SATELITE INTERNET

Satellite Internet access

Satellite Internet services are used in locations where terrestrial INTERNETaccess is not available and in locations which move frequently. Internet access via satelite is available worldwide, including vessels at sea and mobile land vehicles. There are three types of satellite Internet service:

* one way multicast,
* one-way with terrsstrial return, and
* two-way satellite access.

Contents
* 1 One-way multicast
o 1.1 System hardware components
o 1.2 System software components
* 2 One-way with terrestrial return
o 2.1 System hardware components
o 2.2 System software components
o 2.3 Theory of operation
* 3 Two-way
* 4 Reducing satellite latency
* 5 Access Providers
* 6 References
* 7 See also

One-way multicast

One-way multicast satellite Internet systems are used for IP multicast-based data, audio and video distribution. In the U.S., an FCC license is required only for the uplink station and no license is required for users. Note that most Internet protocols will not work correctly over one-way access, since they require a return channel. However, Internet content such as web pages can still be distributed over a one-way system by "pushing" them out to local storage at end user sites, though full interactivity is not possible. This is much like a TV or radio content which offers little user interface.

System hardware components

Similar to one-way terrestrial return, satellite Internet access may include interfaces to the Public Switched Telephone Network for squawk box applications. An Internet connection is not required, but many applications include an FTP server to queue data for broadcast.

System software components

Most one-way multicast applications require custom programming at the remote sites. The software at the remote site must filter, store, present a selection interface to and display the data. The software at the teleport must provide access control, priority queueing, sending, and encapsulating of the data.

One-way with terrestrial return

One-way terrestrial return satellite Internet systems are used with traditional dial-up access to the Internet, with outbound data traveling through a telephone modem, but downloads are sent via satellite at a speed near that of broadband Internet access. In the U.S., an FCC license is only required for the uplink station; no license is required for the users.

System hardware components

The transmitting station is called the teleport (also called "head end", "uplink facility", or "hub"). It has two components:

* Internet connection: The ISP's routers connect to proxy servers which can enforce Quality of Service (QoS) bandwidth limits and guarantees for user traffic. These are then connected to a DVB encapsulator which is then connected to a DVB-S modem. The RF signal from the DVB-S modem is connected to an up converter which is connected via feedline, to the outdoor unit.
* Satellite uplink: The Block Up Converter (BUC) and Low Noise Block converter (LNB, optional) which may use a wave guide to connect to the OMT (optional) which is bolted to the feedhorn which is connected by metal supports to the satellite dish and mount.

At the remote location (Earth station) the setup consists of:

* Outdoor unit
o Satellite dish with mount
o Feedhorn
o Universal Low Noise Block converter (LNB), for Ku band.
o Feedline
* Indoor unit
o DVB-S PCI card internal to a computer
o or, DVB external modem where an RJ-45 Ethernet port or a USB port connects the modem to the computer

Depending on the providers terms of contract, one cost effective way to use 1-way satellite internet is to use GPRS for the back-channel.[citation needed] By utilizing a 9600bps (9.6kb/s) connection that is offered in standard GPRS, the upload volume is very low and since this service is not per-time charged, users are able to surf and download in broadband speeds. There are companies offering speed up to 24Mbits. Another view of using GPRS as return would be the mobility when the service is provided by a satellite that transmits in the field of 50 to 53dBW. Using a 33cm wide satellite dish, a notebook and a normal GPRS equipped GSM phone, users can get broadband everywhere.

System software components

Remote sites require a minimum of programming to provide authentication and set proxy server settings. Filtering is usually provided by the DVB card driver.

Often, non-standard IP stacks are used to address the latency and asymmetry problems of the satellite connection. Data sent over the satellite link is generally also encrypted, as otherwise it would be accessible to anyone with a satellite receiver.

Many IP-over-satellite implementations use paired proxy servers at both endpoints so that clients and servers do not need to accept the latency inherent in a satellite connection. For similar reasons, there exist special VPN implementations designed for use over satellite links because standard VPN software cannot handle the long packet travel times.

Upload speeds are limited by the user's dial-up modem, and latency is high, as it is for any satellite based Internet. Download speeds can be very fast compared to dial-up:1 Mbit/s,4 Mbit/s,16 Mbit/s packages are generally offered.

Theory of operation
The back panel of a satellite modem, with coaxial connections for both incoming and outgoing signals, and an Ethernet port for connection to the internal network.
The back panel of a satellite modem, with coaxial connections for both incoming and outgoing signals, and an Ethernet port for connection to the internal network.

Remote sites use the proxy server at the teleport, which is configured to route all outbound traffic to the QoS server, which makes sure no user exceeds their allotted bandwidth or monthly traffic limits. Traffic is then sent to the encapsulator, which puts the IP packets inside of DVB packets. The DVB packets are then sent to the DVB modem and then to the transmitter (BUC).

Two-way

Two-way satellite Internet service sends data from remote sites via satellite to a hub, which then sends the data to the Internet. The satellite dish at each location must be precisely positioned to avoid interference with other satellites. The oscillators in some radar detectors can cause interference with these systems. Also, each location must use power management to adjust the amount of transmit power to compensate for things like rain fade. There are several types of two way satellite Internet services, such as TDMA or SCPC.

Each remote location is also equipped with a telephone modem; the connections for this are as with a conventional dial-up ISP. Two way satellite systems may sometimes use the modem channel in both directions for data where latency is more important than bandwidth, reserving the satellite channel for download data where bandwidth is more important than latency, such as for file transfers.

Uplink speeds rarely exceed one megabit per second and latency can be up to one second. Satellite phone services such as Iridium also provide data services at the comparatively slow speed of 2400 bit/s.

INMARSAT offers a satellite internet service called BGAN that does not have to be precisely aligned but the speeds are lower than the dish-based systems and bandwidth costs are much higher. Thuraya offers a similar service but this is not as fast as BGAN

See the standard DVB-RCS.

Reducing satellite latency

One solution is to use satellites in much lower orbit very close to the Earth, to shorten the travel distance. Such orbital paths are no longer geostationary, and so would require a large number of satellites in orbit so that at least one is visible in the sky at all times. Communication dishes could no longer be fixed, and would either need some way to track the satellites as they move across the sky, or to work in an omnidirectional manner without causing interference for anything else. The lower orbits would also subject the satellites to a slight drag effect from the upper atmosphere, requiring a means to boost the orbits back up as the satellites gradually slow down.

A theoretical alternative to satellites that is being explored is the use of ultra-light solar-powered airplane (see the Helios Prototype) that could fly in a continuous a circling path perhaps 70,000 feet (20 km) high or an airship (see Stratellite). These would act as flying satellites, providing high-speed service to customers below the aircraft. Since the roundtrip signal distance would only be 30 miles, the latency caused by the speed of light is an almost insignificant 0.1 ms under the craft, and 2 ms at the edge of the covered area, at a 300 km (200 miles) distance. Such service via aircraft is still in the experimental stages as of 2006.

Another practical method which can lower latency is to configure the satellite with a robust computer and cache. Much of the slowdown associated with satellite Internet is that for each request, many roundtrips must be completed before any useful data can be received by the requester.[1] A well-maintained cache located in space would alleviate many of the full round-trips. A caching DNS server would help tremendously. Caching web data would help, too. When cached data is requested, it takes less half of the normal time to receive the response, speeding up the time normally wasted on mere latency. Of course, this method requires some forethought by the people who design the satellite -- it is impractical to retrofit older satellites with new equipment such as this.

Access Providers

Coverage for each provider will vary depending on your intended location. Some large providers utilize a reseller network, either exclusively or optionally. So if you contact a large VSAT or satellite Internet Provider, you might be redirected to a local agent or reseller if they cannot deal directly with end users. Carefully consider whether your provider offers equipment maintenance, Fair Access Policies, installers in your area, and optional features like static IPs, VPN, or VOIP.

WHAT IS FINANCE

2. DEFINE FINANCE
Finance studies and addresses the ways in which individuals, businesses, and organizations raise, allocate, and use monetary resources over time, taking into account the risks entailed in their projects. The term finance may thus incorporate any of the following:
The study of money and other assets;
The management and control of those assets;
Profiling and managing project risks;
As a verb, "to finance" is to provide funds for business.
The activity of finance is the application of a set of techniques that individuals and organizations (entities) use to manage their financial affairs, particularly the differences between income and expenditure and the risks of their investments.
An entity whose income exceeds its expenditure can lend or invest the excess income. On the other hand, an entity whose income is less than its expenditure can raise capital by borrowing or selling equity claims, decreasing its expenses, or increasing its income. The lender can find a borrower, a financial intermediary, such as a bank or buy notes or bonds in the bond market. The lender receives interest, the borrower pays a higher interest than the lender receives, and the financial intermediary pockets the difference.
A bank aggregates the activities of many borrowers and lenders. A bank accepts deposits from lenders, on which it pays the interest. The bank then lends these deposits to borrowers. Banks allow borrowers and lenders of different sizes to coordinate their activity. Banks are thus compensators of money flows in space since they allow different lenders and borrowers to meet, and in time, since every borrower, in theory, will eventually pay back.
A specific example of corporate finance is the sale of stock by a company to institutional investors like investment banks, who in turn generally sell it to the public. The stock gives whoever owns it part ownership in that company. If you buy one share of XYZ Inc, and they have 100 shares available, you are 1/100 owner of that company. You own 1/100 of the net difference between assets and liabilities on the balance sheet. Of course, in return for the stock, the company receives cash, which it uses to expand its business in a process called "equity financing". Equity financing mixed with the sale of bonds (or any other debt financing) is called the company's capital structure.
Finance is used by individuals (personal finance), by governments (public finance), by businesses (corporate finance), etc., as well as by a wide variety of organizations including schools and non-profit organizations. In general, the goals of each of the above activities are achieved through the use of appropriate financial instruments, with consideration to their institutional setting.
Finance is one of the most important aspects of business management. Without proper financial planning, a new enterprise cannot even start, let alone be successful. As money is the single most powerful liquid asset, managing money is essential to ensure a secure future, both for an individual as well as an organization.

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