Turn Off That Phone!

摘要

The frequency of radio waves emanating from mobile phones and airliner avionics is measured in megahertz. The power of a radio signal is measured in decibels relative to milliwatts, with zero dBm equalling one milliwatt. The graph below shows that while the mobile phone broadcasts its intended signal at 1,850 megahertz, it also puts out a low-power buzz over a range of frequencies. Lines beneath the chart indicate possible interference from both types of signals, since aeronautical transmitters broadcast at the same frequencies. Soon after Frontier Airlines flight 469 departed Baltimore for Denver on the night of December 2, 2003, passengers in the Airbus A319 twin-jet doled out $5 each to rent headsets for the carrier's television service. The woman in seat 14E, however, had a cheaper alternative: She powered up a hand-held TV set.