AX.25
Hank Oredson
"Ian" <ian....@att.net> wrote in message
news:3f310dde.03101...@posting.google.com...
> Greetings,
>
> I'm part of a student team working on developing AX.25 code
> for an amature satellite application. We have been considering
> both versions 2.0 and 2.2 but are not clear on the differences
> between the two, if any. Does anyone have a good enough
> understanding to explain them to me? Thank you.
That would be a good homework project, but not really all
that useful, just implement using the 2.2 specification.
Consider adding the PE1CHL enhancements, per the ARRL
networking conference procedings, Volume 14 I think.
Might as well design for these from the start, the protocol
works much better if you include them:
Extended sequence numbers via SABME.
No fixed maximum frame size.
Adaptive FRACK via measured RTT.
Slow start a la TCP.
Selective reject and out-of-sequuece receive frame queueing.
Good research projects:
Adaptive frame size.
Is FRMR really useful?
There is a good deal of source code available, some good,
some very bad. Google will turn it up for you.
--
... Hank
Hank: http://horedson.home.att.net
W0RLI: http://w0rli.home.att.net
Timothy J Salo
Ian <ian....@att.net> wrote:
>I'm part of a student team working on developing AX.25 code
>for an amature satellite application. We have been considering
>both versions 2.0 and 2.2 but are not clear on the differences
>between the two, if any. Does anyone have a good enough
>understanding to explain them to me? Thank you.
One answer is that 2.0 was implemented and used, while 2.2 by and
large was neither implemented or used.
In this day and age, you might consider simply using IP for
satellite communications. A good place to start might be:
http://ipinspace.gsfc.nasa.gov/
-tjs
Clive Wallis
> >I'm part of a student team working on developing AX.25 code
> >for an amature satellite application. We have been considering
> >both versions 2.0 and 2.2 but are not clear on the differences
> >between the two, if any. Does anyone have a good enough
> >understanding to explain them to me? Thank you.
For any amateur satellite application it's very important to get advice
and help from the amateur satellite community, to ensure that your
project uses acceptable protocols. This will smooth the way to a
successful mission.
I suggest that you post your requirements to the AMSAT-BB mailing list.
This will enable you to contact many experts in this field.
The join AMSAT-BB, send an e-mail to majo...@amsat.org, subject ... help
content ... help. The reply will tell you how to join.
For further details look on www.amsat.org
Let me know if you need any more help.
73
Clive G3CWV AMSAT-UK 2221
Hitchin, North Hertfordshire, UK.