# Sampling

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• Created by: apple87
• Created on: 30-04-15 17:33
What sort of numbers represent digital signals?
Binary numbers.
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What does the number of values a digital signal can carry depend on?
The number of bits used.
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Are analogue signals limited in the number of values they can take?
No
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How much do analogue signals vary?
Continuously.
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What happens to an eletrical signal when it is transmitted?
It picks up noise from electrical disturbances.
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Why is it much easier to reconstruct a digital signal?
It had a limited number of values.
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What happens to an analogue signal when it is reconstructed?
Some of the details are lost.
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What is it called when an analogue signal is turned into a digital signal?
It is digitised
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How do you digitise a signal?
Take the value of the signal a regular time intervals, then find the nearest digital value, convert the analogue values into binary numbers.
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What is a limitation of digitising?
The final signal won't be exaclly the same as the original analogue signal.
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What does the quality of a digitised signal depend on?
The difference between the possible digital values(resolution), and the time from one sample to the next(sampling rate)
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How does a high resolution affect the quality of the digitised signal?
The digitised signal will match the original more closely.
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What is resolution determined by?
Number of bits, the greater the number the greater the resolution.
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What is the formula for calculating the maximum number of bits?
log2(Total variation/Noise variation)
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How do you calculate the Minimum rate of sampling?
2 x maximum frequency of signal
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What can a low sampling rate create?
Low frequency signals that weren't there in the first place called aliases.
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List for advantages of Digital signals over analogue signals?
Can be sent, received and reproduced more easily due to limited values, resistant to noise, can represent different kinds of information in the same way eg images, sounds in a string of bits, easy to process using a computer which is a digital device
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What is a disadvantage of digital signals?
Can never reproduce analogue signals exactly.
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## Other cards in this set

### Card 2

#### Front

What does the number of values a digital signal can carry depend on?

#### Back

The number of bits used.

### Card 3

#### Front

Are analogue signals limited in the number of values they can take?

### Card 4

#### Front

How much do analogue signals vary?

### Card 5

#### Front

What happens to an eletrical signal when it is transmitted?