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Encyclopedia > Satellite Internet access

Satellite Internet services are used in locations where terrestrial Internet access is not available and in locations which move frequently. Internet access via satellite is available worldwide, including vessels at sea and mobile land vehicles. There are three types of satellite Internet service: An Earth observation satellite, ERS 2 In the context of spaceflight, satellites are objects which have been placed into orbit by human endeavor. ... Antarctica Oceania Africa Asia Europe North America South America Middle East Caribbean Central Asia East Asia North Asia South Asia Southeast Asia SW. Asia Australasia Melanesia Micronesia Polynesia Central America Latin America Northern America Americas C. Africa E. Africa N. Africa Southern Africa W. Africa C. Europe E. Europe N...

Contents

A simplex communication system is one where all signals flow in one direction. ... Routing Schemes anycast broadcast multicast unicast Multicast is sometimes also used to refer to a multiplexed broadcast, although that is a very different thing and should not be confused. ... A 2. ...

One-way multicast

One-way multicast satellite Internet systems are used for Internet Protocol (IP) multicast-based data, audio and video distribution. In the U.S., a Federal Communications Commission (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 TV or radio content which offers little user interface. The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... Routing Schemes anycast broadcast multicast unicast Multicast is sometimes also used to refer to a multiplexed broadcast, although that is a very different thing and should not be confused. ... Motto: (Out Of Many, One) (traditional) In God We Trust (1956 to date) Anthem: The Star-Spangled Banner Capital Washington D.C. Largest city New York City None at federal level (English de facto) Government Federal constitutional republic  - President George Walker Bush (R)  - Vice President Dick Cheney (R) Independence from... The FCCs official seal. ... A screenshot of a web page. ...


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 File Transfer Protocol (FTP) server to queue data for broadcast. The public switched telephone network (PSTN) is the network of the worlds public circuit-switched telephone networks, in much the same way that the Internet is the network of the worlds public IP-based packet-switched networks. ... “FTP” redirects here. ...


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 transmitting station 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 sent via satellite at a speed near that of broadband Internet access. In the U.S., an FCC license is required for the uplink station only; no license is required for the users. Dial-up access is a form of Internet access through which the client uses a modem connected to a computer and a telephone line to dial into an Internet service providers (ISP) node to establish a modem-to-modem link, which is then routed to the Internet. ... A modem (from modulate and demodulate) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. ... A WildBlue Satellite Internet dish. ...


System hardware components

The transmitting station (also called "teleport", "head end", "uplink facility", or "hub") 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 radio frequency (RF) signal from the DVB-S modem is connected to an up converter which is connected via feed line to the outdoor unit.
  • Satellite uplink: The block upconverter (BUC) and optional low-noise block converter (LNB), which may use a waveguide to connect to the optional orthomode transducer (OMT) which is bolted to the feed horn which is connected by metal supports to the satellite dish and mount.

At the remote location (Earth station) the setup consists of: This article does not cite any references or sources. ... In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service (QoS) refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the... Official DVB logo, found on compliant devices DVB, short for Digital Video Broadcasting, is a suite of internationally accepted open standards for digital television. ... It has been suggested that this article or section be merged with Radio waves. ... The feed line in a radio transmission, reception or transceiver system is the physical cabling that carries the signal to and from the aerial and is very important especially in certain conditions such as high frequency or weak signals or both as they often go hand in hand. ... BUC: Block Up-link Convertor, Ku Band Top: Hughes 1 Watt Bottom: Andrew 2Watt BUC Sweedish Microwave LNB BUC: Block Up-link Convertor, Ku Band 1. ... A low-noise block converter (LNB, for low-noise block, or sometimes LNC, for low-noise converter) is used in communications satellite (usually broadcast satellite) reception. ... Look up waveguide in Wiktionary, the free dictionary. ... OTM, Orthogonal-Mode Transducer VSAT Ku band Out-door Unit, includes Feed Horn, OMT, LNB & BUC Orthogonal Mode Transducer Portensigne France OMT Orthogonale-Mode Transduceur, Polarité Verticale et Horizontale Coté Parabole de lOMT Orthomode transducer also known as the polarisation diplexer is a device forming part of an antenna... In satellite dish and antenna design parlance, a feedhorn (or feed horn) is a horn antenna used to convey radio waves between the transceiver (transmitter and/or receiver) and the reflector. ... Sky Digital mini-dish Astros mini-dish. Special dish for up to 16 satellite positions (Ku-band) Satellite dish antenna for C-Band Satellite Dishes installed on an apartment complex A satellite dish is a type of parabolic antenna designed with the specific purpose of transmitting signals to and...

Depending on the providers terms of contract, one cost effective way to use 1-way satellite internet is to use General Packet Radio Service (GPRS) for the back-channel.[citation needed] By utilizing a 9600 bps (9.6 kbit/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 24 Mbits. 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 53 dBW. Using a 33 cm wide satellite dish, a notebook and a normal GPRS equipped GSM phone, users can get broadband everywhere. The Ku band (kay-yoo kurz-under band) is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 11 to 18 GHz. ... 64-bit PCI expansion slots inside a Power Macintosh G4 The Peripheral Component Interconnect, or PCI Standard (in practice almost always shortened to PCI), specifies a computer bus for attaching peripheral devices to a computer motherboard. ... An 8P8C modular plug that has yet to be crimped onto a cable Cat5 cables with 8P8C modular plugs, wired to EIA/TIA-568B 8P8C is short for eight positions, eight conductors, and so an 8P8C modular connector (plug or jack) is a modular connector with eight positions, all containing... Ethernet is a large, diverse family of frame-based computer networking technologies that operates at many speeds for local area networks (LANs). ... A USB Series “A” plug, the most common USB plug Universal Serial Bus (USB) is a serial bus standard to interface devices. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM and IS-136 mobile phones. ... In telecommunications and computing, bitrate (sometimes written bit rate, data rate or as a variable Rbit) is the number of bits that are conveyed or processed per unit of time. ... A kilobit per second (kbit/s or kbps or kBaud) is a unit of data transfer rate equal to 1,000 bits per second. ... Broadband in telecommunications is a term which refers to a signaling method which includes or handles a relatively wide range of frequencies which may be divided into channels or frequency bins. ... The Megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ... The Decibel watt or dBW is a unit for the measurement of the strength of a signal expressed in decibels relative to one watt. ... Several mobile phones A mobile telephone or cellular telephone (commonly mobile phone or cell phone) is a long-range, portable electronic device used for mobile communication. ...


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. The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. ... Lag is a common term used to describe a symptom often encountered in computing and especially networked systems, where results of actions appear much later than expected. ...


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 Virtual private network (VPN) implementations designed for use over satellite links because standard VPN software cannot handle the long packet travel times. A virtual private network (VPN) is a communications network tunneled through another network, and dedicated for a specific network. ...


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 Mbits,4 Mbits,16 Mbits 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 earth station (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). Image File history File linksMetadata WildBlueSatelliteModemBack. ... Image File history File linksMetadata WildBlueSatelliteModemBack. ... This article does not cite any references or sources. ... The site of the Andover Earth Station was selected by AT&T in December 1960. ...


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 time division multiple access (TDMA) or single channel per carrier (SCPC). Oscillation is the variation, typically in time, of some measure as seen, for example, in a swinging pendulum. ... An early radar detector A radar detector, sometimes called a fuzz buster, is an electronic device used by motorists to determine if their speed is being monitored by a radar unit. ... It has been suggested that Rain fade be merged into this article or section. ... Time division multiple access (TDMA) is a channel access method for shared medium (usually radio) networks. ... Single channel per carrier (SCPC) refers to using a single signal at a given frequency and bandwidth. ...


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. FTP or file transfer protocol is a commonly used protocol for exchanging files over any network that supports the TCP/IP protocol (such as the Internet or an intranet). ...


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. An Iridium phone (without the aerial) The Iridium satellite constellation is a system of 66 active communication satellites and spares around the Earth. ...


International Mobile Satellite Organization (INMARSAT) offers three bidirectional satellite internet services called Broadband Global Area Network (BGAN), Regional BGAN and MPDS, neither of which have to be precisely aligned but the speeds are lower than the dish-based systems and bandwidth costs are much higher. BGAN has the highest data rate. Thuraya offers a similar service but this is not as fast as BGAN. Inmarsat plc is an international telecommunications company founded in 1979, originally as an intergovernmental organization. ... A Broadband Global Area Network (BGAN), is a form of Satellite internet provided by INMARSAT. The system uses two geostationary satellites with an additional satellite planned to be launched in 2007. ... A Thuraya satellite phone Thuraya is a regional satellite phone provider, mainly focused on the Europe, Middle East, and Africa. ...


In 2006 the European Commission sponsored the UNIC project which aims at developing an end-to-end scientific test bed for the distribution of new broadband interactive TV-centric services delivered over low-cost two-way satellite to actual end-users in the home. The UNIC architecture employs DVB-S2 standard for downlink and DVB-RCS standard for uplink. The Commission seat in Brussels The European Commission (formally the Commission of the European Communities) is the executive body of the European Union. ... Unic was a French car manufacturer firm founded by Georges Richard in 1906 after having left Richard-Brasier. ... DVB-S2 is a newer specification of the DVB-S (Digital Video Broadcasting) standard. ... DVB-RCS stands for Digital Video Broadcasting - Return Channel via Satellite (or some people talk about Return channel over system) and is created in 1999 (by SES Global) and is commercialised in 2003. ...


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. A low Earth orbit (LEO) is an orbit in which objects such as satellites are below intermediate circular orbit (ICO) and far below geostationary orbit, but typically around 350 - 1400 km above the Earths surface. ... An omnidirectional antenna is an antenna system which radiates power uniformly in one plane with a directive pattern shape in a perpendicular plane. ...


A theoretical alternative to satellites that is being explored is the use of ultra-light solar powered airplane (see the NASA Pathfinder) that could fly in a continuous, 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. Solar power describes a number of methods of harnessing energy from the light of the sun. ... Helios UAV in flight NASAs Pathfinder and Helios were a series of solar- and fuel cell system-powered unmanned aircraft. ... Image of Sanswire One, a prototype Stratellite. ... A line showing the speed of light on a scale model of Earth and the Moon The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness.[1] It is the speed of all electromagnetic...


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. Caching would assist in speeds as well; When cached data is requested, it takes less than 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.


References

  1. ^ TCP is bound by the low latency of a three-way handshake. See Transmission Control Protocol.

The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite, often simply referred to as TCP/IP. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange streams of data using Stream Sockets. ...

See also


 
 

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