and an optoelectronic hybrid microwave source, and the generated signal is any one of a single-frequency signal, a noise signal, a linear frequency modulation signal or a phase-coded signal. The microwave signal source 1 and the microwave signal source 2 can be realized by independent signal sources or by a multi-output signal source. The dual-bandpass optical filter and the bandpass optical filter are fiber 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 optical domain control module. 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 at 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 path is used as the reference signal, and the other path is output by the circulator to the 1×N optical splitter and then sent to N optical fiber delay devices respectively. 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 to couple with the reference optical signal. The photoelectric detector then completes the de-skewing process to generate an intermediate frequency signal that is sent to the analog-to-digital converter for conversion, and then the data processing module 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+1~2N, photoelectric detectors 2~N+2, power amplifiers 1~N and intensity modulators; 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 ports of the second-stage 1×N optical splitter are respectively connected to the optical signal input ports of the optical delay devices N+1~2N; the optical signal output ports of the optical delay devices N+1~2N are connected to the optical signal input ports of the optical delay devices N+1~2N. 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 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 front end of the antenna; the electrical signal output port of the front end of the antenna 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. In the microwave signal transmitting and receiving module, the optical signal is divided into two paths, one is sent to the intensity modulator as an optical carrier, and the other 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, which are then amplified by N power amplifiers and sent to the front end of the antenna to detect human vital signs. The front end of the antenna receives the echo as the modulation signal of the intensity modulator to perform intensity modulation on the optical carrier. The intermediate frequency signal is sent to the analog-to-digital converter for conversion after the beat frequency of the photoelectric detector is de-skewed, and then the vital sign information is extracted by the data processing module.

[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 The electrical signal output ports of the power amplifiers 1 to N are connected to the N antenna front ends one by one, and the N radio frequency signals are transmitted and received by the N antenna front ends.

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

[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, RF amplifiers, and electrical signal sources can be partially or completely integrated into one module, making the system smaller.

[0049] The working principle of the radar system provided by the embodiment of the present invention is 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 transmission and reception of the optical signal are completed in the laser signal transmitting and receiving module, and the received optical signal is de-skewed. The specific implementation process is: 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 through the delay device and separated from the transmitted optical signal by the circulator, and the echo is output to the 2×1 optical coupler through the circulator to couple with the reference optical signal and then mixed by the photodetector beat frequency. The transmission and reception of the microwave signal are completed in the microwave signal transmitting and receiving module. The optical signal passes through the optical delay device and the photodetector beats to generate a broadband RF signal, which is amplified by the power amplifier and then transmitted through the antenna front end to detect human vital signs. The echo is received by the antenna to the intensity modulator as a modulation signal to modulate the optical signal, and the output optical signal is de-skewed by the photodetector beat frequency. The data generated by the laser signal transmitting and receiving module and the microwave signal transmitting and receiving module are sent to the data processing module to complete the extraction of human vital signs information.

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

[0053] In the optical domain control module, the microwave signal V1(t) generated by signal source 1 is a broadband signal, the microwave signal V2(t) generated by signal source 2 is a single-frequency signal, and 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 They represent the amplitude and frequency of the laser output optical signal respectively.

[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 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, and 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, which 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 modulation 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] The +M-order optical sideband of the -N-order signal and the -M-order optical sideband of the +N-order signal are filtered out by a bandpass optical filter. 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 follows:

[0083]

[0084] Wherein, E0' and E0" represent the amplitudes of the two optical sidebands output by the laser, f3 represents the frequency interval between the various center frequencies and the symmetrical center frequency of the two optical signals, and μ is the frequency modulation slope of the two optical signals. The above optical signals are divided 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 transmitting and receiving module, the optical signal E0(t) is divided into two paths by the first-stage 1×2 optical splitter. One path is sent to the circulator port 1 and then to the first-stage 1×N optical splitter port 2 to be divided into N paths. Then, they are sent to the optical delay devices 1 to N respectively. The optical antenna front end detects the vital signs of personnel 1 to N. Taking the pulse as an example, assuming that the echo signal received from the kth (1≤k≤N) person under test is

[0086]

[0087] Among them, E e ' 1k and E e ” 1k are the amplitudes of the two chirp 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 port 2 of the circulator and exits from port 3, and is sent to the 2×1 optical coupler. The output optical signal is de-skewed by the photoelectric detector beat frequency to adjust the compensation delay τ 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 correspond to the detected persons 1 to N respectively. When the detected persons 1 to N breathe, the Doppler frequencies generated by the pulse micro-movement are f d11 、f d12 …f d1N , the above N intermediate frequency signals generate symmetrical oscillation signals respectively, 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 divided 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 sent to the optical delay devices N+1~2N respectively. The photoelectric detectors 2~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 microwave signal, τ c2k It 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. The polarization current of the intensity modulator is controlled to make it work at the orthogonal bias point. The output signal of the intensity modulator can be expressed as

[0098]

[0099] in, is the phase difference introduced by the two arms of the intensity modulator when the intensity modulator works at orthogonal polarization points, A k is the gain factor of power amplifier k. 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, and the frequency change envelope is extracted to reflect the chest fluctuation of persons 1 to N.

[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 the actual situation. The data processing flow is: data preprocessing, digital filtering, time-frequency analysis, signal smoothing, coordinate transformation and finally extracting the vital sign signal. The following is the specific implementation method.

[0105] First, data preprocessing is required. The digital signal output by the analog-to-digital converter needs to be converted into the input format required by the data processor. For example, the TDMS format file is converted into a BIN or CSV format file. The data with the converted format is screened, and the points that are greater than the threshold (can be the absolute value or the size under other definitions) are replaced with the average value of the previous and next points (can be the arithmetic mean or the average value of other definitions), thereby eliminating wild values. Then the digital signal is digitally filtered. The filter can be a FIR (finite impulse response) filter or an IIR (infinite impulse response) filter. High-pass digital filtering is first performed, and then the signal is divided into N channels. The target intermediate frequency signal is filtered out through N bandpass filters respectively, and then each signal is bandpass filtered M times to filter out M types of digital signals of vital signs. Short-time Fourier transform is performed on the N·M intermediate frequency signals to obtain the time-frequency curves of M types of vital sign signals of N tested persons. The N·M time-frequency curves are smoothed. 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 it into the conversion formula D=T w fc / 2B and V = avg(ff m )c / f c , the actual-distance curve and speed-distance curve can be obtained. The derivative of the converted curve or the number of signal cycles, cycle changes and amplitude changes per unit time can be statistically analyzed to 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] To summarize, the embodiments of the present invention provide a multi-vital sign non-contact sensing radar system based on microwave photonic technology, thereby realizing simultaneous non-contact measurement of the breathing and pulse of a living body, and providing a non-contact, non-destructive and more accurate measurement method for life and health monitoring.

[0107] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, 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 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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 flowchart and / or block diagram. 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 capable of directing a computer or other programmable data processing device to operate 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 A 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 operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions 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] The parts not described in detail in the embodiments of the present invention are all known technologies to those skilled in the art. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which 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 control 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 processing on the received signal, and then extracts the vital sign signal.

2. The multi-vital-signs non-contact sensing radar system based on microwave photon technology as claimed in claim 1, characterized in that: The data processing module comprises: A 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 transformation on the different vital sign signals of different persons after filtering to obtain the signal time-frequency curve; A signal smoothing unit, used for smoothing the signal time-frequency curve; A coordinate transformation unit, used for performing 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 the vital sign from the distance-time curve and the speed-time curve.

3. The multi-vital-signs non-contact sensing radar system based on microwave photon technology as claimed in claim 2, characterized in that: 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=Twfc / 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, 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.

4. The multi-vital-signs 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 within a unit time to obtain the frequency, speed and strength information of the corresponding vital sign.

5. The multi-vital-signs 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 wild values ​​therein, and send the processed data to the digital filtering unit.

6. The multi-vital-signs 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.

7. The multi-vital-signs 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 comprises: 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 photoelectric detector 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 1 to the optical signal output port of the optical domain control module 1; 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.

8. The multi-vital-signs 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 comprises: 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 to the photoelectric detectors 2 to N+1 in a one-to-one correspondence. The optical signal input ports of the photodetectors 2 to N+1 are connected one by 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 front end of the antenna; the electrical signal output port of the front end of the antenna 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.

9. The multi-vital-signs 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.

10. The multi-vital-signs 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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