The short answer is no. Deliberate jamming is rare and usually occurs only in combat zones. Even in those instances, it is very localized, focused, and brief. Things like jamming, interference, and spoofing are extremely rare. We have only verified a handful of instances in all the years C4G has been operating its Real-Time Network. Examples are mostly related to altimeter radar at the end of large runways; it only happens when that is turned on for a plane to land, it is brief, and it simply blanks out any GPS/GNSS reception. Another was near the Pilot Station at the Southwest Pass of the Mississippi. Working under high-power transmission lines is usually OK, but there have been some rare occasions where it messes up the cell and GPS/GNSS signals. 

Other RF interference is rare, and there are no persistent areas of interference that we have been able to verify. Interference, when present, would mostly result in a denial of service and not a false position. A map of persistent interference/jamming zones can be found at https://gpsjam.org/?lat=31.05633&lon=-91.62730&z=6.2&date=2024-05-20.  Incidents of suspected GPS issues should be reported to the U.S. Coast Guard Navigation Center: NAVCEN where they are investigated by multiple federal agencies. Spoofing is when a party deliberately overrides signals to create false positions. It is rare, difficult to do, and would result in values being many miles off, and not just a few tenths.

There are signal jammers like the cheap “trucker jammers” that some people have used to jam their on-board GPS to block being tracked. This is very rare and highly illegal, and only a few cases have been confirmed (nationwide). Plus, the vehicle with the jammer is moving, and you might not notice the few epochs of outage as it passes.

We have spectrum analyzers on our reference stations (and have never seen any persistent interference) which we can use to investigate areas of suspected interference if need be.