Northrop Grumman Systems Corporation

David R Iny

Henry E Lee

Carl D Wise

Clinton W Moulds

Norman F Powell

Mark D Stenoien

An airborne radar interrogates tags on friendly ground vehicles, which when interrogated by a downlink signal from the radar, sends back a very low level uplink message signal that appears noise-like so as to avoid enemy detection and exploitation. This is achieved by retransmitting a time delayed and phase shifted version of the transmitted pulse from the radar. The digital RF tag captures every other pulse from the radar and transmits a digitally coded spread spectrum pulse back to the radar during every other intervening pulse which includes a pseudo random delay (range hop) and a pseudo random phase (direction).

2-d range hopping spread spectrum encoder/decoder system for RF tags

A local area positioning system which includes a plurality of platforms or nodes consisting of airborne and/or ground based vehicles that are coupled in a platform-to-platform local area network. The platforms themselves establish a spatial reference system for location and communication between platforms is accomplished using directive millimeter wave beams, and where measurements and communicated estimates of node locations, in a local inertial reference frame, are processed via Kalman tracking filters to generate updated estimates of position and velocity vectors associated with each node.

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Baltimore, MD, United States of America

David R Iny