Image: Prof Todd Humphreys, Univ Texas Radionavigation Lab

What’s New: A graphic from Prof. Todd Humphreys showing loss of GPS/GNSS signals by satellites in Low Earth Orbit (LEO) because of jamming on the ground.

Why It’s Important:

:Most LEO satellites use location and timing data from GPS or another GNSS to synchronize operations, and so they know where they are, when and how to broadcast.
While most of the satellites are able to carry-over valid time and location as they pass through the area of interference, the more interference they see, the more their operations can be degraded.

What Else to Know:

GPS/GNSS signals, and therefore jamming and spoofing signals, are line-of-sight. This is why aircraft across a large are can be impacted by jamming and spoofing, but receivers on the ground much less so. Satellites can be impacted over an even greater area.
Some LEO satellites get their time from suites of clocks on the ground and are a bit more resilient to interference.

This slide was part of a presentation to CGSIC 2024 in Baltimore by Professor Todd Humphreys. Our thanks to Todd for his on-going insights!