Q. Illustrate the basic working of Modem?

Modem: Modems are generally provided by network operators or by vendors who aren't necessarily the manufacturers of computer systems. Henceforth there is a need to standardize interface between modem and computer equipment. CCITT terminology for modem is data circuit terminating equipment (DCE) and for the computer it's data terminal equipment (DTE). DCE isgenerally referred to as data communication equipment, outside CCITT. It issignificant to recognize that DTE and DCE are generic terms and may be applied to a range of equipments not essentially only to computers or modems . For instance, a DTE can be a terminal, workstation or a computer and a DCE may be a modem or a computer based node in a data network. A series of standards, called V-series has been stated by CCITT for interfacing DTEs to DCEs operating with PSTNs. Series also defines a variety of DCEs using different modulation techniques and operating at different speeds using either a leased PSTN or dial-up line illustration of DTE-DCE interface standards and other standards related to data transmission on PSTN are:V.5 Standardization of data signalling rates for synchronous data transmission in the PSTN

V.24 DTE-DCE interface and control signals

V.28 DTE-DCE electrical characteristics for unbalanced double-current interchange circuits.

V.53 Limits for the maintenance of telephone type circuits used for data transmission.