The process would stop only when a signal was detected.

So far, no signals from the C-141 or the life rafts have been detected, officials said.

In India's tests earlier this month, only one signal was detected by the global network.

The electronic intelligence community, for example, would like to know how such weak signals can be detected.

A higher d indicates that the signal can be more readily detected.

Although the signal could be detected the amplitude appeared variable and was lower than first reported.

A faint signal was detected three days later which indicated that it had gone into safe mode.

Such signals cannot be detected on Earth because of ionosphere interference.

The last signal from that plane, before it dropped off the radar, was detected at an altitude of 600 feet.

Phones ring when a signal is detected during one or more cycles of electric current.