GNSS Interference Events Expanding the Investigation of Recurrent GNSS Interference Events

Potential interference from space?
Over recent months, our INDALOS Premium Static Node installed in Graz has been detecting unusual anomalies on the L1 spectrum.

The interference typically lasts 2–3 hours, with its occurrence time shifting from night to night. The spectrum consistently shows two spikes around the L1 frequency, separated by several hundred kHz. To further investigate, we deployed additional INDALOS nodes at two other locations in Graz. The same interference patterns were observed. To validate our results, we also examined the ‘CW Jamming Indicator’ in u-blox receivers, which showed a significant increase during the periods when INDALOS detected interference. We have now initiated an international investigation campaign. Previous observations in Madrid, Spain—supported by ESSP—revealed a similar phenomenon, occurring at nearly the same time.

It is worth noting that this interference pattern occasionally appears in the morning hours
as well, though with lower power and shorter duration.

Join the Campaign!
We are exploring the possibility of extending this investigation on a broader geographical scale with more monitoring locations — and we invite you to join our campaign. All related results will, of course, be shared with you. You can support the investigation in the following ways for a few days in your region:

1. Provide the output .ubx file from a u-blox receiver equipped with the CW jamming indicator (e.g., M9V, F9P). Please ensure the related Child Message of the ubx is enabled.
2. Provide us access to a computer connected to an SX3 front-end and antenna. We will install an INDALOS monitoring system temporarily.
3. Share raw IQ samples recorded by a front-end on the L1 frequency.

Thank you for your valuable collaboration. To need assistance they can write us.
Let’s make GNSS more secure, because: WE MASTER INTERFERENCE.