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”. 28-29 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 – 1575.42MHz +/- 15 MHz

– GPS L2 – 1227.6 MHz +/- 15 MHz

– Galileo E5A-E5B, GPS L5 - 1164-1215 MHz

– Galileo E4, E6 – 1250-1300 MHz

– Galileo E2, L1, E1- 1550-1600 MHz

– Optionally high resolution tracks

Checking Piszkéstető

GNSS RFI Monitoring Directory Structure

RFI-MONITORING

SUMMARY Location -> mon. time sequence

CATALOGUE Location and monitoring details Data file IDs

DATA-FILES ID, Spectrum images

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