Getting on GreenCube Satellite, part 2

As said in the last email, chasing satellites is an addictive fun. There is something magical about bouncing signals off a 10x10x20cm box, appearing on the horizon 10,000km away. Amateur radio at it’s best – especially if you are a bit of a thinker or a nerd.

Lets talk about the hardware. The best radio to chase satellites is IC-9700. Tribander, plenty of power, full duplex (which enables you to transmit on the main band while receiving on the sub band). Everything else is a messy compromise.

Antenna: most of the GreenCube chasers in VK and ZL are using the Diamond A430S15. Lightweight 15 element yagi with 14.8dBi gain. There is no need or reason to go either smaller or larger. It is necessary to have the antenna steadily directed (can not be held in hand!) so you also need a tripod. I use my old cheap camera tripod with a simple home-made mount which allows elevation adjustment. Again, GreenCube is a 432 / 432 MHz digipeater, so you just need one 70cm antenna.

Power source: again, in today’s day and age, a LiFePo battery is the only way to go. 12.8V 30AH (around $250 plus charger) will provide hours of sat on-air time. Lightweight for capacity!

A short length of coax, 3-5m with N connector at one end and PL259 at antenna end, and you are done. I assume you already have a laptop.

There are three applications which you need to install, but more about that in detail in the next instalment.

For now, let’s focus on an app called ISS Detector. Download it and install it on your mobile phone. ISS Detector is primarily designed to track the International Space Station, but it also tracks hundreds of other flying (and stationary) objects in the sky. It is an essential tool for GreenCube sat chasers.

Upon installation, hide all except for IO-117, which is the official name for GreenCube sat.

There are a few windows. The main one shows next passes as well as maximum elevation for a given pass, so you can plan your activity.  The next window shows when and where the sat is appearing as well as it’s trajectory over the sky, so you can aim your antenna at it. A few degrees here and there are not a problem. Actually, once you point your antenna at sat, it will remain in your bandwidth for a few minutes.

Of course, for the app to work you have to enter your location and set a few other parameters, but it is all straight forward. I suggest you install it now, and play with it while awaiting your hardware. Keep in mind that a compass built into your mobile phone could be finicky. On a new portable location, an old fashioned compass is your best friend!

As per the screen: the satellite will appear in a NW direction, at horizon (0 deg elevation) then travel to the SE, while the elevation will gradually increase to max 50 or so degrees at apex. Easy!

While ISS Detector is a free app, do yourself a favour and go for the paid version ($5 or so). The adverts are annoying and distracting.

To be continued…