WEEK 2

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 covered the signal we expect.

We have to use the band pass filter and solder the connection to reduce the noise, but it did not work. We built the amplifier circuit but have not get the result because of time limitation. We thought it might useless either because the amplifier might also amplify the noise

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WEEK 1

WEEK 1 This smart sports watch has two main functions. First, it can detect the user's heart rate. When users are exercising, paying attention to their heart rate can better protect and regulate themselves. Next, it can detect the user's steps. For sedentary people, it plays a role in urging themselves to exercise. Heart Rate Measurement The aim is to build a heart rate measurement using the LED and photoresistor without a pulse sensor to measure the heart rate on the finger. The materials we intend to use are photoresistor with maximum sensitivity about 650nm and Red LED with 10000mcd brightness. The principle we refer to is as follows. A heart rate is formed by two parts, the systole and the diastole. One heart rate will be measured after a systole and diastole is finished. The systole is the process that the blood is pushed to the body from the heart, conversely, the diastole occurs as blood flows back to the heart from the body. This project measures hea...

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WEEK3

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 Demonstration