Laser Communication System
Tweets at the speed of light
Introduction to Sensors, Instrumentation, and Measurements Course Project
AM radio transmission system built as the final project for Olin's introductory circuits class. My partner and I successfully developed a system capable of sending "Tweet" sized messages using Python, a USB oscilliscope, two basic circuits on a pair of breadboards, and a laser pointer from Petco.
Receiver reading the laser's pulses. I was responsible for the design of the various filters that produced a clean signal ready to be decoded, I aided in the creation of the decoding script in Python, and became skilled in the art of lining up the receiver to capture the laser at a distance.
My partner and I settled on using the ASCII form of the text message encoded as modulated amplitudes in a sine wave. This wave had beginning and end tags added to it and was sent through the laser at a frequency calculated by the length of the message. The receiving end would clean the signal and convert it back to a square wave of ones and zeros through analog circuitry that was then parsed by a Python script for the beginning and end tags. It would then print out the data in between revealing the message at the receiving end.
The transmitting and receiving circuits as circuit and block diagrams. The receiver circuit consisted of a photo-diode, a second order band-pass filter, and a square wave generation filter. Building this filter in a way that removed enough noise and was precise enough to pick up the minute changes in voltage from the photo-diode was the primary challenge in this project.
This project is very special to me in that it seemed like an impossible task at the beginning and yet, through weeks of hard work and incremental development, our goal was achieved. I learned a great deal about Python through peer programming with my partner and put my semester's worth of circuit knowledge to the test. In the end we were able to get the system to work at distances in excess of 100 feet and I'm extremely proud of the product that was produced.