Stern says the underlying radio technology used between the two transceivers, which is based on spread spectrum transmission security, makes it "very difficult" and "extremely unlikely" that anyone could listen in on the transmissions.

"There's probably more risk in someone reading your lips from binoculars on the other side of the field," Stern says. But that's not to say that another radio device operating on the same frequency couldn't disrupt the coach-to-QB communications, as happened to the Jacksonville Jaguars in 2006.

According to an ESPN.com article, there are several ways to get around the coach-to-QB cut off—if a team is willing to cheat.

"A team could reprogram its radio system to remove the cutoff official from the equation, sending signals directly from the coach's headset to the quarterback's helmet," the article states. "It could modify the equipment in the [coaches'] booth to achieve the same end. It could install a separate communications system, allowing another coach or quarterback to provide last-second updates. Or, a team could interfere with wires between the sideline and the press box."

The NFL has used wireless technologies for decades, and recent improvements have helped to limit disruptions. "I remember one time I was playing, I forget where it was, but I could hear the concession communication," said Kerry Collins, an NFL quarterback quoted in the ESPN.com article. "They were asking for popcorn on the second level or something like that. There are glitches from time to time, but all in all it's been a pretty sound system."

At the End of the Day, System Error Is Probably Greater Risk

Dave Aitel is the founder and CTO of security vendor Immunity and a former research scientist with the National Security Agency. "I don't know of any other large enterprise that has to monitor its radio frequencies this carefully," he says of the NFL's efforts. "I don't think there's anything malicious that's going to happen on Sunday, but of course, [the NFL security staffers] have to prepare for every eventuality."

That could range from a cameramen who's on the wrong frequency to a hacker who, just to have some fun, is able to access the broadcast signals and get his face up on the giant TV screens in the stadium. "If you're good enough," he adds. "This is going to require a fairly high level of skill or money. But sometimes money can substitute for skill."

Of course, he adds, the perpetrators better be prepared for the consequences. "All this seems like the sort of thing where you'd get caught," Aitel says, noting that the NFL infosecurity people will use monitoring and triangulation technology to track down illegal signals.