> I think you have read the reaction of Gunnar SG3P. He describes the
> behavior of the system when the internet connection is lost.
Yes, tnx for that.
> We now have plans to workout a model where an RF link can be used as a
> backup link if the internet connection fails. When the internet
> connection is lost, the system automatically should use the RF link. I
> do not know if this is possible with the existing program. We will see
> how things can be done. At this moment we are thinking about the RF
> architecture for the backup link.
Maybe you could use a concept designed by Berni, DL6XB called "monitoring".
Let's pretend you have two repeaters with different locations, one on VHF
and the other on UHF.
On the VHF site you install 3 TRX: 1xRX VHF, 1xTX VHF, 1xMonitor RX UHF.
With the monitor RX you monitor the frequency of the 2nd repeater.
On the 2nd site you build the same system with RX+TX on UHF and the monitor
RX on VHF.
If you start both monitors now you would just hear the audio from every
repeater including rogerbeep, id etc...
To prevent the repeaters from this and from having echoes / loopbacks, you
build an external CTCSS encoder chip. This chip is connected to the TX audio
on the one hand and to the squelch criteria of the RX on the other. If the
squelch is high (and only then) the encoder modulates a CTCSS sub tone onto
the TX signal.
The monitor of the other repeater is configured to open only if the sub tone
is received. This could be done easily with built-in CTCSS decoders or with
a small external chip.
The goal of this is that the two repeaters monitor each other and the audio
of the neighbor repeater is only activated if there is a "real human" signal
on the input.
Many hardware repeater controllers are able to handle two receivers with
Because of the sub tone encoder which must be connected to the squelch of
the RX you cannot use an internal sub tone encoder and have to build it on
your own. There are some explanations how to do this on the net and the
price for it seams to be acceptable at all.
To activate a backup PIC-based repeater controller beside SvxLink, we did
- Connect the home-made backup controller to the parallel port of the Linux
machine which runs SvxLink.
- Change a level on the parallel port from hi to lo and back every 10
seconds. This is done by a software (just a few C++ lines) on the Linux
machine which also controls if SvxLink is still alive.
- If SvxLink or the whole PC hangs, the backup controller will detect it
after a maximum of 10 secs and activate itself.
If you're interested in any further information please let me know...
73s, Nils -DO6NP-