Last week, Dallas broadcaster WFFA turned on its new HDTV transmitter for the first time. Surprisingly, the transmission overwhelmed heart monitors at Baylor University Medical Center, which were operating at the same frequency. Nurses and doctors were temporarily unable to monitor their patients' heartbeats. When the cause of the problem was discovered, WFFA turned the transmitter off.

The heart monitors use wireless transmitters that were operating in a previously unassigned band of the broadcast spectrum. The Federal Communications Commission has long permitted health-care facilities to use unoccupied channels for wireless communications, but last year, the agency issued a warning that broadcasters would soon begin testing HDTV in those frequencies. However, neither the FCC nor the broadcasters made much effort to discover who was using the vacant frequencies.

This incident sent a message to hospitals and other institutions nationwide, who will now have to squeeze their wireless transmissions into other portions of the radio spectrum. Baylor Medical Center has reportedly spent $200,000 to change its transmitters to a new frequency. Luckily for its patients, the interference was discovered and halted before it caused a serious problem.