The VHF APRS network uses 2 main systems to monitor it's health and performance.

The first uses traffic level monitoring at selected locations to indicate the number of packets passing by a station in the last 10 minutes. The threshold is an average of 100 packets per 10 minutes, if the count is greater than 100 per 10 minutes for an extended period of time the RF network becomes inefficient causing access issues.

These traffic counting stations are recognized by the TRF-2xxx icons on your APRS map.

The second method for monitoring uses SiteAlert located at selected Digipeaters around the state. SiteAlert monitors the environmental conditions and traffic levels at the digipeater site and provides selected telemetry data for the digipeater . It will produce an Alarm if selected conditions are met, display an alarm condition on the APRS map and even message, email or SMS the digipeater operator information on the problem. Real time SiteAlert telemetry can be viewed here.

SiteAlert is not yet implemented in NSW, but will be rolled out to selected digipeaters during 2008.

With the use of these two monitoring tools it gives APRS operators good information on the state of the APRS VHF network.