National 2m APRS Network
APRS was developed to convey LOCAL real-time information. As such, we are aiming to minimise the amount of NON-LOCAL data that is transmitted on the VHF network. Although it may be nice to see the location of every repeater in the country, getting the data to your display via RF prevents several mobile stations in the local area from accessing the network due to the high collision rate.
To quote the founder of APRS, Bob Bruninga WB4APR:
SUCCESSFUL APRS: The success of your local APRS is not how many stations you see on your maps, nor how far away, but how reliably your mobile or handheld or portable station can communicate with others in the local area. There is a big difference. This fundamental principal should drive everything we do with APRS in our local areas.
RELIABLE APRS: Said another way, the more stations you see above about 60 to 100 or so in typical areas, the more packets you don't see due to collisions and the less reliable your network is for local real-time APRS use.
For these reasons, the 2m network is generally configured to maximise the availability for mobile/portable stations. The amount of data transmitted from the internet to the VHF network is minimal, so as to allow the maximum amount of airtime for mobile trackers to send thier data into the network.
In some areas a 70cm APRS network has been established that carries additional traffic, making it available via RF, yet keeping the congestion away from the primary 2m frequency to allow the mobile and portable stations to use APRS as it was intended.
In Australia, a single national 2m frequency is used for APRS: 145.175 MHz
There may still be small pockets of APRS activity on other frequencies in areas that are not yet integrated into the national network, however these areas are very small and isolated.
VHF Path Settings
For Mobile stations, the path of APRS v WIDE1-1,WIDE2-1 is used nationally (even Internationally).
For Fixed stations, a path of APRS v WIDE2-1 is generally recommended, however each state may apply slightly different practises. Please check your local state pages for further information.