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[aprssig] OT: DV Dongle a D-Star codec on USB.

Scott Miller scott at opentrac.org
Tue Jul 8 21:07:11 UTC 2008


That's still missing the point.  There is a LEGAL restriction here on 
the technology, not a technical restriction.  It's not about parts, it's 
about on-air data formats and interoperability.

This is a major problem for things like software defined radio.  DVSI 
will NOT license a PC-based version of the CODEC, presumably because it 
would be too easy for someone to reverse engineer.  If you want to build 
a D-STAR compatible SDR, you'll have to buy the hardware and physically 
install an AMBE2000 chip for each voice channel you want to decode, even 
if your SDR hardware happens to have enough processing power to decode a 
hundred channels at once.

With the possible exception of Pactor III (which has never pretended to 
be an open standard) I know of no other area in amateur radio where 
you'd find this sort of intellectual property lock-in.

Consider this unlikely scenario for a moment:  If DVSI decided they 
didn't want to allow use of AMBE on amateur bands, they would be 
completely within their legal rights to stop licensing it that way. 
There would be no technical workaround, no substituting parts, no making 
due with some compatible solution.  No matter what technical means you 
used to produce an AMBE data stream, it would infringe on their IP and 
they could sue your pants off.

Where else in the long history of amateur radio do you find that sort of 
absolute dependence on the IP of a single vendor?

I realize that to a lot of people there's a whole lot of magic in modern 
radio equipment.  Much of that RF stuff is still magic to me, but I've 
made the effort to learn about the digital side, and much of the analog 
stuff.  It's all out there in the textbooks, you can take classes on it, 
and you can build and experiment on your own.  You can spend years 
learning it all, but it can be learned and understood, and more 
importantly applied, adapted, and improved.

AX.25, HDLC, and Bell 202 hold no mystery for me anymore.  I learned 
what I could from others, and then built my own devices from the ground 
up, with my own components and methodology.  Given enough time, I know I 
could do the same with an FM transceiver.  I think this is a critical 
aspect of amateur radio.  But when you throw in something like the AMBE 
codec, you're leaving one inviolable block of magic in it.  And it's not 
something minor that you can build around - it's an absolutely critical 
piece of the system.

To commit to the use of AMBE in amateur systems is to admit that we no 
longer care about understanding how our equipment works.  It's the 
surest sign I can think of that we've resigned ourselves to being 
appliance operators and consumers rather than experimenters and innovators.

Scott
N1VG

John Habbinga wrote:
> You can build a D-STAR radio yourself.  Yes you have to buy a chip
> from a specific company, but that's not unusual in electronics.  There
> are all kinds of processors and integrated circuits that are patented
> and only available from one source.  Sometimes they'll stop making an
> IC and you have to redesign or discontinue your product.  I'm sure
> that's never happened to you.
> 
> If you want to homebrew a D-STAR radio, you should check out
> http://www.moetronix.com/dstar/
> 
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