Channel usage statistics

RTLSDR-Airband can optionally produce channel utilization statistics. The following metrics are currently supported:

• activity counter (for each frequency) - indicate the amount of time the frequency has been busy. This is measured as the number of loops in the output thread during which the frequency was active.
• noise floor (for each frequency) - as displayed in the textual waterfalls.
• sample buffer overflow counter (for each device) - incremented every time the sample buffer of a particular was not drained quickly enough. Non-zero values may indicate insufficient CPU power.

Use stats_filepath global option to enable this feature:

stats_filepath = "/var/tmp/rtl_airband_stats.txt";

The file is updated (rewritten) every 15 seconds. The format is meant to be ingested by Prometheus and is described here.