Project Title:

GPS Enabled Spread Spectrum Altimeter (GESSA)

94-1	08.02	8798		

GPS Enabled Spread Spectrum Altimeter (GESSA)

Abstract:

An innovative approach to satellite ocean altimetry is proposed 
that combines modern advances in navigation and communications. By 
combining the Global Positioning System (GPS), for real time orbit 
determination, spread spectrum precision ranging and solid state 
microwave phased array antenna methods. a system is formed called 
the GPS Enabled Spread Spectrum Altimeter (GESSA). Using the 
precision orbit information on-board the satellite, the spread 
spectrum ranging system can be optimally controlled. The 
electronically steered phased array antenna allows for variable 
altimeter swath widths. In addition to providing 2 cm accuracy 
altimetry. the spread spectrum ranging enables a single frequency 
approach to ionospheric calibration that eliminates the need for a 
second frequency radar on board the satellite which traditional 
incurred significant cost penalties. The GESSA approach is well 
suited to small spacecraft missions while matching or exceeding the 
state-of-the-art in spaceborne ocean altimetry and at a 
considerable savings.

On a world-wide basis, there are now many maturing satellite 
companies that are specializing in very small satellite missions 
which will be customized to specific client needs. GESSA will have 
application for the maritime industry. by exploiting ocean 
altimetry capability in open ocean topographic measurement from 
which circulation anomalies of fronts and eddies can be located. 
Such oceanic topographic information is very useful in the fishing 
industry and to offshore platform operations. In addition, the 
altimetry sensitivity to sea state and sea ice offers an important 
space business opportunity for the real time measurement of sea 
roughness and navigation hazards information development with a fee 
based dissemination service to maritime users. The attractiveness 
of such space business opportunities depends critically upon 
demonstrated GESSA accuracy and affordability of the relevant space 
instrument system. Once the GESSA system is actually demonstrated, 
there will be a great demand for such instruments, and their 
oceanographic data products will enjoy a global market demand.

Key Words

International Series Research, Inc.
4225 26th St., Suite A.
Boulder, CO 80304
(303) 447-8798