P1f: Data transmission

Question 1

What is IR used in(1+3)

Answer 1

to carry information to control electrical or electronic devices over a short distance

to detect body heat

• burglar alarms
• thermal imaging cameras

Question 2

How can IR signals carry information to control electrical or electronic devices? (3)

Answer 2

small IR LED (at end of remote) flashes on and off to send a digital signal

signal uses a set of digital signals (coded series of flashes) to control different functions of electrical/electronic devices

signal is detected by special IR sensors

Question 3

Advantages of digital signals (3)

Answer 3

any interference (noise) affecting the signal can be easily removed as it is clear what state the signal is in as there are only 2 distinct values, giving excellent picture or sound quality

many different digital signals can be sent at once via multiplexing so more info can be sent at any given time, allowing more channels on digital TV
-allowed the switchover to digital TV and radio broadcasts

Question 4

Advantages of using optical fibres (3)

Answer 4

allow the rapid transmission of data through data pulses using light/IR

multiplexing allows more info to be transmitted

lack of interference in the final signal