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Next: Input Devices and Storage Up: Multimedia Systems Technology Previous: Discrete v continuous media

Analog and Digital Signals

We will discuss the mechanism and issues involved in transforming signals from analog-digital in Chapter 6. Here we will introduce some basic definitions before overviewing the technology required to perform such tasks.

The world we sense is full of analog signal, electrical sensors such as transducers, thermocouples, microphones convert the medium they sense into electrical signals. These are usually continuous and still analog. These analog signals must be converted or digitised into discrete digital signals that computer can readily deal with.

Special hardware devices called Analog-to-Digital converters perform this task.

For playback Digital-to-Analog must perform a converse operation.

Note that Text, Graphics and some images are generated directly by computer and do not require digitising: they are generated directly in binary format.

Handwritten text would have to digitised either by electronic pen sensing of scanning of paper based form.

Dave Marshall