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Lowest power tune detector.

I'd like a keyring that responds to a whistled tune, rather than a simple tone, for better noise rejection. One way is to attach my laptop to my keyring, run a FFT over the output of the mic, and then look for spikes in the correlation of the tune with the historical output of the FFT. Needless to say this uses too much power, and is a bit bulky. Another would be to go analog, have several tuned filters outputting to comparators/ADCs, but this has a high component count. This is to go into another device, which has a 3.3V supply. I'd like it to draw under 150uA or so.

Are there micros that can do this? ADC at ~8Khz, clocking at a few tens of Khz, and do the MAC thing for maybe 8 tones?

Reply to
Ian Stirling
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Maybe a low power op amp on the mic providing a logic level output to a PIC in sleep mode. The PIC wakes up on any noise and does FFT to check for the tone. PIC12F675 is a good choise, very low current in sleep mode and 10-bit a/d for the tone input. Run the whole thing on a 3 volt watch battery.

Luhan

Reply to
Luhan

Your're pretty much looking at a multi tone telemetry system. The 60's sounding rockets needed racks full of equipment to do similar. Even now you'll need some -heavy- signal massaging using quite a powerful DSP/Micro. Small PICs won't touch it. FFTs' are way over the top. Need to be using something like the Goertzel algorithm. john

Reply to
John Jardine.

Wrong you are. I have DTMF decoder implemented in a PIC. Its been answering my phone calls for a couple of years now, so I know it works.

Check it out at...

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Luhan

Reply to
Luhan

Do you have perfect pitch, or will your device be responding to intervals rather than absolute frequencies?

Reply to
cs_posting

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