The RFI problem can be mitigated from the receiver’s side. FENIX is a real-time RFI mitigation and anti-jamming system designed to work with GNSS-enabled systems, but also compatible with other remote sensing and communications systems. Thanks to its patented and innovative design, it is cross-GNSS compatible, works in a way that it is transparent to the antenna and the receiver, and it has been built in a standalone and portable case. The last prototype, the FENIX-Lite, has been successfully tested with commercial GNSS receivers using GPS L1 C/A, GPS L2C and Galileo E1 OS codes.
FENIX (Front-End GNSS Interference eXcisor) is a GNSS anti-jamming technology based on the patented (US9596610B1) combination of statistical interference detection, and a multiresolution time-frequency blanking algorithm for jamming mitigation in DSSS-based multi-constellation GNSS receivers. The main goal of FENIX is to increase the C/N0 in the presence of interference signals, thus improving the continuity of GNSS services. Moreover, the mitigation algorithm has been designed to be DSSS multi-constellation compatible (GPS, Galileo, Beidou, new GLONASS, …), frequency independent (i.e. it works at L1 and L2, L5…), and capable of mitigating almost all kinds of jamming signals.
FENIX is placed between the antenna and the receiver. It receives and digitally processes the signal captured by the antenna, which contains the useful GPS satellite signal and the possible undesired Radio Frequency Interference (RFI) signal from a jammer. During the digital signal processing, the undesired RFI signal is excised or blanked out from the useful GPS signal. After that, FENIX delivers the cleaned signal to the GNSS receiver, which can now retrieve the PVT (Positioning, Navigation and Timing) solution even under RFI conditions.
GNSS jammers and PPD are used by criminals, but for personal privacy as well. Thieves and robbers disable GNSS tracking systems to steal high value goods, or vehicles. Truck hijacking is conducted using GNSS jammers to ensure that nobody can track the vehicle. Moreover, jammers can affect unintentionally other GNSS receivers on the area different than the original target such as Local Augmentation Area Systems (LAAS) of airports, automatic geo-located installations at ports and harbours, etc. Many official state cars use jammers for personal privacy that can override nearby systems. State buildings are also equipped with GNSS jammers to prevent for terrorist attacks, but they can interfere other systems in an unintentionally way. The number of possible combinations is high and increasing as the number of GNSS-enabled/depending devices is also growing.
FENIX-lite is the simplest version, and it has been designed to work with the narrower bandwidth GNSS services at L1/E1 band: GPS L1 C/A and Galileo E1 OS. These GNSS services represent the signals used in the 99% of the receivers, and therefore, they are the most used and also jammed GNSS signals. Thanks to the miniaturization of RF front and back-ends, the current version of FENIX-lite has been implemented into a single and small case (11.6 x 7.6 x 2.2 cm) with a power consumption of less than 3 W. This makes it a handheld portable device that can be easily installed in most existing system. FENIX-Lite, has been first tested successfully in laboratory, and then a prototype has been built to demonstrate its performance in a real interference environment.
FENIX-lite demonstrator has been implemented using a Software Defined Radio (SDR) model USRP B205mini. Ot can be tuned either at L1 band (GPS L1 C/A and Galileo E1 OS) or L2 (GPS L2C). FENIX interference detection and mitigation algorithm is running in real-time in theFPGA. Its algorithm detects the interference signal using a statistical domain analysis based on normality tests, while the samples containing most part of interference power signal are excised in the time-frequency space computed using the Multiresolution Fourier Transform (MFT).
FENIX has been co-funded in the framework of the call for grants for innovative projects with potential for incorporation into the productive sector of the AGAUR – Generalitat de Catalunya, with projects “FENIX – Front-End GNSS Interference eXcisor” PRODUCTE (2016 PROD 00062) and LLAVOR (2014 LLAV 0002), and the grant for the recruitment of early-stage research staff FI-DGR 2016 (2016FI-B00738). These projects received 50% funding from the European Regional Development Fund (ERDF) / Fons Europeu de Desenvolupament Regional (FEDER) of the European Union within the framework of the ERDF / FEDER operating program of Catalonia 2014-2020.
Co-funded by project “AGORA: Técnicas Avanzadas en Teledetección Aplicada Usando Señales GNSS y Otras Señales de Oportunidad”, grant ESP2015-70014-C2-1-R, and support grant MDM-2016-0600 to “María de Maeztu Excellence Units” CommSensLab, from the Spanish Ministerio de Economía y Competitividad (MINECO / FEDER)