Which signals carry information that allows electronic and electrical devices to be controlled?
Infrared
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How does a tv remote work?
Pressing a button in the tv remote completes a circuit and a coded signal is then sent to an LED at the front of the remote. This signal includes a start command, instruction command, device code and stop command. The LED transmits the signal to tv.
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Why did we decided to switch from analogue to digital?
Improved signal quality, a reater choice of programmes, interactive programmes, information services such as programme guides and subtitles.
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What do optical fibres do?
Optical fibres allow data to be transmitter very quickly using pulses of light.
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What happens before an analogue signal is transmitted?
It is added to a carrier wave.
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What are the disadvantages of using carrier waves?
Interference from another wave may be transmitted and if the wave is amplified, the interference will also be amplified.
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Why isn't interference apparent in digital signal transmissions?
Because the digital signal only has two values.
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What does multiplexing do?
Multiplexing allows a number of digital signals to be transmitted at thee same time.
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Other cards in this set
Card 2
Front
How does a tv remote work?
Back
Pressing a button in the tv remote completes a circuit and a coded signal is then sent to an LED at the front of the remote. This signal includes a start command, instruction command, device code and stop command. The LED transmits the signal to tv.
Card 3
Front
Why did we decided to switch from analogue to digital?
Back
Card 4
Front
What do optical fibres do?
Back
Card 5
Front
What happens before an analogue signal is transmitted?
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