On Fri, 23 Sep 2005, David Van Horn wrote:

>> Just looking for comments
>
> I've worked with a bunch of different implementations over the years, in
> telephony apps.
>
> It's all about the compromises.
>
> You can get a nice DTMF encoder from Holtek for $0.25 in relatively
> small quantities.  That's a lot of codespace and processor time freed
> up, and the chip is easy to talk to.
>
> Decoders are a bit more, but I think you'd be hard pressed to get equal
> performance in all respects, from a software solution, especially if you
> are looking to do anything else in the same processor. Making something
> that sort of works is one thing. Making something that works with good
> dynamic range, twist tolerant, capable of detecting in 40mS, tolerant of
> noise.. That is likely to involve significant development time if it can
> be done at all.

Not only that but you will never know if it will work out there imho. 
The integrated detectors incorporate a large amount of wisdom gained 
along the years and pass fairly stringent tests (f.ex. wrt false 
detection).

Peter
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