Sensing Ocean, Ice and Land Reflected Signalsfrom Space: Results from the UK-DMC GPS Reflectometry Experiment

The use of Global Navigation Satellite System (GNSS) signals reflected from the Earth\u27s surface has progressed from its beginnings in the early 1990\u27s to a demonstrated practical linkage of measurements to geophysical characteristics of ocean, ice and land surfaces. A pioneering space-based experiment was carried on the UK-DMC satellite launched in September of 2003. The GPS receiver on the satellite was modified to accommodate a downward (nadir) pointing medium gain antenna and to send sampled IF data to a solid-state data recorder [1]. Since its launch it has been successfully used to target and detect specular reflections of GPS signals after scattering from the Earth\u27s oceans, ice sheetsand land surfaces. All data collections under a wide range of conditions have revealed reflected signals, including signals reflected off the ocean under reasonably rough ocean conditions. This demonstrates convincingly that GNSS Reflectometry (or GNSS Bistatic Radar) is a valid future technology for space based Earth remote sensing, even when using modest antenna gain configurations such as that deployed on the UK-DMC low Earth orbiting satellite. This paper presents a summary of the signals collected from over the ocean, and an examination of the signal relationship to the ocean wind and wave conditions is presented. The preliminary results from ice and land surfaces reflection analysis are also described. Reprinted with permission from The Institute of Navigation (http://ion.org/) and The Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation, (pp. 1679-1685). Fairfax, VA: The Institute of Navigation

Instrumentation development for the measurement and characterisation of indoor and urban canyon ambient noise floor in the Galileo frequency bands

The Galileo satellite navigation system will offer new frequency bands as well as share existing spectrum with parallel systems. The development of the Galileo system will significantly improve the already high level of accuracy, availability, reliability and integrity provided by current satellite navigation systems. However, in urban canyon and indoor locations there is a significant performance loss due to high levels of attenuation, signal masking and multipath. Receiver design for positioning in challenging areas like this is dependent on accurate characterization of the signal andnoise environments. Effects of signal propagation into urban canyons and indoors is relatively well known. However, the noise characteristics are largely unknown, especially the effect on the noise floor in the sensitive Galileo bands from the proliferation of electronic devices. This paper describes the design and development of a measurement instrument to characterise the underlying thermal interference noise floor in the various frequency bands in which Galileo will operate. The design trade-offs and designs are presented along with initial instrument testing. The instrument will be used in a joint measurements campaign between Luleå Technical University and the University of Leeds.Godkänd; 2006; Bibliografisk uppgift: Titel på proceedings: Proceedings of the 3rd ESA Workshop on Satellite Navigation User Equipment Technologies, NAVITEC; 20070405 (junered)</p