On Thu, Nov 5, 2009 at 8:40 AM, Alan P. Biddle APBIDDLE@united.net wrote:

There is a very interesting video on management of a satellite so as not to waste energy transmitting "to whales and penguins."  Not new, but a good discussion of the concept and implementation.

http://www.southgatearc.org/news/november2009/satellite_power_saving.htm

Alan WA4SCA

Thanks, Alan --

I'd like to include notes on previous implementations of this idea in the website, but as a hobbyist, I wasn't able to find info on this. I'd appreciate any institutional memory folks can offer.

Also, not mentioned in the video is just how easy it is for people to play with these ideas on their own.

The underlying Plan13 library, as well as the one that stores keplerian elements in EEPROM, are featured in this video http://sites.google.com/site/qrptracker/ , at 1:33, we see the micro-controller run a demo, which is a Predict look-alike.

All the code is open source, published at http://code.google.com/p/qrptracker/ This is a SVN server, and I'd be happy to welcome people who'd like write access.

On the hardware side, an Arduino that will run this code (and leave half of its programming space for further ideas) is available for $20 - $30!

You can't go wrong with this model http://www.sparkfun.com/commerce/product_info.php?products_id=666 but if you think eventually you'd like to go to a breadboard set-up or a mini model (which fits nicely in an altoids box so you can hack on this during your commute :-), I recommend that the USB bridge be implemented off-board. Just be sure to get an arduino with an ATMega328 processor. The ATMega168's 16k of program space just isn't enough to store Plan 13 and do anything with it; whereas, the 328 leaves lots of space, even for a small operating system http://robotgroup.com.ar/noticias/20091102/duinos-sistema-operativo-multitar...

None of this is meant to be an argument in an Atmel vs. Microchip debate, since other considerations come into play in the final hardware choice for inflight micro-controllers. But with C++ libraries and (pretty well) C code, experiments in this context will be pretty portable.

Have fun & 73,

Bruce http://ve9qrp.blogspot.com/