Matching Incoming Audio Tones

[KyleYankan]

Howdy folks, I have a quick question. I'm a Volunteer Firefighter with a bit of a sleeping problem. Our station gets dispatched on a certain frequency by the use of two tones (510.5hz for 2 seconds, then 2271.7 for 2 seconds) to set off the voice pagers/klaxons/strobes/big 'ol siren. I have my scanner connected to my computer via the microphone-in port (I'm running Ubuntu). What's the easiest way to grab information from the microphone, and determine/analyze the sound in such a way I can tell if my fire company is being dispatched?

The whole reason I'm doing this, is that we now use tiny fancy schmancy digital pagers, which can barely get my attention during the day, much lest bring me back from the dead at night. My room is already partially wired to a few relays/etc/etc, so I'd like to strobe the lights a bit, maybe make some noise. Please help this Audio newbie do some simple decoding.

[Zaxo]

Are there any signals you wish to ignore?

PDL::Audio ought to have a way to detect your signals, but the logic of what to respond to isn't clear if some aren't correct. If you must answer all pairs of two-second tones, you don't need to be selective, except for your own information.

[KyleYankan]

Yes, there are several 2-tone-signals, as well as voice transmissions on the frequency. PDL::Audio looks like quite a beast, I'll be spending most of my day laying down a gameplan :-P

[KurtSchwind]

I'm not familiar with the module that's been described, but if you want to know what frequency is coming in a mic, you can use a 'fourier transformation'. Scan the docs for Fourier or Fast Fourier Transformation.

[ByteFreak]

There's an article on developerworks that might help...it uses perl to control sndpeek which does the hard work of analyzing the audio for you, the project reacts to sequences of tones :-)

http://www.ibm.com/developerworks/linux/library/os-whistle/index.html