The Basics of Analogue and Digital System.


Engineers divide measurements into two kinds

  • analogue
  • and digital.

Analogue things come in continuous measures, such as time, space, temperature, or speed.

When you measure them, you can express the measurements in decimals.

For instance, your body’s normal temperature is 37.5°C, acceleration due to the Earth’s gravity is 9.80665 m/s: and so on.

Analogue devices, such as the mercury thermometer or a clock with gears, measure these things continuously.

On the other hand, digital things come in whole numbers.

The most common digital things are light waves and sound waves because there cannot be such a thing as half/quarter of a wave.

After introducing quantum theory, we know that many natural forces are discrete, that is, they come in quanta because they are made up of particles.

  • Electricity is made of moving electrons,
  • Light (including X-rays and Gamma rays) is made of photons,
  • and nuclear radiation is made of alpha or beta particles.

Electronic engineers therefore face a puzzle.

Most of their measurements are in analogue, but the tools they make to measure them are digital.

Converting analogue signals to digital ones that can be displayed takes up much of their time.

How to Convert Analogue to Digital

Digital (derived from the Latin word ‘digit, which means finger’, that we all use to count) means that any measure that engineers call a signal has to be represented as an integer (i.e., a number that can be counted on the fingers).

Therefore, a digital device can only ‘sample’ a continuous signal and produce snippets of that signal (see the above image).

This is called analogue-to-digital conversion.

For electronic engineers, this means that to get a digital signal which represents the original as accurately as possible, they need to become more and more precise, so that the smallest changes in the analogue signal can be picked up.

This is important because many decisions have to be made at very high speeds, such as in a radar detecting a flying plane.

They do this by trying to build sensors that are extremely small through a process called miniaturization. With our improved understanding of semiconductors, we have been able to build devices on very small scales.

Today, with nanotechnology, we can go down to the molecular level and get as accurate a signal as is physically possible.

Digital to Analogue Conversion

Digital displays face a different problem turning a digital signal into an analogue one so that we can make sense of them, otherwise, we wouldn’t be able to hear our friends on the phone or see an image on the TV.

Engineers solve this again through miniaturization, and that’s why you see TVs and cameras sold based on megapixels,

A pixel unit of space which counts as one digital unit and a megapixel is one million pixels.

The smaller the pixel, the better the resolution of a digital image.


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