Posts Tagged ‘radio’

Rafts, Ping-Pong Balls, and Radio Waves

September 9, 2008
[First off, I’m not a signal transmission engineer. I’m a mechanical engineer who knows a lot about metals and corrosion, a little about electrical stuff, and not so much about this (IMHO, unbelievably complex and arcane) signal transmission stuff.
My thanks to all of you in advance for not asking the myriad questions about the physics of signal transmission that I couldn’t  answer to save my life.]   
Waves rolling in

Waves Rolling In


(This is a truly wild and ridiculously oversimplified analogy, but it might be of some help to someone somewhere.)

A broadcast wave (radio, TV, etc) is really two sets of waves: the carrier wave, which is the one you tune your radio to (e.g. 91.5 MHz), and the audio wave, which is at a much higher frequency. 

You might be able to imagine it as something like if you guys were all on the beach, and I were out on a raft too far from shore for you to be able to hear me, but I wanted to tell you elephant jokes. If I had a bucket of red ping-pong balls on the raft, and a bucket of white ones, I could translate my elephant jokes into binary code and place a series of ping-pong balls on the passing waves, using red for one and white for zero (somehow also making sure that they would arrive in their proper sequence). If someone there on the beach with you (let’s call him “Bill”) could then translate them back from binary to English, you’d all get to hear why elephants wear red tennies. :) 

find out why, and read on