Xastir and my KAM TNC (Went with KISS mode)

I found something to occupy my time the last couple of days. I got tired of typing my own APRS positions into a document and sending raw packets to report my position (@240805/3108.03N/08343.16W>000/000/Robbie kk4fgm.com…). Every time I came to a stop at a parking lot and before I exited the vehicle, I took a look at the GPS and the clock and typed the information into a document. Then I sent the raw data in GtkTerm to the TNC. It made my wife mad to have to wait the three to five minutes once we arrived at a destination. Frankly, it made me even more mad because I had to wait for the GPS, open a terminal and VIM a file, then type in the commands to the TNC. I knew that I was going to have to find an automatic program to do this for me. That program is Xastir.

What I didn’t realize was what kind of flaming hoops I was going to have to juggle to get it working. The gui and setup operation of Xastir is simple, but the interaction with my TNC was not. I had everything working with the exception of the TNC communication. Xastir sent commands just fine, but when it came time to send my position, the TNC never entered CONVERSE (k) mode. I’m not sure whether Xastir or the TNC is to blame, but either way it wasn’t working. Xastir sent the ‘k’ command, which works when I manually enter it, but my TNC just says “eh?”. I finally gave up on trying to set up the TNC that way last night.

What I decided to do was to set the TNC to KISS mode. Forget about all that initialization and stuff associated with using the TNC as I would manually do it! I didn’t realize that KISS mode was so nice. I enter ‘INTERFACE KISS’, and then do a soft reset ‘RESET’, and the TNC is ready to roll without any hiccups. I would set the TNC to start up in KISS mode, but my laptop only has the “weird num pad” that I don’t want to rely on to get the TNC out of KISS mode. I’ll just manually enter KISS mode when the TNC is powered on.

The laptop and the TNC are plugged into a dc-ac inverter. I have a dc cable for the TNC, but I don’t want to splice my radio’s power supply cable right now. If the TNC tends to lose power when I crank the Jeep and I get annoyed with having to restart KISS mode, perhaps on that day I will splice and dice. Until that day I am happy with what I have.

In related news. The pictures peppered in this article are of my Garmin eTrex. I rewired the cable that I bought using a credit card instead of the pFranc knockoff that I had on there. The Chinese connector broke shortly after I bought it. That’s the chance you take on eBay. No worries. Another slice and dice moment, a Carnival cruise card, and some hot glue set me straight. I have DC power to run my GPS 24/7/364.25. I have just enough battery power in it to keep it powered if my son pulls the plug.

I have Xastir set to report my position every 7 minutes. At interstate speeds that would be around 6 miles per report. In town it could be 2 to 5 miles and might even show me with a last position in a weird spot since I turn my radio off before I leave the vehicle. The laptop is in the back seat of the Commander, and I don’t plan to run back there to send a final position report unless the situation calls for it.

Gripe time: Xastir’s open source code is cool. I poured through it trying to figure out a way to out a pause in between the control-c command and the next command going to the TNC, but I got tired of looking through thousands of lines of code. I just don’t have the time to do that kind of stuff right now. I did compile my copy in Ubuntu 10.04 manually, but now that I know what I know, I would save myself the time and trouble and just install it from the Ubuntu repository using ‘apt-get install’. All in all, I can go to sleep early knowing that my APRS works now.

About robbie

I am an electronics enthusiest and a ham radio operator (W1RCP). I like to play with electronics. It's fun and educational. I looked forward to working in the engineering field in the future. I have a BS in Electronics Engineering Technology from DeVry University. I also have an Associate's degree in Marketing Management from Moultrie Tech, and a diploma in Electronics from MTC.