Analogue Data
Data that is physically represented.
Analogue data varies continuously identifies each tone of what is being measured.
Examples
• Our voices: as we speak, travel through the air like sound waves. These sound waves are an example of analogue data.
• The sound coming from any acoustic instrument: the sound generated by these are also examples of analogue data.
• Lines (gaps) on a vinyl record.
• Shade on a sun dial.
Digital Data
Digital data is a combination of numbers 1 or 0.
Computers use digital data to represent data.
Examples
• Digital storage of sound, to represent analogue sound as digital data, the sampling process is used.
• Sampling is where hardware, such as a microphone, measures the sound level several times per second and records this as binary digits.
Question!
Graphics
Black and white bitmap graphics use bit (1 or 0) to represent white (0) and black (1) dots.
The dots are called pixels.
It is possible to represent 256 colours by using a byte (8 bits) for each pixel.
Vector graphics are another form of graphic representation. These images do not store the data by pixels but are a set of instructions for drawing a geometric shape.
Sound
To represent analogue sound as digital data, the sampling process is used.
Sampling is where hardware, such as a microphone, measures the sound level several times per second and records this as binary digits.
Sample rate (also known as sampling frequency) and sampling resolution (also known as sampling precision or bit depth) can affect the quality of the sample.
Conversion
In order for analogue data to be processed by a digital computer, it needs to be exchanged first.
An analogue-digital (A/D) converter is an electronic circuit that converts continuous signals into discrete digital numbers. To intercept the signal back, it reverses the process.
A digital-analogue (D/A) converter is an electronic circuit for converting a digital signal to an analogue signal (current, voltage or electrical charge).
• Example of A/D conversion: sound sampling for computer storage.
• Example of D/A conversion: exchange the digital data back to sound in order to play it through headphones or loudspeakers.
Question!
Data type | Analogue Data | Digital Data |
Advantages | As continuous data is stored, there is no deterioration in the quality of the data. | Storage of data in digital form requires less physical space, as digital storage devices are smaller (compare vinyl disk against a memory stick). |
Disadvantages | Analogue data can deteriorate when it is copied or transmitted as a result of signal corruption from recording equipment. | As a result of data being sampled, the data is not recorded as a whole, as a result, digital data may be less accurate and of lower quality than analogue data. |