They simulated stray radio tower signals in UL's echo-free chamber (pictured here)outside Chicago to make sure the signals wouldn't accidentally trigger a car's air bag.

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Also, since radio waves sometimes arrive at your device not directly from the radio tower but rather by being bounced off a building or hill, these signals may be much lower in signal strength than if you had a clear line of sight view to the cell site.

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It leases and manages antenna space on its multi-tenant communications tower sites to wireless service providers and radio and TV broadcast companies.

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But between classical disc-jockeying, slaving at Tower Records ( The Tower That Fell), and writing for classical radio stations, we have channeled our experience to come up with a generic model-listener who has appreciation written all over him or her (enough to have read on thus far), but relatively littleprevious exposure.

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Air traffic operator at Nottingham Airport, Dave Tower, said "aviators could become confused about who to call and what radio frequencies to use".

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What began as a prototype built around a tower of Arduino shields is now a small first-run integrated board with spots for connecting XBee radio cards and a small LCD display.

ENGADGET