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[aprssig] timeslotting on HF ? was > 15. APRS trackers on 10m (Robert Bruninga)

Robert Bruninga bruninga at usna.edu
Sun Nov 27 16:54:30 UTC 2005


>>> kmcaviezel at yahoo.com 11/26/05 1:28 PM >>>
>users could sign up for a couple slots per hour...
>
>If each slot was 2 seconds long...
>Each slot could be defined by a two byte code,

I agree that time slotting would be a good idea 
if it were implemented seamlessly, but would
be impossible and just a nightmare if we had
to "assign" time slots.   I think it is far better
to just decide an algoirthm based on the users
call and to let that automatically assign a time
slot.  The algorithm would be published so that
anyone could implement it and also be able to
determine any conflicts.

I would propose an algorithm based on the
last two letters in the (XX) call plus the SSID (S).
For example, just SUM the ascii value of X+X+S
and subtract 2*64 (the ASCII offset of "A")
and the ASCII offset of "0" would give a range
of 68 slots.  Multiply by 60/68 to scale it to
60 seconds.

And use the Mic-E format which can easily
generate a packet in under .5 seconds and
this wouild allow for the digipeat as well.
Remember, if these are being digipeated 
over to 144.39 with CSMA, then the natural
hold-off until the channel cleared on 144.39
would allow for additional significant savings
by amortizing multiple of these fames in
a single packet with only one TXD. 

We cannot implement slotting on 144.39 
and dont need to, since digipeaters can
do a pretty good job with CSMA because they
do hear pretty much of everything.  The only
place we need the slotting is on the input 
frequency and since we would be starting with
a new virgin frequency with a new design, then
we could make sure that slotting is used and
would avoid the hiddne transmitter problem.

This would be scalable to large numbers which
is just exactly what we need to get APRS more
widely used in the Amater Radio Service.

Remeber, the ARRL is looking for a way to have
AUTOMATIC Station position AND FREQ 
identification so that we can be more responssive
in times of emergency.

NEW IDEA.  THEREFORE any PIC processor designed
for ANY new tracker SHOULD have tha ability to
interrogate any other RADIO in the vehicle so that
it can include the FREUQUENCY of VOICE operation
in the position beacon,.    WOW, this is starting to
look like a REAL forward reaching project!

Bob, WB4APR




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