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Chambers of Super Silence: What's Inside Apple's $100 Million iPhone Radio Test Facility

Apple anechoic chamber

During his spiel to explain why Apple's iPhone 4 doesn't have an antenna flaw in real-world experience, Steve Jobs used some plain science. And he showed off Apple's radio test facilities too, which cost $100 million. Apple's serious about testing.

An anechoic chamber is a room that's specifically designed to be "quiet." We're not talking library-levels of quiet here, either, we're talking amazingly noise-free. These sealed and shielded rooms are built to quiet down specific signal noises of different types, from audible sounds to specific radio frequencies for radar or radio purposes (though even these radio-rooms tend to be quiet to the ear—check out Microsoft's acoustic anechoic room in the video below).

How do they work? Those odd spikes you see lining the walls and floor are very carefully designed to shield the objects you're testing in the middle of the room. The spikes' shape, and the material they're made from, is chosen such that any signal hitting them is scattered off in a new direction and not concentrated in any particular point. This disperses a signal's energy and prevents reflection back to the test stand in the middle of the room. What you're experimenting on can operate in "clean" and isolated conditions, so you can more easily understand how it performs without the distracting effects from any signals other than the ones you choose to put in there.

Anechoic rooms are weird, eerie places to stand in for a number of reasons. First, you're used to experiencing a continual background noise level, and when it's gone your brain really does notice its absence. Second, thanks to the way they're designed, they look like the inside of an alien spaceship, crossed with the wild imaginings of an industrial designer who's experiencing a very dark acid trip.

Apple spent $100 million on 17 of these rooms, and pops its wireless devices in the middle along with test transmitters and, as you can see, people using iPhones in a typical everyday manner. It has to do this so that it can optimize how its antennas work in real-life situations. Though some press reports wondered if the iPhone 4's "dummy" case, seen in the stolen iPhone 4 prototype affair, had masked an antenna design flaw--it was obvious to RF design engineers right from the start that this wasn't true. Apple will have used its anechoic chambers to rigorously test the device, particularly since it had such an innovative design.

And rigorous testing is what anechoic chambers are all about. You may be impressed with the scale of Apple's facility, but check out the military's anechoic rooms. The biggest in the world is large enough to squeeze in a lot more than a dude holding a smartphone. You can pop a fleet of fighter aircraft in the one at the Benefield Facility on Edwards Air Force Base.

Air Force anechoic chamber

Apple press conference image via Engadget.

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