I’m on the volunteer fire dept. in my town and as such, like to keep tabs on when neighboring towns are dispatched. I came up with the idea to make a large map of my area and put an LED in each town that would light up when they get called out. To do this though i would have to find someway to discriminate between towns, and since multiple towns use the same radio frequency, I couldn’t just cross-reference the frequency with the town. Fortunately though every town has a unique tone sent out just prior to the dispatch. It is this tone that i need to look at, process and then match up with its town.

Seeing as this is meant to run constantly , a micro-contoller is the clear choice, and what better than an arduino. Unfortunately, Arduinos don’t have the capability to process a sine wave by themselves, so i needed to give it a little help…