Based On Msp430 Ultra-low Power Processor Monitors Pulse Oximetry Module,

Blood oxygen saturation can be defined as the proportion of oxyhemoglobin in all arterial hemoglobin. Pumpped by heart, the vein blood flow into lung and then the deoxyhemoglobin turn to oxyhemoglobin by discharge carbon dioxide and combination with oxygen intake. Blood oxygen saturation is an important parameter reflecting status of body metabolism, of breath system, and transportation ability of blood. So it has important significance which providing continue detection for valetudinarian.Modern multi-parameter monitor always include module of Blood oxygen saturation. It should have property of simple, stable and realizable circuit structure, of anti-interaction and low power consumption.So in this paper, the principle of electroptical non-invasive dual-ray methods are fist present in detail.in the theorem of simple structure and low power consumption, we select detecter with fitble wavelenth and low power MSP430 processor, and design high stable ray-emitt circuit, low noise pre-amplifier, background disturbance counteract circuit, the signal are low-filtered and sent to MSP430' A/D transform directly to digital signal processing. Thus avoid error of phase-difference between ac-and dc component, and improve accuracy of computed SpO₂.High frequency electri-cutlery and motion artifact are important reasons of measurement error and wrong warning message. So pulse blood oxygen signal and various of interaction noise are analysed, the former have character of strong periodic and can be treated as stable procedure with time correlation. While motion artifact is caused by non-regular shiver of patient. Given enough time delayed, motion artifact signal have poor or even no self-corelation. So do the other sort of interaction noise.thus these two category of signal may be distinguished by there characteristic of self-correlation, and the noise may be eliminated. Three methods of digital signal processing algorithm are proposed to restrain the noise discussed, there are methods of fast fourier transform(FFT), of moving self-correlation, and of least means...