1. TELECOMMUNICATION

2. Communication over a long distance.

3. How the Telegraph Works

4. Sends electronic pulses over wire

5. Consists of: – Battery – Key (sender) – Wire – Sounder (receiver)

6. How the Telephone Works

7. Sound waves cause vibrations.

8. Transmitter – microphone that uses a diaphragm and carbon granules to produce a varying electrical current

9. Receiver – the microphone in reverse

10. Electronic telephones Cellular telephones (pages 126-127)

11. Transmission Channels

12. Copper Wire

13. Coaxial Cable

14. Optical Fibers

15. Microwaves – very short electromagnetic waves

16. Radio Waves – Amplitude: strength of the wave – Frequency: number of waves that pass a given point in one second

17. Radio

18. How Radio Works

19. Antenna picks up waves that have the station’s frequency.

20. How Television Works

21. Broadcast television signals are sent to an antenna.

22. The tv receives the signals and converts them to electrical signals.

23. The video and audio signals are separated.

24. Satellite Communication Systems

25. a device placed in orbit above the earth to receive messages from one location and transmit them to another

26. Geostationary orbit: 22,300 miles above earth traveling at the same speed as the earth rotates.

27. How the System Works

28. Signals are sent to orbiting satellites through earth stations.

29. Uplink: it receives signals and transmits them to the satellite.

30. Downlink: the satellite receives the signals and transmits them to another location back on earth