I’ve been reading about the AMSAT Fox Project, an initiative to deploy small next-generation “cubesats”. The website includes several PowerPoint presentations on the design, testing, and engineering of these birds. A lot of work goes into building a satellite, and the number of considerations is just mind-boggling, with concerns about heat, materials, radiation, and resiliency to failures to name a few. This really is “rocket science.”
I’ve been thinking about a more down-to-Earth project for guys like me who aren’t rocket scientists but are intrigued with little devices like these. I’m not sure what to call this yet (perhaps “CubeCache” or “RadioCache”?), but the idea combines geocaching, fox hunting, beacons, microcontrollers, and a touch of repeaters all in one bundle. Imagine if you could build a tiny device similar to a cubesat and place it somewhere stealthy and have it act like a multi-purpose beacon, a simplex repeater, a fox transmitter, and a data gathering on-the-air geocache. The little box would have a small self-contained battery and be equipped with solar cells for charging them. A microcontroller would control all functions of the unit. During low battery times, the microcontroller would put the unit in power-saving sleep mode, turning off all modules. The unit would have a transmitter and receiver, and a second receiver for telecommand functions to comply with FCC rules.
The unit would have several modes. It would announce itself like a beacon periodically. It would act as a “radio geocache” and would receive digital callsign messages and acknowledge them, storing them in memory for later retrieval. The unit could also act like a real geocache, but with a twist. Users could activate fox mode and radio direction find their way to the unit.
Building such a unit would present some technical challenges. The first would be stuffing everything into a small, weatherproof package that can withstand the elements. Much like geocaches, the unit would have to be stealthy both in construction and placement to avoid being found by “muggles”, the geocaching term for people who are not geocachers. Power management is another challenge, with the need to keep track of battery capacity and make the best use of power. With an experimental project like this, it’s likely the microcontroller software would be changing quite frequently to improve performance and add new features, so a remote over-the-air firmware uploader and bootloader would be helpful.
I’m sure some will ask what the point would be of building such a contraption. Much like a lot of what we do in amateur radio, there often isn’t much of a point other than to experiment, learn, and have some fun. I may explore this idea further in 2012 and build a very simple prototype, place it in my backyard and see where this project goes. If anyone is interested in helping develop this idea, please let me know.
It could use a pseudo-random receive frequency for the telecommand component that utilizes something like the Google Authenticator app. The receive frequency would change based on a key every 3 minutes or something like that. This would make jamming the telecommand frequency essentially impractical.
I remember when we put a dual band HT capable of crossband repeat into a NEMA enclosure along with a decent gel-cel SLA, external BNC jack for the dual band HT duck antenna. I would go in on UHF simplex and come out on 2 simplex (not 52). I would transmit 1 minute long every 4 minutes. It was fun because I could be amongst the hunters watching them tear out of the parking lot to chase down the “fox box” as we called it.
– credit N0NPO for the box