Modems :: essays research papers

Modems     Modems are used to connect devil computers over a phone grapevine. Modem is nearsighted for Modulator Demodulator. Its a device that converts data from digitalcomputer signals to analog signals that can be sent over a phone line. This iscalled modulation. The analog signals are indeed converted back into digital databy the receiving modem. This is called demodulation. A modem is fed digitalinformation, in the form of ones and zeros, from the CPU. The modem thenanalyzes this information and converts it to analog signals, that can be sentover a phone line. Another modem then receives these signals, converts them backinto digital data, and sends the data to the receiving CPU. At connection time,modems send tones to each other to transact the fastest mutually supportedmodulation method that will work over whatever quality line has been establishedfor that call. There are two main differences in the types of modems for PC,internal and external modems.Ev olution of Modems     In the last 10 years, modem users have gone from data transfer rates of300 bps to 1,200 bps to 2,400 bps to 9,600 bps to 14.4Kbps to 28.8Kbps to, and to33.6Kbps. Now new modem standards are emerging, reaching speeds of up to56Kbps. Unlike the 33.6Kbps modems being sold today, 56Kbps is a significantimprovement over 28.8Kbps modems. Viewing colonial graphics or downloading soundfiles improves significantly with 56Kbps. The modem experts keep telling us thatwe are about maxed out. For instance when the 28.8 modems where first introducedthey said that weve reached our maximum speed, and the same function was saidabout the 33.6 and now again for the 56K, but how true is this? The experts saythat the next major improvement will have to come from the telephone companies,when they emerge laying down fibber-optic cables so we can have integratedservices digital network (ISDN) . The thing that makes digital modems betterthan analog is because with analog modem transmitting errors are very frequentwhich results in your modem freezing or just freaking out. These errors arecaused mainly by some kind of noise on the line due to lightning storms,sunspots, and other fascinating electromagnetic phenomena, noise occurs anywhereon the line between your PC and the computer youre communicating with 2,000miles away. Even if line noise is minimal, most modems will automatically reduceits speed to avoid introducing data errors.Baud vs bps     While taking about modems, the transmission speed is the reference book of a lotof confusion. The root of the problem is the fact that the terms "baud" and