International Space Station

Last weekend I attended the RMHAM-U lecture series and heard a talk by Doug Tabor N6UA about working amateur satellites, or AMSAT. I had been exposed to the idea while studying for the exams, but hadn’t really given much serious thought to actually doing it. The talk was illuminating in terms of operating concepts and concrete operating procedures. It turns out, there’s a pretty low barrier to entry to get into AMSAT since it’s low power, line of site, and many satellites use UHF and VHF where even technician licensees can operate. Something as simple as an HT with a long whip antenna can suffice.

The tricky parts are pass prediction, antenna tracking and Doppler shift. Pass prediction is made vastly simpler by smartphone apps, but the satellites don’t always pass directly overhead, so some orienteering is required. Tracking, i.e. pointing the antenna, can be done by hand, but if you’re operating by yourself then the antenna always uses up one hand. Then there’s the Doppler shift: the satellite is operating on a particular frequency (an entire sub-band, actually), but it’s moving fast enough that one has to tune the receive and transmit frequencies slightly off of the desired frequency and continuously adjust throughout the pass of the satellite.

Did I mention that most passes are 15 minutes maximum? An operator has to be extremely efficient and precise to get contacts. There’s equipment and software to automate all of this, of course, if you have money to burn.

The talk turned out to be timely, because a few days later on the RMHAM mailing list, a call went out for volunteers to help a local high school (JFK in Denver) with an ARISS contact proposal. How could I say no helping kids use ham radio to talk to astronauts in space? ARISS and NASA want to make darn sure that astronauts’ time is not wasted on technical difficulties, so they have more stringent equipment requirements than your usual AMSAT operator. However, I’m working with Bob Sterner KB0BS who among many things has done a tele-bridge ARISS contact (video), worked AMSATs and has the proper equipment. I’ve offered to do as much of the paperwork as I can, and watch and learn the technical side. Even if we’re selected, the contact wouldn’t be for at least 8 months, but it’s still exciting!