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Re: AO40rcv and the Kenwood TS-2000

"Timothy J. Salo" wrote:
> The task of the IRLP project looks interesting.  However, I probably
> wouldn't use it as a model of protocol design.  If I understand correctly,
> they are encoding commands as ditigized DPMF audio tones and are using some
> special (and proprietary) hardware (the function of which isn't clear to
> me).
> My sympathy (sort of) to all the electrical engineers on the list who
> thought that satellites and amateur radio were just about hardware...

Great thread , lots of stuff that I can barely keep up with , but this
is one thing I -can- talk about :)

Ok , maybe not as techie as you folks would like , but oh well .......

Ok , so in a quick nutshell ( I am on my lunch hour ) how does IRLP play

Well there are what I will call modules that do their own thing , one is
the "DTMF" module , all it does is monitor the link radio ( local radio
) rx audio through a DTMF decoder chip which has its data lines
connected to lines on the parallel port , software is running that
monitors these lines as well as another line on the parallel port to
monitor COS/COR , when there is a valid COR/COS and there is DTMF coming
in then it compares this data to a lookup table which says , is this a
command to bring up a node or take one down and if so which node ( four
digits ) , or is it a command to do some special function that is
locally programmed ( through scripts ) .

So really the only "proprietary" device is the decoding/COS board , and
a handful of scripts and a couple of binaries to key the local radio (
also through the parallel port ) .

Then there is the functionality of digitizing audio to pass to the other
end , this is done with software called "speak freely " ( oh by the way
this whole system uses Linux as its 'OS for stability) and a handful of
scripts that bring up or down the "sfmike" or "sfspeaker" in that
software .

Each node has a .wav file which ID's that station when it connects to
another one , there are also "echo reflectors " which allow roundtable
"chats" between more than one node , but as has been said earlier this
is a bandwidth hog , though we are only using 8kc pcm sampling and have
great audio .
But since most of us are using dsl or cable modems the bandwidth used is
not an issue , for links using only RF this would obviously have to be
considered . 

So the operation of the system is connection based , it does require
knowing  what the other stations IP is , if you don't know this then you
can't connect of course .
This is accomplished by a central server that constantly updates all the
nodes "node tables" or hosts file  for you linux folks so that it always
knows where all the other nodes are without having to have them have a
real FQDN ( most of us use DHCP DSL so our IP's are always changing ) .

This system is by no means perfect , but it does work very well and at
the moment has over 70 nodes after only being up for about 2 years .

I am sure I left out some crucial bit , if you want to know more you can
ask Dave Cameron ( though he is very busy ) VE7LTD as he is the fellow
who is the spearhead of this group , I am just a lowly node
owner/operator , try the website http://www.irlp.net and poke around .

I don't think this would be something that we would want to do with
satellites but it may give you folks who know better something to chew
on so you could come up with your own setup/protocol/system .....

Anyway , back to the rockpile I go to bang on more radio's ;^}

Douglas Cole   N7BFS
Spokane IRLP node 
AMSAT#26182 , K2 # 544
Registered Linux user # 188922
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