Computer Networks

The Information to be communicated in a data communications system is the message. In data communication, message is transmitted from one point to another via network system which are designed to convey information from the point of origing to the destination.

A modem (modulator-demodulator) is the device that converts digital signals from a computer into analog signals for transmission over telephone lines and vice versa.

The device used to carry digital data an analog lines is called as Modulator.

An analog-to-digital converter, or ADC as it is more commonly called, is a device that converts analog signals into digital signals. ... One example is a modem which turns signals from digital to analog before transmitting those signals over communication lines such as telephone lines that carry only analog signals.

A modulator is a device that performs modulation. A demodulator (sometimes detector or demod) is a device that performs demodulation, the inverse of modulation. A modem (from modulator–demodulator) can perform both operations.

This process of imposing an input signal onto a carrier wave is called modulation. ... This is called amplitude modulation or AM. Frequency of an input signal can also be changed. If this input signal is added to the pure carrier wave, it will thereby change the frequency of the carrier wave.

An example of digital communication is DDT.

DDT was the first modern pesticide and is arguably the most well known organic pesticide. Overall, it is known that DDT concentrates in biological systems (particularly in body fat), that it is a toxin, and that it bioaccumulates up the food chain, reaching its greatest concentrations in higher animals such as humans.

DDT was a commonly-used pesticide for insect control in the United States until it was canceled in 1972 by the United States Environmental Protection Agency (EPA). DDT was initially used by the military in WW II to control malaria, typhus, body lice, and bubonic plague (1).

DDT (dichlorodiphenyltrichloroethane) was outlawed in Britain in 1986 and banned as a pesticide worldwide under the Stockholm Convention in 2001 after it was discovered to be dangerous to wildlife and the environment.

A device that can convert digital signals to analog signals is Modem

An analog-to-digital converter, or ADC as it is more commonly called, is a device that converts analog signals into digital signals. Analog information is transmitted by modulating a continuous transmission signal by amplifying a signal's strength or varying its frequency to add or take away data.

A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts between these two forms.

In general terms a data converter is a device that converts analog signals to digital data or vice versa. Devices that convert analog signals to digital are frequently referred to as ADC. Devices that convert digital signals to analog are called DAC.

Analog to Digital Converter samples the analog signal on each falling or rising edge of sample clock. In each cycle, the ADC gets of the analog signal, measures and converts it into a digital value. The ADC converts the output data into a series of digital values by approximates the signal with fixed precision.

Modem used to converts digital signals to analog signals. It enables a computer to transmit data.

IEEE 802-3 is Analog based non deterministic.

IEEE 802.3 is a working group and a collection of institute of electrical and electronic engineers (IEEE) standards produced by the working group defining the physical layer and data link layer’s media access control (MAC) of wired Ethernet. This is generally a local area network (LAN) technology with some wide area network (WAN) applications.

Connectivity is being acknowledged as a sixth element of the computer system. The manner in which a particular computer system is connected to others say through telephone lines, microwave transmission, satellite link, etc. is the element of  connectivity.

DSL (Digital Subscriber Line) is a technology for bringing high- bandwidth information to homes and small businesses over ordinary copper telephone lines. xDSL refers to different variations of DSL, such as ADSL, HDSL, and RADSL.

High bandwidth is available for transmission in LANs as compared to WANs

Internet is a set of rules to communicate between computers

LAN Experiences fewer data transmission errors, while WAN has more data transmission errors as compared to LAN

Every computer connected on the network should have an unique address, and this address is known as IP address

In LAN, If there is a need to set-up a couple of extra devices on the network, it is not very expensive to do that and hence cost associated to setup a LAN is less

For WANs since networks in remote areas have to be connected the set-up costs are higher. 

An intranet is a private network that uses internet protocols (like TCP/IP) and web technologies to share information and resources within an organization, restricted to authorized users.