hi every1, i,m new to this forum ,and i have certain doubts regarding digital communication .I hope u'll solve my problem.

Function of analog to digital converter is to convert an analog signal into sampled VERSION. Now source coding techniques, such as PCM,DPCM ,DELTA MODULATION also converts an analog signal to codeword(digital signal).
my question is that what is the difference between analog to digital converter and source coding technique and in what application pcm,dpcm are used?

hope i have written all the stuffs to understand the question.

 

Function of analog to digital converter is to convert an analog signal into sampled VERSION

Your use of "VERSION" is hard to understand. An analog signal is sampled by the A to D converter and becomes a digital value. A discrete number.

Additionally, you are literally trying to compare apple and oranges. As above, an A to D converter produces a number that corresponds to the magnitude of the analog signal input. That is all that happens. The process is local.

The things you mention (which are not particularly new) are modulation techniques for data that gets transmitted. PCM, for instance, was developed in 1937 - http://en.wikipedia.org/wiki/Pulse-code_modulation The other techniques you mention are similarly used to do data transmission over distance. The process is continuous.

In the case of music, for instance, the A to D converter outputs values corresponding to the amplitude of the analog signal at the time of each sample. Those numbers may be placed into a file as is, or compressed to save space. The file may be played back, burned onto a CD, or sent over the internet.