FREDERICK A NILES
Pilots at Hilltop Ct, Laurel, MD

6278404, Aug 21, 2001

Jul 7, 1999

9/348875

Frederick A. Niles - Laurel MD

The United States of America as represented by the United States National
Aeronautics and Space Administration - Washington DC

H01Q 300, G01S 514

342359

The satellite selection method as utilized by the spaceborne Global Positioning System receiver provides navigational solutions and is designed for use in low Earth orbit. The satellite selection method is a robust algorithm that can be used a GPS receiver to select appropriate GPS satellites for use in calculating point solutions or attitude solutions. The method is takes into account the difficulty of finding a particular GPS satellite phase code, especially when the search range in greatly increased due to Doppler shifts introduced into the carrier frequency. The method starts with an update of the antenna pointing and spacecraft vectors to determine the antenna backplane direction. Next, the GPS satellites that will potentially be in view of the antenna are ranked on a list, whereby the list is generated based on the estimated attitude and position of each GPS satellite. Satellites blocked by the Earth are not entered on this list.

6211822, Apr 3, 2001

Jul 7, 1999

9/348876

Lamar F. Dougherty - Fairfax VA
Frederick A. Niles - Laurel MD
Miriam D. Wennersten - Havre DeGrace MD

The United States of America as represented by the Administrator of the
National Aeronautics and Space Adminstrations - Washington DC

H04B 7185

34235712

The spaceborne Global Positioning System receiver provides navigational solutions and is designed for use in low Earth orbit. The spaceborne GPS receiver can determine the orbital position of a spacecraft using any of the satellites within the GPS constellation. It is a multiple processor system incorporating redundancy by using a microcontroller to handle the closure of tracking loops for acquired GPS satellites, while a separate microprocessor computes the spacecraft navigational solution and handles other tasks within the receiver. The spaceborne GPS receiver can use either microcontroller or the microprocessor to close the satellite tracking loops. The use of microcontroller provides better tracking performance of acquired GPS satellites. The spaceborne GPS receiver utilizes up to seven separate GPS boards, with each board including its own set of correlators, down-converters and front-end components. The spaceborne GPS receiver also includes telemetry and time-marking circuitry.