COMPUTER NETWORK
What is meant by computer network??
Computer Network is connecting a computer with other computers or other devices to enable them to communicate with each other. In addition, communication devices to transmit or to send data from sources to destinations.
NETWORKING COMPONENTS
A network component's functions are not necessarily handled by a specific device. If you browse a networking products catalog, you will find that many products combine several networking components in a device. For example: a router that has a built-in switch, a residential gateway that includes a broadband modem, etc. So, be sure to check the product specification before buying to avoid duplication. You must also check interfaces that are supported by a product. They must be compatible with the ports available in your computers or other devices. A network component's functions may also be performed by a software application. For example, Windows XP provides built-in support for Network Bridging that handle a bridge's functions in a home network with mixed media. There are also built-in or add-on software applications that handle modem, router, or gateway functions. However, the software-only alternative is mostly suitable for small networks.
Do you know what are meant by:
- Router: A specialized network device that determines the next network point to which it can forward a data packet towards the destination of the packet. Unlike a gateway, it cannot interface different protocols.
- AM : Amplitude Modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent.
- FM : frequency modulation (FM) conveys information over a carrier wave by varying its instantaneous frequency.
- Bridge: a device that connects multiple network segments along the data link layer.
Basic Differences Between AM and FM
We need to mention a couple of other things before we leave the discussion of how radio works. We've talked about AM and FM radio, but we haven't explained the real difference.
In fact, there is a lot of difference — and not just a difference in the station numbers on your radio dial.
The first type of radio service — the one we've been talking about in the last couple of modules — was AM (amplitude modulation) radio.
The term modulation refers to how sound is encoded on a radio wave called a carrier wave; or, more accurately, how the sound affects the carrier wave so that the original sound can later be detected by a radio receiver.
In the top-left of this drawing the RF energy (carrier wave) is not modulated by any sound. There would be silence on your radio receiver.
In the broadcast process sound is made to affect (modulate) AM carrier wave by changing the amplitude (height) of the wave, as shown on the left.
Unfortunately, this type of modulation is subject to static interference from such things as household appliances — and especially from lightening.
AM also limits the loud-to-soft range of sounds that can be reproduced (called dynamic range) and the high-to-low sound frequency range (called frequency response, to be explained below).
FM radio, which came along in the 1930s, uses a different approach than AM. It's virtually immune to any type of external interference, it has a greater dynamic range, and it can handle sounds of higher and lower frequencies. This is why music, with its much greater frequency range than the human voice, sounds better on FM radio.
Note on the left that when the carrier wave of FM radio is modulated with sound that the distance between the waves, or the frequency of the carrier wave, changes.
Thus, AM radio works by changing the amplitude of the carrier wave and FM radio works by changing the frequency of the carrier wave.
TERMINAL AND WORKSTATION
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A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has also been used to refer to amainframe computer terminal or a PC connected to a network.
In computers, a terminal (sometimes qualified as a "dumb" terminal) is an end-use device (usually with display monitor and keyboard) with little or no software of its own that relies on a mainframe or another computer (such as a PC server) for its intelligence.
Transmission Media is to transmit signal or electrical pulse through a medium. There are two types of transmission media such as BOUNDED AND UNBOUNDED.
Example for BOUNDED are:
- Twisted Pair Wire
- Co-Axial
- Fiber Optic Cable
Example for UNBOUNDED are:
- Tv Broadcasting
- Microwave radio
- Infrared signals
NETWORK ELECTRONIC DEVICES
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Network devices are components used to connect computers or other electronic devices together so that they can share files or resources like printers or fax machines. Devices used to setup a Local Area Network (LAN) are the most common type of network devices used by the public. A LAN requires a hub, router, cabling or radio technology, network cards, and if online access is desired, a high-speed modem. Happily this is much less complicated than it might sound to someone new to networking.
In a network, one computer is designated as the server, and the others, clients. The server is connected to an external hub, which the clients are also connected to. Now that the computers each have one foot in a common electronic door (the hub), they can use the hub to pass signals back and forth. To direct these signals, the hub contains a device known as a router. The router is the equivalent of an electronic traffic cop that handles data traffic between the computers. Example of network electronic devices are bridges, routers, HUBS, gateway and Front End Processors.
NETWORK OPERATING SYSTEM
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