Basic but Important question about Modulation

[wony4ever]

HI.
I'm new member of complextorial.
I'm happy to meet you.

My question is that the difference between analog modulation and
digital modulation.
I have to prepare for my seminar for my lecture
I need to know it more detail
If you have, send to me text or pdf file to..

[e-mail]

thank you all

[tmcdavid]

Wony: This matter does not require a file. You should read the tutorials and the answer will be obvious. Digital modulation strives to achieve selected states from a finite set. Analog permits a continuous degee of modulation. In the transmission medium all is analog. But noise will be added in the medium if it is not at absolute zero temperature. So a modulated signal interpreted by an analog demodulator can take on any value in the range of values permitted by the circuitry, but will allways be corrupted in some degree (however slight or great) compared to the original. A modulated signal interpreted by a digital demodulator will experience a threshold effect. Since the demodulator is expecting a finite set of possibilities, a minor amount of noise will not lead to a mistake in interpreting what the modulation was intended to represent. But once the noise in the transmission medium has enough power to occasionally cause a wrong decision, the result becomes chaotic. The transition from near-perfect to near-trash is very steep for digital modulation. For analog, it is quite gradual but the corruption is never zero.