Characterization of error in a Near-Field Electromagnetic Ranging (NFER) Real-Time Location System (RTLS)

We provide results and error analysis for over four hundred individual measurements of a Near-Field Electromagnetic Ranging (NFER^®) Real-Time Location System (RTLS). The system operated over ranges from 1.41m to 23.4m and the bulk of the points were taken “through wall” in a non-line-of-sight configuration. We break the error down into orthogonal range and transverse components in order to assess the relative impact of range versus bearing errors in the system. We found an average range error of 34.0cm, an average transverse error of 35.5cm, and a corresponding total location error of 55.1cm. These error values are on a per receiver basis, and will tend to reduce by 1 / √N as measurements from N receivers are combined to yield a solution.