[OZAPRS] VK3 Freq change looks good!

[Richard Hoskin]

Gday Scott,

> 
> Noticed last night that VK3RGI-1 & VK3REB-1 & VK3VHF-1 have made it all
> the
> way to Kingston Tassie (south of Hobart!)
> 
> 
> 
> This is promising as the summer troppo improves we should see this
> regularly
> one should think?

APRS is a nice tool to use for indicating good propagation conditions
however this is not such a good thing for the APRS network as a hole as it
can increases the Data levels on the RF network to the point were it may
easily become congested.

APRS is designed to be on a local RF network. It's based on the cellular
phone system where the coverage area of an individual cell is small so
that
the same frequency can be reused in other cells. The cell does not
re-radiate the signal, it takes the signal from the air and passes it to
it's destination via a wired line system. In the case of ARPS this is the
IGate. 

We compromise a little in APRS as the IGates are not at every digipeater
(cell) but normally within a range of 1 or 2 digis (in VK3). This means
that
a mobile APRS station will only cross a maximum of 2 digi cells to get to
it's local IGate.

Below is an example of a congestion issue. This station has his beacon
rate
set to 10 seconds. This may not have a big impact on his local RF system
but
it creates big problems for the system 2 or 3 digipeater hops away. In
this
case VK3.

(Note that this data is from findu and does not contain all the possible
digipeated combinations that occurred. It only contains the first instance
to reach the findu database.)

20061017063134,VK7YBI-9>4QP7V3,WIDE1-1,WIDE2-2,qAo,VK7DC:`IS+o*#j/"6?}
20061017063144,VK7YBI-9>4QP7U6,WIDE1-1*,WIDE2-2,qAo,VK7DC:`IS0o @j/"6C}
20061017063154,VK7YBI-9>4QP7T9,WIDE1-1*,WIDE2-2,qAo,VK7DC:`IS6np$j/"6C}
20061017063219,VK7YBI-9>4QP7R6,VK7RAA,WIDE1*,WIDE2-2,qAo,VK7DC:`IS8o-Tj/"6
9}
20061017063242,VK7YBI-9>4QP7Q1,WIDE1-1*,WIDE2-2,qAo,VK7DC:`IS6o $j/"67}
20061017063252,VK7YBI-9>4QP7P0,VK7RAA,WIDE1*,WIDE2-2,qAo,VK3VHF-1:`IS9o>4j
/"
60}

This type of issue can flow in both directions too.

Today we effectively have one big network not two smaller isolated
networks.
What ever happens to one will have an influence and affect the other,
that's
why we all need to work together.

Cheers
Richard
VK3JFK

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