90 results about "Conduction time" patented technology

The invention relates to the technical field of deep learning, in particular to a dialysis hypotension risk prediction system and method based on deep learning, and the system comprises a multi-point signal collection module, a signal processing module, a multi-scale causal expansion convolutional network prediction module, an osmotic pressure correction module and a dialysis plan automatic adjustment module. The method comprises the following steps: synchronously collecting physiological signals of a patient through a finger tip photoelectric volume sensor and a radial artery piezoelectric sensor array, carrying out band-pass filtering and morphological refinement processing on the signals, extracting features, and calculating pulse wave conduction time and a change rate thereof; inputting the characteristic parameters into a multi-scale causal expansion convolutional network to predict the hypotension risk in dialysis; dynamically correcting the prediction result according to electrolyte monitoring data; based on the corrected risk, a hierarchical response strategy is adopted to automatically adjust dialysis parameters, a multi-scale causal expansion convolutional network is adopted to capture physiological parameter changes on different time scales at the same time, and high-precision prediction of hypotension is achieved.

The invention discloses a motor cortex excitability evaluation method based on threshold tracking magnetic stimulation, and relates to the technical field of biomedical engineering. The motor cortex excitability assessment method based on threshold tracking magnetic stimulation comprises the following steps: performing electrical stimulation on median nerves of a wrist of a subject, recording on an abductor politics brevis (APB), recording a stimuli-response curve, determining a stimuli-response (SR) curve of cortex stimulation by increasing the magnetic stimulation intensity to the following level, and determining the stimuli-response (SR) curve of cortex stimulation according to the stimuli-response (SR) curve. And calculating statistical parameters of the average value and the standard deviation of the excitability threshold values, and judging the dynamic trend of cortical excitability. According to the method, the stimulation-reaction curve of cortex stimulation is determined by improving the magnetic stimulation intensity to the following level, the central movement conduction time is calculated through the F-wave method based on the stimulation-reaction curve, initial stimulation and threshold determination are completed, subsequent threshold tracking is carried out on the technology, and the accuracy and the reliability of the system are improved. And an efficient and accurate brain motor cortex function detection means is provided for diagnosis of nervous system diseases.

The invention discloses an arteriosclerosis detection method, device and system and an arteriosclerosis detector, and relates to the technical field of medical instruments.The method comprises the steps that after carotid artery pulse waveforms and femoral artery pulse waveforms are subjected to preprocessing and differential processing, division is conducted according to heartbeat cycles; acquiring a carotid artery signal maximum value and a femoral artery signal maximum value in each heartbeat cycle; determining conduction time in each heartbeat cycle according to the carotid artery signal maximum value and the femoral artery signal maximum value in each heartbeat cycle; according to the distance between the carotid artery measuring point and the femoral artery measuring point and the conduction time in each heartbeat cycle, the conduction speed of the pulse wave of the tested person in the arterial system in each heartbeat cycle is determined; determining an average conduction velocity according to the conduction velocity of the pulse wave of the testee in the arterial system in each heartbeat cycle; and determining the arteriosclerosis degree according to the average conduction velocity. The technical problem of low arteriosclerosis measurement precision in the prior art is solved.

A high-safety transistor testing system and method with nanosecond-level delay is disclosed, belonging to the field of transistor testing. It enables transistor characteristic testing under arbitrary drain voltage stress values, drain voltage stress durations, and load currents based on nanosecond-level measurement delays, while ensuring the safety of the testing system and personnel. The circuit includes: a switch. S 1, S 2, S 3. Resistance R A , R C Schottky diode D 1, D 2. Power Inductor L ,power supply V DD Control switch S 1. The conduction time can control the high voltage that the subsequent circuit can withstand. V DD Duration; control switch S 2. On-time can control the power inductor L Current value at the end of charging; test switch S From the voltage and current of 3, we can determine the switch. S 3. Switching transient characteristics, on-resistance characteristics, etc. Simulation and experiments show that the measurement delay of switching to the test state after the drain voltage stress ends is on the order of nanoseconds, and there is no situation of "accidental opening of series switch leading to large current conduction", so the circuit safety is higher.

The invention discloses a method, a device, equipment and a product for positioning the position of a balloon in an aorta, and the method comprises the steps: building a blood conduction distance model which is used for representing the corresponding relation between the blood conduction distance and the blood conduction time and the systolic pressure value of the position of the balloon; an electrocardio waveform signal and a blood pressure waveform signal of the position where the balloon is located are obtained, and blood conduction time is calculated; determining a blood conduction distance by using a blood conduction distance model according to the calculated blood conduction time and the acquired systolic pressure value; and determining the position of the balloon in the aorta according to the blood conduction distance. According to the method, the position of the balloon in the aorta is determined by using the blood conduction distance model based on the electrocardiogram waveform signal and the blood pressure waveform signal, marking of the balloon in the artery and use of fluoroscopy equipment are not needed, dependence on experience of professional medical staff is greatly reduced, and the method has the advantages of being accurate in positioning, convenient to operate and wide in application range.

The application relates to a critical conduction mode control method of a totem-pole PFC converter, which utilizes energy equivalence to determine the resonance process of inductor current at switching commutation, carries out totem-pole Boost inductor current value estimation, and on this basis, utilizes a current zero-crossing point prediction algorithm to calculate the turn-on and turn-off time to generate corresponding active tube-synchronous rectifier tube commutation dead time T d,f , synchronous rectification conduction time T SR , rectifier tube-active tube commutation dead time T d,r ; the PWM drive signals of high-speed switching tubes Q1 and Q2 are generated by T on , T d,f , T SR , T d,r ; the power frequency drive signals of low-speed switching tubes Q3 and Q4 are generated by comparing the input alternating voltage v ac with a hysteresis comparison loop and 0. The method can effectively get rid of the dependence on a current zero-crossing detection circuit and a current sensor, reduces the cost and improves the system stability.

Implantable medical device for stimulating a heart includes a proximal electrode pole, and first and second distal electrode poles. During operation, the device performs: a) detecting an intrinsic atrial contraction of the heart; b) detecting an intrinsic ventricular contraction of the heart; c) determining a first intrinsic atrioventricular conduction time between i) the intrinsic atrial contraction or the stimulation of the atrium and ii) the intrinsic ventricular contraction detected with the first distal electrode pole; and determining a second intrinsic atrioventricular conduction time between i) the intrinsic atrial contraction or the stimulation of the atrium and iii) the intrinsic ventricular contraction detected with the second distal electrode pole; d) setting a stimulated atrioventricular conduction time for stimulating the ventricle of the heart with the first and / or second distal electrode poles, the stimulated atrioventricular conduction time being shorter than the shorter of the first and second intrinsic atrioventricular conduction times.

This invention discloses an intelligent psychological guidance system for harmonizing the Qi of the internal organs based on TCM emotional differentiation, belonging to the field of medical electronic equipment. The system includes a multi-node physiological signal acquisition module, a central control and data processing module, and an acoustic intervention output module. The system synchronously acquires multi-channel bioimpedance, volumetric pulse wave, and electrocardiogram signals, extracts pulse wave conduction time and local blood perfusion index, constructs Qi characteristic parameters, and maps them to generate emotional tags. The central control module locks the target resonance unlocking frequency according to the tags, modulates low-frequency vibrations with reference audio to synthesize a multimodal signal, and further combines physiological pulse transmission delay to perform phase compensation, controlling the precise output of the intervention signal during ventricular diastole. Steady-state determination and closed-loop tracking are performed based on the dynamic gradient of impedance variance. This invention achieves objective quantification of TCM differentiation and ensures high-precision physical alignment between intervention energy and the hemodynamic state of the internal organs.

A method that selects high-quality data within recorded signals from patient monitoring devices, where portions of the signals may be corrupted by noise and should therefore be excluded. Signals are compared to models of expected signal characteristics, and portions of the signals that do not match the models may be excluded. Some models may check for expected relationships between signals from different devices. One such model identifies feature points in two signals from two different devices and calculates the time difference between each feature point in one signal and the earliest subsequent feature point in the other signal; data is excluded if this time difference exceeds an expected range. For example, an expected relationship between electrocardiogram and blood pressure signals is that the R-wave peak should be followed by a blood pressure peak within an expected delay time (the pulse transit time); this check can exclude invalid ECG / BP data.

The invention relates to the technical field of physiological parameter detection, in particular to a physiological parameter detection method adaptive to individual difference factors, which comprises the following steps: (1) acquiring an electrocardiosignal and a PPG signal, and respectively performing primary filtering, primary high-frequency filtering and secondary filtering on the signals; (2) extracting an RR interval, a pulse rate, a heart rate and heart rate pulse conduction time based on the signal after the secondary filtering processing; (3) processing a differential signal corresponding to the electrocardiosignal through a first window filter coefficient, and calculating q RR interval mean values of the first window filter coefficient; (4) processing the PPG signal through a second window coefficient to obtain q differential values and pulse rates of the second window coefficient; (5) obtaining the heart rate; and (6) calculating the R wave position within the range of 20-50ms after each frame of electrocardio is finished by using the electrocardio signal, and calculating the corresponding pulse conduction time, so that the individual adaptability of physiological parameter detection is remarkably improved.

The invention relates to the technical field of pulse power, in particular to a time sequence synchronous trigger control method for a multi-path pulse switch of an LTD module, which comprises the following steps: S01, measuring the inherent delay time of each discharge branch in the LTD module from trigger signal input to gas switch conduction; and S02, inputting the measured inherent delay time value of each branch into a pulse time sequence controller as a compensation parameter, and setting the delay time of each output channel of the pulse time sequence controller. Through system calibration and programmable delay compensation of the pulse time sequence controller, in combination with high-precision time sequence control of the FPGA, the multi-way switch conduction time deviation can be controlled at the nanosecond level, the energy synthesis efficiency is greatly improved, inductance isolation transmission is achieved through magnetic ring coupling, traditional resistance isolation is replaced, pulse leading edge distortion is avoided, and the energy synthesis efficiency is improved. And meanwhile, high-voltage isolation safety is guaranteed, and trigger signal transmission quality is stable.

The application belongs to the field of heart disease treatment and natural medicine compound, and provides application of bufalin or a pharmaceutically acceptable salt thereof in preparation of a medicine for treating reperfusion arrhythmia. Experiments in vitro and in vivo prove that bufalin inhibits L-type calcium channels in a concentration-dependent manner, reduces extracellular calcium ion inflow, and further reduces the incidence of ventricular arrhythmia, arrhythmia, reduces ventricular conduction time, increases left ventricular conduction velocity, and reduces ventricular conduction dispersion; and provides a new drug selection for the treatment of reperfusion arrhythmia.

The invention provides a dead time adjusting method, a self-adaptive ZVS control method and a switching power supply, and the method comprises the steps: 11) obtaining a first time length, collecting a second time length of a current period, and comparing the first time length with the second time length; step 12) if the first duration is greater than the second duration, reducing the conduction time of the clamping tube by a preset duration in the next period; if the first duration is smaller than the second duration, increasing the conduction time of the clamping tube by a preset duration in the next period; if the first duration is equal to the second duration, the conduction time of the clamping tube is kept in the next period; and (13) returning to the step (11) to sequentially adjust the dead time between the clamping tube and the main switch in each period. According to the invention, self-adaptive control in a dead time full-load range between the upper clamping tube and the main switching tube can be accurately realized, the safety is high, the loss of the main switching tube is small, the system efficiency is high, and the application range is wide.

The invention discloses a cycle-by-cycle current pre-estimation protection method and a cycle-by-cycle current pre-estimation protection system for a multiphase TLVR circuit, and after pre-storage of current change rates under different working conditions is completed, the cycle-by-cycle current protection system orderly executes the following steps under unified scheduling of a state machine: each phase of inductive current is sampled by an ADC and then sent to an inductive current real-time calculation module; meanwhile, a PWM signal is received; when a certain phase of PWM signal is at a high level, the inductive current real-time calculation module performs cycle-by-cycle current calculation by taking a digital current value obtained by sampling as an initial value, and outputs an estimated current value; the estimated current value is compared with a preset CBC protection threshold value, and then the conduction time of the phase is adjusted; the current increment is calculated in each clock period, the maximum current value which can be reached in the PWM conduction period is predicted, and protection is carried out in time. According to the invention, the problem of local current peak caused by the coupling effect in the TLVR circuit can be effectively solved, and the influence of driving delay is eliminated.

A pulse wave transit time measurement device includes a pulse wave transit time calculator that calculates a pulse wave transit time based on a peak time difference between an electrocardiographic signal and a pulse wave signal, a posture classifier that classifies time serial data of the pulse wave transit time based on a posture detected by an acceleration sensor, and a fluctuation identifier that sets a reference posture from among classified postures, corrects, in conformity with the reference posture, the time serial data of the pulse wave transit time classified into the posture different from the reference posture, and determines fluctuations in the pulse wave transit time based on the time serial data of the pulse wave transit time in the reference posture and the time serial data of the pulse wave transit time having being corrected.

The present application relates to the technical field of medical monitoring, in particular to an intelligent multi-parameter risk early warning system for critical patients. The system transforms ventricular electrical amplitude sequence and pulse pressure difference sequence in a preset sliding data window to determine relative electrical amplitude sequence and relative pulse pressure sequence. The pulse pressure variability is determined based on the pulse pressure difference sequence in the window. The reference conduction time is determined according to the electrical-mechanical delay sequence in the window. The matching cost matrix is constructed according to the reference conduction time, the relative electrical amplitude sequence and the relative pulse pressure sequence, and the optimal matching relationship is solved. The excitation-response data pair set is constructed according to the optimal matching relationship, and the waveform difference index is determined. The response reverse sequence ratio is determined according to the set. The pulse pressure variability, the waveform difference index and the response reverse sequence ratio are used for hierarchical screening to determine the physiological state and output the corresponding risk warning, thereby significantly improving the early cardiovascular abnormality recognition ability.

The utility model relates to the technical field of medical instruments, in particular to an intelligent wireless medical foot switch circuit and device, a control circuit is provided with a timer, and the control circuit identifies the conduction time of the switch circuit through the timer so as to control a first output end or a second output end to output a control signal. According to the utility model, one pedal switch is used for controlling a plurality of medical devices, so that a plurality of pedal switches are omitted, and the risk of mistakenly touching the plurality of pedal switches is avoided. And the first communication module and the second communication module can be wireless communication modules, so that the interference of a line of the wired foot switch on the examination work of a doctor is avoided, and the risk that the line is infected with bacteria is eliminated. And the control safety and the control efficiency of the medical equipment are effectively improved.

To provide a wearable physiological signal detection system applicable to an application scene such as in-home-care, walking support, labor safety and health management, and voluntary health prediction.SOLUTION: A wearable physiological signal sensing system disclosed in the present invention includes: a system circuit board having an upper surface and a lower surface; a stethoscope installed on the lower surface for sensing a cardiac sound signal of a user; a plurality of electrocardiographic electrodes installed on the lower surface, adjacent to the stethoscope for sensing an electrocardiographic signal of the user; and a blood oxygen concentration analyzer installed on the upper surface for sensing a blood oxygen concentration and a pulse wave signal of the user. The system circuit board is electrically connected to the stethoscope, the plurality of electrocardiographic electrodes, and the blood oxygen concentration analyzer. The system circuit board acquires a pulse wave transmission time of the user through comparison between the electrocardiographic signal and the pulse wave signal or comparison between the cardiac sound signal and the pulse wave signal, and estimates a continuous blood pressure of the user on the basis of the pulse wave transmission time.SELECTED DRAWING: Figure 13(a)

The invention discloses an upper limb artery occlusion assessment method and system based on portable multi-camera equipment, terminal equipment and a medium, and relates to the technical field of artery occlusion assessment. The method comprises the following steps: acquiring a reference signal, a left hand pulse wave signal and a right hand pulse wave signal based on the portable multi-camera equipment; the reference signal, the left-hand pulse wave signal and the right-hand pulse wave signal are synchronized by taking the acquisition time as reference time; performing feature extraction on the reference signal, the left-hand pulse wave signal and the right-hand pulse wave signal to obtain a signal transduction time difference feature and a signal waveform similarity feature; and inputting the signal transduction time difference feature and the signal waveform similarity feature into a pre-trained evaluation model to obtain an upper limb artery occlusion evaluation result. According to the method, the portable multi-camera equipment is used for collecting physiological signals of three positions of a human body at the same time, and the obstruction condition of the upper limb artery is simply, conveniently and accurately evaluated by using the signal transduction time difference characteristic and the signal waveform similarity characteristic.

A blood pressure prediction method and apparatus, an electronic device, and a computer-readable storage medium. The method includes: synchronously collecting physiological signals, the physiological signals include electrocardiogram signals, pulse signals and heart sound signal; extracting features from the physiological signals to obtain signal features, the signal features include pre-ejection duration and pulse wave transit time; and inputting the signal features into a pre-trained blood pressure prediction model to cause the blood pressure prediction model to output a blood pressure prediction result.

The invention discloses an overcurrent protection method applied to a TLVR, and belongs to the technical field of switching power supplies. The method comprises the following steps of: modeling and predicting an inductive current rising process in a PWM (Pulse Width Modulation) conduction process by stages, calculating the maximum allowable conduction time when the inductive current in each stage reaches an overcurrent protection threshold value, and outputting a PWM cut-off signal before the threshold value is predicted to be reached, so that an overcurrent protection mechanism is accurately started in advance. According to the invention, the accuracy and response timeliness of overcurrent protection are improved, and current overshoot is effectively suppressed within a safe range; accurate compensation of the TLVR coupling effect is achieved, and the adaptive capacity and robustness of the system under complex working conditions are enhanced.

This invention discloses an intelligent physiotherapy control system and method based on multi-scenario, multi-element collaboration, relating to the field of physiotherapy technology. The method includes the following steps: performing short-time Fourier transforms on the driving waveform of the magnetotherapy module and the excitation waveform of the phototherapy module respectively, extracting the dominant frequency component, harmonic frequency band, and energy density parameters within each working cycle, and constructing a set of magnetic-optical dual-channel spectral feature vectors; based on the spectral feature vector set, calculating the relative frequency ratio and energy superposition ratio between the dominant frequency point of magnetotherapy and the dominant frequency point of phototherapy and their higher harmonics, obtaining a spectral coupling degree index. This invention achieves quantitative assessment of the risk intensity of magnetotherapy and phototherapy by constructing a joint resonance superposition degree, and dynamically adjusts the waveform timing based on this index. By delaying the rising edge and limiting the conduction time, it achieves peak-shifting control of energy output, effectively reducing instantaneous superposition density and improving physiotherapy safety and system adaptability.

A system and method for contactless determination of pulse-transit time from a received image sequence. The method including: determining hemoglobin concentration (HC) signals over time at a first region of interest (ROI) and a second ROI, the first ROI and the second ROI forming a pair of ROIs, the second ROI located downstream from the first ROI along a common pulse wave path; determining a pulse transit time based on a time difference between peaks in the HC signals; and outputting the pulse transit time. The method can further include determining pulse wave velocity (PWV) using the determined PTT and a distance between the pair of ROIs, and outputting the determined PWV. The method can further include determining an estimate of blood pressure using the determined PWV with a trained machine learning model, and outputting the determined estimate of blood pressure.

The invention discloses a circuit control method and device, a storage medium and electronic equipment, and the method comprises the steps: obtaining a phase lag angle and a resonance frequency of equivalent impedance, obtaining a theoretical conduction time length based on the phase lag angle and the resonance frequency, obtaining a load voltage, a power supply voltage, a transformation ratio and an actual conduction time length, when the load voltage is smaller than a target voltage, reducing the actual conduction duration by unit duration to obtain a first conduction duration, determining a target conduction duration based on the first conduction duration and a theoretical conduction duration, and when the load voltage is larger than a preset voltage, increasing the actual conduction duration by unit duration to obtain a second conduction duration, and determining a target conduction duration based on the second conduction duration and the half-cycle duration, and adopting the target conduction duration to control the working state of a switching tube in the target circuit. According to the invention, the charging feedback phenomenon of the target circuit is controlled, so that the target circuit can still work in a high-gain state during charging and discharging, and the working performance of the target circuit is improved.

The application discloses a brain-muscle function change coupling analysis method based on bidirectional delay compensation, which comprises the following steps: designing an experiment paradigm, collecting signals and pre-processing the signals; determining a bidirectional cortical muscle delay estimation algorithm based on a sliding window and transfer entropy TE, and quantifying the conduction time of the EEG->EMG outgoing path and the EMG->EEG incoming path of the cortical muscle of a test person; performing signal time alignment compensation, calculating the transfer entropy with delay compensation and the average delay compensation transfer entropy, and constructing a directional delay compensation directional cortical muscle connection CMC network based on the transfer entropy with delay compensation and the average delay compensation transfer entropy; extracting evaluation features, and performing brain-muscle function change coupling analysis based on the evaluation features; and the evaluation features are extracted based on the dimensions of the CMC coupling strength, the hemispheric lateralization index and the correlation of the delay-motor function behavior index score based on conduction delay, hemispheric division and task stage. The application also discloses a corresponding system, an electronic device and a computer readable storage medium.

The invention relates to a switching tube control method and device and a vehicle. The switching tube control method comprises the following steps: acquiring estimated conduction time of a switching tube of a motor controller; acquiring narrow pulse time and a switching tube period corresponding to the switching tube; determining a time difference value according to the narrow pulse time and the switching tube period; comparing the estimated conduction time with the narrow pulse time and / or the time difference value to obtain a comparison result; according to the comparison result, the actual conduction time of the switching tube is determined, and the actual conduction time is the narrow pulse time, the time difference value, the switching tube period, the estimated conduction time or 0; and controlling the switch tube according to the actual conduction time. According to the method, the reliability and stability of the switching tube can be improved, the reliability and stability of motor control are further improved, and the control performance of a motor controller is improved.

The present invention discloses a detection system and method for the degree of arteriosclerosis based on a photoelectric sensor, including collecting the I or II lead ECG analog waveform to obtain an electrocardiogram analog signal, and synchronously collecting a photoelectric pulse wave analog signal through the photoelectric sensor; synchronously collecting and conditioning to obtain an electrocardiogram and photoelectric pulse interconnected waveform signal, and then obtaining the best electrocardiogram and photoelectric pulse interconnected waveform signal; according to the best electrocardiogram and photoelectric pulse interconnected waveform signal, using the slope method to identify and calculate the peak feature points of the electrocardiogram R waveform, using the slope method to identify and calculate the peak feature points of the photoelectric pulse wave, and then calculating the conduction time RPT of the photoelectric pulse wave in the arterial blood vessel of the best electrocardiogram and photoelectric pulse interconnected waveform signal; at the same time, calculating the main wave width tu of the photoelectric pulse wave; if the conduction time RPT is less than the set threshold, the degree of arteriosclerosis of the arterial blood vessel is abnormal, and if the main wave width tu of the photoelectric pulse wave is greater than the set threshold, the degree of arteriosclerosis of the arterial blood vessel is abnormal.

An edge-aligned PWM modulation method includes the following steps: Step 1) Determine the sector according to the synthesized voltage vector and determine the conduction sequence of PWM according to different sectors; Step 2) Calculate the action duration of the effective vector according to the synthesized voltage vector; Step 3) Insert the U7 vector based on the known action time of the effective vector; Step 4) Perform phase-shifting operations according to different sectors. The present invention solves the problems existing in the phase current sampling and reconstruction process in the existing single-bus current system, such as inaccurate reconstruction, increased extra conduction times, dependence on motor model parameters, high cost, large volume, etc. Compared with the conventional method, the method provided by the present invention is easy to implement, has a small amount of calculation, does not increase the switching times of power devices, and improves the three-phase current reconstruction accuracy.

The application relates to the technical field of wearable medical devices, in particular to a sleeveless continuous blood pressure monitoring method based on fusion of double-path pulse wave transit time and posture. The sleeveless continuous blood pressure monitoring method based on fusion of double-path pulse wave transit time and posture comprises the following steps: S1, device wearing and system initialization; S2, multi-modal signal synchronous acquisition; S3, signal pretreatment; S4, effective measurement state judgment; S5, wrist and heart height difference calculation; S6, pulse wave feature point recognition and transit time calculation; S7, initial blood pressure value calculation; S8, hydrostatic pressure correction; S9, result output and storage; and S10, returning to step S2 and performing next blood pressure measurement. The technical problems that blood pressure monitoring cannot be continuously measured, is easily disturbed by body position changes, has low measurement precision and lacks individualized calibration in the prior art are solved.

The vital sign detection device of the present invention includes one or more sensors, which can detect a plurality of vital sign signals of a test subject in a non-contact manner, and output corresponding a plurality of vital sign information, thereby achieving fast and accurate vital sign detection. The invention also relates to a combined multi-functional detection device, which includes a camera, a radar sensor, an infrared sensor and a sensor driving unit, used for measuring vital signs. The invention also provides a non-contact blood pressure measurement method and device. The method includes receiving radar echoes and video signal streams at first and second parts, extracting first and second pulse wave signals therefrom, obtaining a measured pulse wave transit time, matching the measured pulse wave transit time with a reference pulse wave transit time, and obtaining a blood pressure value.