Enhanced accuracy for a complex image theory position estimator using frequency diversity

Complex image theory has been proposed as a means to efficiently calculate the fields induced by a magnetoquasistatic source above the earth. In position location applications, this has enabled an accurate determination of position from measured field strengths. While promising, complex image theory is only an approximation of the true field; inherent errors in position estimation occur due to the limitations of this approximation. In this work we show that the estimation errors are frequency dependent and that by combining multiple frequency signals, the overall RMS estimation error can be significantly reduced. We demonstrate this by finding the estimation error over an xy plane of 20 m for two frequencies individually and then combined. Our results show a 12.9 % and 45.2 % reduction in position error over the respective individual frequencies.