Altimetry precision of 1 cm over a pond using the wide-lane carrier phase of GPS reflected signals

Abstract

The capability of global navigation satellite system (GNSS) reflected signals for ocean altimetry can be enhanced by the use of carrier-phase measurements. The reflected signals have a Doppler spread inherent to the geometry of the measurement system, in our case of interest, a satellite in low Earth orbit flying over the rough sea surface illuminated by a constellation of GNSS transmitters. Carrier-phase measurements are thus difficult because of the short coherence time of the signal and their not obvious relation to the average water surface because of the roughness-induced fluctuations. In the near future, however, the global positioning system (GPS) and the European Galileo GNSS system will transmit several civilian signals on at least three different carriers. Using wide-lane processing, that is, the combination of the phases from the different carriers, a more coherent observable is obtained which is quite powerful for ocean remote sensing. The paper presents the first step in our research on carrier-phase processing of GNSS-reflected signals, consisting of an experiment over the smooth water surface of a pond. In addition to altimetry, the measurement of GNSS multi-carrier reflected signals can potentially provide accurate wind speed estimations based on the analysis of the statistical fluctuations of the carrier phases.