Summer 2008 Issue

FM

Report from Dayton

By Bob Witte, KØNR

Photo 1. Jim McClellan, N5MIJ, speaks to a packed crowd at this year’s Dayton Hamvention® D-STAR Forum.  (All photos by KØNR)

The Dayton Hamvention® is the “big one,” held in Dayton, Ohio in May and sponsored by the Dayton Amateur Radio Association (DARA). I was fortunate enough to attend the event again this year, and here is a report on some of the things I saw, with a VHF emphasis.

D-STAR Action

The VHF/UHF digital modulation format known as D-STAR continues to generate a high level of interest in the ham radio community. The D-STAR forum at Dayton was packed with attendees, even though it was held in one of the larger conference rooms. The forum was moderated by Greg Sarratt, W4OZK, with the Alabama D-STAR Group.

One major theme of the forum was the strong growth in D-STAR systems and users. According to Jim McClellan, N5MIJ, the number of D-STAR users showing up on the system has gone from 534 to 2400 in the past year (photo 1). The daily usage of gateway-connected D-STAR machines has gone from 100 users per day to 700 users per day. These numbers are small when compared to the total number of licensed amateurs, but they are growing at a very fast rate. To see the level of activity yourself, go to the D-STAR Users website listed in the References section of this column. This site has a real-time listing of stations active on D-STAR and plots of usage statistics on the D-STAR network.

Another key theme of the D-STAR forum was user education. D-STAR technology employs new methods of signal routing that your typical repeater user will need to learn. I won’t go into great detail here, but I’ll give you a rough idea of how the system works.

Each radio is programmed with four callsigns: MYCALL, URCALL, RPT1, and RPT2. MYCALL is the callsign of the radio user—that is, I program my radio with my call. URCALL is the radio amateur being contacted; it is the “other ham” in the QSO. You can enter a specific callsign as URCALL or use CQCQCQ to make a general call. RPT1 is generally the callsign of the repeater you are using locally, and RPT2 is a remote repeater. (This reminds me of programming an AX.25 packet TNC with your call and digipeater routing information.) There are a number of details that must be configured just right for the message routing to work, and I don’t think anyone claims that this is obvious. It requires some learning on the part of the user, and you’ll notice D-STAR system owners spending time educating their local radio community.

Most users are going to want to carefully set up their radios with the aid of programming software and use the memories to configured different callsign routing settings. Then flipping through memories will let the user call the right radio amateur or repeater system. With analog FM repeaters, the user has to select the right frequency, the right transmit offset, and (often) the right CTCSS access tone. Some users find this to be a challenge. With D-STAR you can forget the CTCSS tone, but you’ll also need to set up URCALL, RPT1, and RPT2 to get the right thing to happen. (MYCALL generally will just stay the same on a particular radio.)

There is no question that D-STAR really is a different animal, and it requires some learning on the part of repeater users. This is typical of new technology entering ham radio and is a fun part of the hobby. The D-STAR presentations given at Dayton are available on the ARRL Alabama Section website (see References), including information on the callsign settings. If you are interested in this technology, take some time to review those files.

One important development is that some technically-minded hams have reverse-engineered the D-STAR protocol, including specific ICOM implementation details. Robin Cutshaw, AA4RC, touched on this briefly in his presentation and a portion of his talk is available on youtube.com (see URL in References). One product that came out of this work is the DV Dongle, which enables a PC user to converse via the D-STAR network. Yes, that’s right: You can be sitting at your PC working radio hams on your favorite D-STAR repeater. This development shows that others (besides ICOM) can create products that conform to the D-STAR protocol and work with D-STAR radios and repeaters.
 

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