| A | B |
|---|
| FREQUENCY | The number of times that a radio wave changes direction from positive to negative each second. Frequency is measured in cycles per second. |
| ELECTROMAGNETIC WAVES | Waves of energy that travel through space. Radio and TV signals and light are examples of electromagnetic waves. |
| BROADCASTING | When one transmitter sends out a signal to many listeners. |
| RECORDING SYSTEMS | Electronic communication systems that store a message. |
| STEREOPHONIC | Recordings that have two sound channels. VIDEO: In television broadcasting |
| CLOSED-CIRCUIT TV | The television camera is connected directly to a monitor with a cable. |
| GEOSYNCHRONOUS ORBIT | When a satellite stays above the same place on earth. The satellite orbits the earth at the same speed as the earth is rotating. Geo means earth and synchronous means together. |
| UPLINK | A transmitting station on the earth sends signals to a satellite on one frequency. The satellite receives the signal and changes it into a different frequency. |
| DOWNLINK | A satellite receives a signal and in turn sends a changed signal back towards the earth. |
