How to locate a device

Three or more nodes with GPS can estimate where a device is. This guide runs a hunt from start to reading the position.

This uses triangulation, which is experimental. Treat the result as an area, not a point.

What you need

• Three or more nodes on the same mesh, spread around the target rather than in a line.
• A GPS fix on each node.
• The target's MAC address, or a tracer ID (T-xxxx) from the randomized MAC tracer.

1. Confirm the nodes have GPS

On each node, check System → Diagnostics for a GPS fix, or send @ALL STATUS and look for GPS in the reply. A node without a fix does not contribute a reading.

2. Set the environment

Pick the environment that matches the site so the distance estimate is right. For an open area send nothing extra; indoors, add the environment number (see the triangulation table).

3. Start the hunt

Send the hunt to one node, which runs it with every other node on the mesh:

@AH01 TRIANGULATE_START:AA:BB:CC:DD:EE:FF:120

This hunts the target for 120 seconds. A longer hunt gathers more readings from a target that transmits rarely.

4. Read the position

@AH01 TRIANGULATE_RESULTS

The node returns the coordinates, the estimated error in meters, and a map link. A large error means the readings disagreed; add nodes, spread them out, or calibrate them.

Better accuracy

Calibrate each node at a known distance before the hunt: @AH01 CALIBRATE:AA:BB:CC:DD:EE:FF:5 for 5 meters. Send @AH01 CALIBRATE_RESET after you move a node. See Triangulation.