Raytheon Company

General Dynamics Corp., Pomona Division

Benjamin G Lewis

Lawrence M Frazier

A bistatic passive radar system is used in conjunction with a host transmitter that is a determinable distance D from the radar system for determining the distance D and for displaying video images of a selected target, the position of the radar system and the position of the transmitter on a display. The invention is characterized by a system and method of using the display to determine the slant range S and the altitude H of the selected target relative to the position of the radar system. Three alternative embodiments of the invention are disclosed.

System and method for bistatically determining altitude and slant range to a selected target

A bistatic passive radar system having a display; a first directional antenna for determining the angle between the reference azimuth of the bistatic passive radar system and the line of sight to a host transmitter; an omnidirectional antenna for receiving reflected radar pulses from targets at any bearing; and a second directional antenna for determining the angle B between the line of sight to the host transmitter and a second line which extends from the bistatic passive radar system to a selected target. The angle of the second directional antenna is indicated by a B cursor on the display. The system includes a bistatic range correction circuit that utilizes an empirical determination of the distance D between the bistatic passive radar system and the host transmitter for determining the correct range for display of a selected target. The distance D is manually varied on the display until the B cursor on the display bisects the video image of a selected target toward which the second directional antenna is pointing. This technique is applicable for all targets and receivers that lie in the plane of rotation of the host radar.

Bistatic passive radar system with improved ranging

A bistatic passive radar system and method for airborne use in a first aircraft in conjunction with a host transmitter located in a second aircraft that may be at a different altitude than the first aircraft, characterized by a system and method for determining the distance between the aircraft. The system for determining the distance between the aircraft includes a system for receiving radar signals from the host transmitter directly and via reflection from a selected ground target located between the two aircraft; a system coupled to the receiver for determining the apparent range R.sub.a from the host transmitter on the second aircraft to the receiver on the first aircraft in response to receipt of the radar signals; a device on the first aircraft for determining the altitude H of the first aircraft; a device on the first aircraft for determining the angle .theta. with respect to vertical at which the radar signals are received directly from the host transmitter; a device on the first aircraft for determining the angle .phi. with respect to vertical at which the reflected radar signals from the ground are received; and a computer system on the first aircraft for computing the distance D between the two aircraft from the determined values of R.sub.a, H, .theta. and .phi.. The system further includes an alphanumeric display device coupled to the computer system for providing an alphanumeric readout of the computer value of the distance D between the aircraft.

Growing community of inventors

Corona, CA, United States of America

Benjamin G Lewis