Abstract: Multiple radar altimeters on a constellation of individual satellites in the same orbit plane relate an advanced ocean altimetry system. Earth rotation separates the respective measurement tracks of each satellite on the ocean surface. Each satellite can host a monostatic radar altimeter, which may contain a co-located transmitter and receiver that generates one surface track of ocean height measurements at nadir. Further, each satellite payload can include a bistatic radar altimeter, comprising a transmitter and a receiver located respectively on neighboring satellites. The bistatic altimeter comprises a virtual nadir altimeter that generates an additional surface track of ocean height measurements along the locus of midpoints on the surface between the satellites' nadir points.

Abstract: A radar ice sounder which employs parallel Doppler processing obtains more reliable and accurate radar ice sounding. The invention uses both incoherent and coherent techniques, in the same paradigm, to achieve simultaneously high Signal-to-Noise Ratio, high Signal-to-Speckle standard deviation Ratio, and high Signal-to-Clutter Ratio.

Abstract: A delay compensated Doppler radar altimeter which eliminates the relative delay curvature associated with the energy reflected by a scatterer located in the along-track direction of an aerial platform for which a most accurate estimation of scatterer elevation is desired. By Doppler shifting each return, the range indicated for each scatterer over its illumination history is equal to the minimum range x.sub.h experienced when the relative velocity between the aerial radar and the ground is effectively zero. Compensating each signal so that its entire along-track history can be used for elevation estimation leads to an advantage of more than 10 dB in gain improvement over existing systems, and less degradation from surface topography.