D-Star Open  Source / Dextra project  by Scott Lawson, KI4LKF

His D-Star work spawned from his rtpdir bridge project of 2007 and at some point in 2013 he discontinued his work and was no longer answering emails.

While Scott may be gone from the development scene, fortunately a lot of his software has been archived and mirrored.  His code has also been the base for several forked projects, that are derived from his initial work.

The D-Star implementations of his project moved around many times.  

He coded the first Open D-Star G2 gateway + repeater.  As well as first open source GMSK node adapter repeater / hotspot software.
D-Star G2 Gwy and DSTAR rptr with GMSK RF: register a DSTAR rptr, DSTAR routing, link to Reflectors, DSTAR local RF/GMSK, TRUST server updates.
It runs as a D STAR G2 Gwy/Rptr not like a fake like Dplus hotspot.

His original rpt_dir project ran into opposition first from Robin Cutshaw, AA4RC as that is how it tied in to D-Star.  Robin's Dplus protocol wasn't documented, but Scott figured it out.  That feud fueled Scott to write Dextra, an open replacement for Dplus.  But since dextra was still the underdog, he later he tried to link it at the G2 gateway level.   Same basic issue, the trust server guys and him didn't play well together.  So he wrote an open G2, and when he exposed how flawed that was, some German guys came up with ircddb.  There was no way to tie a home brew D-star repeater into any network until his work came about.  His work likely inspired Jonathan, G4KLX who started developing GPL'ed D-Star software in January 2009 and actually worked with Scott for a short time.

Going back to the non D-Star side of things with rptdir, Scott showed IRLP, Echolink and Allstar could all play together.  I think the only group open minded enough to work with Scott's idea was the Allstar/app_rpt guys.  Code was added to Allstar in 2008 with (David Cameron, VE7LTD's permission) to link all three.  Scott's rptdir was the proof of concept.  

And in 2007 the ARRL released an "seems to us" interoperability statement, that likely helped encourage these groups to work together.

In 2012 David Cameron requested support and functionality for IRLP connectivity be officially dropped from the app_rpt/Allstar project.    There were  "cease and desist" notices that Dave Cameron was sending, saying IRLP was a trademark. Ironically trademark/patent/copyright searches in the USA and Canada show nothing.

Some Background:

While the D-STAR specification does use a proprietary vocoder (AMBE), the actual specification (for on air) is open (though you need to be able to read Japanese for the full specification), as developed by the Japanese Amateur Radio League (JARL).

All of the non-air protocol callsign routing functionality of the Icom proprietary gateway software, as well as the proprietary D-Plus add-on have all since been reverse engineered, and mostly all by Scott.

The AMBE chip can be bought in single quantities from DVSI for $20, or one can use the DV Dongle developed by Robin, AA4RC, and Moe, AE4JY. or the new DVSI USB 3K

There is an open source replacement codec in development called codec2, being developed by David, VK5DGR and endorsed by Bruce Perins, K5BP.  However this is expected to be incompatible with the AMBE codec chip in the Icom Radios.  An interesting open source Digital Speech decoder program does decode some DVSI codec's, but does also have some possible patent infringements as this time.

It should be noted there were some personality clashes in his development efforts.  Scott's development/testing methodology differed greatly from those of the USTrust/K5TIT and the D-Star add-on Dplus by AA4RC.  Both USTRUST and Dplus teams are focused on reliability and stability of their TRUST.

Dextra was a response to DPLUS, Scott wanted to ride on DPLUS (interoperate), but a feud exploded between the two authors.  

However there are also portions of the community that have different needs and requirements.  Scott filled that need by creating Dplus replacement tools like Dextra, and a whole splinter experimentally minded D-Star network (using his open source G2 gateway code) called the multi-trust, which has its own reflectors based on his system called DExtra. It's similar to DPlus but with a completely open protocol. It includes D-Star repeaters using sound cards connected to radios as well as the GMSK node adapter.

His software, network and footwork encourages development of homebrew hardware and software solutions and aims to give developers a network to connect their systems to which has fewer restrictions.

Not being able to connect in at the D-Plus layer led Scott to investigate connecting at a G2 Gateway layer.  Discovering that callsign routing updates were sometimes taking up to 2 hours, and the closed nature of the Icom/USTRUST/K5TIT trust prompted him to write his Open G2.  An open source replacement to the $300 ICOM RS-RP2-G2 D-Star repeater gateway software.

This led to the development of X-Trust/Multi-Trust Network.  The Xtrust network which is centered on activity in Germany and other parts of Europe.

The X-Trust/Multi-Trust system uses a distributed architecture, using multiple Trust Servers which have synchronized databases, each Trust Server then supports the gateways in the usual G2 form. Users can connect using G2 routing throughout the X-Trust/Multi-Trust network in the normal way, as far as the end user is concerned there is no difference.

In the summer of 2010 a team of enterprising German hams (Hans Barthen, DL5DI, Michael Dirska, DL1BFF, and Jann Traschewski, DG8NGN ) released a D-STAR Gateway add-on software package that allows callsign routing to function between US-TRUST and non-TRUST users.  The software uses “irc” (Internet Relay Chat) protocol to share data.  

The user does not need to take any action or change any behavior to take advantage of the update.  All of the work is “behind the scenes”.  It does make callsign routing more valuable, since subscribing Gateways can track the last repeater a user accessed with almost no delay.

http://ircddb.net/ For more information and a list of subscribing Gateways.  There is an English language explanation available in the links on the left of the home-page.

http://download.ircddb.net/tools/dextra_ng/ For support to connect to XFR conference reflectors

http://www.va3uv.com/Vulnerability.htm - A very interesting observation about D-Plus.

Michael, DL1BFF and Scott collaborated to write g2_ircddb used at D-STAR repeaters to take advantage of the ircDDB network.


Miscellaneous Archived KI4LKF Software:

rptr_v2.93_Linux.zip - DSTAR Repeater for GMSK Modems 

open_G2_srv.tgz - OpenG2 Gateway that can accept one of the following as repeater controller: rptr/GMSK modem repeater by KI4LKF & DG1HT, or the ICOM RP2C repeater controller hardware, or Jonathan, G4KLX's sound FOB repeater program plus board.


mux.tgz - version 1.14 - rptr_mux (Repeater Multiplexer)  acts as the intermediary between Icom G2 and the home brew system.  It multiplexes repeater bands A,B,C of only one repeater
under one G2 Gateway. It does the same job as the ICOM RP2C repeater controler, but it does it in software only.

dplus_client_win.zip - package for connecting to the D-STAR/dplus network with a DV Dongle

dplus_client_linux-3.4.zip -  package for connecting to the D-STAR/dplus network with a DV Dongle

The D-Star Hot Point software converts your radio station to a dstar RF gateway. It uses your d-star dongle, an analog base radio and a radio interface like a rigblaster, VA3TO, or ULI, signalLink or WB2REM or any USB interface board or RASCAL,...

The software will use RTS or DTR to key up the base radio. For COS, the software will try to detect CTS or DSR or CD. (Instead of COS, you can use VOX with the VOX threshold).

The basic setup is, you will have a analog base radio at your QTH attached to your computer (Linux or Windows) thru the radio interface(rigblaster,ULI board, signalLink,WB2REM,VA3TO,USB-based adapter).

Any local RF user tuned to your base radio's frequency will access the dstar network, because the dstar_hot_point software will open a connection to a remote D-Star node. You will be able to control the dstar_hot_point software and command it to disconnect or connect to any remote dstar node you want, by using DTMF tones on your HT.

Also, the dstar_hot_point software allows you to use the computer MIC and speakers if you do not want to use a radio.

DSTAR Gateway D-Extra (R2G2_X) V1.21 Windows Linux
DSTAR Gateway D-Plus (R2G2_P) Windows Linux
DSTAR Reflector List in the XREF network README

The r2g2_x and r2g2_xr are DSTAR Spot (to link to Reflectors) programs used with the DSTAR repeater software rptr/Linux or rptr_win/Windows in combination with the GMSK modem/adapter/USB device

Software packages described:

rtpDir - software bridge for D-Star, IRLP, Echolink, Asterisk VoIP networks.  
chan_dstar - D-Star channel driver for AsteriskRequires a DV dongle to convert analog to digital audio and back
dextra_srv - software is Open Source and it is the G2 add-on linking tool  for linking ICOM G2 dstar Gateways to Open Source DSTAR reflectors.
rptr - software to build D-Star repeaters/nodes using a GMSK modem/adapter
dvrptr - software to build D-Star repeaters/nodes using a DVRPTR board version 1, firmware 1.10e
dvrptr2 - software to build D-Star repeaters/nodes using a DVRPTR board version 1 or DVRPTR board version 2, firmware X-DVRPTR
dvap_rptr - software to build D-Star repeaters/nodes using a DVAP dongle
snd_rptr - software to build D-Star repeaters/nodes using the computer's sound card, or a USB sound fob
- the software to use to create open source G2 DSTAR Reflectors (XRF reflectors)
G2_dstarNet - STN group server/gateway for the Dstar G2 gateway protocol and ircDDB routing. 
g2_ircddb / ircddb-gateway -  a Dstar G2 gateway for the Dstar network with ircDDB routing and USroot routing, adapted from the OpenG2 
g2_link - for home-brew systems and ICOM systems not affiliated with USroot
r2g2 - a Dstar HotSpotNode program for connecting to DCS reflectors. It follows the ICOM G2 Dstar protocol.
XRF_addon_for_ICOM_RP2C - does the XRF linking/unlinking, for the ICOM G2-RP2C gateways, or USroot Gateways.
dstar_hot_point -  It uses your D-Star dongle, or analog base radio to create a D-Star RF gateway
dplus_client - software to use a DV dongle to connect via D-Plus.
dplus_streamer - used to stream D-STAR audio to a web server.
- acts as the intermediary between Icom G2 and the home brew system.  It multiplexes repeater bands A,B,C of only one repeater under one G2 Gateway. It does the same job as the ICOM RP2C repeater controler, but it does it in software only.
- does the XRF linking/unlinking, for the ICOM G2-RP2C gateways, or USroot Gateways.
dextra_reflect - software for creating D-Star reflectors. 




Full collection of Scott's software



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