On Wed, 29 Mar 2000 06:12:33 -0600 Scott Dattalo writes: > On Tue, 28 Mar 2000, Andy Kelley wrote: > > > Anyone have a cheap ( also real-estate is at a premium ) method > for > > detecting wheter or not ANY tone is present? > > Andy, > > It's hard to answer your question optimally without addition > information. > > 1) What's the frequency of the tone? Variable. I am using the circuit to decode cw and would like to be able to vary the tone. > 2) What's the amplitude? A nice sinewave. > 3) Is there any additional signal present along with the tone? static... > Tony alluded to a comparator. Now if you have a pic in your design > (why wouldn't > you?) and the answer to the above questions are "suitable", then the > comparator > could be an I/O pin and you could run the algorithm described here: > > http://www.dattalo.com/technical/theory/dtmf.html > > Most of what's discussed there pertains to decoding single frequency > tones even > though the web page describes dtmf decoding. I wouldn't be ideal since I would have to use another pic and the tone varies. > Scott ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: http://dl.www.juno.com/get/tagj.