The activity aims at developing a tool that can investigate the failure modes of GNSS systems. Such tool can then be used for detection of failures, and/or to characterise the tolerance of GNSS system or subsystem architectures to failures. Focus will be given primarily to failures and failure modes that may impact critical services (e.g. Safety-of-Life). The tool shall be able to model GNSS systems and subsystems (i.e. ground or space segments, elements and/or components) and its failure modes in a modular way.

The issue of Radio Frequency Interference (RFI) generated by artificial sources is an increasing problem. Areas affected by the radio spectrum pollution include: Earth Observation using passive and active microwave remote sensing, ground based remote sensing of the atmosphere, space based radio experiments and radiostronomical observations.The current level of RFI contamination on ground based and spaceborne passive sensors is already an issue.

More and more applications rely on the Position and Time solution provided by a GNSS equipment to enable services of critical nature.

SWIR and IR optical lens materials are difficult to machine, since often they are based on micro-crystalline or crystalline substrates which makes them also brittle and difficult to polish. SWIR spectrometer optics for CarbonSat, Sentinel 5 or NISP (Euclid) for instance are highly critical with respect to straylight performance. For mass and volume reasons the optical design of the camera of the spectrometer is based on lenses (Si, ZnSe, ZnS).

Currently the size limit for primary mirrors of large telescopes is - due to the available Ariane-5 fairing - typically at 3.5m (Herschel). Future science (and most likely also Earth observation missions) will call for larger telescope sizes due to more demanding requirements on the light collecting efficiency and angular resolution.

The next generation of GNSS is expected to be more demanding in terms of RF power transmission in order to guarantee a proper availability and quality of the service, hence, enhanced interference immunity and indoor positioning could be achieved.The HPA currently under development for this application are targeting power levels in excess of 300 W.

Over the last decades, the spaceborne remote sensing community has been focused on the development of imaging radars at RF frequencies such as S-band, L-band, C-band and X-band.

ITU regulations currently permit the use of Ka-band for active spaceborne microwave remote sensing but only few missions are considering applying this frequency band such as the SARAL mission with the ALtiKa instrument (launched 2013).

The effects of propagation impairments, in particular multipath on GNSS receivers is well known, affecting availability, accuracy and continuity of service. Initial investigations on the possibility to reduce complexity of channel models for characterizing GNSS Rx in terms of tracking and/or PVT performance has been performed for example in the "GALILEO SIS TESTING" activity.Although promising results have been seen for the characterization of the statistics of the Rx, still limitations exist in this model reduction for characterising punctual fails (e.g. false lock due to high delay).