VDF Fix RNAV

If you have two position lines (in this case, QDRQDR —Magnetic bearing from a beacon or station to an aircrafts or QTEQTE —True bearing from a beacon or station to an aircrafts) from two separate ATCATC —Air Traffic Control units, then given good geometry you can plot them on a map and they will cross at one point, giving you a two dimensional fix.

Therefore, it is possible for a ground station to triangulate your position if your transmission is received by two antenna listening on the same frequency. This happens with the guard frequency, 121.5, which many ATCATC —Air Traffic Control units will be listening to in addition to their working frequency.