5. Communication technology for now and for the future

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5. Electromagnetic waves have potential for future communication technologies and data storage technologies

5.1 - Digital communication data

Identify types of communication data that are stored or transmitted in digital form

Digital communication changes analog signals into binary

The amplitude is measured by the binary, and the frequency is also automatically included

The data, once transmitted, is decoded by a digital-to-analog converter

Types of communication that use digital signals include CDs, DVDs, GPS, internet communication, hard disk storage and digital mobile telephones

5.1P - Identify data sources, gather, process and present information from secondary sources to identify areas of current research and use the available evidence to discuss some of the underlying physical principles used in one application of physics related to waves, such as: Global Positioning System, CD technology, the internet (digital process), DVD technology

CD technology

The digital data stored on CD are encoded and stored as a series of reflective and non-reflective bumps (pits) along a track that spirals from the centre to the outer edge of the disk. The CD is read by an infrared laser from the inside to outside as the disk is spun. The pits are read as 1s and 0s which form the digital data. The information is fed into a microprocessor and turned into a continuous analogue signal, which is then amplified or sent to speakers or headphones. (Physical property - Reflection of waves)