Abstract: A method includes providing a radar sensor onboard a vehicle, and one or more active radar beacons around a landing site. Each beacon produces a pattern of one or more artificial echoes that is different from a pattern of echoes produced by others of the beacons. The method further includes guiding the vehicle toward the landing site by transmitting radar signals from the radar sensor to an area around the landing site; receiving return signals from the area around the landing site, including ground reflected signals and transmitted signals from each beacon; and determining whether artificial echoes are detected in the received return signals. When artificial echoes are detected, beacon parameters are loaded from an onboard active beacons database; patterns in the artificial echoes are identified and associated with corresponding beacons from the database; and a slant range to each of the beacons is estimated through the patterns.

Abstract: A method includes providing a radar sensor onboard a vehicle, and one or more active radar beacons around a landing site. Each beacon produces a pattern of one or more artificial echoes that is different from a pattern of echoes produced by others of the beacons. The method further includes guiding the vehicle toward the landing site by transmitting radar signals from the radar sensor to an area around the landing site; receiving return signals from the area around the landing site, including ground reflected signals and transmitted signals from each beacon; and determining whether artificial echoes are detected in the received return signals. When artificial echoes are detected, beacon parameters are loaded from an onboard active beacons database; patterns in the artificial echoes are identified and associated with corresponding beacons from the database; and a slant range to each of the beacons is estimated through the patterns.