In addition to the real-time traffic we also gather statistics about the rest of the ADS-B on the radio channel that we do not forward. These stats help us understand how busy the radio channel is and will allow us to develop things like heat maps.
We send the following information:
Start time and current time - so we can work out how long the feeder has been running.
Counts for Mode-A/C, Mode-S (short) and Mode-S (extended) messages received off-air.
Counts for each of the 32 ADS-B downlink format (DF) message types.
Counts for the number of duplicate messages received for Mode-A/C, Mode-S (short) and Mode-S (extended) messages.
Counts for each type of message sent to the aggregator.
Total traffic counts in messages and bytes.
By default statistics are sent every 900 seconds (15 minutes).
You can disable stats by setting the interval to zero by adding -s 0 to the configuration in /etc/default/radar
For detailed information on the stats and how it is collected the code is in stats.c and stats.h.