DTMF = Dual Tone Multi Frequency.
So you need to get a date for the dance - what do you do?
You pick up school directory and call your top five choices, right?
OK - as your "fingers-do-the-walking" over the phone keypad - you are generating DTMF tones!
Two signals are mixed/generated.
Press 1 and you're sending 1209 Hz and 697 Hz to your intended date.
Press 2 and you're sending 1336 Hz and 697 Hz to your intended date.
Check out the matrix* table below. You don't have to walk around with this stuff in your head but hey - if you want to write a Rap song about it - go ahead.
Note: The A - B - C - D Column represents new tone frequencies opened by the phone companies. They may not be physically on the phone but these tone frequencies are within the DTMF Matrix.
| If you get the concept here - call yourself a Rocket Scientist. Me, I like Phone Guy and Phone Guys learn something new every day. |
*And you thought you'd never use matrices in real life.