What does digital data mean?

Answer 1

A digital signal is a physical signal that is a representation of a sequence of discrete values (a quantified discrete-time signal), for example of an arbitrary bit stream, or of a digitized (sampled and analog-to-digital converted) analog signal. The term digital signal can refer to either of the following:

1. any continuous-time waveform signal used in digital communication, representing a bit stream or other sequence of discrete values
2. a pulse train signal that switches between a discrete number of voltage levels or levels of light intensity, also known as a line coded signal or baseband transmission, for example a signal found in digital electronics or in serial communications, or a pulse code modulation (PCM) representation of a digitized analog signal.

A signal that is generated by means of a digital modulation method (digital passband transmission), to be transferred between modems, is in the first case considered as a digital signal, and in the second case as converted to an analog signal.