Continuous vs discrete signals
A continuous signal is a quantity that varies over continuous time. That is, the smallest measurement of time is infinitesimal. A very simple example is where .
A discrete signal is where the time values are discrete. For example, where . This would lead to pairs: . That is, the x-axis values are discrete.
You can convert a continuous signal to a discrete signal by picking a set of discrete numbers. This is sampling. See that page for an example.
In the world of audio:
- Analog signals, such as recording a singer, are continuous
- Digital signals, i.e. a stream of bits from an analog-to-digital converter, are discrete