FAQ: The 411 on radio frequency interference

Ever wonder what causes that annoying "buzz" from a speaker? It's called radio frequency interference.

Your brand new Apple iPhone is sitting next to the PC on your desk at work as you're typing away, listening to some music from your computer's speakers, when all of a sudden you hear it.

It might start out as a "hiss" or a "dit-dit-dit-dah-dit-dit-dit-dah" like someone sending you a message using Morse code. And finally your iPhone rings, and your speakers blare out a full "buzzzzzz!" Your computer monitor also starts going a little berserk with static-like lines flashing on your screen.

"What is happening?" you ask, jumping up from your computer.

In a nutshell, you've just experienced radio frequency interference.

This annoying phenomenon is not unusual. Message boards all over the Web are filled with complaints from iPhone users about this very problem. But it's not just iPhone owners that struggle with RF interference, loads of cell phone users have experienced the same issue for years. And everyone from cell phone manufacturers to operators admit that there isn't much that can be done to stop it.

In this FAQ, CNET News.com spells out what causes this annoying "buzz" and how you can minimize the impact.

So what causes the buzz?
Basically, what is happening is that electromagnetic energy that is being transmitted from the phone is being detected and amplified by speakers. But it's not just speakers that can be affected. Computer monitors, car radios, public announcement systems, TVs, audio recording equipment and even traditional landline phones can also experience the same interference.

Can this wireless interference cause damage to any of the consumer electronics or PCs that it's interfering with?
Not really. The interference is generally more of an annoyance than something that can cause serious damage to another device. But some audio engineers and TV producers say that they require people in the recording studio or on set to turn off their cell phones to ensure that the static or buzz doesn't make its way into a recording or show taping.

If this is such a common problem, why don't cell phone manufacturers or the Federal Communications Commission do something about it?
Well, the short answer is, it's not really their fault. Cell phones are designed to emit radio frequencies and to have two-way communications with nearby cell phone towers. Phones are constantly pinging cell towers to update them on their location. And the towers are pinging phones to make sure they're still in a particular cellular area. The phones themselves are operating within the range that the FCC has deemed safe. And the mobile operators, whose networks these phones operate on, are all transmitting signals from their cell towers only within the spectrum bands that they have been allotted from the government.

So who is to blame and how can this noise be stopped?
The real culprits are the speaker, car stereo, PC and other consumer electronics manufacturers for not designing their products to fend off this interference. With proper metal enclosures for motherboards and for wires that connect into these electronic components, the device can be shielded from picking up and amplifying stray radio frequency.

The problem, of course, is that many of the components and the products themselves are manufactured on the cheap overseas in places such as China and South Korea. And over the past couple of decades consumers have grown accustomed to getting PCs and other consumer electronic devices for bargain basement prices.

Cell phone manufacturers are working with the consumer electronics industry to come up with a new standard that will help provide guidance to manufacturers so they can build shielding into their products. But this will no doubt raise prices.

For now, even if consumers are willing to pay more for a particular product, it's very difficult to know if the speakerphone or car stereo they've just bought will be properly shielded from RF interference.

Apple has recognized this problem. And it's posted a notice in the FAQ section of its Web site about the iPhone urging iPhone users to look for a logo on products that says "Works with iPhone." These audio accessories should be free of any interference.

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