DOPPLER IMAGING OF TARGETS

Abstract

A method and apparatus for imaging a target, such as a ship, exhibiting rotational movement about respective, mutually orthogonal axes. The method involves identifying a scattering center at the target exhibiting rotational movement about one axis only (the yaw axis, say, in the case of a ship) and then correlating an electrical signal related to the Doppler frequency of a return derived from that scattering center, and indicative of the angular velocity of the target about the one axis, with other electrical signals related to the Doppler frequencies of returns derived from other scattering centers. Correlation signals generated in this way provide an indication of the relative positions of the other scattering centers in relation to the one axis. The apparatus may include means (12, 13, 14, 15) for generating electrical signals indicative of the Doppler frequencies of returns derived from different scattering centers at the target and means (17) for selecting signals derived from a scattering center exhibiting rotational movement about the one axis. An electrical signal indicative of the angular velocity of the target about the one axis is then computed at (21) and correlated at (22) with electrical signals indicative of the Doppler frequencies of returns derived from other scattering centers at the target. The correlation signals generated at 22 are then passed to a display (23) which presents the positions of the other scattering centers in relation to the one axis. A circuit (30) is used to generate another electrical signal related to the Doppler frequency of a scattering center exhibiting rotational movement only about a mutually orthogonal axis (the roll axis, say, in the case of a ship). The signal is also correlated at (22) so that a two dimensional representation of the target can be developed at the display (23).

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1ROGER VOLES