Flashcards
OCR Gateway P1f
Flashcards do conjunto (8)
- 1P1f - Data Transmission
- 2Analogue Signals
- 3Digital Signals
- 4NoiseAll signals become weaker as they travel long distances, and they may also pick up random extra signals. This is called noise, and it is heard as crackles and hiss on radio programmes. Noise may also cause an internet connection to drop or slow down, as the modem tries to compensate.
- 5Effect of NoiseNoise adds extra random information to analogue signals. Each time the signal is amplified, the noise is also amplified. Gradually, the signal becomes less and less like the original signal. Eventually, it may be impossible to make out the music in a radio broadcast against the background noise.
Noise also adds extra random information to digital signals. However, this noise is usually lower in amplitude than the amplitude of the ON states. As a result, the electronics in the amplifiers can ignore the noise and it does not get passed along. This means that the quality of the signal is maintained, which is one reason why television and radio broadcasters are gradually changing from analogue to digital transmissions. - 6A remote controlPressing a button on a remote control device completes the circuit. A coded signal is sent to a LED at the front of the remote.
The signal includes a start command, the instruction command, a device code and a stop command.
The LED transmits the series of pulses. This is received by the device and decoded to allow the television to change channel/volume. - 7Infrared RadiationsWe cannot see infrared radiation, but we can feel it as heat energy.
- 8Optical FibresOptical fibres can carry more information than an ordinary cable of the same thickness. The signals in optical fibres do not weaken as much over long distances as the signals in ordinary cables.
Optical fibres can carry more data because of multiplexing. This is where several digital signals are interleaved or carried together without being mixed. Digital radio and TV broadcasts also carry more data than analogue broadcasts: they can also be multiplexed.
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- Descrição
- FlashCards sobre OCR Gateway P1f, criado por Zaaaara em 20-05-2014.
- Criado por
- Zaaaara
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