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Old October 24th 15, 06:55 PM posted to rec.radio.amateur.moderated,rec.radio.amateur.equipment
Paul W. Schleck Paul W. Schleck is offline
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First recorded activity by RadioBanter: Jun 2006
Posts: 74
Default [K0NR] Digital Voice Balkanization

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In writes:

In article
(K0NR via rec.radio.amateur.moderated Admin) writes:

.png Wouldn't it be cool if we had one digital communications format for the
VHF/UHF amateur bands with all equipment manufacturers offering compatible
products? The basic modulation and transport protocol would be standard with
manufacturers and experimentersÂ* able to innovate on top of that basic
capability. There would be plenty of room to compete based on special
features but all radios would interoperate at a basic level. You know, kind
of like analog FM.


Then we could be locked in a present day set of protocols, and in 10 years
would be wondering why we are stuck with these obsolete protocols while on-line
protocols are so much better in quality and compression. Similarly, we would
be stuck with the modulation method, while the multi-carrier COFDM folks would
be running data at 5 to 10 times the data rate in the same bandwidth (or some
such, recognizing Shannon limitations).


But, I agree with the advantage of analog FM. We can quickly tell how well
the signal is doing by listening to it. Everyone can do it. Bandwidth used
is reasonable. I don't see why we would want to go away from it.


Alan



Technology in digital communications changes rapidly enough that to be
worthwhile, a radio implementing a digital communications standard would
have to be at least firmware-updatable to incorporate new and improved
protocols and CODEC's. You would not only need agreements about
protocols, you would also need vendor support for upgrades.
Software-Defined Radios (SDR's) can inherently do this, so are probably
why most digital experimentation in amateur radio uses SDR's.

Some digital encoding standards can be engineered with
backwards-compatible upgrades, supporting all receivers even if not
updated. For example, AAC Plus (used by Sirius/XM) is
backwards-compatible with AAC, so an AAC radio can receive AAC Plus,
just without the benefit of the audio-quality improvements. Some
Sirius/XM receivers can even receive and update their CODEC's over the
broadcast channel (perhaps not sufficiently practical or secure for an
ad-hoc communications system like amateur radio).

Another idea would be some sort of protocol negotiation between radios
to find the best CODEC that both of them will support (perhaps with the
option to drop all the way down to analog, if necessary). Ideally, this
should only be necessary at the start of communications, or between
radios that have been positively ID'd about their supported CODEC's
during previous communications.

(73, Paul, K3FU)

- --
Paul W. Schleck

http://www.novia.net/~pschleck/
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