title: Normalized GNSS interference pattern technique for altimetry.
abstract: It is well known that reflected signals from Global Navigation Satellite Systems (GNSS) can be used for altimetry applications, such as monitoring of water levels and determining snow height. Due to the interference of these reflected signals and the motion of satellites in space, the signal-to-noise ratio (SNR) measured at the receiver slowly oscillates. The oscillation rate is proportional to the change in the propagation path difference between the direct and reflected signals, which depends on the satellite elevation angle. Assuming a known receiver position, it is possible to compute the distance between the antenna and the surface of reflection from the measured oscillation rate. This technique is usually known as the interference pattern technique (IPT). In this paper, we propose to normalize the measurements in order to derive an alternative model of the SNR variations. From this model, we define a maximum likelihood estimate of the antenna height that reduces the estimation time to a fraction of one period of the SNR variation. We also derive the Cramér-Rao lower bound for the IPT and use it to assess the sensitivity of different parameters to the estimation of the antenna height. Finally, we propose an experimental framework, and we use it to assess our approach with real GPS L1 C/A signals.
authors.affiliation: Electronics and Signal Processing Laboratory (ESPLAB), École Polytechnique Fédéralede Lausanne (EPFL), Maladière 71B (Microcity), CH-2002 Neuchâtel, Switzerland. miguel.ribotsanfelix@epfl.ch.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Ribot
authors.affiliation: Laboratoire d'Informatique, Signal et Image de la Côte d'Opale (LISIC), Univ Lille Nord de France, F-59000 Lille, France. Université du Littoral Côte d'Opale (ULCO), 50, rue Ferdinand Buisson,BP719-62228 Calais cedex, France. kucwaj@lisic.univ-littoral.fr.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Kucwaj
authors.affiliation: Electronics and Signal Processing Laboratory (ESPLAB), École Polytechnique Fédéralede Lausanne (EPFL), Maladière 71B (Microcity), CH-2002 Neuchâtel, Switzerland. cyril.botteron@epfl.ch.
authors.forename: Cyril
authors.initials: C
authors.lastname: Botteron
authors.affiliation: Laboratoire d'Informatique, Signal et Image de la Côte d'Opale (LISIC), Univ Lille Nord de France, F-59000 Lille, France. Université du Littoral Côte d'Opale (ULCO), 50, rue Ferdinand Buisson,BP719-62228 Calais cedex, France. serge.reboul@univ-littoral.fr.
authors.forename: Serge
authors.initials: S
authors.lastname: Reboul
authors.affiliation: Laboratoire d'Informatique, Signal et Image de la Côte d'Opale (LISIC), Univ Lille Nord de France, F-59000 Lille, France. Université du Littoral Côte d'Opale (ULCO), 50, rue Ferdinand Buisson,BP719-62228 Calais cedex, France. stienne@lisic.univ-littoral.fr.
authors.forename: Georges
authors.initials: G
authors.lastname: Stienne
authors.affiliation: Electronics and Signal Processing Laboratory (ESPLAB), École Polytechnique Fédéralede Lausanne (EPFL), Maladière 71B (Microcity), CH-2002 Neuchâtel, Switzerland. jerome.leclere@epfl.ch.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Leclère
authors.affiliation: Laboratoire d'Informatique, Signal et Image de la Côte d'Opale (LISIC), Univ Lille Nord de France, F-59000 Lille, France. Université du Littoral Côte d'Opale (ULCO), 50, rue Ferdinand Buisson,BP719-62228 Calais cedex, France. jean-bernard.choquel@univ-littoral.fr.
authors.forename: Jean-Bernard
authors.initials: JB
authors.lastname: Choquel
authors.affiliation: Electronics and Signal Processing Laboratory (ESPLAB), École Polytechnique Fédéralede Lausanne (EPFL), Maladière 71B (Microcity), CH-2002 Neuchâtel, Switzerland. pierre-andre.farine@epfl.ch.
authors.forename: Pierre-André
authors.initials: PA
authors.lastname: Farine
authors.affiliation: Laboratoire d'Informatique, Signal et Image de la Côte d'Opale (LISIC), Univ Lille Nord de France, F-59000 Lille, France. Université du Littoral Côte d'Opale (ULCO), 50, rue Ferdinand Buisson,BP719-62228 Calais cedex, France. mohammed.benjelloun@lisic.univ-littoral.fr.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Benjelloun