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[aprssig] D710 GPS Port

Scott Miller scott at opentrac.org
Tue Aug 14 17:46:51 UTC 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:

Licensing

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.

Scott
N1VG


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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