Question

I am working on a Remote Controller via Headphone jack of iPhone. It requires:

• In Sending mode, Send signal (19kHz) and signal (10kHz) as 1 and 0 respectively
• In Learning mode, it receive corresponding signal from other remote controller

I read a site that it introduces AudioUnit (http://cocoawithlove.com/2010/10/ios-tone-generator-introduction-to.html) to do tone generation for sending

But How about Learning mode ? How can my application detect 19kHz and 10kHz as 1 and 0 ?

Thanks.

Answer 1

A simple DSP Goertzel filter will be able to detect those tones at low data rates. For higher data rates, look for FSK demodulation code, perhaps in amateur radio magazines or websites.