Performance Assessment of Single and Dual Frequency, Commercial-based GPS Receiver for LEO Orbit

Testing and qualification of a commercial dual-frequency GPS receiver has been done for a joint project by CSA and JAXA. This paper reports the results of performance assessment of the NovAtel OEM4-G2L dual frequency receiver with modified firmware. The signal simulator tests for LEO mission are performed, and the initial tracking/acquisition performance, single point navigation accuracy and the effect of the deterioration of the L2 (Pseudo-Y) signal on the navigation accuracy are evaluated in this study. Furthermore the comparison of a navigation performance between the NovAtel OEM4-G2L and the JAXA micro GPS receiver developed based on a single frequency terrestrial GPS receiver is discussed. INTRODUCTION The JC2Sat-FF is a nanosatellite mission consisting of two nanosatellites demonstrating the feasibility of maintaining spacecraft formation using aerodynamic drag. This mission will be the first project developed in the scheme of international collaboration between Canadian Space Agency (CSA) and Japan Aerospace Exploration Agency (JAXA). The primary objective of this project is to demonstrate spacecraft formation keeping technology powered by aerodynamic drag control and GPS-based relative navigation. The principle advantage of this concept is that no propulsion system is required. A literature survey of all proposed or planned FF missions indicates that a propulsion system is imperative which inherently increases the complexity and cost of the spacecraft design. There is no mission, for any class of satellite, which attempts to demonstrate the FF concept utilizing aerodynamic drag only. One of the challenges of this project is to demonstrate that the nanosatellite which has capability to carry out several advanced experiments, can be built at low cost, with a small team and in a short time frame. Low cost and high performance GPS navigation system is key to this mission. Compared with a system with single-frequency GPS sensors, GPS dual-frequency carrier-phase observations enable one to provide higher accuracy, to adapt on larger baseline applications up to few hundreds of kilometers, and also to improve the identification of systematic measurement errors. Despite the significant advantages of the GPS dual-frequency sensor system, only few space missions have adopted this system due to the practical limitation on the available selection of space-capable dual-frequency receivers. Space qualified dual-frequency GPS receivers are extremely expensive, especially for a small satellite project. An attractive approach for a mission with limited cost is to adopt a commercial GPS receiver. In some previous studies, it has been confirmed that