Wednesday, May 7, 2014

APRS Station On a Boat - Part 1

Since purchasing my boat last year I have been wanting to add a 2m radio on it to access local repeaters. Recently while playing with my Yaesu VX-8DR HT  I recent began to experiment with APRS. APRS functionality is built into the radio and is fairly easy to setup. While its usefulness with the built in antenna is minimal I was able to reach some digipeaters while outside with the radio. Connecting the radio to my roof mounted 2m J-Pole resulted in a huge improvement, the coverage area was significantly impressive with this setup. At this point I was hooked, I wanted APRS on my boat, if anything it would allow family and friends to see where I'm at via

For the new station, I wanted a simple reliable system with a permanent and rugged 2m mobile for use on my boat. The Alinco DR-135 was a contender as it has a TNC built directly into the radio. Another unique feature is it has the capability for an APRS module to be directly inserted into the radio itself replacing the TNC. With this installed and configured, I could pull NEMA 0183 data right off my SIMRAD NMEA network into the radio making it a standalone APRS device. Unfortunately none were on the used market at the moment so I will be keeping watch for one in the future.

The next option I liked would be for some older Yaesu mobiles including the FT-2400 and FT-2500m. Both of these radios are built better than the Alinco to military standards and have all necessary external hookups available through the 8pin RJ45 mic connector. This would make it an easy single cable interface to my TNC and laptop. Another option is the Yaseu FT-2600m which I ultimately purchased as I came across one for cheap. The 2600m does not use the older RJ45 mic connector, but it does have a DB9 serial connector on the back which also contains all the connections available for a TNC.

Another benefit to the three Yaesu radios is that they can be modded to allow TX from 134Mhz to 170Mhz allowing them to be used as a backup marine radio in an emergency. Transmitting on the marine band through the 2m antenna would not be a great idea, but since the marine and ham radio will be near each other, I could quickly swap antennas to my marine band antenna if the need were to ever occur.

For the TNC I ultimately decided on the TNC-X. It is available in kit form, is inexpensive, supports the KISS protocol, has a USB interface, and has great reviews. I hadn't built a kit in probably 15 years, but I found this kit to be a simple build taking about an hour.

For APRS software I chose Xastir. I found it to be the best Linux based APRS application available and is available built in the Fedora 19 repos, although I ended up building an rpm for the latest version anyways as the builds currently available were a few versions older. For testing, I plugged both my TNC-X and a Garmin GPS receiver into my laptop, fed the speaker output of my Yaesu ft-8100r into the TNC-X temporarily and configured Xastir for the two devices. Once setup I began immediately receiving APRS message data.

Right now I have been spending most of my time with clearing and de-winterizing my boat as I have a scheduled date with my marina next week to place it in the water, so not too much time will be spent installing the station until it is in the water. Once I do set it up, it will consist of a 2m marine antenna going to the Yaesu FT-2600m, the TNC-X, NMEA-0183 GPS data from my existing network, and a laptop running Xastir. While definitely not as compact as the Alinco solution would be, I always have a laptop on my boat anyway so it will not be a big deal.