Interferometer and angle encoding navigation system

Claim 1

An interferometer navigation system for determining the space angle between the longitudinal axis of a vehicle and a reference course line as established by a remote source of electromagnetic radiation, said system comprising in combination: a first and a second receiving antenna mounted respectively on each side of the forward portion of said vehicle, said antennas being located along a line substantially transverse to said longitudinal axis of said vehicle; circuit means coupled to said first and second antenna and being operable to receive a portion of the electromagnetic energy received by said antennas from said source to provide an output signal corresponding to one frequency radiated from said source; a first and second electronic signal coupler respectively connected to said first and second antenna; first and second phase modulation means respectively coupled to said first and second electronic signal couplers, said first and second phase modulation means being adapted to operate in opposite phase senses with respect to each other to translate the frequency of electromagnetic energy coupled thereto up and down in frequency respectively to effectively create upper and lower sidebands of said one frequency; a modulation signal source commonly coupled to said first and second phase modulation means, said source generating and applying a relatively low frequency modulation signal with respect to said one frequency thereto for providing said frequency translation; an RF signal combining network coupled to the output of said circuit means and said first and second phase modulation means, providing an output therefrom corresponding to said one frequency having a phase component with respect to said low frequency modulation voltage which is a function of the space angle of the vehicle relative to said remote source; detector means coupled to said RF signal combining network for providing an output therefrom of said relatively low frequency including said phase component and which corresponds to the difference in RF phase of the signals received at said first and second antenna; and phase comparator means coupled to said envelope detector and said modulation signal source for comparing said relatively low frequency modulation signal and the output of said detector means for providing an output thereof corresponding to the angle of the longitudinal axis of said vehicle with respect to saiD reference course line.