21.   Atomic clocks synchronize with the atomic clock maintained by the National Institute of Standards and Technology in Boulder, Colo., via radio signals.

22.   At this instant, radio signals from alien worlds might be passing through our atmosphere, through your home, through your very body.

23.   Belarussian officials said it was approaching a military air base and did not respond to radio signals and warning shots.

24.   A crewman would sit in the bomb bay, with binoculars and a joystick, guiding the bomb toward its target by radio signals or, later, radar.

25.   A satellite will test whether beaming radio signals between satellites can improve weather forecasting.

26.   A second source of error is distortion of the radio signals in the ionosphere, a high-altitude layer of magnetically charged particles.

27.   A wireless phone works by transmitting and receiving radio signals to and from the nearest cell site.

28.   A wireless keyboard communicates with the PC via radio signals and has a flat touch-pad for controlling the cursor.

29.   After a radio signal leaves the transmitter, it starts hitting metal everywhere and bouncing around.

30.   But flight controllers, monitoring a faint radio signal, could tell that Pathfinder was indeed diving through the atmosphere and decelerating.