Re: [Asterisk] DTMF noise

[Matti Aarnio]

On Thu, Jan 09, 2003 at 05:32:51PM -0600, David D. Hagood wrote:
> Well, I found out that while we have the DTMF test tape at work, it is 
> exactly that - a cassette tape that is copyrighted. So, no easy/legal 
> way to make it available for testing...

What does such tape contain ?
 - DTMF tones buried in various degrees of distortions,
   which should be decodable ?
 - DTMF tones buried in varying noises which should not be
   decodable ?
 - Other multi-tone signals which should not decode ?

For the last, I know of cases where test was done by playing a radio 
station on the decoder for 2-3 days, and seeing when does it trigger
DTMFs (if ever).

For that matter, the Linux kernel ISDN audio DTMF detection is exactly
of the last variant.

/Matti Aarnio