JP2020157000A - Biological signal processor and biological signal processing program - Google Patents

Abstract

To highly accurately detect a biological signal.SOLUTION: A reflection response to a microwave radiated on a living body includes an amplitude component and a phase component. Ideally, analysis of a reflection component hv(t) from the living body may be used. However, a reflection response component h(t) includes a reflection component hf(t) from a wall, an article of furniture, or the like other than the living body in addition to the reflection component hv(t) from the living body, which makes an origin for the analysis deviate from the origin O. The deviation causes a signal error that affects detection accuracy. Accordingly, a signal processor 4 analyzes an acquired signal and calculates a virtual origin O' to be a reference for analyzing the hv(t) to calculate a phase and amplitude components from the virtual origin O', which enables acquisition of a signal matching with a phenomenon as compared with the conventional system using a filter. More specifically, the signal processor 4 takes a difference between the origin O and the virtual origin O' as an offset amount in order to calculate a phase and amplitude from the virtual origin O' and performs offsetting on the h(t) using the offset.SELECTED DRAWING: Figure 1

Description

The present invention relates to a biological signal processing device and a biological signal processing program, for example, to analyze a biological signal.

Vital measurement (biological measurement) such as pulse wave measurement is very important for grasping daily health condition and finding signs of illness.
In particular, there is a demand for vital measurement that can be easily performed non-invasively (without sticking a needle) and non-contact (without attaching a device) from the desire to easily measure on a daily basis, and is being actively researched and developed.

As a technique for performing such non-invasive and non-contact vital measurement, there is a technique using a microwave radar.
When the human body is irradiated with microwaves by the radar, the reflected waves undergo a Doppler shift (frequency transition) due to respiration, heartbeat, body movement, etc., so by detecting this, respiration, heartbeat, and body movement information are included. The baseband can be detected.

By the way, when simply irradiating microwaves and detecting the reflected waves, the Doppler signal strength decreases if the distance between the radar and the human body is an integral multiple of the wavelength of the microwave used (null detection position). There is a phenomenon.
In order to improve this phenomenon, the technique of Non-Patent Document 1 detects biological signals by IQ demodulation.

IQ demodulation detects the I signal and the Q signal orthogonal to the I signal from the reflected wave. When one of the I signal and the Q signal has the lowest Doppler signal strength, the other is optimal and the other is in the intermediate state. At this time, the other is also in an intermediate state, so that they can complement each other and alleviate the decrease in sensitivity.

Various methods have been proposed to detect vital frequency changes by combining IQ channel signals in this way. For example, a method of selecting an IQ channel using principal component analysis, an arctangent composite method, and a complex signal composite method. Laws have been proposed.
In the technology of detecting vital components from the human body using these Doppler radars, the phase components of reflection are reproduced using a filter or the like, and further separated by frequency components to obtain biological signals such as respiration and heartbeat. ..

However, the reflected wave contains components not only from the human body but also from peripheral fixed objects such as walls and furniture, and in the prior art, there is a problem that these are also reproduced as phase components and an error occurs. ..
Although it is possible to detect the respiratory rate and heart rate by the conventional technology and it is useful, there has been a demand to provide a better service by analyzing the signal with higher accuracy.

"Development of non-contact monitoring system for respiration and heartbeat" Tokyo Metropolitan Industrial Technology Research Center Research Report, No. 9, 2014, p6 to p9

An object of the present invention is to detect a biological signal with high accuracy.

(1) In order to achieve the above object, in the invention according to claim 1, the present invention acquires a complex signal composed of an in-phase signal and an orthogonal signal of a reflected wave of a microwave transmitted to a living body. The complex signal acquisition means and the center position of the arc-shaped locus drawn by the acquired complex signal on the complex plane are specified, and the fixed component due to the reflection from the fixed object contained in the complex signal is estimated from the center position. An estimation means, a correction means for correcting the acquired complex signal by removing the estimated fixed component from the acquired complex signal, and a biological signal acquisition for acquiring the biological signal of the living body from the corrected complex signal. Provided is a biological signal processing device including means and an output means for outputting the acquired biological signal.
(2) In the invention according to claim 2, the correction means sets the position of the origin of the complex plane with respect to the specified center position as an offset amount, and offsets the complex signal by the offset amount in the complex plane. The biometric signal processing apparatus according to claim 1, wherein the acquired complex signal is corrected by the above method.
(3) The invention according to claim 3, wherein the biological signal acquisition means acquires a signal corresponding to the pulse wave of the biological signal from the amplitude or phase of the complex signal in the time region. 1 or the biological signal processing apparatus according to claim 2.
(4) The invention according to claim 4, wherein the biological signal acquisition means acquires a signal corresponding to the pulse wave by differentiating the moving average of the waveform of the amplitude. The described biosignal processing apparatus is provided.
(5) The invention according to claim 5, wherein the complex signal acquisition means acquires the complex signal from a reflected wave propagating in a plurality of paths, among claims 1 to 4. The biological signal processing apparatus according to any one of the above is provided.
(6) In the invention according to claim 6, the complex signal acquisition function for acquiring a complex signal composed of an in-phase signal and an orthogonal signal of a reflected wave of a microwave transmitted to a living body and the acquired complex signal are From the estimation function that identifies the center position of the arc-shaped locus drawn on the complex plane and estimates the fixed component due to the reflection from the fixed object contained in the complex signal from the center position, and the acquired complex signal, the above A correction function for correcting the acquired complex signal by removing the estimated fixed component, a biological signal acquisition function for acquiring the biological signal of the living body from the corrected complex signal, and an output for outputting the acquired biological signal. It provides a biological signal processing program that realizes functions and on a computer.

According to the present invention, a biological signal can be detected with high accuracy by removing a fixed component from the reflected wave.

It is a figure for demonstrating the structure of the measuring apparatus. It is a figure for demonstrating the method of finding the virtual origin O'. It is a figure for demonstrating the correction of a channel. It is a figure for demonstrating the phase waveform by the signal before correction. It is a figure for demonstrating the phase waveform by the corrected signal. It is a figure for demonstrating the amplitude waveform by the signal before correction. It is a figure for demonstrating the amplitude waveform by a corrected signal. It is a figure for demonstrating the relationship between a pulse wave and an amplitude waveform. It is a figure for demonstrating the hardware-like configuration of a signal processing apparatus. It is a flowchart for demonstrating the procedure of signal processing.

(1) Outline of the Embodiment As shown in FIG. 1, the reflection response of the microwave irradiated to the living body has an amplitude component and a phase component, and ideally, the reflection component hv (t) from the living body is analyzed. do it.
However, the reflection response component h (t) includes a reflection component hv (t) from a living body and a reflection component hf (t) from a wall or furniture other than the living body. As a result, the origin for analysis deviates from the origin O, which becomes a signal error and affects the detection accuracy.
Therefore, the signal processing device 4 analyzes the obtained signal to obtain a virtual origin O'which is a reference for analyzing hv (t), and obtains a phase and amplitude component from the virtual origin O'to obtain a conventional filter. It is possible to obtain a signal that matches the phenomenon more than the method using.

More specifically, in order to obtain the phase and amplitude from the virtual origin O', the signal processing device 4 sets the difference between the origin O and the virtual origin O'as an offset amount, and offsets h (t) by this.
As a result, since the virtual origin O'matches the origin O, the phase and amplitude components from the virtual origin O'can be analyzed using the phase and amplitude components with respect to the origin O.

(2) Details of the Embodiment FIG. 1 is a diagram for explaining a configuration of a measuring device 1 for measuring a biological signal (vital sign, vital signal). In this embodiment, respiration and pulse waves are measured as biological signals.
The measuring device 1 is composed of a microwave circuit 2, a control device 3, a signal processing device 4, and the like.
Further, the microwave circuit 2 is composed of a transmitter 21, a distribution phase shift unit 24, mixers (mixers) 26 and 27, a transmitting antenna 23, a receiving antenna 25, and the like.
Further, although not shown, a chair for seating the subject 7 of the biological signal measurement is installed in the direction of microwave irradiation by the microwave circuit 2.

In the present embodiment, since the measuring device 1 is used in the laboratory, the subject 7 is seated on a chair. This is an example, and for example, it is mounted on a vehicle to detect the biological signal of the driver. It can be widely used in various usage scenarios, such as detecting the biological signals of these users in hospitals and nursing care facilities, or installing them on a washbasin at home to detect the biological signals of the washers. it can.

The control device 3 is a control device that controls the drive of the transmitter 21.
The control device 3 supplies electric power to the transmitter 21 and drives the transmitter 21 to generate microwaves.
The transmitter 21 includes a device for oscillating microwaves, and generates and transmits microwaves having a predetermined frequency (in the present embodiment, microwaves of 5.018 [GHz] are used).
The microwave transmitted by the transmitter 21 is transmitted to the transmitting antenna 23 via the transmission path, and a part of the microwave is distributed and transmitted to the distribution phase shift unit 24 as a reference wave.

The distribution phase shift unit 24 has a distribution function and a phase shift function (for example, it is configured by combining a distributor and a phase shifter), distributes a reference wave into two waves, and one of them is a reference wave. Is input to the mixer 26 in the same phase as, and the other is phase-shifted by a phase amount of 90 ° and input to the mixer 27.
In this way, the distribution phase shift unit 24 generates a reference wave having the same phase as the microwave output by the transmitting antenna 23 and a reference wave having a phase orthogonal to the reference wave, and inputs the reference wave to the mixer 26 and the mixer 27, respectively. ..

The transmitting antenna 23 is composed of a 16-element patch array antenna, and irradiates the subject 7 with the microwave generated by the transmitter 21.
The receiving antenna 25 is composed of an 8-element patch array antenna, receives the reflected microwave wave transmitted by the transmitting antenna 23, distributes the reflected wave, and transmits the reflected wave to the mixers 26 and 27.

In the experiment, the transmitting antenna 23 was installed at a height of 0.719 m, and the receiving antenna 25 was installed at a height of 0.975 m.
Further, the distance from these patch array antennas to the subject 7 was set to 0.3 m, and the distance between the elements of the patch array antenna was set to 0.5 wavelength of the microwave transmitted by the transmitter 21.
As described above, the measuring device 1 employs MIMO (Multiple Input Multiple Output) that transmits and receives with a plurality of antennas, and the figure shows one set of these.

In addition to being able to sharpen the directivity of microwaves with MIMO, the direction of microwaves can be fine-tuned to make microscopic areas where pulse waves can be detected well (according to the inventor's experiment, around the heart of subject 7). Can irradiate waves.
Even if the subject 7 is dressed or is wearing a futon at a hospital or a nursing care facility, the microwave is transmitted through them. Therefore, the subject 7 is irradiated with the microwave from the transmitting antenna 23, and the subject is subjected to the microwave. The reflected wave reflected on the body surface of No. 7 can be received by the receiving antenna 25.

Since the body surface near the chest of the subject 7 moves back and forth by respiration as shown by the arrow line 60 with respect to the measuring device 1, the reflected wave of the microwave is Doppler-shifted by this.
In addition, the body surface of the subject 7 repeatedly expands and contracts due to the pulse, which also causes a Doppler shift.
As described above, the reflected wave received by the receiving antenna 25 includes information on respiration and pulse wave.

The mixer 26 mixes the reflected wave received by the receiving antenna 25 with the in-phase reference wave by the transmitter 21, thereby generating a beat (beat, mixed wave) and outputting it to the signal processing device 4.
The mixer 27 mixes the reflected wave received by the receiving antenna 25 with the reference wave whose phase has been shifted by 90 °, thereby generating a beat and outputting it to the signal processing device 4.

The signal processing device 4 is a device that functions as a biological signal processing device. The signal processing device 4 includes a detection device that detects the mixed waves output by the mixer 26 and the mixer 27, respectively, and has an I signal of the in-phase component output by the mixer 26 and an orthogonal component output by the mixer 27. A complex number signal (complex signal) h (t) = I (t) + jQ (t) represented by the equation 22 is generated from the Q signal. Here, j is an imaginary unit and t represents time.

As described above, the signal processing device 4 includes a complex signal acquisition means for acquiring a complex signal composed of an in-phase signal (I signal) and an orthogonal signal (Q signal) of the reflected wave of the microwave transmitted to the living body. ing.
As a result, the measuring device 1 can suppress a decrease in sensitivity due to the null detection position, and the subject 7 can use the measuring device 1 without worrying about the positional relationship with the measuring device 1.

In addition to the component hv (t) due to the reflection from the subject 7, the component hf (t) due to the reflection from the object 50 fixed to the environment such as furniture or a wall is superimposed on h (t).
Originally, we want to extract a biological signal from hv (t), but since hf (t) is superimposed on h (t), when performing precise measurement using hv (t), this is removed by some method. There is a need to.
Therefore, the signal processing device 4 estimates hf (t) as follows, corrects it by removing it from h (t), and reproduces hv (t) from h (t).

As shown in FIG. 1 (b), h (t) is the sum of hf (t) due to reflection from the object 50 and hv (t) due to reflection from the subject 7 when expressed on the complex plane. It has become a thing.
In this complex plane, the horizontal axis, which is the real axis, is the axis of the same phase (in-phase component) as the carrier wave (also called the I axis), and the vertical axis, which is the imaginary axis, is the phase (orthogonal phase component) orthogonal to the carrier wave. It is an axis (also called a Q axis).

Since hf (t) is due to the object 50 fixed to the environment, it is fixed and has fixed components (DC component, DC component).
On the other hand, hv (t) changes periodically by the respiration of the subject 7, and is on the arc 61 centered on the virtual origin O'(this point is estimated and is called virtual as described later). Is synchronized with the respiration of the subject 7 to perform a periodic movement back and forth between the clockwise direction and the counterclockwise direction.

Since hf (t) plus hv (t) is observed as h (t) on the complex plane, the locus of h (t) has the center of the periodic motion of hf (t) as the virtual origin O'. It will be shifted to.
As described above, since h (t) does not vibrate around the origin O, the waveform of the biological signal is distorted and detected.

Therefore, in the present embodiment, paying attention to the property that hv (t), which is a reflected wave from the subject 7, draws an arc, the center of the periodic motion of hv (t) is determined from the position and shape of the arc 61. It is specified by estimating the position of the virtual origin O', which is a point. As a result, hf (t) from the origin O to the virtual origin O'can be estimated.
In this way, the signal processing device 4 specifies the center position of the arcuate locus drawn by the complex signal on the complex plane, and estimates the fixed component due to the reflection from the fixed object contained in the complex signal from the center position. It has an estimation means to do.

Then, as shown in FIG. 1 (c), the signal processing device 4 offsets h (t) so that the virtual origin O'consists with the origin O, thereby shifting h (t) from h (t) to hf (t). Make a correction to remove.
As described above, the signal processing device 4 includes a correction means for correcting the complex signal by removing the estimated fixed component from the complex signal.
Then, the correction means corrects the complex signal by using the position of the origin of the complex plane with respect to the specified center position as an offset amount and offsetting the complex signal by the offset amount in the complex plane.

As a result, hv (t) (corrected h (t)) draws an arc 62 centered on the origin O, so that the phase and amplitude can be measured with reference to the origin O, and a more precise biological signal can be detected. be able to.
As will be described later, a pulse wave can be extracted as a biological signal from the amplitude, and the signal processing device 4 can output this to a display or the like.
As described above, the signal processing device 4 includes a biological signal acquisition means for acquiring a biological signal of a biological body from the corrected complex signal, and an output means for outputting the biological signal.

FIG. 2 is a diagram for explaining a method of obtaining the virtual origin O'.
FIG. 2 represents a complex plane, and the signal processing device 4 arranges a large number of search points 75, 75, ... As candidates for the virtual origin O'on the complex plane at predetermined intervals.
The signal 65 is a plot of the sampled points of h (t) on a complex plane, and is a sum (composite) of the I channel and the Q channel of h (t). Then, the locus of the point of the signal 65 has an arc shape as described above.
In this experiment, the sampling frequency was set to 200 Hz and the measurement was performed for 70 seconds.
A diagram in which signals are plotted on a complex plane with the horizontal axis in phase and the vertical axis in orthogonal phases is called a constellation.

At the search points 75, 75, ... Arranged in this way, the signal processing device 4 sets the distance r from all the points of the signal 65 (that is, the points obtained by sampling h (t)) to each search point 75. calculate. Then, the search point 75 that minimizes the variance of r is set to the virtual origin O'.
Since the distances from the respective points of the signal 65 are approximately the same, the search point 75 having the minimum variance is the most suitable point as the center point of the arc.

FIG. 3 is a diagram for explaining channel correction.
FIG. 3A shows the signal 66 due to h (t) before correction, and the virtual origin O'is located at a position away from the origin O in the complex plane. It is presumed that this offset component is due to hf (t).
As shown in the figure, this figure is based on the path of the second transmitting antenna 23 and the first receiving antenna 25 of the patch array antenna 90.

As shown in FIG. 3B, the signal processing device 4 calculates the signal 67 by offsetting (moving) the signal 66 by the difference between the virtual origin O'and the origin O.
By this correction, the virtual origin O'of the arc formed by the signal 67 becomes the origin O, and this becomes the component of hv (t) obtained by removing hf (t) from h (t).
The signal processing device 4 calculates the signal 67 by hv (t) by performing the correction for offsetting each point of the signal 66 by h (t) as described above.
That is, the signal processing device 4 converts the uncorrected propagation channel represented by the signal 66 into the corrected propagation channel represented by the signal 67.

Since the biological signal appears as the phase and amplitude of h (t), how these are improved before and after the correction will be described.
FIG. 4 is a diagram for explaining a phase waveform due to the signal (h (t)) before correction.
As shown in FIG. 4A, the arc indicated by the signal 66 of h (t) is not centered on the origin O, but is centered on the virtual origin O'away from the origin O.
The phase around the origin O is measured in the angular direction around the origin O indicated by the arrow line in the figure, but since the center of the arc of the signal 66 deviates from the origin O by a fixed component, the origin of the signal 66 When the time change of the phase with respect to O is graphed, as shown in FIG. 4B, the sine curve is not a beautiful one, but the apex of the sine curve is flattened and distorted.

In addition, this graph shows 10 seconds from 25 seconds to 35 seconds after the start of measurement. The same applies hereinafter.
As described above, since the signal 66 before correction is distorted by the amount of the fixed component, it is not suitable for detecting a precise biological signal.

FIG. 5 is a diagram for explaining a phase waveform based on the corrected signal (hv (t)).
As shown in FIG. 5A, the signal 67 by hv (t) is reproduced on the complex plane by removing the fixed component by the offset and correcting the signal 66.
Since the origin O and the virtual origin O'are the same, the arc indicated by the signal 67 is an arc centered on the origin O.
As a result, the time change of the phase around the origin O becomes a beautiful sine curve as shown in FIG. 5 (b).
Since the corrected signal is distorted and has a normal waveform, a biological signal (for example, respiration) can be suitably extracted from the signal.

FIG. 6 is a diagram for explaining an amplitude waveform due to the signal (h (t)) before correction.
As shown in FIG. 6A, the arc indicated by the signal 66 of h (t) is not centered on the origin O, but is centered on the virtual origin O'away from the origin O.
Therefore, when the amplitude is measured by the distance from the origin O to each point of the signal 66 as shown by the arrow line, the time change is predominantly affected by respiration as shown in the graph of FIG. 6 (b). Although it appears, it becomes a distorted sine curve.

FIG. 7 is a diagram for explaining an amplitude waveform due to the corrected signal (hv (t)).
As shown in FIG. 7A, since the origin O and the virtual origin O'are coincident with each other, the amplitude direction with respect to the origin O faces the center direction of the arc indicated by the signal 67.
From this, when the time change of the amplitude of the signal 67 is graphed, as shown in FIG. 7B, the fine structure hidden by the distortion in the signal 66 before the correction appears as the amplitude change.
As shown in the figure, components that are considered to be pulse waves were confirmed in the regions 83, 83, ... Enclosed by the broken line.

FIG. 8 is a diagram for explaining the relationship between the pulse wave and the amplitude waveform.
The inventor of the present application attached a blood pressure sensor to the finger of the subject 7, thereby measuring the pulse wave and at the same time measuring h (t) with respect to the body surface of the subject 7 by the microwave.
FIG. 8A is a pulse wave of the subject 7 from 45 seconds to 55 seconds after the start of the experiment detected by the blood pressure sensor.
In the figure, the pulse wave is shown by a broken line. As shown in the figure, a clean waveform was measured. A small peak after the pulse peak is a common waveform in the elastic blood vessels of young people.

FIG. 8B shows a waveform obtained by averaging the amplitude waveform of the signal 67 by a moving average and then differentiating it with respect to time.
As can be seen from the figure, a peak appears near the peak of the pulse wave.
FIG. 8C shows the pulse wave and the amplitude moving average differential waveform superimposed.
As is clear from the figure, the peak of the pulse wave and the peak of the amplitude moving average differential waveform coincide with each other. Therefore, it is considered that a pulse wave appears at the signal 67.
According to the experiment of the inventor of the present application, it was found that the pulse wave (heartbeat) component is strengthened by adding the corrected amplitude waveforms in all the paths.

By correcting the signal 66 by moving the origin in this way, the pulse wave buried in the distortion could be extracted from the complex signal.
In the present embodiment, the pulse wave is detected from the amplitude waveform because the pulse wave appears remarkably in the amplitude waveform, and the phase waveform also contains the component due to the pulse wave.

As described above, the biological signal acquisition means included in the signal processing device 4 acquires the signal corresponding to the pulse wave of the biological body from the amplitude or phase of the complex signal in the time domain.
Then, the biological signal acquisition means acquires the signal corresponding to the pulse wave by differentiating the moving average of the amplitude waveform.
Further, the complex signal acquisition means can strengthen the component of the pulse wave by acquiring the complex signal from the reflected wave propagating in the plurality of paths.

FIG. 9 is a diagram for explaining a hardware configuration of the signal processing device 4.

The signal processing device 4 is configured by using a CPU (Central Processing Unit) 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, a detection device 44, an input device 45, an output device 46, a storage device 47, and the like. Has been done.

The CPU 41 corrects h (t) according to a signal processing program stored in the ROM 42 or the storage device 47, extracts a biological signal from the corrected h (t) (that is, hv (t)), and the like.
The ROM 42 is a read-only memory that stores basic programs, parameters, and the like that operate the signal processing device 4.

The RAM 43 is a readable and writable memory, and provides a working memory when the CPU 41 operates according to a signal processing program.
More specifically, generation of h (t) from I signal and Q signal, calculation of virtual origin O'from search point 75, correction to signal 67 by offset of signal 66 before correction, phase from signal 67. It provides a memory for calculation when generating waveforms and amplitude waveforms.

The detection device 44 detects the mixed wave output by the mixers 26 and 27 and outputs an I signal and a Q signal.
The input device 45 includes, for example, an input device such as a touch panel, a keyboard, and a mouse, and receives an operation from a user of the signal processing device 4.
The output device 46 includes output devices such as a display, a speaker, and a printer, displays the operation screen of the signal processing device 4 on the display, and outputs the analyzed biological signal to these output devices.

The storage device 47 includes, for example, a large-capacity medium such as a semiconductor storage device or a hard disk, and a signal processing program for extracting a biological signal such as a pulse wave from the I signal and the Q signal detected by the detection device 44. , Other programs, and data of past measurement values are stored.

FIG. 10 is a flowchart for explaining a procedure of signal processing performed by the signal processing device 4.
The following processing is performed by the CPU 41 according to the signal processing program.
First, the CPU 41 acquires the data necessary for the analysis (step 5).
The CPU 41 performs this process by storing the I signal and the Q signal detected by the detection device 44 in the RAM 43.

Next, the CPU 41 performs an origin correction operation (step 10).
The CPU 41 generates h (t) and stores the point sequence of the signal 66 in the RAM 43, calculates the variance of the distance r with respect to each search point 75 for all the points of the signal 66, and stores it in the RAM 43. Do it by doing.

Next, the CPU 41 acquires the virtual origin O'(step 15).
The CPU 41 performs this process by setting the search point 75, which has the smallest variance stored in the RAM 43, at the virtual origin O'and storing it in the RAM 43.

Next, the CPU 41 corrects the origin (step 20).
The CPU 41 estimates hf (t), which is a fixed component, from the displacement of the virtual origin O'with respect to the origin O, and offsets each point of the signal 66 by −hf (t) to obtain the corrected signal 67. This is done by calculating and storing in the RAM 43.

Next, the CPU 41 detects the pulse wave (step 25).
The CPU 41 performs this processing by calculating an amplitude waveform from the signal 67 stored in the RAM 43, moving averaging the amplitude waveform, further differentiating the waveform, and storing the peak time and amplitude in the RAM 43.

Next, the CPU 41 outputs information about the pulse wave by displaying it on the display of the output device 46, for example, 70 times per minute (step 30).
This is the end of the signal processing performed by the signal processing device 4, but since the virtual origin O'changes depending on the surrounding environment, the CPU 41 repeats the above processing at predetermined time intervals to update the virtual origin O'. And the pulse wave will be updated.

In the embodiment described above, by moving the virtual origin O'to the origin O, the phase / amplitude measurement with reference to the virtual origin O'was performed by measuring the phase / amplitude with reference to the origin O. This is just an example, and since the position of the virtual origin O'on the complex plane can be known, the phase / amplitude of hv (t) may be measured directly with reference to the virtual origin O'.

According to the embodiment described above, the following effects can be obtained.
(1) The origin of the biological signal component included in the complex channel can be estimated by utilizing the fact that the biological signal draws an arc on the complex plane.
(2) The phase and amplitude can be measured from the biological signal with reference to the origin of the estimated biological signal component.
(3) By removing the fixed component due to the fixed reflected wave other than the fluctuating part from the reflected wave of the living body, the correct waveform can be restored by removing the distortion of the phase and amplitude caused by the deviation of the origin.
(4) It is possible to measure a waveform containing information equivalent to pulse wave measurement in a non-invasive and non-contact manner.
(5) The amplitude of the reflected wave was dominated by what was considered to be a respiratory component before the correction, but after the correction, the pulse wave became prominent, and a waveform with a larger amount of information than the conventional method can be obtained.

1 Measuring device 2 Microwave circuit 3 Control device 4 Signal processing device 7 Target person 21 Transmitter 22 type 23 Transmitting antenna 24 Distribution phase shift part 25 Receiving antenna 26, 27 Mixer 41 CPU
42 ROM
43 RAM
44 Detection device 45 Input device 46 Output device 47 Storage device 60 Arrow line 61, 62 Arc 65, 66, 67 Signal 75 Search point 83 Area 90 Patch array antenna

Claims (6)

A complex signal acquisition means for acquiring a complex signal consisting of an in-phase signal and an orthogonal signal of a reflected microwave wave transmitted to a living body, and
An estimation means for identifying the center position of an arcuate locus drawn by the acquired complex signal on the complex plane and estimating a fixed component due to reflection from a fixed object contained in the complex signal based on the center position.
A correction means for correcting the acquired complex signal by removing the estimated fixed component from the acquired complex signal, and
A biological signal acquisition means for acquiring the biological signal of the living body from the corrected complex signal, and
An output means for outputting the acquired biological signal and
A biological signal processing device characterized by being provided with. The correction means corrects the acquired complex signal by setting the position of the origin of the complex plane with respect to the specified center position as an offset amount and offsetting the complex signal by the offset amount in the complex plane. The biometric signal processing apparatus according to claim 1. The biological signal processing according to claim 1 or 2, wherein the biological signal acquisition means acquires a signal corresponding to the pulse wave of the biological signal from the amplitude or phase of the complex signal in the time domain. apparatus. The biological signal processing device according to claim 3, wherein the biological signal acquisition means acquires a signal corresponding to the pulse wave by differentiating the moving average of the waveform of the amplitude. The biological signal according to any one of claims 1 to 4, wherein the complex signal acquisition means acquires the complex signal from a reflected wave propagating in a plurality of paths. Processing equipment. A complex signal acquisition function that acquires a complex signal consisting of in-phase signals and orthogonal signals of microwave reflected waves transmitted to a living body, and
An estimation function that identifies the center position of the arcuate locus drawn by the acquired complex signal on the complex plane and estimates the fixed component due to reflection from the fixed object contained in the complex signal based on the center position.
A correction function for correcting the acquired complex signal by removing the estimated fixed component from the acquired complex signal, and
A biological signal acquisition function that acquires the biological signal of the living body from the corrected complex signal, and
The output function that outputs the acquired biological signal and
A biological signal processing program that realizes the above with a computer.

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