I didn't really take in your transmitter location but obvious if you have unmanned drones flying over head and the Aberporth radar and telemetry you could of course be getting radio interference from temporary equipment. I'm sure when that big radar swings around you could get zapped and I note the coastal footpath sign warns against the nature of the radar in use
. So it may well have been pseudo military interference which us town / home county dwellers don't get. Expect you are going to say you live at the opposite end of all of this.
I see they carried out a satnav jamming experiment in the 90s with boat owners not happy but you were fine if you were not in line of sight of Aberporth, perhaps times change and freeview is now a target
.