Keyless Remotes To Cars in Waldorf Suddenly Useless
The technology is similar to that used in garage door openers and remote-controlled toys. The remote acts as the transmitter, sending an encrypted message on a weak radio signal to the receiver in the car, which decodes the message and activates door locks and other functions.
But unlike other more powerful radio signals, keyless entry remotes are not licensed by the Federal Communications Commission. They are allowed to operate on frequencies used by licensed customers as long as their signals are sufficiently weak and don't interfere with others. But because of this outlaw status, their own signals can be jeopardized.
"Car entry systems, they have no rights at all," said Bruce Romano, who works in the office of engineering and technology at the FCC. "If they get interference, that's too bad for them."
Interference can occur when a stronger signal on the same or similar frequency overwhelms the receiver, and the low-powered message from the remote cannot be "heard." An engineer compared the situation to trying to have a conversation at a stock car race, where the roar of the vehicles will drown out the voices.
"In all likelihood, the disturbance is probably some fairly high-intensity signal that is only radiating at certain times, and therefore, it makes it very difficult to locate where the source of the problem is, because it's not always up," said John Daher, a research engineer who studies electromagnetic effects on electronic systems at the Georgia Tech Research Institute in Atlanta.
Some of the devices that have failed in Waldorf operate on a frequency of 315 megahertz. Another common keyless entry frequency is 302 MHz. Both of these frequencies fall within a range licensed primarily for use by the military and the federal government.
In a summary of radio spectrum use from the National Telecommunications and Information Administration, the frequencies in the range from 225 MHz to 328.6 MHz "are heavily used worldwide for critical military air traffic control and tactical training communications." Specific functions include "air-ground-air communications for combat weapons training carried out at and in the vicinity of all major air bases and military training areas worldwide."
"High-powered transmissions in this spectrum from presidential and military aircraft are thought to be responsible for interference," said Mike Swanston, a spokesman for the Consumer Electronics Association. "But the government doesn't have to say what they're doing or how often."
Military radio signals have been implicated in other frequency mishaps in recent years. In Bremerton, the home of the Puget Sound Naval Shipyard, the first outage occurred about the time the USS Carl Vinson returned to port. Less than a month later, the second failure of keyless entry corresponded with the arrival of another aircraft carrier for maintenance, according to news reports. A subsequent FCC investigation could not prove the cause of the outages.
Manufacturers of keyless entry systems say they have been battling interference for years with little recourse. Engineers from electronics manufacturer Lear Corp., based in Southfield, Mich., have made several trips across the country to sites where disturbances have been reported. In the past several years, said Tom Tang, an engineering manager at Lear, manufacturers have improved the keyless entry technology by narrowing the range of signals that can reach the receiver, in effect closing the door on unwanted interference. But an identical or very powerful signal still can foul up the keyless entry.
"These devices by their nature, and because of FCC rules, have to accept harmful interference," said John Dicroce, a product development manager at Audiovox Electronics Corp. in Hauppauge, N.Y. "We can't control any FCC approved devices."
About 15 miles north of Waldorf is Andrews Air Force Base in Prince George's County. Officials there said they have not heard about the disturbances, nor do they have an explanation for them.
However, in Waldorf, along Old Washington Road, a 300-foot-tall AT&T tower built in 1955 has several microwave dishes and a blinking white light affixed to it. The primary function of the tower, known as a "point of presence," is to coordinate local and long distance telephone service, as well as cell phone service. But on certain days, said operations manager Philip Clark, the tower also sends out a different signal.
Clark would not specify the purpose of the signal or when it is used. Another employee, who spoke on condition of anonymity, said the signal was related to "government" work.
"I've had problems with [my keyless entry] also," Clark said. The disturbance "is probably coming from our transmitter."
Clark, who works with AT&T Government Solutions, stood outside what appeared to be a windowless concrete building in front of the tower. The glass front door of the building opened into a small entryway, which led to a second white door. On the wall of the entryway was a circular convex mirror. Hanging next to it was a surveillance camera.
"We don't have a schedule when we use that signal; it occurs when necessary," Clark said. "I think it will go on . . . but we can see about not using that frequency."
A security keypad hung to the left of the white door. As Clark spoke, he smiled. "I didn't realize it was disturbing other folks," he said.
© 2004 The Washington Post Company