N1AHH

So many toys, so little time.

I have been writing a program that controls a radio. The radio is a Kenwood D-700, and one of these radios is carried on the International Space Station. Actually it is two radios in one. This Dual Band radio is designed for a unique amateur service called Amateur Position Reporting System (APRS). It is a digital mode that is sort of like text messaging on steroids. But more about that later.

The program provides automatic communication with the space station. When the space station is not above my horizon, the radio changes frequency and links into an amateur terrestrial network, providing a form of radio e-mail. It has taken me quite a bit of work to write and de-bug the program, but now it is working well. Yesterday I added a component that watches my solar charging system and monitors the battery charge.

Soon I will begin placing notices on the Space Station system that will advise interested hams that they can come to this blog to discuss the program and its application. You are invited to ride along and see what (if anything) happens. If you have used the link about our present position on the left side of this blog, you have seen the APRS system at work.

The program works like this. I use a very nice satellite tracking program called SatScape which provides, among other things, a list of times that the Space Station will be within radio range of my location (remember line of sight?). My program reads this information and at the correct time, switches to the space stations frequency, changes its mode to APRS and waits to hear the Space stations Beacon. When the program hears the beacon, it sends my beacon. Actually the beacon is a complex, but quite short digital burst crammed with information. It contains, my call sign, my location (accurate to about 15 feet), and then, in my case, a status message, “In Service” and a short text message. Usually something about it being an automated station. The space station, repeats my beacon. Some station on the ground, that is connected to the Internet, will hear the repeated beacon and pass the data thru to the Internet It then shows up on the Internet as a position report, about 3 seconds after I send it.

Other stations send similar beacons, although the details of their contents vary. If I were moving, it would send my location, speed, direction, altitude and more. If I happened to have weather instruments connected, it would send a complete weather report. There a a lot of beacon variations.

After sending my beacon, it watches the calls of other users. If I want to send a message to another user, I load the other persons call and a short message into the programs memory. If the program sees the other persons call being repeated from the Space Station, it sends the message to the space station which repeats it, sending the message to the other station. The other station receives the message and replies with an acknowledgment, which is repeated by the space station and the program hears and stores the acknowledgment.

When the space station moves beyond the horizon, the program changes the radios frequency and mode so that it can become a personal mailbox on the amateur terrestrial digital e-mail network.

It also watches the camper battery levels and displays a graph of the charge/discharge rate. We use solar panels for our electricity much of the time, although at the moment we are plugged into regular power. However between the various radios, computers and satellite Internet system, we use a bit of electricity and I need to monitor it closely. As long at the Space station program is running 7/24, I decided to add a few more things that need a computer running 7/24 as well.

So that is what has been providing a bit of “bubble gum” for my brain during the last several weeks. At some point, I will get back to the radio series, but it looks like it will be on hold until I get the radio control program running the way I want it.

I will get back to the radio series.....eventually.....

# posted by Ron @ 4:10 PM