[OZAPRS] RE: [aprssig] DTMF Weather telemetry
bruninga at usna.edu
Fri Aug 20 09:40:07 CDT 2004
I think the TTone spec requires dead time between
each character even if it is different. That is part
of the high reliability detection scheme... I think... Bob
>>> scott at 3xf.com 8/15/04 12:45:26 PM >>>
Sure, but your data rate is somewhat limited. I think the minimum
time is 40 ms, so that's 25 characters per second, 4 bits per
100 bits per second. If you're lucky. You still need to worry about
say you've got a long run of '3's - the tone isn't going to change.
need a clock at the receiver synced to the transmitter's clock to know
each character starts.
From: aprssig-bounces at lists.tapr.org
[mailto:aprssig-bounces at lists.tapr.org]On Behalf Of Andrew Rich
Sent: Saturday, August 14, 2004 11:56 PM
To: TAPR APRS Special Interest Group
Cc: ozaprs at marconi.ics.mq.edu.au
Subject: [aprssig] DTMF Weather telemetry
Has anyone ever used DTMF to send telemetry ?
Wind 278 deg Speed 015 Temp 027
Or even APRS ?
27*34*45A = 27.34.45B (assuming * = . and A = North and B = South)
153*06*21C = 153.06.21E ( assuming * = . and C = West and D = East)
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