4.5.6 Representing images, sound and other data Flashcards
What is analogue data?
• Analogue data is continuous, there are no limits to the values that the data can take.
What kind of data is digital?
• Discrete, it can only take specific data values
What does it mean for analogue data to be continuous?
There are no limits to the values that the data can take.
What kind of values can analogue data take?
Analogue signal can take any values and can change as frequently as required.
What kind of values can digital signals take?
Digital signal must always take one of a specified range of values, and can only change value at specified intervals.
How is the trace of a digital signal’s value characterised?
The trace of a digital signals value against time is characterised by sharp edges and vertical drops as the signal changes value.
How is the trace of an analogue signal’s value defined?
Smooth curves with sharp peaks.
What device is used when converting from digital to analogue?
A digital to analogue converter/DAC
How does a DAC work?
Device reads a bit pattern representing an analogue signal and outputs an alternating, analogue, electrical current.
What is a use of DAC?
Convert a digital audio signal to an analogue signal.
How do computers make use of analogue signals?
When computers need to make use of analogue signals output by sensors, they use analogue to digital converters.
Analogue to digital converter, ADC.
What does an ADC do?
Converts analogue signal to a digital bit pattern.
How does an ADC work?
• Takes a reading of an analogue signal at regular intervals and recording the value in a process called sampling.
How are samples taken?
Samples are taken at a specific frequency, in Hertz, which determines the number of samples taken per second.
Why is the hertz usually a high number?
Greater sampling frequencies results in a better reproduction of the analogue signal.
