Airborne direction finding method based on Doppler-phase measurement

Abstract

A new direction finding (DF) method, in which the high-accuracy measuring can be realized only with single baseline, is presented used for airborne based on Doppler-phase measurement. The analysis discovers that the integer of wavelength in radial distance can be directly derived compositely, making use of the velocity vector equation and Doppler shift, as well as Doppler changing rate equation. From this, the integer difference of wavelength in path length difference of radial distance between two adjacent antenna elements can be obtained. As soon as the value less than a wavelength in path length difference is determined by phase difference measurement, the direction angle of target can be obtained. As compared with now existing interferometry first determining phase difference, this sort of direction finding method combining Doppler with phase difference first by determining path length difference does not have phase ambiguity nor require restricting base length. By simple mathematical identity transformation, we can prove that the equation derived in this paper is equivalent to an existing one from phase interferometry. The new method presented in this paper will certainly increase new developing force for the research and development of airborne single station direction finding system.