Analog vs Digital transmission

help!!

same media can be used for digital and analog communication. okay
but how to differentiate between these 2?

ordinary telephony media acts as band pass channel and user has bandwidth(hertz) between 0-30K, and for digital it acts as low pass and requires infinite bandwidth.

but bandpass channel can be low pass as well and digital signal is a composite of analog.

so?

how to differentiate between these 2?
what is analog and digital voice?

when we use telephone cable for modem based internet phone then it is digital.

so is transmission type entirely dependent on reciever/transmitter?
what is the concrete answer to distinguish between digital and analog with respect to medium and signal?



i m an absolute rookie, please help!

we use telephone cable for modem based internet phone then it is digital.

"Digital transmission" in current context usually means that the data that is actually being transported is digital. All (except optical may be) transmission schemes are analog, in the sense a square wave kind of signal is never sent in a communication system.

So "digital voice" means that voice is first digitised before it is transmitted. In contrast, in the traditional phone, the voice is carried as it is (analog and unmodulated).

In cable modem or traditional modem, the transmission is analog. If you were to see the signal on the phone line in a scope, it will be an analog signal, but the data which is being carried is digital iel ones and zeros. In normal radio transmission the signal that is being carried, as well as the transmission scheme, are both analog.

HTH
- b