Systems Engineering Seminar

Weak-signal, Fast-Acquisition GPS Receiver Technology and its Application to Spacecraft Navigation

Presented by:
Luke B. Winternitz / 596

August 5, 2008, 1:00 p.m.
Building 3 Auditorium

Abstract:

Weak-signal, Fast-Acquisition GPS Receiver Technology and its Application to Spacecraft Navigation

GPS has found wide application for precision spacecraft navigation and formation-flying applications, but it has primarily been limited to use in low Earth orbits (LEO). Recent advances in GPS receiver designs and signal processing capabilities now make it feasible to consider using GPS to provide autonomous, on-board navigation capabilities for geostationary (GEO) and other high-altitude space missions that venture above the constellation of GPS satellites. The main difficulty with operating "above the constellation" is the sparsity and weakness of the GPS signals available (satellites must be tracked from the opposite side of the Earth).

Recently, GSFC has developed a unique space-borne GPS receiver, called Navigator, designed specifically for high-altitude applications. The special capabilities of this receiver, namely fast-acquisition and high-sensitivity, give it advantages over other receivers in a host of applications, from LEO to cis-lunar orbits. Navigator will get its first flight opportunity as part of the Relative Navigation Sensor (RNS) experiment on the HST Servicing Mission-4 this fall, and will be a critical navigation sensor for the MMS mission, as a core component of it's Inter-satellite Ranging and Alarm System (IRAS) unit. Other future work includes GPM and GOES-R.

This talk will cover the basics of traditional GPS receiver design and its limitations. We then will discuss special signal processing techniques that can improve acquisition sensitivity and speed, particularly those employed in Navigator. Finally, we will show, based on simulation results with Navigator, how these advancements can improve GPS performance in a range of space-navigation applications.

Biography:

Luke B. Winternitz is an Electrical Engineer in the Hardware Components and Systems Branch (Code 596) at NASA Goddard. He has worked at Goddard since 2001 primarily in the development of GPS receiver technology. He received Bachelors degrees in Electrical Engineering and Mathematics from the University of Maryland, College Park in 2001 where he is currently pursuing a PhD in Electrical Engineering.