Re: "The frequency that they're using is just below the classification of a weapon"
"What about Operation Overlord?"
What about it? There was a war going on, so not a lot of cross-channels chatter. And if you look at the story of Overlord you will see there was a HUGE amount of effort put into distraction, false information etc just in case enemy spies did get a sniff of it. Nazi spies were generally pretty useless in the UK, but even so a massive counter espionage operation went on.