中英文翻译

y of 100Hz. Power frequency notch filter link in order to filter out the mains 50HZ interference.

Capacitor tantalum capacitor should be selected for the compensation capacitor, hardware power frequency notch and software filtering and measures taken to the city electrical noise, experimental results show that the use of digital filtering techniques, the inhibitory effect of frequency interference signals better electromagnetic signal suppression has mainly taken two ways, one signal line shield is designed for fourth-order Butterworth low-pass filter cutoff frequency of 100 Hz.Jitter noise for the human body mainly through the software filter to filter out, mainly using the anti-pulse interference average filtering method. Sunplus, the algorithm implementation, the basic idea is that the 256 data measured as a queue, each time a new measurement, put the measurements into the tail, and remove the original team the first time data, such there is always 256, \ 256-by-comparison data to remove the maximum and minimum, and then calculate the average of 254 data. This filtering method for periodic interference of inhibition, but also occasionally filter out the pulse of human jitter generated interference. Found that, despite the person's body temperature is kept constant, but the wrist skin surface temperature of the outside temperature changes still, and the skin of the wrist with the sensor surface, the temperature difference will have a great impact to the measurement requires the elimination of The temperature effect of the use of human pulse(1Hz) Thermal noise signal.

As the body of the pulse signal has a low frequency, amplitude interference, instability, randomness, and other characteristics, makes very strict requirements on the acquisition of the pulse signal amplifier design, especially the anti-interferencebecomes very important , need to design low-pass filter for filtering. Select amplifier from the gain, frequency response, input impedance, common-mode rejection ratio, noise, drift, several aspects to be taken into account.

(1) anti-jamming

First,power frequency the 50HZ interference and its harmonics The use of frequency 50HZ electricity electronic equipment devices can cause detection system will have a greater interference, and its amplitude is about 50% of the pulse signal peak to peak, is the main source of interference;

Then,EMG interference

The contraction of the muscle will produce microvolt potential, its amplitude is about 10% of the pulse signal peak to peak hold time is 50ms, the frequency range in 0HZ 10000HZ;

Finaly,breathing caused by baseline drift and ECG amplitude variations Breathing caused by baseline drift sinus component (sinusoidal) can be seen as a respiratory frequency by adding the ECG signal, the amplitude and frequency of this sine components of change. Breathing caused by changes of the ECG signal amplitude can reach 15%. The baseline drift of the frequency from 0.15 ~ 0.3HZ. (2) low noise, low drift

Pulse amplifier, high gain, noise and drift are the two important parameters. Noise in the pulse amplifier running the electronic circuit of the inherent thermal noise and shot noise, these are the white noise, the amplitude for the normal distribution. In order to obtain a certain signal to noise ratio of the output signal, the amplifier's low noise performance, there are strict requirements. In addition, the temperature change will cause zero drift, drift limits the amplifier's input range, the weak slowly varying signals can not be enlarged. The pulse signal has a very low frequency components to normal measurements, measures must be taken to limit the drift of the amplifier. Therefore, the amplifier should use low drift, high input impedance and high common mode rejection ratio of the integrated operational amplifier circuit.

Other sensors First,piezoelectric sensor

Currently used disposable ECG electrodes, which is obtained by printing methods Ag/Agcl sensor. This sensor uses the method of separation then buckl

e sensitive areas, can significantly reduce the interference due to human movement. Electrode The quality of the collected ECG signal quality plays a vital role, using the electrode should be posted strong, can be tightly attached to the surface of the body, soft, absorbent, polarization voltage low, good electrical conductivity characteristics . Electedelectrode sensor, three electrodes were placed in the left and right hands and left leg, constitute the standard ECG. Clinical order to unify and to facilitate the comparison of the pulse signal, the detected pulse signal, the connection of the electrode position, lead the amplifier has a strict uniform provisions.

Currently on the market a new type of polymer piezoelectric material poly (vinylidene fluoride) piezoelectric sensor developed by its high sensitivity, good frequency range, simple structure, easy to use. When the finger front end by a slight pressure, you can feel the finger front end in a relaxation of the blood pressure, this signal is extracted from the sensors into electrical signals, through refers pulse waveform detection, you can get the pulse of the human body signal. Secondly,photoelectric sensor

Blood is a highly opaque liquid, light in the general organization of penetrating than blood several times, whereby the characteristics of the photoelectric effect finger pulse sensor to pick up the pulse signal. Photodiode reverse bias, the reverse current with light intensity increases, the photoelectric effect characteristics, a linear relationship in a certain light intensity within the photosensitive diode reverse current and light intensity. The volume of fingertip blood vessels and transmittance heart stroke changes will enable optical transistor diode receive a different light intensity, and the resulting photocurrent will be a corresponding change. Commonly used in testing the pulse of photoelectric sensors is divided into infrared tube tube and infrared radiation.

Infrared Emitting Diode, will hose clamp on the finger ends of finger blood concentration changes with the heart beating, infrared tube corresponding to the signalwill change accordingly, collecting the signal after amplifi

cation, filtering, and compare and other processing can be the ideal signal.

Reflection type of infrared tube. The heart rate monitor on the market now commonly used in this sensor signal acquisition, because this infrared tube receiver and transmitter are on the same side of the finger, and therefore do not need to consider each person different fingers trouble. Received blood diffuse reflected light, this signal can accurately measure intravascular volume changes. Lastly,integrated sensor

At present, there are many types of integrated ECG sensors, its high sensitivity, high integration, you can directly reflect the changes in heart rate, and includes filtering, anti-jamming circuit, the waveform has been amplified to deal directly with use. The disadvantage is that the price is very expensive, generally 500yuan, the design, taking into account the funding and exercise their own purposes, do not choose to use this type of sensor.

The optical advantages of high sensitivity, easy to operate, fast response, simple structure. But changes in the external light source have a greater impact on the measurement results; need to purchase specialized medical photoelectric sensor, the more expensive and difficult to buy; such devices had little contact with its possible to debug be greater difficulties.

Piezo advantages of simple structure, good real-time, band, simple application circuit, and low prices. However, the disadvantage is that direct contact with the human body, human muscle tremor interference, and vulnerable to the interference of other signals of the outside world. The integrated advantages of high integration, contains a filter, amplifier, you can direct the output signal, easy to operate, effectively reduce the interference of all kinds. But the drawback to reduce the difficulty of the task, if the sensor only need to be directly connected to the microcontroller can be realized function, and the price is very expensive. Taking into account these ci