Detection Performances of Evil Waveform Monitors for the GPS L5 Signal

Paul Thevenon (1) , Quentin Tessier (2) , Denis Maillard (3) , Margaux Cabantous (3) , Francisco Amarillo-Fernández (4) , Filipe de Oliveira Salgueiro (4) , Olivier Julien (2)

1 CNES - Centre National d'Études Spatiales [Toulouse]
2 ENAC - Ecole Nationale de l'Aviation Civile
3 Capgemini [Toulouse]
4 ESA - Agence Spatiale Européenne = European Space Agency

Evil Waveform (EWF) are signal distortions that can create persistent errors (bias) on the pseudo-range measurement of several meters. They are of particular interest for differential GPS users and for safety critical users. For instance, differential corrections do not remove this bias if the reference receiver and the rover receiver use different receiver parameters (notably RF input bandwidth and correlator spacing). In order to protect Civil Aviation users from this kind of errors, the ICAO has standardized a model for this failure, which can then be monitored by high-integrity systems such as SBAS and GBAS. In parallel to the standardization of the model, a family of Signal Quality Monitoring (SQM) techniques has been established for GPS L1 signal. With the appearance of the new GPS L5 signal, Civil Aviation users will be allowed to benefit from increased positioning performances. However, it is necessary to extend the signal deformation models and detection metrics to this new signal. This study uses data collected from modern receivers to evaluate the performances of SQM techniques on L1 C/A and L5 pilot signals. The methodology for establishing the detection thresholds is detailed and applied to 4 different datasets. The results show that the legacy SQM techniques does not reach the required performances when using modern receivers, which have larger pre-correlation bandwidth. For L5 users, an adaptation of the SQM techniques provides compliant results. The study also discusses the performances experienced by different types of users (from unmonitored independent users to differentially-corrected, protected users) and the dependency of the monitoring performances with regard to the receiver parameters. Finally, the paper also discusses the use of a statistical description of collected measurements, which may not provide enough information to correctly model the metrics distribution.

Domaines: Réseaux et télécommunications [cs.NI]; Electronique

Paul Thevenon, Quentin Tessier, Denis Maillard, Margaux Cabantous, Francisco Amarillo-Fernández, et al.. Detection Performances of Evil Waveform Monitors for the GPS L5 Signal. ION GNSS+ 2014, 27th International Technical Meeting of The Satellite Division of the Institute of Navigation, Institute of navigation, Sep 2014, Tampa, Florida, United States. ⟨hal-01094176⟩