NASA engineers win the ION Burka Award for the experiment to characterize GPS antennas – Inside GNSS
The Institute of Navigation has presented a team of NASA engineers with the Samuel M. Burka Award. The award was given to a publication in connection with NASA’s GPS Antenna Characterization Experiment (GPS ACE).
The GPS-ACE effort used GPS signal data received from spacecraft in geosynchronous orbit to map GPS signal patterns. The comprehensive models developed by the team helped the navigation community understand GPS sidelobes, which complement the main lobe signals to provide critical navigational data to spacecraft at higher elevations. In fact, NASA spacecraft have determined their location almost halfway to the moon using GPS, and a future commercial lunar payload service recipient is expected to get the first GPS fix on the lunar surface.
Jennifer E. Donaldson, Joel JK Parker, Michael C. Moreau, Dolan E. Highsmith, and Philip D. Martzen wrote a 2020 paper entitled “Characterizing GPS Transmit Antenna Patterns In Orbit for Space Users” that was published in the Institute’s Navigational Journal has been.
[Image above: The geometry for reception of GPS signals in high Earth orbits. Courtesy NASA/Donaldson.]
From the summary of the paper:
The GPS Antenna Characterization Experiment (GPS ACE) made extensive observations of GPS-L1 signals received at geosynchronous altitude (GEO) with the aim of developing comprehensive models of the signal levels and power in the sidelobes of the GPS transmit antenna. The GPS-ACE architecture has been collecting observations with extreme sensitivity for several years, thus enabling the accumulation of full azimuthal coverage of the GPS transmit gain patterns over time. The results discussed in this paper include the reconstructed transmit gain patterns versus available preflight gain measurements from GPS vehicle manufacturers. For GPS blocks with extensive ground measurements, the GPS-ACE results show remarkable agreement. For blocks without extensive ground measurements, the GPS-ACE results provide the only available evaluations of the full transmit gain patterns. The paper also includes results of the pseudorange deviation analysis used to assess systematic errors associated with GPS sidelobe signals.