Packet Radio Using Remote Control Through SSH Server

Recently I have been messing with APRS and other packet radio transmissions, and I haven’t really found it to be all that enjoyable in its present form. Don’t get me wrong. I have had plenty of fun with it, but it hasn’t been what I want to do. My previous articles about getting Xastir up and running and sending packets through the ISS show that I enjoyed what I was doing, but the problem is that neither situations were very convenient. With APRS, I had to start up a laptop and initialize the TNC or I had to keep it running and risk killing the car battery. With the ISS I had to be ready to go at a moment’s notice, and since many of the passes were during work hours, I was not able to leave and drive to the clearing to make contact. Now, I think I’ve come up with a solution.

I purchased a power supply from a member of my local club, so now I am ready to run my mobile radio from my shack. I cleaned all of the equipment from the Jeep and took it to the shack. Before I left for work, today, I quickly plugged the TNC into an open serial port on the back of my Ubuntu file/print/ssh server, and turned it on.

At break time, I opened up Putty on my Windows machine and SSHed into my server at home and ran Minicom. Since the TNC was already running, I typed in ‘U’ and the TNC printed my unproto settings. “SCORE!!!!!” I was now in remote control of my TNC. Sadly, I do not have my radio ready to go, but I will in the near future. I’m waiting on a shipment of Anderson Powerpole connectors at this time.

As a side note, here’s how my server works. A few times a day, the server queries for my IP address that is assigned by my ISP’s dynamic DNS service. It puts this information into a text file. Next, the server compares the IP address to the previous IP address. If there is a difference in the IP address, another job sends out an email to me with the new IP address. It’s amazing what you can do with a CRONjob (an automatic task scheduler in Linux) and a couple of scripts. My cell phone has my email checked, and I scroll through to find the latest IP address. No matter where I am, as long as my server is running properly I know right when the IP address changes. Using either Putty or a Linux terminal I can easily access my computer from anywhere in the world that allows it.

Once I have my radio in the shack and powered up, I’ll test this from my other computer located in the shack. If it works, I will be able to take a shot at communicating with the ISS at any time of day. I could wake up in the middle of the night and fire up a terminal without having to leave my bed. Perhaps now I need to design a power strip that I can control using commands from a serial port. If the radio turned on automatically when power was applied, I’d be in good shape.

Part 97.109

(a) Each amateur station must have at least one control point.

(b) When a station is being locally controlled, the control operator must be at the control point. Any station may be locally controlled.

(c) When a station is being remotely controlled, the control operator must be at the control point. Any station may be remotely controlled.

(d) When a station is being automatically controlled, the control operator need not be at the control point. Only stations specifically designated elsewhere in this part may be automatically controlled. Automatic control must cease upon notification by a District Director that the station is transmitting improperly or causing harmful interference to other stations. Automatic control must not be resumed without prior approval of the District Director.

According to the above rules, the type of control being performed in this description is legal. I am the control operator, and my SSH window is the control point. Only I know how to access my server, and that procedure is a secret only to me. You’d have to know my IP address, port, username, and my password to be able to access this system.

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.