Lecture31_Signal_Processing_I_Optical_Sensing
In
this lecture, you will use a photodiode to collect optical events and
convert the optical signal into voltages. You will use Arduino to
collect the voltages and process the data to publishable quality.
Use a 10 k resistor, a photodiode, and an Arduino board to connect the
circuit like the following:
Use the serial
communication function to collect optical events. The optical pulses
can be created by the flash light of your phone. Make sure that the
'Longer pin' of the photodiode is connected to '5V'. The circuit is
working in this way: The photodiode won't be conductive if there is no
light shines on it. Stronger light will create stronger photo current
in the photodoide. When there is no photo current in the photodoide
(you move your flash light away from the photodoide), there is no
current flow in the circuit, so there is no voltage drop across the
resistor. In this case, A0's voltage will be GND, 0V. When the flash
light shines on the photodiode, the voltage potential will be pulled up
to 5V.

An example
figure shows the optical events in Matlab:

Tasks:
1. Collect your optical events and save the data on your hard drive.
2. Plot the data. Convert the X
and Y axis to the correct time/voltage labels.
3. Use the peak
detection method to label the 'real peaks' and count the number of
peaks in your data.
4. Modify
the figure title/frame/line width/font size/marker size/labels to make
it looks presentable.
Submit an electronic version of your report to the email. Again, have
figures, captions, title, explanations, and your code as the appendix.
Due Friday.