HOW DOES SATELLITE INTERNET WORKS

 

 

 

How do you access the Internet other than dial-up if you live too far from a phone company office for DSL and there is no cable TV on your street? Satellite Internet access may be worth considering. It's ideal for rural Internet users who want broadband access.

Satellite Internet does not use telephone lines or cable systems, but instead uses a satellite dish for two-way (upload and download) data communications. Upload speed is about one-tenth of the 500 kbps download speed. Cable and DSL have higher download speeds, but satellite systems are about 10 times faster than a normal modem.

Firms that offer or plan to offer two-way satellite Internet include StarBand, Pegasus Express, Teledesic and Tachyon. Tachyon service is available today in the United States, Western Europe and Mexico. Pegasus Express is the two-way version of DirecPC.

Two-way satellite Internet consists of:

* * Approximately a two-foot by three-foot dish
* * Two modems (uplink and downlink)
* * Coaxial cables between dish and modem

The key installation planning requirement is a clear view to the south, since the orbiting satellites are over the equator area. And, like satellite TV, trees and heavy rains can affect reception of the Internet signals.

Two-way satellite Internet uses Internet Protocol (IP) multicasting technology, which means up to 5,000 channels of communication can simultaneously be served by a single satellite. IP multicasting sends data from one point to many points (at the same time) by sending data in compressed format. Compression reduces the size of the data and the bandwidth. Usual dial-up land-based terrestrial systems have bandwidth limitations that prevent multicasting of this magnitude.

Some satellite-Internet service still requires you to have a dial-up or cable modem connection for the data you send to the Internet. The satellite data downlink is just like the usual terrestrial link, except the satellite transmits the data to your computer via the same dish that would allow you to receive a Pay-Per-View television program.

So, if you are in a rural area and you want broadband access to the Internet, satellite Internet may be for you!

NETWORK SECURITY

Network security is a complicated subject, historically only tackled by well-trained and experienced experts. However, as more and more people become ``wired'', an increasing number of people need to understand the basics of security in a networked world. This document was written with the basic computer user and information systems manager in mind, explaining the concepts needed to read through the hype in the marketplace and understand risks and how to deal with them.

Some history of networking is included, as well as an introduction to TCP/IP and internetworking . We go on to consider risk management, network threats, firewalls, and more special-purpose secure networking devices.
This is not intended to be a ``frequently asked questions'' reference, nor is it a ``hands-on'' document describing how to accomplish specific functionality.
It is hoped that the reader will have a wider perspective on security in general, and better understand how to reduce and manage risk personally, at home, and in the workplace.

What is a Network?

A ``network'' has been defined[1] as ``any set of interlinking lines resembling a net, a network of roads || an interconnected system, a network of alliances.'' This definition suits our purpose well: a computer network is simply a system of interconnected computers. How they're connected is irrelevant, and as we'll soon see, there are a number of ways to do this.

The ISO/OSI Reference Model

The International Standards Organization (ISO) Open Systems Interconnect (OSI) Reference Model defines seven layers of communications types, and the interfaces among them. (See Figure 1.) Each layer depends on the services provided by the layer below it, all the way down to the physical network hardware, such as the computer's network interface card, and the wires that connect the cards together.

An easy way to look at this is to compare this model with something we use daily: the telephone. In order for you and I to talk when we're out of earshot, we need a device like a telephone. (In the ISO/OSI model, this is at the application layer.) The telephones, of course, are useless unless they have the ability to translate the sound into electronic pulses that can be transferred over wire and back again. (These functions are provided in layers below the application layer.) Finally, we get down to the physical connection: both must be plugged into an outlet that is connected to a switch that's part of the telephone system's network of switches.
If I place a call to you, I pick up the receiver, and dial your number. This number specifies which central office to which to send my request, and then which phone from that central office to ring. Once you answer the phone, we begin talking, and our session has begun. Conceptually, computer networks function exactly the same way.
It isn't important for you to memorize the ISO/OSI Reference Model's layers; but it's useful to know that they exist, and that each layer cannot work without the services provided by the layer below it.

 Firewalls

As we've seen in our discussion of the Internet and similar networks, connecting an organization to the Internet provides a two-way flow of traffic. This is clearly undesirable in many organizations, as proprietary information is often displayed freely within a corporate intranet (that is, a TCP/IP network, modeled after the Internet that only works within the organization). In order to provide some level of separation between an organization's intranet and the Internet, firewalls have been employed. A firewall is simply a group of components that collectively form a barrier between two networks.

A number of terms specific to firewalls and networking are going to be used throughout this section, so let's introduce them all together.

Bastion host.

A general-purpose computer used to control access between the internal (private) network (intranet) and the Internet (or any other untrusted network). Typically, these are hosts running a flavor of the Unix operating system that has been customized in order to reduce its functionality to only what is necessary in order to support its functions. Many of the general-purpose features have been turned off, and in many cases, completely removed, in order to improve the security of the machine.

Router.

A special purpose computer for connecting networks together. Routers also handle certain functions, such as routing , or managing the traffic on the networks they connect.

Access Control List (ACL).

Many routers now have the ability to selectively perform their duties, based on a number of facts about a packet that comes to it. This includes things like origination address, destination address, destination service port, and so on. These can be employed to limit the sorts of packets that are allowed to come in and go out of a given network.

Demilitarized Zone (DMZ).

The DMZ is a critical part of a firewall: it is a network that is neither part of the untrusted network, nor part of the trusted network. But, this is a network that connects the untrusted to the trusted. The importance of a DMZ is tremendous: someone who breaks into your network from the Internet should have to get through several layers in order to successfully do so. Those layers are provided by various components within the DMZ.

Proxy.

This is the process of having one host act in behalf of another. A host that has the ability to fetch documents from the Internet might be configured as a proxy server , and host on the intranet might be configured to be proxy clients . In this situation, when a host on the intranet wishes to fetch the web page, for example, the browser will make a connection to the proxy server, and request the given URL. The proxy server will fetch the document, and return the result to the client. In this way, all hosts on the intranet are able to access resources on the Internet without having the ability to direct talk to the Internet.

HISTORY OF INDIA

The history of India begins with evidence of human activity of Homo sapiens as long as 75,000 years ago, or with earlier hominids including Homo erectus from about 500,000 years ago. The Indus Valley Civilization, which spread and flourished in the northwestern part of the Indian subcontinent from c. 3300 to 1300 BCE, was the first major civilization in India. A sophisticated and technologically advanced urban culture developed in the Mature Harappan period, from 2600 to 1900 BCE. This Bronze Age civilization collapsed before the end of the second millennium BCE and was followed by the Iron Age Vedic Civilization, which extended over much of the Indo-Gangetic plain and which witnessed the rise of major polities known as the Mahajanapadas. In one of these kingdoms, Magadha, Mahavira and Gautama Buddha were born in the 6th or 5th century BCE and propagated their śramanic philosophies.

Almost all of the subcontinent was conquered by the Maurya Empire during the 4th and 3rd centuries BCE. It subsequently became fragmented, with various parts ruled by numerous Middle kingdoms for the next 1,500 years. This is known as the classical period of Indian history, during which India has sometimes been estimated to have had the largest economy of the ancient and medieval world, controlling between one third and one fourth of the world's wealth up to the 18th century.
Much of northern and central India was once again united in the 4th century CE, and remained so for two centuries thereafter, under the Gupta Empire. This period, witnessing a Hindu religious and intellectual resurgence, is known among its admirers as the "Golden Age of India". During the same time, and for several centuries afterwards, southern India, under the rule of the Chalukyas, Cholas, Pallavas, and Pandyas, experienced its own golden age. During this period, aspects of Indian civilization, administration, culture, and religion (Hinduism and Buddhism) spread to much of Asia.
The southern state of Kerala had maritime business links with the Roman Empire from around 77 CE. Islam was introduced in Kerala through this route by Muslim traders. Muslim rule in the subcontinent began in 712 CE when the Arab general Muhammad bin Qasim conquered Sindh and Multan in southern Punjab in modern day Pakistan setting the stage for several successive invasions from Central Asia between the 10th and 15th centuries CE, leading to the formation of Muslim empires in the Indian subcontinent such as the Delhi Sultanate and the Mughal Empire.
Mughal rule came from Central Asia to cover most of the northern parts of the subcontinent. Mughal rulers introduced Central Asian art and architecture to India. In addition to the Mughals and various Rajput kingdoms, several independent Hindu states, such as the Vijayanagara Empire, the Maratha Empire, and the Ahom Kingdom, flourished contemporaneously in southern, western, and northeastern India respectively. The Mughal Empire suffered a gradual decline in the early 18th century, which provided opportunities for the Afghans, Balochis, Sikhs, and Marathas to exercise control over large areas in the northwest of the subcontinent until the British East India Company gained ascendancy over South Asia.

Beginning in the mid-18th century and over the next century, India was gradually annexed by the British East India Company. Dissatisfaction with Company rule led to the Indian Rebellion of 1857, after which India was directly administered by the British Crown and witnessed a period of both rapid development of infrastructure and economic decline. During the first half of the 20th century, a nationwide struggle for independence was launched by the Indian National Congress and later joined by the Muslim League. The subcontinent gained independence from the United Kingdom in 1947, after being partitioned into the dominions of India and Pakistan.

WI-MAX

WiMAX stands for Worldwide Interoperability for Microwave Access. It is a telecommunications technology providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. It is based on the WirelessMAN (IEEE 802.16) standard.
WiMAX is a highly scalable, long-range system, covering many kilometers using licensed spectrum to deliver a point-to-point connection to the Internet from an ISP to an end user. WiMAX can be used to provide a wireless alternative to cable and DSL for broadband access, and to provide high-speed data and telecommunications services. WiMAX can also be used to Connect many Wi-Fi hotspots with each other and also to other parts of the Internet.

When using WiMAX device with directional antennas, speeds of 10 Mbit/s at 10 km distance is possible, while for WiMAX devices with omni-directional antennas only 10 Mbit/s over 2 km is possible. There is no uniform global licensed spectrum for WiMAX, although three licensed spectrum profiles are being used generally – 2.3 GHz, 2.5 GHz and 3.5 GHz

With WiMAX enabled handsets and laptops coming into the market, people could connect to the fast broadband internet from anywhere, without having to depend on the slow rate mobile network data transfer. You can work on broadband, call friends and colleagues and watch real-time TV from the top of a forest hill station many kilometers away from the access point – without compromising on quality, speed or screen size!
WiMAX could connect remote Indian villages to the Internet using broadband. This would avoid hassles in cabling through the forests and other difficult terrain only to reach a few people in remote places. Maintaining such system would also be easy. WiMAX could provide Internet access, voice and IPTV to those areas.
Comparison with Wi-Fi
Simply put, if WiMAX provides services analogous to a cellphone, Wi-Fi is more analogous to a cordless phone.

Wi-Fi is a shorter range system, typically hundreds of meters, typically used by an end user to access their own network. Wi-Fi is low cost and is generally used to provide Internet access within a single room or building. For example, many coffee shops, hotels, railway stations and bus stations contain Wi-Fi access points providing access to the Internet for customers.
Wireless Routers which incorporate a DSL-modem or a cable-modem and a Wi-Fi access point, often set up in homes to provide Internet-access and inter-networking to all devices connected (wirelessly or by cable) to them. One can also connect Wi-Fi devices in ad-hoc mode for client-to-client connections without a router. Wi-Fi allows LANs to be deployed without cabling for client devices, typically reducing the costs of network deployment and expansion. Wireless network adapters are also built into most modern laptops.
For example, I have a BSNL DataOne broadband Wireles DSL modem at home. I can freely work from my Wi-Fi enabled laptop anywhere in my home or even from its premises.

WIRELESS SENSOR NETWORK

A Wireless Sensor Network (WSN) consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants., and to cooperatively pass their data through the network to a main location. The more modern networks are bi-directional, enabling also to control the activity of the sensors. The development of wireless sensor networks was motivated by military applications such as battlefield surveillance; today such networks are used in many industrial and civilian application areas, including industrial process monitoring and control, machine health monitoring, environment and habitat monitoring, healthcare applications, home automation, and traffic control.

The WSN is built of nodes - from a few to several hundreds or even thousands, where each node is connected to one (or sometimes several) sensors. Each such sensor network node has typically several parts: a radio transceiver with an internal antenna or connection to an external antenna, a microcontroller, an electronic circuit for interfacing with the sensors and an energy source, usually a battery. A sensor node might vary in size from that of a shoebox down to the size of a grain of dust, although functioning "motes" of genuine microscopic dimensions have yet to be created. The cost of sensor nodes is similarly variable, ranging from hundreds of dollars to a few pennies, depending on the complexity of the individual sensor nodes. Size and cost constraints on sensor nodes result in corresponding constraints on resources such as energy, memory, computational speed and communications bandwidth. The topology of the WSNs can vary from a simple star network to an advanced multi-hop wireless mesh network. The propagation technique between the hops of the network can be routing or flooding.

In computer science and telecommunications, wireless sensor networks are an active research area with numerous workshops and conferences arranged each year

MICROSOFT XBOX360

The Xbox 360 is the second video game console produced by Microsoft, and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles. As of January 2011, there are over 50 million Xbox 360 consoles worldwide.
The Xbox 360 was officially unveiled on MTV on May 12, 2005, with detailed launch and game information divulged later that month at the Electronic Entertainment Expo (E3). The console sold out completely upon release in all regions except in Japan.

Some major features of the Xbox 360 are its integrated Xbox Live service that allows players to compete online, download arcade games, game demos, trailers, TV shows, music and movies and its Windows Media Center multimedia capabilities. The Xbox 360 also offers region specific access to third-party media streaming services such as Netflix and ESPN in the US or Sky Player in the UK.
At their E3 presentation on June 14, 2010, Microsoft announced a redesigned Xbox 360 that would ship on the same day.The redesigned console is slimmer than the previous Xbox 360 model and features integrated 802.11 b/g/n Wi-Fi, TOSLINK S/PDIF optical audio output, 5 USB 2.0 ports (compared to the 3 from older versions) and a special AUX port. Older models of the Xbox 360 have since been discontinued. The first new console to be released features a 250 GB hard drive, while a later, less expensive SKU features 4 GB internal storage.

With the announcement of the Xbox 360 S, Microsoft have said that they believe that the console is only mid-way through its life-cycle and will continue through 2015 In 2009, IGN named the Xbox 360 the sixth greatest video game console of all time, out of a field of 25^.

The world's smallest Hard Disk

September 8, 2007 With hard disk capacity accelerating faster than Moore’s Law for computer chips, Toshiba nudged ahead of Hitachi today when it announced the commercialization of the world’s largest 1.8-inch hard disk drive. Dubbed the MK1626GCB, the device offers a storage capacity of 160GB, and Toshiba has started to shipping samples. The disk is clearly destined to end up inside the next generation of consumer electronics requiring high capacity storage in a small form-factor – notebooks, personal media players, and high def digital video cameras.
The new drive has an improved read-write head and enhanced magnetic layer that boosts recording density, and achieves an areal density of 353 mega-bit per square millimeters (228 gigabits per square inches). The drive uses CE-ATA (an HDD interface that optimizes performance in consumer electronics applications) and fulfils another key criteria for drives destined for battery-powered portable electronics, in that it is 33% more energy efficient than Toshiba’s current range-topping 1.8-inch HDD, the MK1011GAH

4G Technology

4G stands for the fourth generation of cellular wireless standards. It is a successor to 3G and 2G families of standards. Speed requirements for 4G service set the peak download speed at 100 Mbit/s for high mobility communication (such as from trains and cars) and 1 Gbit/s for low mobility communication (such as pedestrians and stationary users).
A 4G system is expected to provide a comprehensive and secure all-IP based mobile broadband solution to smartphones, laptop computer wireless modems and other mobile devices. Facilities such as ultra-broadband Internet access, IP telephony, gaming services, and streamed multimedia may be provided to users.
Pre-4G technologies such as mobile WiMAX and first-release 3G Long term evolution (LTE) have been on the market since 2006 and 2009 respectively, and are often branded as 4G. The current versions of these technologies did not fulfill the original ITU-R requirements of data rates approximately up to 1 Gbit/s for 4G systems. Marketing materials use 4G as a description for Mobile-WiMAX and LTE in their current forms.
IMT-Advanced compliant versions of the above two standards are under development and called “LTE Advanced” and “WirelessMAN-Advanced” respectively. ITU has decided that “LTE Advanced” and “WirelessMAN-Advanced” should be accorded the official designation of IMT-Advanced. On December 6, 2010, ITU announced that current versions of LTE, WiMax and other evolved 3G technologies that do not fulfill "IMT-Advanced" requirements could be considered "4G", provided they represent forerunners to IMT-Advanced and "a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed."
In all suggestions for 4G, the CDMA spread spectrum radio technology used in 3G systems and IS-95 is abandoned and replaced by OFDMA and other frequency-domain equalization schemes. This is combined with MIMO (Multiple In Multiple Out), e.g., multiple antennas, dynamic channel allocation and channel-dependent scheduling

Pen Size Device Projects Full Size Keyboard

The size of a writing pen, the Virtual Keyboard uses light to project a full-sized computer keyboard onto almost any surface, and disappears when not in use. Used with Smart Phones and PDAs, the VKey provides a practical way to do email, word processing and spreadsheet tasks, allowing the user to leave the laptop computer at home. "The VKey allows the business user to avoid lugging the laptop computer around and eliminates all of the laptop airport security hassles," says Peter Hanowich, President and CEO of Virtual Devices, the company that developed this technology.

"This is the ultimate solution for travel-weary laptop users," says Hanowich.
VKey observes the user's finger movements to interpret and record keystrokes and mouse functions. "And since the virtual keyboard is an image projected in light, it completely disappears when not in use," said Hanowich.
The VKey unleashes the word processing, email and spreadsheet functionality of Smart Phones and PDAs by providing a practical way to enter data. "Since VKey technology can be incorporated directly into a PDA or Smart Phone, we are seeking to work with a manufacturer," says Hanowich, who is experienced in turning technology ideas into successful businesses. "Responses and the feedback from consumers has been even more positive than expected," said Hanowich. "86% of first responses were positive," says a respected market research firm. "68% of business users would leave their laptop athome." "Regarding pricing, we feel certain that it will be affordable for consumers," said Hanowich.

"Ultimately, VKey's incredible portability will enable the product to enhance personal computing devices and allow everyone to carry a fully functional pocket computer." "In addition to a broad-based consumer electronics market," Hanowich said "VKey technology has many applications in various high-tech and industrial sectors. These include data entry and control panel applications in hazardous and harsh environments and medical markets where sterile data entry is an issue."