[amsat-bb] Re: DTMF on HF?

Unfortunately, in some cases the differences are very close. "C" and "3" have pairs with a differential only 1 Hz apart.

Perhaps some heuristic approach which examines several consecutive tone-pairs, looking for a single offset that would make them all valid?

On 01/10/2014 06:31 PM, Joe Leikhim wrote:

Since DTMF has two tones for each number, it would seem possible that you could have some DSP detect the difference frequency of each pair and then either adjust its decoders or QSY the receiver's VCO to get a lock. There are a ton of small development boards like Raspberry PI that have hardware that might be able to do this.

Has anybody got the AMSAT-bb daily digest to work through their e-mail provider other than Gmail?