2. Heart Rate Detector
(1).
Use the simple filter, the
result can be observed, but with many noises.
(2) So, we build the second order
filter combinated with low pass filter and high pass filter.
LOW-PASS FILTER
HIGH-PASS FILTER
Part 1 - Pedometer The whole algorithm was shown below. Part 2 - Heart Rate Sensor 1.Use simple band-pass filter (1-3Hz) to reduce the affect of the noise. f1=1/(2*pi*R1*C1)=1Hz f2=1/(2*pi*R2*C2)=3Hz where C1=1uF R1=560K C2=5.3uF R2=10K The band-pass filter with a pass-band from 1 Hz to 3 Hz to allow the heart beat signal to come through and the rest of the signal noise to be rejected. 2. Use amplifier to amplify the signal we expected. Gain = 1 + (R2/R1) Gate= 1+1M/10K=101 The oscilloscope was used to measure the voltage drop on the photoresistor. As expect, the voltage will change because the red light through the figure will change with the oxygen content of blood. The expected result is a pulse wave similar to human heartbeat, but the amplitude was about 3mV measured by multimeter. However, the noise was larger that the pulse although a filter was connected. The noise co
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