[ICOM] D-Star

[Gary Pearce KN4AQ]

At 11:33 PM 7/6/2007, you wrote:
>Can somebody define D-Star in a sentence or so?  Is it and expanded APRS?
>
>Thanks, Jim KG0KP


Can't do it in one or two, but I'll try to condense it.  Look for my 
article in QST in September for details:

D-STAR is a digital voice and data system for VHF/UHF, originated by the 
Japan Amateur Radio League. For voice, works more or less like conventional 
FM radios and repeaters - you push the mic button to talk, let go to 
listen, and your signal is relayed by the repeater on that tall building, 
tower or mountain. There are some differences, though.  The big one is that 
there is no "noise" - no mobile flutter or picket fencing.  You get a clear 
signal down to the threshold.  Signals at the threshold are subject to some 
"garble", but with just a little less signal, the receiver just cuts off.

D-STAR digital voice signals are totally incompatible with analog FM - they 
appear as "white noise," like open squelch, on an FM receiver. All current 
D-STAR radios, though, are dual-mode, and operate in conventional FM as 
well as digital modes. Icom's D-STAR repeaters are not dual-mode, and 
operate only in digital mode. At this time, Icom is the only manufacturer 
of D-STAR equipment, but the protocol is open, so anyone can build D-STAR. 
It uses an inexpensive AMBE vocoder for A to D conversion.  Icom has a 
pretty complete line of equipment including single and dual band HTs and 
mobiles, and repeaters for 144, 440 and 1200 MHz.

The repeaters can be networked via the Internet and/or 10 GHz links. You 
route your signal through the network by entering callsigns into your radio 
(via the front panel or a computer interface): your callsign, the call of 
the local repeater you want to talk through, and the call of the distant 
repeater you want to talk through. Or you can just enter the call of the 
individual STATION you want to talk to, and the network will find him or 
her based on the last time they keyed up a D-STAR networked repeater 
anywhere in the world.

On 2 meters and 70 cm, a "low speed" 1200 bps data signal rides along with 
the digital voice signal. You can use it for whatever you want - text 
messages, small files, GPS/APRS data.  D-STAR users are developing software 
programs to take advantage of this capability, and many are available now.

The 1200 MHz system also has a higher-speed data-only capability at 128 
kbps (ISDN speed, almost triple the best dial-up speeds, but well below 
typical broadband Internet connection speeds).  With this, an Internet 
connection at the repeater can be distributed to mobiles and fixed 
stations. The Icom ID-1 1200 MHz radio has an ethernet port, and when 
connected to a PC it appears as just another network. Open up a browser and 
surf the web (at moderate speed).

Again, details in the September QST, and at Icom's web site.

73,
Gary KN4AQ



ARVN: Amateur Radio//Video News
Gary Pearce KN4AQ
508 Spencer Crest Ct.
Cary, NC 27513
kn4aq at arvidnews.com
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