Well, of course we can't miss that topic – so we did a lot of testing in the field. There are several assumptions we made, which aren't 100% correct, also the hardware of each receiving unit is a bit different.

Probable causes for inaccuracy:

  • Multipath propagation
  • Propagation path slightly different
  • Unsymetric antenna radiation pattern
  • Bad antenna setup
  • Bad antenna cable connections
  • Unequall impedance (really small effect)
  • Bad antenna cable
  • Unequal receiver responsivities
  • FFT-Calculation Problems

Test Setup

  • Error of the centorid to the real location: 6.17m
  • No pre-calibration done
  • Distance between stations: 91m
Yellow: Stations with each four antennas
Red: Position of transmitter
Blue: all biangulated points
30s timeslots
Blue: Centroid of all localization