CN115153459A - Top-mounted millimeter wave radar heartbeat and respiration detection device and detection method - Google Patents
Top-mounted millimeter wave radar heartbeat and respiration detection device and detection method Download PDFInfo
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Abstract
The invention discloses a top-mounted millimeter wave radar heartbeat and respiration detection device which comprises a transmitting antenna, a receiving antenna, a control circuit connected with the transmitting antenna and a base provided with the control circuit, wherein the base is arranged on a roof, the transmitting antenna and the receiving antenna of the base face a detection target respectively.
Description
Technical Field
The invention relates to the field of monitoring equipment, in particular to a top-mounted millimeter wave radar heartbeat and respiration detection device and a detection method.
Background
Heartbeat breath detection devices are now widely used in the medical electronics industry and are gradually moved to individual homes for frequent monitoring of physical health conditions. The radar wave is an electromagnetic wave, so that the radar wave has the characteristic of being not influenced by environmental factors along with temperature, light and the like.
At present, the domestic heartbeat breath detection mainly comprises two types of contact type and non-contact type, and contact type heartbeat breath detection equipment mainly has the following defects and shortcomings:
1. the equipment must contact with the human body constantly, for example, adopt modes such as wearing formula, SMD, wear-type or face guard to detect, this has just caused certain constraint to the human body to the ability of certain free activity of human body has been restricted.
2. The traditional breathing heartbeat detection equipment has the defects that medical staff is required to operate and detect, the cost is high, the traditional breathing heartbeat detection equipment cannot be used for long-term human health detection, and the traditional breathing heartbeat detection equipment is not suitable for common users. And has large volume and strange shape, which is not beneficial to moving.
There are three main types of radar used for non-contact physiological signal detection: continuous Wave (CW) doppler radar, ultra-Wideband (UWB) pulse radar, and Frequency Modulated Continuous Wave (FMCW) radar. The continuous wave Doppler radar has the advantages of simple structure and low power consumption, but has no distance resolution, so the physiological signal detection of the continuous wave Doppler radar is easily interfered by other objects or human body reflected signals in the environment. The ultra-wideband radar system has the characteristics of strong penetrating power, high range resolution and the like, but signals are easily controlled by pulse width and peak signal intensity. The FMCW radar not only has the ranging capability of an ultra-wideband radar, but also has the sensitivity and robustness of a continuous wave Doppler radar. In addition, the FMCW radar has the advantages of small size, light weight, low power consumption and the like.
Therefore, a heartbeat breath detection device which is simple in operation, low in cost, convenient to move, free of constraint on a human body by adopting a non-contact mode and suitable for long-term health detection of the human body is needed. Furthermore, the invention provides a heartbeat and respiration detection scheme of the ceiling type millimeter wave radar, and solves the existing problems.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a top-mounted millimeter wave radar heartbeat and respiration detection device and a detection method,
in order to achieve the purpose of the invention, the invention adopts the technical scheme that:
a kind of ceiling type millimeter wave radar heart beat breathes the checkout gear, including transmitting antenna, receiving antenna, control circuit linking with transmitting antenna, and mount the base of the control circuit, the said base is mounted to the roof, its transmitting antenna and receiving antenna are towards detecting the goal separately;
the control circuit comprises a receiving branch and a transmitting branch, wherein the receiving branch comprises a frequency mixer, a band-pass filter, a first amplifier, an ADC (analog-to-digital converter) and a signal processing module which are sequentially connected, and the frequency mixer is connected with a receiving antenna; the transmitting branch comprises a signal generator and a second amplifier which are sequentially connected, and the second amplifier is connected with a transmitting antenna;
the signal generator is also connected to the mixer.
Furthermore, the receiving antenna and the transmitting antenna are microstrip antennas, the receiving antenna is used for receiving millimeter wave signals containing heartbeat breathing signals, and the transmitting antenna is used for generating original millimeter wave signals.
Furthermore, the band-pass filter adopts a fourth-order band-pass filter consisting of a second-order low-pass filter and a second-order high-pass filter, the pass band range is 120Hz to 15Hz, high-frequency signals and noise signals generated by frequency mixing are filtered, and the signals are amplified through the second amplifier.
A detection method of a top-mounted millimeter wave radar heartbeat and respiration detection device comprises the following steps:
s1, installing a ceiling type millimeter wave radar indoors, generating an electromagnetic wave signal by using the millimeter wave radar, transmitting the electromagnetic wave signal to a human body, and receiving the electromagnetic wave signal after the electromagnetic wave signal is reflected by the human body to obtain an echo signal containing heartbeat frequency and respiratory frequency;
s2, mixing the echo signal obtained in the S1 with an original transmitting signal to obtain an intermediate frequency signal S IF (t), performing analog-to-digital conversion sampling on the intermediate frequency signal, and performing fast Fourier transform on a sampling point obtained by sampling;
s3, obtaining the coordinates (x, y) of the measured object according to the space position of the measured object, extracting the phase information of the distance interval of the position of the measured object, and recovering the phase of the intermediate frequency signal by utilizing an arc tangent function
S4, selecting a random time interval T d Sampling the intermediate frequency signals at intervals, accumulating sampling points, taking the average value to obtain direct current correction offset, and performing difference between the direct current correction offset and the intermediate frequency signals to obtain new correction signals;
s5, carrying out noise suppression on the new correction signal obtained in the S4 to obtain a mixed signal containing a phase, separating the respiration signal and the heartbeat signal according to the difference value of the respiration frequency and the heartbeat frequency of the human body, and respectively filtering to obtain output sequences of the respiration signal and the heartbeat signal;
s6, calculating the output sequence of the heartbeat signals obtained in the step S5 on a fast time axis and a slow time axis by utilizing an autocorrelation algorithm, and obtaining autocorrelation coefficients rho of the heartbeat signals on the slow time axis and the heartbeat signals on a block time axis i ；
S7, utilizing continuous wavelet transform to convert autocorrelation coefficient rho i And (4) transforming the time-frequency signal, and obtaining the heart rate changing along with time by using a sliding window algorithm.
Further, the echo signal containing the heartbeat frequency and the respiratory frequency in S1 is represented as:
wherein A is R For the amplitude of the received signal, τ is the round-trip time of the electromagnetic wave traveling between the radar and the target object, c is the speed of light, T x For the pulse width, f, of the chirp signal min The initial frequency of the radar transmission signal, B the bandwidth of the radar transmission signal, m the signal sequence, and phi (t) the phase noise.
Further, the intermediate frequency signal in S2 is represented as:
wherein, A is S A R Is the amplitude of the intermediate frequency signal, f IF Is the frequency of the intermediate frequency signal and,
i is the phase of the intermediate frequency signal and is in units of imaginary numbers.
Further, in S3, the phase of the intermediate frequency signal is recovered by using an arc tangent function
The calculation method is as follows:
wherein x is R (t, m) and x R And (t, m + 1) respectively represent two paths of orthogonal ground band signals.
Further, the new correction signal in S4 is represented as:
S(t,n,T d ,m)＝S IF (t,m)-S d (t,n,T d )
wherein, T d Is a random time interval, N is the number of samples, S d (t,n,T d ) For each 0 to N, there is an internal T d The amount of offset correction produced, S (T, n, T) d M) is the new correction signal.
Further, the S6 autocorrelation coefficient ρ i Expressed as:
wherein H (t) is a heartbeat signal on a fast time axis, mu is an average value of H (t), sigma is a deviation of H (t), and t s For the heartbeat signal on the fast time axis to be shifted in time along the time axis, E ·]As desired.
Further, the step S7 specifically includes the following steps:
s71, performing continuous wavelet transformation on the autocorrelation coefficients, and changing a scale scaling factor and a time shifting factor to cover the whole signal to obtain a two-dimensional matrix of the wavelet coefficients, wherein the row of the two-dimensional matrix represents time information and the column represents frequency information;
s72, selecting the maximum value of the corresponding frequency of each time point along the row of the binary matrix to obtain a time spectrum;
s73, frequency calculation is carried out by using a sliding window algorithm to obtain the heart rate changing along with time, and the calculation mode is as follows:
wherein, (t) is a time series signal, WTF (e, v) represents continuous wavelet transform on the function f (t), e is a scale scaling factor, v is a time shifting factor,
are sub-wavelets.
The invention has the following beneficial effects:
1. compared with the traditional contact type respiration and heartbeat detection device, the non-contact type millimeter wave detection method is adopted, so that the human body is free from the constraint of equipment in the detection process, people can detect in a certain range, and errors caused by movement in the measurement of contact type equipment are greatly reduced.
2. The FMCW millimeter wave radar chip is adopted, the problem that the distance resolution of the continuous wave Doppler radar is insufficient is solved, the position coordinate of the measured object is accurately measured, and the interference of other objects or human body reflected signals in the environment in signal detection is reduced. The size and the consumption of equipment have been reduced greatly, enable it to be used for monitoring human heartbeat respiratory rate for a long time, adopt the design of ceiling type outward appearance, not only make things convenient for the removal of equipment, can also reduce the interference of barrier on every side, improved the rate of accuracy that detects.
3. Compared with a non-contact biological radar, the adopted millimeter wave of the 76.4GHz frequency band is closer to the displacement of the respiratory thorax of the human body, and a more accurate and easier-to-separate human body signal is obtained. After the mixed signal of the heartbeat breath is obtained, the phase signal is processed by wavelet packet decomposition, compared with the traditional wavelet decomposition, the wavelet packet analysis further improves the time-frequency resolution, and solves the problem of insufficient resolution of the traditional non-contact radar.
Drawings
Fig. 1 is a schematic structural diagram of a heartbeat and respiration detection device of a ceiling-mounted millimeter wave radar.
Fig. 2 is a schematic diagram of a control circuit of the top-mounted millimeter wave radar heartbeat breath detection device according to the embodiment of the invention.
Fig. 3 is a schematic view illustrating an installation of the top-mounted millimeter wave radar heartbeat and respiration detection device according to the embodiment of the present invention.
Fig. 4 is a schematic flow chart of a detection method of the top-mounted millimeter wave radar heartbeat respiration detection device according to the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
A top-mounted millimeter wave radar heartbeat and respiration detection device is shown in figure 1 and comprises a transmitting antenna, a receiving antenna, a control circuit connected with the transmitting antenna and a base provided with the control circuit, wherein the base is arranged on a roof, and the transmitting antenna and the receiving antenna of the base face a detection target respectively, as shown in figure 3;
as shown in fig. 2, the control circuit includes a receiving branch and a transmitting branch, the receiving branch includes a bottle fetch, a band pass filter, a first amplifier, an ADC converter and a signal processing module, which are connected in sequence, wherein the mixer is connected to a receiving antenna; the transmitting branch comprises a signal generator and a second amplifier which are sequentially connected, and the second amplifier is connected with a transmitting antenna;
the signal generator is also connected with the frequency mixer.
Specifically, the millimeter wave transceiver module comprises a transmitting antenna TX and a receiving antenna RX, wherein the antennas are microstrip lines and are used for generating original millimeter waves and receiving millimeter wave signals containing heartbeat breathing signals;
the signal generator module comprises an oscillator and an amplifier and is used for generating an oscillating signal, and the oscillating signal is transmitted by the antenna after being amplified;
the frequency mixing module adopts a Mixer to mix the received signal and the oscillation signal to generate an intermediate frequency signal;
band-pass filter: a fourth-order band-pass filter consisting of a second-order low-pass filter and a second-order high-pass filter is adopted, the pass band range is 120Hz to 15Hz, high-frequency signals and noise signals thereof generated by frequency mixing are filtered, and the signals are amplified through an amplifier;
an ADC analog-to-digital converter: adopting an ADC12DJ5200RF digital-to-analog converter of TI to carry out envelope detection on the received signal and carry out analog-to-digital conversion;
a detection method of a top-mounted millimeter wave radar heartbeat and respiration detection device is shown in fig. 4, and comprises the following steps:
s1, installing a ceiling type millimeter wave radar indoors, generating an electromagnetic wave signal by using the millimeter wave radar, transmitting the electromagnetic wave signal to a human body, and receiving the electromagnetic wave signal after the electromagnetic wave signal is reflected by the human body to obtain an echo signal containing heartbeat frequency and respiratory frequency;
in the embodiment, the spatial distance between the FMCW radar and the measured object is assumed to be
x(t)＝R(t)+d 0
Wherein d is 0 The distance between the human body and the radar is shown, R (t) is the displacement of the thoracic cavity movement, the emission signals are m orthogonal cosine signals, and the emission signals x S (t, m) can be approximately expressed as
Wherein fmin is the initial frequency of the radar emission signal, A S For the amplitude of the transmitted signal, phi (T) is the phase noise, B is the bandwidth of the radar transmitted signal, T x Is the pulse width of the linear frequency modulation signal, m is the signal sequence, T is the time, and the range is more than 0 and less than or equal to T d 。
The original signal is transmitted to the measured object through the transmitter antenna (TX), and the echo signal obtained by the radar receiver antenna (RX) after the reflection of the human body can be approximately expressed as:
m＝0,1,2,3…
in the formula, A R The amplitude of the received signal, τ is the round-trip time of the electromagnetic wave transmitted between the radar and the target object, and c is the speed of light. Will transmit signal x S (t, m) and echoSignal x R (t, m) are mixed to obtain an intermediate frequency signal, which is denoted as
Wherein A is s A R Is the amplitude of the intermediate frequency signal, f IF Is the frequency of the intermediate frequency signal and,
is the phase of the intermediate frequency signal, λ is the radar signal wavelength, and i is the imaginary unit.
The received echo signal is processed by the next-stage module.
S2, mixing the echo signal obtained in the S1 with an original transmitting signal to obtain an intermediate frequency signal S IF (t), performing analog-to-digital conversion sampling on the intermediate frequency signal, and performing fast Fourier transform on a sampling point obtained by sampling;
s3, obtaining the coordinates (x, y) of the measured object according to the space position of the measured object, extracting the phase information of the distance interval of the position of the measured object, and recovering the phase of the intermediate frequency signal by utilizing an arc tangent function
In the embodiment, FMCW millimeter wave radar is used for collecting two paths of data of human body vital signals, and transmitting signals x S (t, m) and echo signal x R (t, m) mixing to obtain an intermediate frequency signal S IF (t, m), performing analog-to-digital converter (ADC) sampling on the intermediate frequency signal, and performing FFT fast Fourier transform on sampling points of the intermediate frequency signalObtaining the position coordinates of the measured object according to the following formula
x＝d 0 sinθ
Wherein d is the antenna spacing, λ is the wavelength, and θ is the azimuth angle, thus obtaining the coordinates (x, y) of the measured object.
After the human body position information is obtained, phase information on a distance interval where the human body position is located is extracted. Recovering phase of signal using arctangent function
Namely that
x R (t, m) and x R And (t, m + 1) respectively represent two paths of orthogonal baseband signals. The phase of the demodulation generally falls within [ - π, π]And if the phase difference is larger or smaller than +/-pi, performing phase correction by adding or subtracting 2 pi.
S4, selecting a random time interval T d Sampling the intermediate frequency signal at intervals, accumulating and averaging sampling points to obtain a direct current correction offset, and performing difference between the direct current correction offset and the intermediate frequency signal to obtain a new correction signal;
in this embodiment, the DC offset is corrected by a random mean step elimination method, wherein a time interval T is randomly selected first d To the intermediate frequency signal S IF (t, m) sampling N at intervals, accumulating the sampling points, taking the average value to obtain the DC correction offset, and comparing the DC correction offset with the intermediate frequency signal S IF (T, m) are subtracted to obtain a new correction signal, and during the next time interval T d+1 Repeating the above steps, and so on to obtainTo a continuous correction signal, the formula is specified below
S(t,n,T d ,m)＝S IF (t,m)-S d (t,n,T d )
Wherein, T d Is a random time interval, N is the number of samples, S d (t,n,T d ) For each offset correction amount, S (T, N, T), generated at Td within 0 to N d M) is the new correction signal.
S5, carrying out noise suppression on the new correction signal obtained in the S4 to obtain a mixed signal containing a phase, separating the respiration signal and the heartbeat signal according to the difference value of the respiration frequency and the heartbeat frequency of the human body, and respectively filtering to obtain output sequences of the respiration signal and the heartbeat signal;
obtaining S (T, n, T) after phase extraction and direct current offset correction d M), noise suppressing the phase signal using Wavelet Packet Decomposition (WPD). And 5-level wavelet packet decomposition is carried out on the obtained phase signal, and wavelet coefficients comprising 32 nodes can be obtained at a 5 th layer, wherein the frequency difference between the nodes is 0.3125Hz. The low frequency components of the 1 st to 3 rd nodes are used for reconstructing the respiratory signal, and the high frequency components of the 6 th to 12 th nodes are used for reconstructing the heartbeat signal. The specific decomposition algorithm is
Reconstructing the signal by the specific algorithm
Phi (t) represents the phase signal, l represents the number of layers of the phase signal decomposition, m represents the position of the node of the l layer decomposition, k is the scale parameter of the phase decomposition, and h (n) and g (n) represent the low-pass and high-pass filters, respectively.
The obtained phase is subjected to phase difference after discrete processing, and the formula is as follows
A mixed signal S (T, n, T) is thus obtained which contains the final phase f (T) d ,m)。
According to the large difference value of the respiratory frequency and the heartbeat frequency of the human body, the reasonable bandwidth is set through the filter to separate signals in two ranges, and the IIR band-pass filter is adopted to set the reasonable frequency value on the frequency domain to separate the respiratory signal from the heartbeat signal. The difference equation for easily obtaining the impulse response of the IIR band-pass filter is
Wherein x is i-k For input of denoised phase signals, y i-l For the output of denoised phase signals, a i Is a forward coefficient, y i-l Are inverse coefficients.
Adopting a fourth-order IIR band-pass filter, carrying out z transformation on the formula to obtain a fourth-order filter transfer function of
Wherein k (k =1,2,3,4) is a cascade number.
The heartbeat and respiration signal output sequences can be obtained respectively through the filtering of the respiration and heartbeat frequency ranges, and the heartbeat signal of 50-120 times/min and the respiration signal of 15-45 times/min are separated.
S6, calculating the output sequence of the heartbeat signals obtained in the S5 on a fast time axis and a slow time axis by utilizing an autocorrelation algorithmObtaining the autocorrelation coefficient rho of the heartbeat signal on the slow time axis and the heartbeat signal on the block time axis i ；
And (3) introducing autocorrelation calculation to analyze the heartbeat signals from the two aspects of a fast time axis and a slow time axis, wherein the signals on the fast time axis are original heartbeat signals, and the signals on the slow time axis are autocorrelation coefficients of the heartbeat signals after translation and the original heartbeat signals. Firstly, a reconstructed heartbeat signal H (t) is selected as an original signal, and then an autocorrelation coefficient of the heart beat signal after translation and the original heartbeat signal is obtained based on an autocorrelation calculation formula which is as follows
Where H (t) is the original heartbeat signal, E is the expected value, μ is the mean value of H (t), σ is the deviation of H (t), t S Representing the time of the translation of the original heartbeat signal along the time axis.
Finally, t is changed e And repeat until t e Covering the whole fast time axis to finally obtain a series of autocorrelation coefficients rho i 。
S7, utilizing continuous wavelet transform to convert autocorrelation coefficient rho i And (4) transforming the time-frequency signal, and obtaining the heart rate changing along with time by using a sliding window algorithm.
In particular, the method comprises the steps of,
s71, performing continuous wavelet transform on the autocorrelation coefficients, changing a scale scaling factor and a time shifting factor to cover the whole signal to obtain a two-dimensional matrix of the wavelet coefficients, wherein the row of the two-dimensional matrix represents time information, and the column represents frequency information;
s72, selecting the maximum value of the corresponding frequency of each time point along the row of the binary matrix to obtain a time spectrum;
s73, frequency calculation is carried out by using a sliding window algorithm to obtain the heart rate changing along with time, and the calculation mode is as follows:
wherein, (t) is a time series signal, WTF (e, v) represents continuous wavelet transform on the function f (t), e is a scale scaling factor, v is a time shifting factor,
are sub-wavelets.
For the heart rate, in the present embodiment, the window length is set to 20s, and the sliding window length is set to 5s; for breathing, the window length is set to 50s and the sliding window length is set to 5s.
The principle and the implementation mode of the invention are explained by applying specific embodiments in the invention, and the description of the embodiments is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.
Claims (10)
1. A top-mounted millimeter wave radar heartbeat respiration detection device is characterized by comprising a transmitting antenna, a receiving antenna, a control circuit connected with the transmitting antenna and a base for mounting the control circuit, wherein the base is mounted on a roof, and the transmitting antenna and the receiving antenna of the base face towards a detection target respectively;
the control circuit comprises a receiving branch and a transmitting branch, wherein the receiving branch comprises a frequency mixer, a band-pass filter, a first amplifier, an ADC (analog-to-digital converter) and a signal processing module which are sequentially connected, and the frequency mixer is connected with a receiving antenna; the transmitting branch comprises a signal generator and a second amplifier which are sequentially connected, and the second amplifier is connected with a transmitting antenna;
the signal generator is also connected with the frequency mixer.
2. The ceiling type millimeter wave radar heartbeat respiration detection device of claim 1, wherein the receiving antenna and the transmitting antenna are microstrip antennas, the receiving antenna is used for receiving millimeter wave signals containing heartbeat respiration signals, and the transmitting antenna is used for generating original millimeter wave signals.
3. The ceiling type millimeter wave radar heartbeat respiration detection device according to claim 1, wherein the band pass filter is a fourth-order band pass filter composed of a second-order low pass filter and a second-order high pass filter, the pass band range is 120Hz to 15Hz, the high frequency signals generated by mixing and the noise signals thereof are filtered, and the signals are amplified through the second amplifier.
4. A detection method of a top-mounted millimeter wave radar heartbeat and respiration detection device is characterized by comprising the following steps:
s1, installing a ceiling type millimeter wave radar indoors, generating an electromagnetic wave signal by using the millimeter wave radar, transmitting the electromagnetic wave signal to a human body, and receiving the electromagnetic wave signal after the electromagnetic wave signal is reflected by the human body to obtain an echo signal containing heartbeat frequency and respiratory frequency;
s2, mixing the echo signal obtained in the S1 with an original transmitting signal to obtain an intermediate frequency signal S IF (t), performing analog-to-digital conversion sampling on the intermediate frequency signal, and performing fast Fourier transform on a sampling point obtained by sampling;
s3, obtaining the coordinates (x, y) of the measured object according to the space position of the measured object, extracting the phase information of the distance interval of the position of the measured object, and recovering the phase of the intermediate frequency signal by utilizing an arc tangent function
S4、Selecting a random time interval T d Sampling the intermediate frequency signal at intervals, accumulating and averaging sampling points to obtain a direct current correction offset, and performing difference between the direct current correction offset and the intermediate frequency signal to obtain a new correction signal;
s5, carrying out noise suppression on the new correction signal obtained in the S4 to obtain a mixed signal containing a phase, separating the respiration signal and the heartbeat signal according to the difference value of the respiration frequency and the heartbeat frequency of the human body, and respectively filtering to obtain output sequences of the respiration signal and the heartbeat signal;
s6, calculating the output sequence of the heartbeat signals obtained in the step S5 on a fast time axis and a slow time axis by utilizing an autocorrelation algorithm, and obtaining autocorrelation coefficients rho of the heartbeat signals on the slow time axis and the heartbeat signals on a block time axis i ；
S7, utilizing continuous wavelet transform to convert autocorrelation coefficient rho i And (4) transforming the time-frequency signal, and obtaining the heart rate changing along with time by using a sliding window algorithm.
5. The detection method of the ceiling millimeter wave radar heartbeat and respiration detection device according to claim 4, wherein the echo signals containing the heartbeat frequency and the respiration frequency in S1 are expressed as:
wherein A is R For the amplitude of the received signal, τ is the round-trip time of the electromagnetic wave traveling between the radar and the target object, c is the speed of light, T x For the pulse width, f, of the chirp signal min The initial frequency of the radar transmission signal, B the bandwidth of the radar transmission signal, m the signal sequence, and phi (t) the phase noise.
6. The detection method of the ceiling-mounted millimeter wave radar heartbeat respiration detection device according to claim 4, wherein the S2 intermediate-frequency signal is expressed as:
wherein, A is S A R Is the amplitude of the intermediate frequency signal, f IF Is the frequency of the intermediate frequency signal and,
i is the phase of the intermediate frequency signal and is in units of imaginary numbers.
7. The detection method of the top-mounted millimeter wave radar heartbeat respiration detection device according to claim 4, wherein in S3, the phase of the intermediate frequency signal is recovered by an arc tangent function
The calculation method of (A) is as follows:
wherein x is R (t, m) and x R And (t, m + 1) respectively represent two paths of orthogonal baseband signals.
8. The detection method of the ceiling-mounted millimeter wave radar heartbeat respiration detection device according to claim 4, wherein the new correction signal in S4 is expressed as:
S(t，n，T d ，m)＝S IF (t，m)-S d (t，n，T d )
wherein, T d Is a random time interval, N is the number of samples, S d (t，n，T d ) For each 0 to N, there is an internal T d The amount of offset correction generated below, S (T, n, T) d M) is the new correction signal.
9. The detection method of the top-mounted millimeter wave radar heartbeat respiration detection device according to claim 4, wherein the S6 autocorrelation coefficient p is i Expressed as:
wherein H (t) is the heartbeat signal on the fast time axis, mu is the mean value of H (t), sigma is the deviation of H (t), t s For the heartbeat signal on the fast time axis to be shifted in time along the time axis, E ·]As desired.
10. The detection method of the detection device for heartbeat and respiration of the ceiling-mounted millimeter wave radar according to claim 4, wherein the step S7 specifically comprises the following steps:
s71, performing continuous wavelet transformation on the autocorrelation coefficients, and changing a scale scaling factor and a time shifting factor to cover the whole signal to obtain a two-dimensional matrix of the wavelet coefficients, wherein the row of the two-dimensional matrix represents time information and the column represents frequency information;
s72, selecting the maximum value of the corresponding frequency of each time point along the row of the two-bit matrix to obtain a time spectrum;
s73, frequency calculation is carried out by using a sliding window algorithm to obtain the heart rate changing along with time, and the calculation mode is as follows:
wherein, (t) is a time series signal, WTF (e, v) represents continuous wavelet transform of the function f (t), e is a scale scaling factor, v is a time shifting factor,
are sub-wavelets.
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