 | In the frame of the French metrology organization, the laboratory Systèmes de Référence Temps-Espace (SYRTE) in Observatoire de Paris (OP) is in charge of fundamental activities in the time and frequency domain. Among other systems, the laboratory is operating stations receiving signals from global navigation satellite systems (GNSS) like the Global Positioning System (GPS) or Galileo, aiming at accurate time transfer with other remote time laboratories. Since November 2018, the GNSS signal reception in the L1-band has been jammed by a powerful signal transmitted near to OP in a frequency band allocated to space to Earth satellite telecommunication. This signal power was originally more than 35 dB above the GNSS spread-spectrum power level. A formal complaint was raised in early January 2019 to the Agence Nationale des Fréquences (ANFR). The paper describes the jamming signal and its consequences. The effect of this signal on L1-band reception was not the same on all OP stations, depending on the bandwidth of the antenna around the L1 carrier, but also on the receiver's different types. It went from no effect at all for GPS-only stations to large data loss and noise increase for multi-GNSS stations. The power of the jamming signal is changing with time and remains under observation. We discuss what might be done to overcome this issue. |
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