DSTAR plus Asterisk based conference bridge - A beginning.
- [Background for those seeing this subject for the first time:
There is a project to use the open sourced Asterisk PBX as conference bridge between multiple amateur radio networks such as IRLP and Echolink. One of the key authors, whom this email is addressed to, has expressed an interest in extending this work to include DSTAR. This has great opportunities, especially in providing interoperability for major networks, EMCOMM and otherwise.
The primary discussion group for the project "rptDir" is http://tech.groups.yahoo.com/group/rtpDir/ - all interested parties should join this group for continued discussion.
PLEASE DO NOT REPLY TO ALL OF THE ABOVE ADDRESSES - Join the rtpDir group and reply there.]
In response to your query, Icom will probably not be your best resource for developing the codec module for DSTAR, nor what I will call channel_DSTAR, the channel for communicating from rptDir to DSTAR.
The CODEC module:
The DSTAR Codec is a patented hardware solution using the AMBE protocol. This chip is relatively inexpensive at about US$20, however the chip by itself isn't of much use, it needs to be interfaced to the PBX. Eventually, I would love to see a pluggable card with an array of these chips for use in Asterisk based systems such as rtpDir. In the meantime, there is a great tool in a USB2.0 attached device called the "DV Dongle" (http://dvdongle.com) which is available through major Ham Radio outlets such as HRO and AES. This product has a Java based user tool called "DVTOOL" written by AA4RC (aa4rc@...). The low level driver code is available from Moe Wheatley, AE4JY, at http://www.moetronix.com/dvdongle/index.htm to get you started on the CODEC/Vocoder module.
The Channel (channel_DSTAR):
For channel_DSTAR, there is a lot to the protocol, starting with the JARL specification, a portion of which is at http://www.arrl.org/FandES/field/regulations/techchar/D-STAR.pdf (the complete protocol is available from the JARL - it would be very helpful is Kanji skilled, native english speaker or speakers, would undertake a full translation -- any volunteers?). Fortunately there are experts in all levels of the protocol, most notably Robin AA4RC, aka "Mr. Packet Sniffer".
channel_DSTAR will have more potential capabilities than you have heretofore experienced with IRLP and Echolink. You can address individual radios by callsign (think assign a DID or extension to a radio - 360-555-1212 <-> WA7XXX [free area code 360,425,253, and 206 DIDs are available from IPKALL.COM]), a repeater, a multi-cast group of repeaters, DSTAR reflectors (like IRLP reflectors), or to individual DV Dongles. The DV DSTAR protocol also has a data subchannel (not error corrected) for messaging; e.g. SIP messaging, control, GPS coordinates, chat, text, that is fully interleaved with the AMBE voice signal.
Once the channel is properly created the whole power of Asterisk can be brought to play; conference bridges, interactive voice response, call out, autopatch, voice recognition (could really help with the routing issues between DSTAR and Analog - see: http://k7ve.ampr.org/index.php?option=com_content&task=view&id=19&Itemid=26), follow me (call a station on DSTAR and if the amateur operator isn't available on the radio, ring his phone), on and on ....
Many of us will be behind your efforts, and please, please make your work open source. Let us know what we can do to help, code, testing, documentation, loan of equipment, etc. (You may get some resistance from the net paranoid, but open source is the best way to get both security and quality and if someone really wants to take down a system, there a plenty of ways to do it without knowing the network's protocols.)
My SIP address is below if you want to call and discuss this further. I have spent a fair amount of time thinking about it for around 2 years, but have not had some of the tools or time to push through a project.
73 de K7VE--