[aprssig] APRS tone encode question
vk4tec at tech-software.net
Mon Aug 23 16:46:16 EDT 2004
Scott how do you get this waveform ? RC ?
From: Scott Miller [mailto:scott at 3xf.com]On Behalf Of scott at opentrac.org
Sent: Tuesday, 24 August 2004 4:17 AM
To: vk4tec at tech-software.net; 'TAPR APRS Mailing List'; 'TAPR PIC
Development Special Interest Group'
Subject: RE: [aprssig] APRS tone encode question
Yeah, I'd expect 16 levels. Haven't had a chance to look at my TT3 to see
what it's actually doing.
Here's a snapshot of an OpenTracker's output. Steps aren't really visible
on this 'scope...
The OpenTracker uses PWM for D/A. In AFSK mode it uses 4 bits resolution,
and in BPSK mode it's 8. Works pretty well. I'll have to do a comparison
of the output waveforms of the TT3, OpenTracker, and MX614 sometime. For
audio stuff, Yoshimasa Electronic's RAL package is great. It's got a nice
oscilloscope and FFT analyzer display, plus a signal generator and assorted
From: aprssig-bounces at lists.tapr.org
[mailto:aprssig-bounces at lists.tapr.org]On Behalf Of Andrew Rich
Sent: Monday, August 23, 2004 2:40 AM
To: TAPR APRS Special Interest Group; TAPR PIC Development Special
Subject: [aprssig] APRS tone encode question
I threw the tinytrak audio onto a CRO and compared it to a sine wave from a
How come a DAC ladder network of 4 resistors only produces 8 steps ?
Should it not end up being 16 steps ?
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