Patent ID: 6437742
Filing Date: 2002-08-20
Classification: G01S

Abstract:
A Doppler direction finding system for determining the relative azimuth and elevation of a source of RF emissions, comprising:a first pair of antennas for receiving incident RF; a first rotatable mounting, said first rotatable mounting having a center of rotation about a first axis; each of said antennas in said first pair of antennas being mounted to said first rotatable mounting for rotation in a circle centered about said center of rotation of said first rotatable mounting; a second pair of antennas for receiving incident RF; a second rotatable mounting, said second rotatable mounting having a center of rotation about a second axis, said second axis being oriented orthogonal to said first axis; each of said antennas in said second pair of antennas being mounted to said second rotatable mounting for rotation in a circle centered about said center of rotation of said second rotatable mounting; motor means for rotating said first rotatable mounting about said center of rotation at a predetermined angular speed and for rotating said second rotatable mounting about said center of rotation of said second rotatable mounting at said predetermined angular speed, whereby said antennas in said first pair continuously move in a circular path to impose a Doppler shift on external RF incident on said antennas, said Doppler shift produced at one of said antennas of said first pair being out of phase with that Doppler shift produced at the other of said antennas of said first pair of antennas and said antennas in said second pair continuously move in a circular path to impose a Doppler shift on RF received by said antennas of said second pair, said Doppler shift produced at one of said antennas of said second pair of antennas also being out of phase with that Doppler shift produced at the other of said antennas of said second pair of antennas; and whereby a Doppler shift is produced irrespective of the orientation of said first and second axes relative to the position of the source of said incident RF.