True, But fixing on the receive end would be more spectrum efficient. And you need to autotune the suppressed carrier anyway requiring receiver side complexity, so why not give DSP a challenge to do it in the blind?

With DSP so readily available, I am surprised doppler correction of voice has not been explored.

On 1/11/2014 12:05 AM, kc6uqh@cox.net wrote:

Joe, A -16dB pilot carrier would solve the frequency offset problem. This was a common solution for Marine shore stations in the last century. Art, KC6UQH

-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Joe Leikhim Sent: Friday, January 10, 2014 2:31 PM To: amsat-bb@AMSAT.Org Subject: [amsat-bb] Re: DTMF on HF?

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?

-- Joe Leikhim

Leikhim and Associates

Communications Consultants

Oviedo, Florida

JLeikhim@Leikhim.com

407-982-0446

WWW.LEIKHIM.COM

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