GPS Tracking of a Nanosatellite – The CanX-2 Flight Experience

Abstract

CanX-2, which was launched in April 2008, is a Canadian “triple-CubeSat” satellite that carries a dualfrequency
\nGPS receiver to assess the feasibility of ionospheric profiling from a nanosatellite platform. A
\nNovAtel OEM4-G2L receiver is employed on CanX-2, which offers geodetic grade measurements at favorably
\nlow power. While various other CubeSats have carried GPS receivers into space before, CanX-2 is apparently
\nthe first mission to successfully deliver GPS navigation fixes and raw measurements thanks to proper attitude
\ncontrol and onboard data handling systems. Even though the achieved signal quality falls below expectations
\ndue to limitations of the employed antenna system, the receiver provides both L1 C/A tracking and semicodeless
\nL2 P(Y) tracking on a regular basis. The paper presents the CanX-2 GPS subsystem, the receiver
\nqualification for space use and the necessary tasks for receiver operations. The in-flight performance is
\ncharacterized in terms of tracking coverage, raw measurements and navigation accuracy. Furthermore, shortarc
\nprecise orbit determination results based on dual-frequency carrier phase measurements are presented,
\nwhich are considered to be accurate to the meter level.