On AREDN nodes with USB, uses an attached GPS device (such as the VK-162 USB GPS Dongle) to update the time and location of the node every 10 minutes.
AREDN nodes without a local GPS device with automatically look for DtD connected nodes with WhereAndWhen (with attached GPS) installed and will sync time and location from them. This allows the use of a single GPS dongle per site with all nodes benefiting.
Particularly handy for nodes being used at different locations in the field.