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Results from the GPS Flight Experiment on the High Earth Orbit AMSAT OSCAR-40 SpacecraftA GPS receiver flying on the High Earth Orbit (HEO) AMSAT-OSCAR 40 (AO-40) spacecraft has been returning GPS observations from high above the altitude of the GPS constellation. AO-40, an amateur radio satellite launched November 16, 2000, is currently in a low inclination, 1000 by 59000 lan altitude orbit. This low-cost experiment utilizes a mid 1990's era, 6-channel, CIA code receiver configured with high gain receiving antennas for tracking above the GPS constellation. The receiver has performed well, despite operating significantly outside of its original design environment. It has regularly returned GPS observations from points all around the orbit, with over ten weeks of GPS tracking data collected to date. Signal to noise levels as high as 48 B-Hz have been recorded near apogee, when the spacecraft was at an altitude of close to 60000 km. GPS side lobe signals have been tracked on several occasions, primarily from Block IIR GPS satellites. Although the receiver has not computed a solution in real-time, point solutions have been computed on the ground using simultaneous measurements from four satellites. This experiment has provided important experience dealing with the many challenges inherent to GPS tracking at high altitudes, and the measurements returned are providing valuable information about the characteristics of GPS signals available for future HE0 users.
Document ID
20030055629
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Bauer, Frank
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Moreau, Michael C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Davis, Edward P.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Carpenter, J. Russell
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kelbel, David
(Computer Sciences Corp.)
Davis, George W.
(Emergent Space Technologies)
Axelrad, Penina
(Colorado Univ. Boulder, CO, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Subject Category
Space Communications, Spacecraft Communications, Command And Tracking
Meeting Information
Meeting: ION GPS 2002
Location: Portland, OR
Country: United States
Start Date: September 24, 2002
End Date: September 27, 2002
Distribution Limits
Public
Copyright
Public Use Permitted.
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