[d-star] [Fwd: Fw: [illinoisdigitalham] Re: New D-STAR Radio Projects]

[Doug Reed]

A couple interesting points. The voice codec chip and the network
protocol work in progress.

73, Doug Reed, N0NAS.

-------- Original Message--------

From: moe_wheatley <ae4jy at bellsouth.net>
To: illinoisdigitalham at yahoogroups.com
Sent: Saturday, July 21, 2007 4:38:38 PM
Subject: [illinoisdigitalham] Re: Motorola Mototrbo vs D-Star?


--- In illinoisdigitalham at yahoogroups.com, "ANDY" <ajr6400 at ...> wrote:
>
> Not quite "homebrew", but intersting...
> 
> http://www.moetronix.com/dstar/
> 
> Andy..G6MRI....Available via GB7IC  B
>

Im not familiar with Mototrbo but have played a bit with dstar.  The
DVX project on my website i thought was homebrew but maybe I dont
know the definition.  I didn't make the IC's or components but did
the design, firmware, and PCB layout.

A key component in all these digital voice systems is the vocoder.
P25 uses IMBE from DVSI.  It costs $150K to get the rights to play
with that mode plus $5 a seat.  There is no off the shelf IC to do it.

DStar uses AMBE from DVSI.  Same $150K if you want the software
source but they do offer a single chip solution for $20 single qty
and are happy to sell to hams.  There seems to be a lot of hand
wringing because the DVSI chip's source code is not available to hack
and so hams should not use it.  I look at it as just another chip
like a Pentium processor or ethernet controller ic, who cares that I
dont have access to the chip's internal mask set as long as i am able
to use it however i want.

The Dstar protocol is all open and can be designed to with a little
work.  The internet backbone is also now understood and being
documented thanks to Robin,aa4rc.

Am working on two dstar related projects now.  One is now working and
is an "AMBE Dongle" which plugs into a PC usb port and looks like a
serial port.  The dongle contains an AMBE2020 chip and can be used
for voice compression/decompression using a PC.  This will allow
dstar operation using a pc and soundcard over the network or whatever.

The other project is a dstar GMSK modulator/demodulator that will
allow dstar operation using a non-icom radio. this project is still
in the planning stages.  The user interface is the kicker.

Someday i may get back to finishing the original DVX radio project
but alas time seems to be a diminishing resource :(

moe ae4jy