Comments on "Square-Wave Correlation Phase Detector with VLF Atmospheric Noise"

Abstract

DF reading is not used in the estimation of the emitter position. Since the position estimate is obtained only from the parameters of the trajectory of the observer, under the condition of constant apparent angle of signal arrival, any systematic error in the DF does not affect the estimate.A major advantage of the method discussed here is the complete absence of ambiguities. It not only does not introduce extra ambiguities such as the circulation method does; it even resolves the basic ambiguity present in DFs, thus eliminating the need for a sense antenna.The main drawback of the spiral method proposed in this work is that the trajectory required to be executed by the observer is somewhat complicated. However, the principle on which the trajectory is based, viz., keeping a certain system output constant, is fairly simple and is used in several navigation schemes, both automatic and manual.