On Dec 11, 2009, at 6:03 PM, Larry Rappaport wrote:
Yes, but so what? I don't mean to be a smartass, it's a really
genuine
question. Amateur radio has been analog forever. Most important is
the
word "radio". Certainly the internet component is not radio, and
there is
digital radio which is a combination of both digital and analog
techniques.
IRLP totally avoids the patent problem; and I can say, as one who has
investigated both, seems to come out far ahead.
I don't know what D-Star can do that IRLP can't. IRLP uses servers
which
have the ability to do all kinds of connections. IRLP puts the
fanciest
logic in the servers. D-Star puts it mostly in the radios
themselves. I
don't see the advantage, but D-Star certainly costs a lot more!
As I recall IRLP uses a CVSD (continuously variable slope delta
modulation) CODEC. CVSD is pretty archaic as CODECs go. It also
doesn't support signaling over the RF portion of the link except for
in-band DTMF. Not exactly 2010 technology (more like 1960).
I was looking at D-Star sometime back and it had some really glaring
holes that made my eyes go wide and had me saying WTF? One really
basic thing that was missing was a field in the header to allow one to
identify the type of payload. You need that when you want to run
different protocols above. Given that we want to send both voice and
data over the same link it seems an obvious need. That is just so
basic in any real networking protocol that I was shocked.
Amateur radio is no longer at the forefront of communications. If you
want to see how this stuff is done for real just reach into your
pocket and take our your mobile phone. There you have an I/Q
transceiver that is transmitting voice and data over a single digital
data link. It can carry several different types of payload at the same
time.
Of course, I am working from memory and very likely making a mistake.
--
73 de Brian, WB6RQN/J79BPL
Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com
PGP key ID: EEBBCEB1BD0671C0
PGP key fingerprint: 3E8B 35BC F840 3288 AAB4 9E44 EEBB CEB1 BD06 71C0
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