[aprssig] D710 GPS Port
scott at opentrac.org
Tue Aug 14 12:46:51 CDT 2007
See my last post about the state of the spec. I think it might be
enough (if you can read the bits of the PDF that seem to be missing a
Japanese font) to build a working system IF you had a working example to
start from and analyze.
The layer 1 stuff is REALLY sparse. It lists a modulation method of
GMSK, QPSK, or 4FSK, with a maximum data rate of 128 Kbps. That's it -
no more details on modulation, speed negotiation, or anything.
Plus, it uses the AMBE codec. From the Wikipedia article:
AMBE is controversial in that the licensing terms are very restrictive.
While a licensing fee is due for most codecs, DVSI does not disclose
software licensing terms. Anecdotal evidence suggests a minimum fee from
$100,000 to $1 Million. PC implementations are not allowed. For the
purposes of comparison, MP3's licensing starts at $15,000. For
small-scale use and prototyping, the only option is to purchase a
dedicated hardware IC from DVSI.
Now is that in any way in the spirit of ham radio? That the only way to
generate a compliant signal is to buy a dedicated IC, that comes with a
huge EULA and costs $33 in lots of 5?
Using a restricted, proprietary codec really irks me - ham radio's
always been about experimentation and homebrewing, about knowing how
your equipment works and being able to work to improve it. And here
Icom selects as a critical, central component a device that we're not
ALLOWED to try to understand, to duplicate, or to reverse-engineer.
I know a lot of people have already shelled out a significant amount of
money for D-Star equipment, but to be honest I really hope that it never
catches on. Every little proprietary black box we come to rely on is
another nail in the coffin of amateur radio.
William McKeehan wrote:
> As for the proprietary stuff, I thought the same thing until I read this
> months QST. They have a overview of D-star that says it's open to other
> manufactures. I was wondering if anyone is building D-star hardware like
> a HAMhud without the need for an Icom radio.
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