Due to pulse oximeters have some disadvantages such as high cost of import, high power consumption, poor interference immunization, and small detection range. In this study, we presented a kind of digital pulse oximeter with low cost and power consumption. A digital detector based on light-frequency converter and with high resolution was adopted to improve precision and detection range, A DC tracking filter was used to cancel baseline drift to improve anti-interference ability, and a pulse rate detection algorithm using rising and falling edge was utilized to improve detection accuracy. In this study, stable pulse waveform and pulse rate could still be captured when body moved gently and fingers trembled slightly. After repeating the experiment under different conditions by Fluck Index2 oximeter simulator, we found that the accuracy was 1% when oxygen saturation was 35% to 100 %, the accuracy was 4% when low perfusion was smaller than or equal to 0.2%; and the pulse rate error is less than 1. In this study, the design had been improved in aspects of high precision, large scale, repetitiveness and anti-jitter. It is suitable for families, communities and other medical care occasions.
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