Normalized GNSS Interference Pattern Technique for Altimetry
Miguel Angel Ribot,
Jean-Christophe Kucwaj,
Cyril Botteron,
Serge Reboul,
Georges Stienne,
Jérôme Leclère,
Jean-Bernard Choquel,
Pierre-André Farine,
Mohammed Benjelloun
Affiliations
Miguel Angel Ribot
Electronics and Signal Processing Laboratory (ESPLAB), École Polytechnique Fédéralede Lausanne (EPFL), Maladière 71B (Microcity), CH-2002 Neuchâtel, Switzerland
Jean-Christophe Kucwaj
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
Cyril Botteron
Electronics and Signal Processing Laboratory (ESPLAB), École Polytechnique Fédéralede Lausanne (EPFL), Maladière 71B (Microcity), CH-2002 Neuchâtel, Switzerland
Serge Reboul
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
Georges Stienne
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
Jérôme Leclère
Electronics and Signal Processing Laboratory (ESPLAB), École Polytechnique Fédéralede Lausanne (EPFL), Maladière 71B (Microcity), CH-2002 Neuchâtel, Switzerland
Jean-Bernard Choquel
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
Pierre-André Farine
Electronics and Signal Processing Laboratory (ESPLAB), École Polytechnique Fédéralede Lausanne (EPFL), Maladière 71B (Microcity), CH-2002 Neuchâtel, Switzerland
Mohammed Benjelloun
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
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.