Vitek VTC-3516 Dokumentacja Pobierz pdf (Strona 82)

Design and Applied Technology (Secondary 4-6)

The transmitter receives the voice from a user, and converts the acoustic pressure waves

produced by the voice into electric currents of different strengths. The ups and downs of these

currents are transmitted along the telephone line to the receiving end. The receiver feeds the

currents into its coil, which acts as a loudspeaker to reproduce the acoustic pressure waves of

the transmitter to the recipient’s ear(s).

When a party of either side hangs up the call, the DC ceases to flow, signalling the telephone

exchange to disconnect the telephone call.

B. Wired Telephones to Wireless Mobile Phones

(a) Different generations of wired telephones

(b) Different generations of wireless mobile phones

C. Follow-up Activities

(a) Describe the technologies used in different generations of telephones.

(b) Describe how the designs of telephones have evolved.

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Vitek VTC-3516 Dokumentacja Strona 82