Sparkfun Weekend Recap

Over Christmas break I stumbled upon some classes listed on the Sparkfun website. Two of them happened to be scheduled over a three day weekend early in January. At approximately 16 hours, the drive from Edwardsville, IL to Boulder, CO couldn’t be much longer and still be truthfully be described as a “day trip.” But when else would I have a chance to learn about microcontrollers and programming in a classroom environment? I decided to make the journey and give the classes a try.

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First Contact: XBee Radios

XBee Series 2While this post may technically be off topic – I can’t really claim it’s connected to my Sprite or the KickSat in any direct way – I’ve decided to post it as its own project anyway. The XBee radios run off the Arduino microcontroller platform and interact using radio transmissions, so I thought I’d shoehorn them in after the last post about the Sprites’ wireless communications and following a stint of microcontroller talk.

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Captain’s Log, Stardate 12008.8

At the most general level, the KickSat project has two phases: writing the flight code for the chipsat and tracking the board once it reaches orbit. To date, most of my posts have focused on the first phase of the project. So, even though tracking the Sprite is far in the future, I’d like to take a post to explain some of the details of what that process will involve.

The Cornell team plans to track and record the transmissions of all Sprites that are deployed by the KickSat. In addition, the team intends to make all the information and software necessary for receiving signals from the Sprites readily available (whether the data will be made easily accessible to those with little technical knowledge of radio communication remains to be seen). The team will track the chipsats using the GENSO network, a worldwide network of university and amateur radio ground stations.

GENSO is organized by the Education Office of the European Space Agency with the support of the International Space Education Board. Over the past five years it’s been developed mainly by university students in Europe, Japan, and the United States. The network is composed of universities and amateur station operators running the GENSO Ground Station Server software. When a satellite passes within range of one of these ground stations, session data is recorded. After the session is authenticated by a central server, the data is forwarded to the owners of the satellite who are running the GENSO Mission Control Client software.

One advantage of using GENSO is that data can be recorded at several points in the satellite’s orbit instead of only during the limited time that the satellite is overhead. But it also means that someone else is tracking your satellite for you – and where’s the fun in that? The Cornell team has released more detailed information about the transmissions for those who are interested in receiving Sprite communications locally.

According to the KickSat website, the signals will be in the 70 cm band, which corresponds to approximately 437 MHz. The exact frequency must be coordinated with the International Amateur Radio Union, something that cannot be done until the KickSat has been slated for a specific launch. All the Sprites will be on the same frequency but will be uniquely identified by orthogonal pseudo-random noise spreading codes. The signals will be broadcast at about 10 dBm EIRP.

A yagi antenna, a rotator, a low-noise amplifier, and a software-defined radio are required in order to receive the Sprite’s signals locally. Software-defined radios can interface with computers and are designed to use software in order to perform functions that are traditionally performed by hardware. The Cornell team aims to make everything work with the FUNcube SDR, a dongle originally designed for a UK amateur radio educational cubesat. I can’t help but borrow their About image, as it explains it all:

FUNcube Concept