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[aprssig] Beacon rate feedback

Robert Bruninga bruninga at usna.edu
Mon Nov 24 21:18:03 UTC 2008


You are correct that beacon rates are discussed with religious
fervor.  Here are a few more comments from my perspective.. 

>> Before we get into a Ford vs Chevy war...
> 
> In this case (driving up the CA coast) 
> I really don't see any advantage to 
> proportional pathing. 

Since I view APRS as a network of souls trying to communicate in
the wilderness, (and not so much a map tracking thing) I like
the 1 minute direct rate of proportional pathing so that I can
easily detect a fellow soul when we get within Voice Alert
range.  At a 120 MPH net crossing speed and a typical 5 mile
simplex comm range, this only gives 2 hits to possibly make
contact before we pass each other. 

This is also why I tend towards the fixed repetition rate of
porportional pathing, because it gives consistent updates and
gives me an idea about when to expect his next packet too.  I
think of communications in an APRS network as being
communictions in the time domain with regular updates from all
participants.  Hence the regular intervals of porportional
pathing.

Smart Beaconing is a variable rate system for trackers and those
who think more in the map-domain and like to TX high rates while
maneuvering.  But then on the open highway, you might miss them
if their rate drops too low or if they are stuck in traffic, or
if they have pulled over.  

> I'm trying to come up with a scheme for the 
> Tracker2... that'll allow flexible but reasonably 
> simple configuration of multiple paths, 
> multiple rates, and multiple transmit 
> frequencies...

In designing such flexibility, please consider all the wrong
ways each method can be used, and the damage to others if a user
sets it one way, and then droves off to do something else.  Some
trackers are set-and-forgotten and if they are one-way, the
ownewr is not aware of the havoc he is making on the network.

Please consider having the protection of the network from QRM as
being the overall top-level design driver, then some flexibilty
can be added below that, but with safeguards to overrule poor
settings.

That's why I like proportional pathing.  It provides all the
flexibilty in multiple paths and multiple rates all the time
without having to change a thing.  It works locally at a high
rate, but lower rates at a distance with one-fifth the QRM
potential of a typical 2 hop path.  But the most important value
is that it does not need to be changed by the operator to go
from DX to local use.  And by the same token, it does not
provide too much QRM if taken from local use to traveling.  IE,
the user never has to change it in most cases.  It can be a nice
set-and-forget path.

So it really boils down to whether one thinks of APRS as humans
in the time domain (my preference) or as tracking devices in a
map domain (which I believe tends to get others to think away
from the full potential of APRS as a service to ham radio
operators)...

Sorry for rambling, but I did think it worthwhile to point out
the different schools of thought about APRS in the TIME versus
SPATIAL domains.

For what its worth...

Bob, WB4APR




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