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[aprssig] Re: Feeding multiple stations into one for digipeating?

Patrick Green pagreen at gmail.com
Mon Jun 12 02:57:07 UTC 2006


On 6/11/06, Stan - N0YXV <n0yxv at gihams.org> wrote:
> Some where I thought I'd read something about doing what you want with
> Pseudo TTY ports in Linux. Although this explanation is long it's really
> only an overview. You'd create a Pseudo port such as /dev/ttyp3 and then
> point that Pseudo port to the other "Receive Only" station. Then on the
> primary large area "Transmit-Receive" station you would simply hook up
> multiple serial ports. Say your main station was running Digi_Ned you'd have
> the standard port /dev/ttyS0 with a TNC directly attached to the main
> computer. Then you'd setup a Pseudo Terminal such as /dev/ttyp0 and point
> that at another computer in another location that has a TNC attached. The
> remote computer sends packets back by attaching your KISS TNC via ax.25 to
> another Pseudo terminal on the remote computer. On the remote computer your
> kissattach would look something like /usr/sbin/kissattach /dev/ttyp0 ....
> When your done on the main computer Digi_Ned would be looking at what it
> thinks are two TNC's. One located at /dev/ttyS0 and the other located at
> /dev/ttyp0. The thing I can't remember is how to get your Pseudo terminal
> attached to an IP address. Played with the idea a long time ago and don't
> recall all the correct ways to do it.

This is something I'll read into.  This would be no different in the level of
configuration as finding out how to encapsulate BPQether over the internet.

> As for the question _should_ you do it or not I'll leave that up to the
> master minds. So far it looks like most people aren't following your
> original question.
>
> The question wasn't how to use RF to bring small coverage Digi's into a Wide
> area Digi. The question...as I read it...was how to take small receive only
> stations and bring those via IP into a central station. That way if two
> packets are transmitted at the same time you can recover both. An example
> would be if two stations send a packet at the same time but are far enough
> away from each other so that neither transmitter can hear the other but the
> central digi can hear both. Normally only one packet (or none) would make it
> to the digi.
>
> If you had two separate receivers feeding back into one central station you
> might be able to recover both packets. That's assuming that one receiver is
> relatively close to the first station transmitting and the other receiver is
> relatively close to the second station transmitting. Both receivers would
> hear the station that are close to them and capture a complete correct
> packet for retransmission via IP to the central Digi where both received
> packets could then be Digi'd out correctly over time. With correct dup
> checking (which Digi_Ned does) it should work in theory anyway.

This is *exactly* what I'm after.

73 de Pat --- KA9SCF.




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