It is unclear from this NOTAM whether this is an intentional perturbation of the satellite signals vs. a terrestrial transmitter (my money is on the latter), but it illustrates why one might want geographically dispersed time sources on one's network, as well as why the current trend towards decommissioning LORAN (and in the future, other navaids) in favor of reliance on a single source is a Bad Plan.
I'd be curious to see what effects (if any) those who use GPS-disciplined NTP references in Southeastern Georgia see from this experiment. https://www.faasafety.gov/files/notices/2011/Jan/GPS_Flight_Advisory_CSFTL11-01_Rel.pdf -r
