1.   A transmitter connected to the door bell sends radio signals to a portable receiver.

2.   Alec monitored a variety of radio signals, but rarely responded himself.

3.   But if so, we might have expected to he contacted by them, or at least to detect their radio signals.

4.   Most of the time, though, he processed requests to collect radio signals from targeted coordinates.

5.   Police say radio signals were probably used to set the bomb off.

6.   Radio signals were sent into deep space.

7.   Tall buildings can distort radio signals.

8.   The biggest surprise was the sudden reappearance of the radio signals.

9.   The equipment compresses the radio signal into digital form, then adds buffers to make up for any sound lost in transmission.

10.   The radio signals are bounced off a satellite.