Should the carrier wave of a digital communication system be digital?

Question

Should the carrier wave of a digital communication system be digital?

Answer 1

By which means or criterion would you consider a carrier wave analog or digital? Digital or analog will be our perception (or receiver´s perception). A wave will always be a wave but if we insist in calling it digital or analog i will tell you about that criterion. Analog wave (both the carrier and the modulating signal) is such as to be perceived in accordance with same intensity, noise and distortion produced by its own source and our environment while digital (both the carrier and the modulating signal) will be perfect when received and zero when distorted enough as to be "not perfect" so you will have either a good signal (complete) or just nothing, on the other hand, carrier signal might be still present while modulating signal is gone and you won´t even know there is a signal because that carrier will be listened (at both frecuency and intensity FIXED) ONLY by a receiver circuit, now tell me, can a carrier be called digital? I would tell Aviophage tank circuits are not useful for transmission purposes but that´s what we are taught at school because tank circuits are a base to build oscillators.

Answer 2

A carrier wave will be an electromagnetic wave, which is neither analog nor digital.  You will need some kind of tank circuit to generate the wave, and that is an analog circuit, but it can be detected by either an analog or a digital circuit.

Some more reading about radio circuits and wave forms might help.