Waiting for Godot
Last week, we received a great picture from Nanoracks:
That’s astronaut Koichi Wakata, floating inside the International Space Station, next to the Nanoracks CubeSat Deployer, which contains SkyCube. That’s where your satellite has been waiting for the past 6 weeks since launch.
Before you ask “Where can I submit my tweet and image requests” - the answer is: “You can’t … yet.” The picture above is the reason why. As I’ve said all along, we’ll begin accepting those requests after the satellite is deployed and confirmed working on orbit. And that hasn’t happened quite yet.
In the meantime, we’ve been doing anything but waiting.
Ground Software Update
I’d like to introduce Robert Olivier. Robert joined the team last October, initially to develop a quick-and-dirty platform to let us test SkyCube with the MC3 and Saber Astro ground stations. Robert did such a good job that we retained him to redevelop our entire server infrastructure. Over the past few months, he’s done this. And last tuesday, we tested Robert’s rebuilt system with our spare satellite, “Omega”, at the MC3 ground station at the Naval Postgraduate School. By the end of the day, Robert’s server was transmitting commands and images reliably through MC3, to the ground station several miles away.
Based on other CubeSat teams’ experience, we expect to spend the first few weeks after deployment seeing how well the entire system actually performs on orbit. It’s a bit nerve-wracking; half of the 28 CubeSats deployed on the ORS-3 “warmup” launch last November have not yet been heard from in space. Odds like that do not engender confidence. Yet we have every reason to believe SkyCube will work. It passed all of our preflight tests and comm checks; and the “spare” unit is also communicating well.
But we expect that those first moments, listening for responses to the initial commands we transmit, will be pretty tense. Eat lots of peanuts.
Desktop PCs are now fast enough to record and process digitized radio samples, the same way they revolutionized digital audio processing and sound editing in the 1990s. Radio operates at much higher frequencies than audio, and so requires a lot more CPU power to process. Over the past few years, a small revolution in software defined radio (SDR) has taken place. Open-source software transforms inexpensive USB TV and FM radio tuners for desktop computers into general-purpose SDR devices.
SeeDeR is the brainchild of Team SkyCube’s own Scott Cutler. It began in 2012 as an experiment to see if these sub-$20 USB SDR devices could decode AX.25 data transmissions from SkyCube’s radio. And they worked! In the 18 months since, Scott has added many features to SeeDeR - a graphical user interface with a spectrum analyzer and “waterfall” diagram, support for many more USB SDR hardware devices, an automatic doppler-shift correction algorithm, and a full-blown Windows installer.
At our radio test last week, SeeDeR easily decoded AX.25 data transmissions from SkyCube’s twin, “omega”, at a couple miles’ range, using a 900 MHz Yagi antenna costing under $100. Signal levels suggest that the same system should work at orbital range. We’re not the only CubeSat team experimenting with this kind of technology: in the UK, the FunCube-1 CubeSat (AO-73) has been transmitting signals to radio amateurs around the world, who are listening with a similar USB software defined radio called the FunCube Dongle. (SeeDeR supports the FunCube dongle, by the way!)
We’re very close to releasing a public beta version of SeeDeR. To give it a spin, you’ll need a Windows PC, a USB SDR device (either FunCube Dongle, BladeRF, or RTL-SDR), and an antenna. If you’re interested in helping beta test, send Scott an email.
We’re getting very close. I hope you’re as excited as we are. The moment of truth is coming soon.
-Tim, Scott, Rouslan, Robert, Mark, and everyone else over at Team SkyCube.