At 12:35 PM +0200 9/26/06, Davide Vosti wrote:
I'm part of a student team delevoping ax.25 for a cubesat. I want to ask you if you advice to you this protocol or not,
AX.25 is still current, but before going too far into implementation you will want to consider the needs of your application. Connected mode in AX.25 doesn't scale very well for multiple user access to spacecraft, but it's reasonably appropriate for a single station uploading critical data.
Depending on what you're trying to do in your CubeSat, you might want to consider using the PACSAT Protocol Suite, which builds on AX.25. See http://www.amsat.org/amsat/sats/nk6k/msatpro.html for protocol documentation. There are several groundstation implementations available. This has been the standard for amateur store-and-forward digital satellites since AO-16 in 1990.
If your needs are more modest, you may be able to simply ignore most of AX.25 and use only AX.25 UI frames as datagrams. The APRS standard may or may not be relevant to your application.
Regardless of what you implement on top of AX.25, I would call your attention to the FX.25 protocol extension for FEC that was proposed by Jim McGuire KB3MPL of the StenSat group. It's still just a proposal, but it seems to have promise. http://eludium.stensat.org/mcguire/FX-25_01_06.pdf
We are developing ax.25 based on this document (http://www.nj7p.org/AX25.2.2-Jul%2098-3.pdf) but we have found that some information are missing... Do you have some others document?
That looks like the document, though I'm not sure of the status of the 2006 changes. I would assume that http://www.tapr.org/pub_ax25.html is the authoritative source for AX.25.
There's a TAPR mailing list for AX.25 discussions. That would probably be the best place to ask technical questions about AX.25 issues. https://lists.tapr.org/cgi-bin/mailman/listinfo/ax25-layer2
73 -Paul [email protected]