Principal Investigator: R. Keith Raney, Johns Hopkins University Applied Physics Laboratory

Proposal Title: The New Generation of Radar Altimeters: Proof of Concept

?The objective is to demonstrate through airborne flight tests the fundamental viability and desirability of an innovative altimeter concept (D2P), the first of its kind. The D2P altimeter is built around two techniques. The delay/Doppler technique [1] enhances along-track resolution and measurement precision, and also reduces transmitter power requirements. The phase monopulse technique measures the across-track angle-of-arrival of the height waveform, which mitigates cross-track slope errors. In future satellite versions, a flight-proven D2P radar altimeter will offer unprecedented measurement accuracy over continental ice sheets, and better precision from a smaller instrument over the open ocean. For the first time, near-shore (1 km) satellite-based radar altimetry will be possible. Variations on the D2P approach should support remote depth sounding of ice (over the Earth's polar ice sheets, or those of Europa), or terrestrial elevation altimetry. The D2P concept is the first of a new generation of radar altimeters that simultaneously satisfies high signal-to-noise ratio, high signal-to-speckle ratio, and high signal-to-clutter ratio. These characteristics represent a substantial and innovative breakthrough [2], [3], [4]. This project will (1) complete the detailed design of the altimeter, (2) build and test the altimeter in the laboratory, (3) perform demonstration aircraft flight tests of the altimeter over the ocean and ice sheets, and (4) evaluate the results. The size, cost, and performance of a future satellite version of this altimeter will be estimated.

  1. Raney, R. K., Delay Compensated Doppler Radar Altimeter, U. S. Patent No. 5,736,957, Issued April, 1998.
  2. Raney, R. K., Radar Altimetry, invited article for Encyclopedia of Electrical and Electronics Engineering, 24 Volumes, John Wiley and Sons, (March 1999 scheduled publication).
  3. Raney, R. K., The Delay/Doppler Radar Altimeter, IEEE Trans. Geoscience and Remote Sensing, 36 (5), 1578-1588, September 1998.
  4. Jensen, J. R. and R. K. Raney, Delay/Doppler Radar Altimeter: Better Measurement Precision, Proc. IEEE IGARSS'98, July, 1998.

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