Biological information detection system, biological information detection method, and program

Abstract

To provide a biological information detection system that can acquire biological information on a person to be measured from Doppler data with a high degree of precision.SOLUTION: A biological information detection system includes: a biological information acquisition unit 300 for acquiring biological information on a person to be measured by applying data processing including parameters to Doppler data; a reliability determination unit 320 for calculating reliability of the biological information acquired by the biological information acquisition unit 300; and a parameter changing unit 310 for changing the parameters on the basis of the reliability.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a biological information detection system, a biological information detection method, and a program, and particularly to the detection of biological information using a microwave Doppler sensor.

Background Art

[0002] Various monitoring systems for measuring the biological information of a subject are being studied. In a conventional system that measures the electrocardiogram by bringing electrodes into contact with the subject, since the burden on the subject is large, a system that measures biological information non-contact using a microwave Doppler sensor is regarded as promising (see Patent Document 1). According to the microwave Doppler sensor, biological information such as the respiration rate and heart rate can be obtained by measuring the movement of the subject's body surface or inside the body.

[0003] The microwave Doppler sensor outputs Doppler data indicating the movement of the subject's body surface or inside the body. An arithmetic means such as a computer can obtain biological information such as the respiration rate and heart rate by applying various data processes to this Doppler data. However, since the actual Doppler data includes various movement components such as respiration, heartbeat, body movement such as turning over, and shaking of the bed, frequency filters and other filters for removing noise components are generally included in the above data processing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the case of a frequency filter, it is necessary to preset the passband. However, if this setting is fixed, it may not be appropriate for some subjects being measured. In this case, the accuracy of the biological information obtained by data processing will deteriorate. Similarly, there are several setting items in other data processing for obtaining biological information from Doppler data, and if these are fixed, the accuracy of the biological information will deteriorate depending on the subject being measured.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a biological information detection system, a biological information detection method, and a program capable of accurately obtaining biological information of a subject from Doppler data.

Means for Solving the Problems

[0007] (1) In order to solve the above problems, a biological information detection system according to the present invention includes: a biological information acquisition means for acquiring biological information of a subject by applying data processing including parameters to Doppler data; a reliability calculation means for calculating the reliability of the biological information acquired by the biological information acquisition means; and a parameter change means for changing the parameters based on the reliability.

[0008] (2) In the biological information detection system according to the above (1), the data processing including the parameters may include a band-limiting filter. The parameters may relate to the passband of the band filter.

[0009] (3) In the biological information detection system according to the above (1) or (2), the biological information acquisition means may calculate a frequency spectrum based on the Doppler data and calculate biological information based on the maximum peak of the frequency spectrum. The reliability calculation means may calculate the intensity ratio between the maximum peak of the frequency spectrum and the next largest peak of the frequency spectrum as the reliability.

[0010] (4) In the biological information detection system according to any one of (1) to (3) above, the reliability calculation means may calculate the reliability based on the number of times the biological information satisfying a predetermined condition is continuously calculated.

[0011] (5) In the biological information detection system according to any one of (1) to (4) above, the parameter change means may calculate the biological information and the reliability using a plurality of parameters. Further, one of the plurality of parameters may be selected based on the reliability calculated in this way.

[0012] (6) The biological information detection method according to the present invention includes a biological information acquisition step of acquiring biological information of a subject to be measured by applying data processing including parameters to Doppler data, a reliability calculation step of calculating the reliability of the biological information acquired by the biological information acquisition means, and a parameter change step of changing the parameters based on the reliability.

[0013] (7) The program according to the present invention is a program for causing a computer to function as a biological information acquisition means for acquiring biological information of a subject to be measured by applying data processing including parameters to Doppler data, a reliability calculation means for calculating the reliability of the biological information acquired by the biological information acquisition means, and a parameter change means for changing the parameters based on the reliability. This program may be stored in a computer-readable information storage medium such as a semiconductor memory or a magneto-optical disk.

Advantages of the Invention

[0014] According to the present invention, it becomes possible to accurately acquire the biological information of the subject to be measured from Doppler data.

Brief Description of the Drawings

[0015]

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Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0017] FIG. 1 is a configuration diagram of a biological information detection system according to an embodiment of the present invention. As shown in the figure, the biological information detection system 1 includes a Doppler sensor 2 and a signal processing device 3. The biological information detection system 1 is set, for example, in a house and detects the biological information of a subject, for example, during sleep. In this embodiment, as an example, the heart rate of the subject is detected.

[0018] The Doppler sensor 2 is provided, for example, near the bed and directed toward the chest of the subject to be measured. Microwaves are emitted from the Doppler sensor 2, and the reflected wave near the subject's heart is received by the Doppler sensor 2. Due to the Doppler effect, the reflected wave has a frequency shift, and by observing this, the heart rate of the subject to be measured can be obtained. From the reflected wave, a Doppler signal including an I signal that is the in-phase component with the transmitted wave and a Q signal that is the quadrature component is detected by quadrature detection, and is output to the signal processing device 3 as Doppler data including digital-form I and Q components. The Doppler data input to the signal processing device 3 is time-series data, indicating the amplitudes of the I and Q components at each time.

[0019] The signal processing device 3 may be configured by a known computer including, for example, a CPU, a memory, an input device, and a display, and generates the heart rate of the subject to be measured based on the Doppler signal output from the Doppler sensor 2.

[0020] FIG. 2 is a functional block diagram of the signal processing device 3 according to an embodiment of the present invention. As shown in the figure, the signal processing device 3 includes a biological information acquisition unit 300, a parameter change unit 310, and a reliability calculation unit 320. The biological information acquisition unit 300 acquires the heart rate by performing various data processes on the Doppler data. Since the acquired heart rate is an estimated value, the reliability calculation unit 320 calculates the reliability of this estimated value. The various data processes executed by the biological information acquisition unit 300 include adjustment factors by parameters as described later. Therefore, the parameter change unit 310 changes those parameters based on the reliability calculated by the reliability calculation unit 320. Specifically, the parameters are changed so that the reliability increases. Thereby, an estimated value of the heart rate with higher reliability, that is, higher accuracy (more reliable), is obtained.

[0021] The biological information acquisition unit 300 includes a heartbeat data extraction unit 30, a filter unit 31, an FFT unit 32, a peak identification unit 33, a peak tracking unit 34, a peak memory unit 35, a temporary heart rate calculation unit 36, a temporary heart rate memory unit 37, and a heart rate determination value calculation unit 39. The reliability calculation unit 320 includes an amplitude ratio calculation unit 320a. The parameter change unit 310 includes a heart rate data storage unit 310a and a heart rate and reliability recalculation unit 310b.

[0022] These functional blocks are realized by executing a signal processing program in the signal processing device 3 which is a computer. This signal processing program may be stored in various computer-readable information storage media such as a semiconductor memory, and loaded from the medium to the signal processing device 3. Alternatively, it may be downloaded to the signal processing device 3 via a data communication line such as the Internet.

[0023] The heartbeat data extraction unit 30 applies a time window to the Doppler data and extracts the data portion (heartbeat data) of the time window. FIG. 3 is a diagram for explaining the processing of the heartbeat data extraction unit 30. As shown in the figure, a predetermined number of time windows (here, time windows W(1) to W(30)) are applied to the data of the I component and the Q component per a predetermined time (here, for example, 1 minute), and a predetermined number (here, for example, 30) of heartbeat data are extracted. The width of the time window is constant. The start timing of each time window is shifted by a predetermined time (here, for example, 2 seconds).

[0024] As will be described later, a temporary heart rate HR(i) is generated from the time window W(i) (i = 1 to 30). Also, based on the temporary heart rates HR(1) to HR(30), a heart rate determination value HR is generated. That is, the heart rate determination value HR is generated here every minute.

[0025] The heartbeat data (data of I component and Q component) of each time window W(i) is sequentially input to the filter unit 31, and noise is removed. Here, the filter unit 31 includes a first filter unit 31a and a second filter unit 31b. The first filter unit 31a may be constituted by, for example, various band-pass filters, and extracts the frequency components corresponding to the heartbeat included in the heartbeat data. The first filter unit 31a has a pass frequency band that can be changed, and a pass band parameter for specifying the upper and lower limits of the pass frequency band is supplied by the parameter change unit 310. That is, the first filter unit 31a outputs the frequency components of the band specified by the pass band parameter supplied from the parameter change unit 310 among the input heartbeat data.

[0026] The second filter unit 31b further removes the large trend derived from noise such as respiration from the output of the first filter unit 31a. For example, as shown in FIG. 4, the second filter unit 31b includes a first moving average calculation unit 312, a second moving average calculation unit 313, and a difference calculation unit 314. The first moving average calculation unit 312 calculates a moving average for a relatively short time in order to make the signal component derived from the heartbeat easier to understand. The length of the period for which the first moving average calculation unit 312 calculates the moving average is specified by the first period length parameter. This first period length parameter is also supplied by the parameter change unit 310.

[0027] Also, the second moving average calculation unit 313 calculates a moving average for a relatively long time in order to capture the signal component derived from respiration or the like. The length of the period for which the second moving average calculation unit 313 calculates the moving average is specified by the second period length parameter. This second period length parameter is also supplied by the parameter change unit 310. Then, the difference calculation unit 314 subtracts the output of the second moving average calculation unit 313 from the output of the first moving average calculation unit 312. Thereby, the large trend derived from respiration or the like can be removed.

[0028] The heartbeat data that has been noise-removed as described above is input to the FFT unit 32. The FFT unit 32 converts each heartbeat data into a frequency spectrum. Fig. 5 is a diagram showing the output of the FFT unit 32. Fig. (a) of the same figure shows the frequency spectrum at time t, and Fig. (b) shows the frequency spectrum at time t + 1. As shown in these figures, the frequency spectrum output from the FFT unit 32 generally includes various peaks of different magnitudes.

[0029] The peak identification unit 33 identifies the peaks included in the frequency spectrum of each time window. Among the peaks identified by the peak identification unit 33, the information of the peaks that satisfy a predetermined condition is stored in the peak storage unit 35 by the peak tracking unit 34. The data stored here includes the frequency and amplitude of each peak. Note that, as will be described later, in order to evaluate the reliability of the peak, the peak identification unit 33 selects the second largest peak in amplitude in each time window and stores the amplitude value of that peak in the peak storage unit 35.

[0030] The peak tracking unit 34 determines whether the peaks included in the frequency spectrum of each time window include the peak immediately stored in the peak storage unit 35, that is, the peak corresponding to the peak extracted from the frequency spectrum related to the previous time window (corresponding peak). For example, if a peak within a predetermined width Δf (e.g., ±0.1 Hz) before and after the frequency of the peak immediately stored is included, that peak is determined as the "corresponding peak". Then, the data of such a corresponding peak is stored in the peak storage unit 35. In the example of Fig. 5, at time t, peaks A_t, B_t, and C_t exist in descending order of amplitude (a). And at time t + 1, there also exist peaks A_t+1 corresponding to peak A_t, peaks B_t+1 corresponding to peak B_t, and peaks C_t+1 corresponding to peak C_t (b). That is, the frequency differences between peak A_t and peak A_t+1, between peak B_t and peak B_t+1, and between peak C_t and peak C_t+1 are all less than or equal to Δf. Note that this Δf may also be made changeable from the parameter change unit 310 as a variable parameter.

[0031] FIG. 6 shows an example of the stored content of the peak memory unit 35. As shown in this figure, in time window No. 1, data with peak IDs = 001 to 003 are stored in the peak memory unit 35. That is, at the start of the operation of the peak identification unit 33, from the frequency spectrum related to time window No. 1, data of a predetermined number (here, three) of peaks in descending order of amplitude are stored in the peak memory unit 35. In this figure, the presence of these three peaks is indicated by "〇".

[0032] From the frequency spectrum related to time window No. 2, peaks corresponding to peak IDs = 001 to 003 are identified, and data (frequency and amplitude) of those peaks are stored in the peak memory unit 35. Also, from the frequency spectrum related to time window No. 2, a peak (additional peak) having the maximum amplitude among the peaks for which peak IDs have not yet been assigned is selected, and for this additional peak as well, the frequency and amplitude are stored in the peak memory unit 35. A unique peak ID = 004 is assigned to this additional peak. In the example of FIG. 5, peak D_t+1 corresponds to the additional peak.

[0033] From the frequency spectrum related to time window No. 3, corresponding peaks are extracted for peak IDs = 001, 003, and 004, but there is no corresponding peak for peak ID = 002. The fact that there is no corresponding peak for peak ID = 002 is indicated by "×" in this figure. An additional peak is also selected from the frequency spectrum related to time window No. 3, and for this additional peak, the frequency and amplitude are stored in the peak memory unit 35. A peak ID = 005 is assigned to this additional peak.

[0034] From the frequency spectrum related to time window No. 4, corresponding peaks are extracted for peak IDs = 001, 003 to 005, and a peak with peak ID = 006 is added.

[0035] From the frequency spectrum related to time window No. 5, corresponding peaks are extracted for peak IDs = 001, 003, 004, and 006, and a peak with peak ID = 007 is added. At this time, for peak IDs = 001 and 003, since corresponding peaks are extracted in five consecutive time windows, those peaks are regarded as "valid peaks". This is indicated by "●" in the figure. That is, in the peak memory unit 35, in association with each peak ID, it is memorized whether it is a "temporary peak" (indicated by "〇" in the figure) before being promoted to a "valid peak", whether it is a "disappeared peak" (indicated by "×" in the figure) where the corresponding peak no longer exists and has already disappeared, or whether it is a "valid peak". Here, if a corresponding peak exists in five consecutive time windows, the peak is regarded as a "valid peak", but it may be set as a "valid peak" when a corresponding peak exists in any number of consecutive time windows of three or more.

[0036] Figure 7 is a flowchart showing the processing of the peak tracking unit 34. The processing shown in the figure is executed for the frequency spectrum of each time window. The peak tracking unit 34 first selects one from the temporary peaks and valid peaks stored in the peak memory unit 35 (S101). Next, it determines whether there is a corresponding peak of the peak selected in S101 among the peaks included in the frequency spectrum of the latest time window (S102). If there is a corresponding peak, the data of the corresponding peak is stored in the peak memory unit 35 (S103). Also, if a corresponding peak exists in a predetermined number (for example, five) of consecutive time windows (S104), it memorizes that the peak is a "valid peak" in association with the peak ID of the peak. If it is determined in S102 that there is no corresponding peak, it memorizes that the peak is a "disappeared peak" in association with the peak ID of the peak selected in S101.

[0037] Then, the processes of S102 to S106 are repeated for all the temporary peaks and valid peaks stored in the peak memory unit 35 (S101 and S107). When the processes of S102 to S106 are executed for all the temporary peaks and valid peaks (S107), next, an additional peak is selected from the latest frequency spectrum, and the data of the additional peak is stored in the peak memory unit 35. At this time, a new peak ID is assigned to the additional peak, and the note "temporary peak" is associated with the peak ID.

[0038] When the data of the valid peak is stored in the peak memory unit 35 as described above, the heart rate of the subject is generated based on the data.

[0039] The temporary heart rate calculation unit 36 includes a temporary reliability determination unit 36a. The temporary reliability determination unit 36a calculates the temporary reliability for each valid peak in each time window stored in the peak memory unit 35. Here, the temporary reliability is the average value of the relative amplitudes in the immediately preceding predetermined number (for example, 5) of time windows. The relative amplitude is a value obtained by dividing the amplitude of the valid peak by the amplitude of the peak having the maximum amplitude in each time window. The temporary heart rate calculation unit 36 selects the valid peak with the highest temporary reliability, and obtains the heart rate (BPM) from the frequency of the peak. Then, this heart rate is stored in the temporary heart rate memory unit 37 as the temporary heart rate. Also, the amplitude of the selected valid peak is stored in the temporary heart rate memory unit 37. Further, the second largest amplitude in each time window is stored in the temporary heart rate memory unit 37 as the second amplitude.

[0040] FIG. 8 is a diagram schematically showing the stored content of the temporary heart rate memory unit 37. As shown in the figure, the temporary heart rate memory unit 37 stores the temporary heart rate HR(i), the amplitude A(i) of the valid peak corresponding to the temporary heart rate, the second amplitude A2(i), and a confirmation flag for each time window. The initial value of the confirmation flag is 0 (unconfirmed). The temporary heart rate memory unit 37 stores the temporary heart rates for a determination period of the heart rate (here, 1 minute). For example, when the time window is set to shift by 2 seconds each time and the determination period of the heart rate is 1 minute, 30 temporary heart rates are stored.

[0041] The reliability determination unit 320 determines the reliability of the provisional heart rate stored in the provisional heart rate storage unit 37 for each time window. Specifically, the reliability determination unit 320 includes an amplitude ratio calculation unit 320a. The amplitude ratio calculation unit 320a calculates the amplitude ratio (A(i) / A2(i)) by dividing the amplitude A(i) of the peak corresponding to the provisional heart rate for each time window by the second amplitude A2(i). If this amplitude ratio is greater than or equal to a predetermined threshold value greater than 1 (for example, 1.5), the reliability determination unit 320 changes the value of the confirmation flag to 1. As a result, the provisional heart rate is treated as a confirmed value. Since the provisional heart rate is treated as a confirmed value only when the amplitude ratio is greater than or equal to a predetermined threshold value greater than 1, 1) it is possible to avoid calculating the heart rate using a valid peak that is not the maximum amplitude, and 2) it is also possible to avoid calculating the heart rate using a valid peak with a small amplitude ratio to the second largest peak. Thereby, the reliability of the finally calculated heart rate can be improved. Note that the reliability determination unit 320 may impose additional conditions in order to change the confirmation flag to 1. For example, an additional condition that the amplitude of the valid peak exceeds a predetermined threshold value may be imposed. The reliability determination unit 320 obtains the average value of the amplitude ratios (A(i) / A2(i)) of the time windows for which the confirmation flag is 1, and supplies this as the first reliability to the parameter change unit 310. Also, the reliability determination unit 320 supplies the number of time windows for which the confirmation flag is 1 to the parameter change unit 310 as the second reliability.

[0042] The heart rate confirmed value calculation unit 39 selects only those provisional heart rates HR(i) stored in the provisional heart rate storage unit 37 for which the confirmation flag is 1, and calculates their average value. Then, this average value is output as the heart rate confirmed value. At this time, if the confirmation flag is not 1 for a predetermined number (for example, 15) or more of the provisional heart rates calculated within the determination period, the heart rate confirmed value may not be output. By doing so, it is possible to avoid outputting a heart rate with low reliability. The output heart rate confirmed value may be displayed by a display device (not shown). Also, when the heart rate confirmed value is not within the normal range, the measured person may be notified to that effect, or it may be transmitted to another computer via a communication network to that effect.

[0043] The parameter change unit 310 includes the heart rate data storage unit 310a and the heart rate and reliability recalculation unit 310b as described above. The heart rate data storage unit 310a stores the heart rate data acquired by the heart rate data extraction unit 30. At this time, the heart rate data storage unit stores not only the heart rate data of a predetermined number (here, 30) of time windows that are currently the processing target, but also the heart rate data of a predetermined number (here, 30) of time windows that were the processing target in the past.

[0044] The heart rate and reliability recalculation unit 310b passes the heart rate data stored in the heart rate data storage unit 310 to the biological information acquisition unit 300 to recalculate the heart rate. At this time, the reliability determination unit 320 calculates the reliability of the recalculated heart rate based on the stored contents of the peak storage unit 35 and the temporary heart rate storage unit 37 that are regenerated during the recalculation of the heart rate.

[0045] The parameter change unit 310 determines the band parameter to be supplied to the first filter unit 31a based on the reliability calculated by the heart rate and reliability recalculation unit 310b. Also, it determines the first period length parameter and the second period length parameter to be supplied to the second filter unit 31b.

[0046] FIG. 9 is a flowchart showing the processing of the parameter change unit 310. The processing shown in the figure may be executed each time the biological information acquisition unit 300 outputs a heart rate determination value and the reliability determination unit 320 outputs a first reliability and a second reliability. As shown in the figure, the parameter change unit 310 first acquires the first reliability (amplitude ratio) and the second reliability (number of certainty flags with a value of 1) output from the reliability determination unit 320 (S201). Next, it determines whether it is necessary to change the parameters of the filter unit 31 based on the first reliability and the second reliability (S202). For example, if the first reliability is less than a predetermined threshold value, or the second reliability is less than a predetermined value, it may be determined that parameter change is required. Alternatively, the first reliability and the second reliability may be substituted into a predetermined evaluation function, and if the value of the evaluation function does not satisfy a predetermined condition, it may be determined that parameter change is required.

[0047] Next, when it is determined that parameter change is required, the optimal parameters are then specified (S203). Specifically, a candidate parameter set including a band parameter, a first period length parameter, and a second engine length parameter is set, and those candidate parameter sets are tentatively set in the first filter unit 31a and the second filter unit 31b. Then, the heart rate and reliability recalculation unit 310b causes the biological information acquisition unit 300 and the reliability determination unit 320 to recalculate the heart rate and reliability. At this time, the heart rate data that was used as the processing target immediately before (that is, the heart rate data used when obtaining the heart rate determined to require parameter change) is used for the recalculation of the heart rate and reliability. This recalculation of the heart rate and reliability is repeated for a number of parameter candidate sets. Then, the candidate parameter set with the highest recalculated first reliability, or the candidate parameter set with the highest recalculated second reliability, or the candidate parameter set for which the value of the above evaluation function is the most preferable value (maximum value or minimum value) is specified as the set of optimal parameters.

[0048] Thereafter, using the heart rate data that was used as the processing target in the past (for example, the heart rate data used when calculating the heart rate determination value for which parameter change was determined to be unnecessary last time), the heart rate and reliability recalculation unit 310b causes the biological information acquisition unit 300 and the reliability determination unit 320 to execute the recalculation of the heart rate and reliability (S204). Then, if the first and second reliabilities each satisfy a predetermined condition (S205), the optimal parameter set specified in S203 is set in the first filter unit 31a and the second filter unit 31b (S206). The predetermined condition may be a condition that the first reliability is equal to or greater than a threshold value, a condition that the second reliability is equal to or greater than a threshold value, or a condition that the value of the evaluation function obtained by substituting the first and second reliabilities is equal to or greater than (or equal to or less than) a threshold value, or a combination of those conditions. In addition, in S205, if it is determined that the first and second reliabilities do not satisfy the predetermined condition, the process is interrupted. In this case, voice output, display output, data transmission to an external management computer, etc., indicating an error may be performed.

[0049] According to the biological information detection system 1 described above, the parameter change unit 310 selects an optimal parameter set so that the first and second reliability levels become higher, and sets it in the first filter unit 31a and the second filter unit 31b. As a result, the biological information acquisition unit 300 can calculate a more reliable (higher-precision) heart rate.

[0050] Note that the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above description, in S203 and S204 of FIG. 9, the recalculation of the heart rate and reliability is performed by the biological information acquisition unit 300 and the reliability determination unit 320 in the signal processing device 3. However, in another computer such as a cloud computer, functions equivalent to those of the biological information acquisition unit 300 and the reliability determination unit 320 are implemented by software, and the recalculation of the heart rate and reliability may be performed there.

[0051] Also, here, the heart rate is taken as an example of the biological information, but the present invention may be similarly applied to a system for detecting the respiration rate.

Explanation of Reference Numerals

[0052] 1 Biological information detection system, 2 Doppler sensor, 3 Signal processing device, 30 Heartbeat data extraction unit, 31 Filter unit, 31a First filter unit, 31b Second filter unit, 32 FFT unit, 33 Peak identification unit, 34 Peak tracking unit, 35 Peak storage unit, 36 Temporary heart rate calculation unit, 36a Temporary reliability determination unit, 37 Temporary heart rate storage unit, 39 Heart rate determination value calculation unit, 300 Heartbeat data acquisition unit, 301 Heart rate generation unit, 312 First moving average calculation unit, 310 Parameter change unit, 310a Heart rate data storage unit, 310b Heart rate and reliability recalculation unit, 320 Reliability determination unit, 320a Amplitude ratio calculation unit 312 First moving average calculation unit, 313 Second moving average calculation unit, 314 Difference calculation unit.

Claims

1. a biological information acquiring means for acquiring biological information of a subject by applying data processing including parameters to the Doppler data; a reliability calculation means for calculating the reliability of the biometric information acquired by the biometric information acquisition means; a parameter changing means for changing the parameter based on the reliability; A biological information detection system comprising:

2. 2. The biological information detection system according to claim 1, The biometric information detection system, wherein the data processing including the parameter includes a band-limiting filter, and the parameter relates to a passband of the band-limiting filter.

3. 2. The biological information detection system according to claim 1, the biological information acquiring means calculates a frequency spectrum based on the Doppler data, and calculates biological information based on a maximum peak of the frequency spectrum; the reliability calculation means calculates, as the reliability, an intensity ratio between the maximum peak of the frequency spectrum and a second largest peak of the frequency spectrum; Biometric detection system.

4. 2. The biological information detection system according to claim 1, the reliability calculation means calculates the reliability based on the number of times that the biometric information satisfying a predetermined condition is consecutively calculated; Biometric detection system.

5. 2. The biological information detection system according to claim 1, the parameter changing means calculates the biometric information and the reliability using a plurality of parameters, and selects one of the plurality of parameters based on the reliability thus calculated. Biometric detection system.

6. a biometric information acquiring step of acquiring biometric information of the subject by applying data processing including parameters to the Doppler data; a reliability calculation step of calculating the reliability of the biometric information acquired by the biometric information acquisition means; a parameter changing step of changing the parameter based on the reliability; A biological information detection method comprising:

7. a biological information acquiring means for acquiring biological information of a subject by applying data processing including parameters to the Doppler data; a reliability calculation means for calculating the reliability of the biometric information acquired by the biometric information acquisition means; and A parameter changing means for changing the parameter based on the reliability. A program that makes a computer function as a

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