[OZAPRS] UPDATE on VK3 APRS Network Design

Richard Hoskin lhoskin at bigpond.com
Fri Sep 26 13:15:45 EST 2003


This is to inform you of the upcoming changes to the VK3APRS Network.

The major limiting factor in the size of the APRS RF network is channel
capacity. The aim of this change in design is to reduce the current VK3
APRS RF traffic by between 10% to 20%. This will allow for future growth
of the VK3 APRS RF network, especially in the Metropolitan areas. The
Mildura IGate has not been included in this design as it has little
impact on the VK3 RF network at present.

The new design will comprise of 4 full-time RF RX ONLY Posit (Position
Transmissions) IGates and one TX/RX Posit IGate (VK3SB). You may have
noticed that the majority of the RX ONLY IGates are already in
operation. (VK3HAP-1, VK3JTM-5, VK3JFK) These are represented on UI-View
as stations with blue boxes around them.

The RX Only IGates will receive all local APRS RF traffic and pass it to
the Internet. They will also TX/RX messages for local stations. The main
TX/RX IGate will Transmit Posits and Objects to the VK3 RF network. This
is to some extent already done by VK3SB.

The reduction in traffic levels will be achieved in two ways. 

1) All mobile and home stations will be within 2 hops (digipeaters) from
an RX IGate. 

2) The majority of internet to RF traffic will come from one
transmitter. This will result in a controlled transmissions pattern
(similar to pond ripple) with minimal packet collisions from hidden
transmitters. The additional advantage is the extended coverage of the
current internet traffic to the NE of the state. (VK3KQU-1 has been
performing this function part-time in the NE but may not be operational
after 12/10/03)

The introduction of the RX Only IGates will also provide 2 additional

1) Better APRS messaging network as most messages will be sent via the
internet rather than RF. This will increase reliability and speed for

2) Greater reliability for POSITS to enter the APRS Internet network,
creating more reliable tracking of Mobile stations via internet client

It is very important that VK3 has only one TX/RX IGate as this stops
packet looping and RF traffic congestion. 

It is planed to implement the new design once VK3MY-1 (Mt Dandenong) is
back on air. It is also preferable that a permanent RX Only IGate be
established in NE Victoria to cater for the 2 hop requirements.

I you have any ideas that you think could improve this design or you can
see issues with the design please let me know.


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