Question

What role does a modem play in our communications system? Do we always need a modem or similar device?

In addition, how are we able to compress digital data and make it so much smaller than its analog equivalent?

Answer 1

The role of modem in communication system is that to modulate/demodulate signals.It converts serial digital data signals into analog signals required for the transmission over analog cicuits or devices and vice versa is also possible.

Yes, we need modem or similar devices in communication because through this modem ,it's gets possible for any communication device to support a wide variety of data communications .For example :- in tele communications, we can get data such as e-mail, facsimile transmision between fax machines or downloading files from servers.And,can prevent loss of data plus encryption and decryption also takes place so that the data security is also increased

Such compression of data in such manner; at first the message is analysed and then it can be found out that certain characters are used much more frequently than others.By analysing the message before transmission, so here it will assign short binary codes to the repeatedly used characters while longer codes are assigned to rarely used characters.So, by this we can reduce the size. This is the basic concept behind the data compression.