[OZAPRS] Help with digi paths

[Richard Hoskin]

Hi David,

It depends what you want to achieve and the traffic load on you network.

The Slottime and Persistence in UIDIGI can be used to control which
digipeater has priority in the network and therefore what areas receive
priority coverage.

Your comments are based on the USA experience where they have a large
number
of ARPS operators, Operators with excessive paths of greater than 2 hops
and
legacy digipeaters (Digis that run KPC or Pacomm firmware).

One thing is for certain, to have an effective APRS Digipeater network you
need to have it properly and tightly co-ordinated so that every digi is
singing the same song.

Cheers
Richard
VK3JFK


> 
> It looks like two or all three of the digis are set up with nice polite
> Persistance and SlotTime values as per the values normally used on
> connected mode packet channels, so that everybody shares the channel.
> 
> With APRS, the values should be such that digis transmit immediately so
> that in your particular case, when you beacon, the three digis should
> immediately retransmit your beacon without waiting a few milliseconds to
> see if they might collide and probably wait for the other digis to
> finish sending your beacon.  Thus you're seeing three digis individually
> sending your beacon, instead of all three simultaneously.
> 
> Due to FM Capture Effect, you should only see one digi repeating your
> beacon: the strongest one into your receiver.
> 
> The proper values for UIDIGI are Persistance=255 and SlotTime=1 but the
> config files up to maybe a year ago (plus or minus) have "normal packet"
> polite default values unfortunately, e.g. Persistance=64  :-(
> 
> With improper ('polite') values, people receive (in your case) three
> times as many packets as they need (i.e. unneeded duplicates clogging
> up the channel).
> 
> 73 David.


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