Location fusion

The Particle Tracker provides three methods of geolocation:

  • GNSS (GPS) is the primary method of geolocation, and uses a set of satellites to accurately obtain position and elevation information, up to 1.8 meter precision.
  • Wi-Fi geolocation uses nearby Wi-Fi access points to determine location. This is especially helpful indoors and outdoors in "urban canyons" in downtown areas where building block views of the GNSS satellites, but there are many nearby Wi-Fi networks.
  • Cell tower location uses a database of cellular tower identifiers to locate the tower you are connected to. This has the lowest resolution.

The last two are used in the location fusion feature, new in Device OS 3.0 and Tracker Edge v12. A geolocation service is used by the Particle cloud to provide these additional location services when the GNSS does not have a good location available. The geolocation service is included with your Tracker, and you only need to have it enabled to use it; there is no additional charge and no need to sign up for additional services.

Wi-Fi geolocation does not connect to the Wi-Fi access points. Most access points are configured to periodically broadcast their presence to make it easy for Wi-Fi devices to connect. This public broadcast is used in combination with the geolocation service to provide an approximate location. Not all Wi-Fi access points are in the database.

The best-case and worse-case resolution of the various technologies is:

Technology Best-Case Worst-Case
GNSS 1.8 meters 100 kilometers
Wi-Fi 24 meters
Cellular Tower 123 meters 10 kilometers

The worse-case GNSS precision is theoretical, based on visibility of a minimum number of satellites, combined with multi-path interference. Practically speaking, when there is a GNSS lock, the reported location is generally within 500 meters (1640 feet, or 1/3 of a mile) of the actual location, and often within 10 meters.