That Blue Square Thing

Computer Science GCSE

Note: this page deals with the old Edexcel GCSE (grades A-G) which no longer exists. I'm keeping it as an archive and because a number of the resources will still apply to newer (grades 1-9) courses. The AQA GCSE CompSci pages deal with a current course.

Sound, Temperature and Light Intensity Encoding

Anything that needs to stored on a computer has to be reduced to a series of numbers. Sound, temperature and light intensity data can all be stored on computers, but reducing them to numbers is not straightforward.

Just as images need to be broken down into pixels so that they can be encoded as numbers, sound data needs to be broken down into sections.

Analogue Data

The process of encoding sound, temperature and light intensity data is difficult because all three are examples of analogue data. This means that they are continuous with values which constantly change. The graph you'd draw showing the volume, for example, would be smooth. No matter how many times per second you try and measure the volume there would always be values between the values you record.

This makes encoding the data more difficult. You need to decide how often to record the volume - how often to sample it. These samples can then be recorded as numerical values using binary encoding, turning them into digital data (the process of quantisation).

The key points you need to understand include:

Make sure that you're aware of how each of the three types of data (sound, temperatures and light intensity) can be sampled to reduce them to numerical values.

PDF iconSound, Temperature and Light Intensity - detailed resource sheet with all the key information

PDF iconLimits to digital files - quantisation and bit length slides

How sound data is encoded is dealt with in a section of the BBC Bitesize sitewiki link. This gets into data compression as well as the content crosses over. Make sure you can apply the same information to how temperature and light intensity can be measured.