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RE: SUNSAT PAROT Mode thought...



> The parrot mode pass I heard last night was pure bedlam!  I 
> don't have any packet equipment (yet) but I suspect that you 
> are right about how it would better utilize parrot mode than FM voice.
> 
> I'll just be glad to see the sat return to normal voice 
> passes and hopefully on mode B as that doesn't seem to be as 
> susceptible to interference from repeater inputs, outputs, 
> and whover those Spanish speaking guys are.

One problem I did see on parrot mode last night is that some operators
haven't yet caught on to how it works.  We had 2 locals chatting away as
they were on a local simplex frequency, and wondering why they didn't have
any luck via the bird!  Might have to pop them an email with a couple of
pointers. :-)

OK, for the benefit of anyone who cares to give it a try, here's part two of
taming the parrot. :-)

Firstly, anyone who runs packet terrestrially will recognise the similarity
between a normal digipeater and the parrot mode (watching a trace on a
moderately loaded digi may be instructive here).  Both are effectively
simplex parrot (as far as the data payload goes, in the case of the digi)

Basically, with a digi, if you see a connection request go out from a nearby
station, you'll see it go to the digi, then it will be relayed by the digi.
It is only _after_ the destination station receives the packet _relayed via
the digipeater_ that it will respond, again, via the digi!  This is
_exactly_ how parrot ops should be conducted, whether you're in simplex
range or not.  An additional constraint is that unlike packet or terrestrial
simplex repeaters, all timing is controlled 100%  by the satellite's 10/10
cycle.

Now, we humans don't have the benefit of a tightly controlled protocol such
as AX.25 to determine whether it's our turn to transmit or not, so we have
to use a little intelligence and common sense to fulfill the task of
"channel management".

When calling, the sequence should be:

1.  Wait for single tone of a suitable time slot (i.e. when there is no
other unfinished QSO in progress)
2.  When the downlink falls silent, put out your call (you have 10 seconds,
and if it's busy, the latter half of the slot may be more effective for
calling, as other stations outside your simplex range finish their calls).
3.  If all is well, you should hear yourself come back down after the double
tone burst.

4.  Regardless of whether you heard yourself or someone else in step 3, DO
NOT TRANSMIT after the next single tone!  The reason is because if you were
successful, this uplink window is for others to respond to you.  If you
weren't successful, and another call/QSO came over the top, transmitting now
would cause unecessary QRM and spoil it for others.
5.  If all went well, you should hear the double tone and any replies to
your call.  If someone else had the bird, you should hear the next part of
their QSO.

6.  If you're in QSO, the next uplink slot is the time to send your report
and close the QSO.  If not, oyu can try another call, if there is no other
QSO in progress.

Note that is the other station is within simplex range, you will hear them
direct on the uplink.  However, to avoid confusion, WAIT UNTIL THE OTHER
STATION'S AUDIO HAS BEEN TRANSMITTED BY THE SATELLITE before responding.
Work within the parrot repeater's cycles at all times, the satellite's
timing is is the overriding factor here.

It will feel a bit un natural at first, but this does work, and works well.
Be careful not to hog the bird, as you will tend to attract more QSOs if you
follow the above technique, or at least have a much higher success rate.

Successful parrot operation takes a degree of skill, a lot of patience and a
bit of good luck thrown in, but it can be good fun, especially for portable
stations.

For the big gun stations, please consider making the parrot passes more fun
for all, and instead of the kW and long Yagi, take the HT for a walk and
work it portable.  This really is a mode that should be left for portable
operators.  Just as linear transponders are kept for SSB/CW/PSK-31/Hell/SSTV
for technical and courtesy reasons, the parrot should be the domain of
portable and mobile stations, as it is the easiest mode to access when
running with limited power and/or antennas.

Maybe high powered base operation should be frowned upon on the parrot, and
/QRP /P amd /M calls given priority. :-)

Just my 2.2 cents worth (10% GST included!) here. :-)
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