Page 81 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Exposure to Computer Disciplines

Notes 4.3.13.3 Wireless Technologies
 Terrestrial microwave - Terrestrial microwaves use Earth-based transmitter and receiver. The
equipment looks similar to satellite dishes. Terrestrial microwaves use low-gigahertz range,
which limits all communications to line-of-sight. Path between relay stations spaced approx,
30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills,
and mountain peaks.
 Communications satellites - The satellites use microwave radio as their telecommunications
medium which are not deflected by the Earth’s atmosphere. The satellites are stationed in
space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earth-
orbiting systems are capable of receiving and relaying voice, data, and TV signals.
 Cellular and PCS systems - Use several radio communications technologies. The systems
are divided to different geographic areas. Each area has a low-power transmitter or radio
relay antenna device to relay calls from one area to the next area.
 Wireless LANs - Wireless local area network use a high-frequency radio technology similar
to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum
technology to enable communication between multiple devices in a limited area. An example
of open-standards wireless radio-wave technology is IEEE.
 Infrared communication, which can transmit signals between devices within small distances
not more than 10 meters peer to peer or ( face to face ) without any body in the line of
transmitting.

4.3.13.4 Scale
Networks are often classified as local area network (LAN), wide area network (WAN),
metropolitan area network (MAN), personal area network (PAN), virtual private network
(VPN), campus area network (CAN), storage area network (SAN), and others, depending on
their scale, scope and purpose, e.g., controller area network (CAN) usage, trust level, and access
right often differ between these types of networks. LANs tend to be designed for internal use
by an organization’s internal systems and employees in individual physical locations, such as
a building, while WANs may connect physically separate parts of an organization and may
include connections to third parties.

Network classification and Network types.

4.4 Summary

• A computer network, often simply referred to as a network, is a collection of computers and
devices interconnected by communication channels that facilitate communications among
users and allows users to share resources.
• A data can be saved on the network so that other users who access the network can share
the data from network.
• The network link feature in Google Earth provides a way for multiple clients to view the
same network based or web-based KMZ data and automatically see any changes to the
content as those changes are made.

• Connecting computers in a local area network lets people increase their efficiency by sharing
files, resources and more.

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