Interference Monitoring in the Central European GPS Geodynamic Reference Network István Fejes FÖMI Satellite geodetic Observatory Penc, Hungary ESF Workshop on “Active Protection of Passive Radio Services: towards a concerted strategy” October 2004, Cagliary, Italy

The use of GNSS for Earth sciences Presently the most important tool for monitoring tectonic processes beside VLBI and SLR Applied in Earth rotation and reference frame studies Atmospheric sciences –water vapor content determination –ionosphere studies All these are based on the operation of high precision GPS networks. –High precision networks need high quality data RFI harmful to GNSS signals –reduces S/N – leads to rough positioning errors –causes data loss –inhibits measurements

The Central Europe GPS Geodynamic Reference Network (2003) Epoch sites Permanent sites

The interference monitoring programme Monitor CEGRN sites regularly Collect and document user feed back Report interference to frequency management authorities Warn users

The monitoring rules Equipment: Advantest spectrum analyser Frequency bands: –Broad band – 1-2 GHz –GPS L1 – MHz +/- 15 MHz –GPS L2 – MHz +/- 15 MHz –Galileo E5A-E5B, GPS L MHz –Galileo E4, E6 – MHz –Galileo E2, L1, E MHz –Optionally high resolution tracks

Checking Piszkéstető

Example data files

Conclusion GNSS RFI mapping –Tool for site selection –Assists site quality monitoring –Assists GPS data reduction and analysis –Warns GPS users of „hot spots” –Alerts authorities –Mitigate harmful consequences