Brief introduction to satellite communications
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Brief introduction to satellite communications, Short version, made by Sally Sheridan for Gilat Satelites, Technical Trainer Job Interview

Brief introduction to satellite communications, Short version, made by Sally Sheridan for Gilat Satelites, Technical Trainer Job Interview

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Brief introduction to satellite communications Brief introduction to satellite communications Presentation Transcript

  • Introduction to Satellite Communications, Presented By Sally Sheridan B. Introduction to Satellite Communications Presented by Sally Sheridan
  • Why Satellite? Introduction to Satellite Communications Presented by Sally Sheridan
  • SATELLITE COMMUNICATIONS ARE: • Highly Survivable (Physical Survivability and Robustness) • Independent of Terrestrial Infrastructure • Able to Provide The Load Sharing and Surge Capacity Solution for Larger Sites • Best for Redundancy: They add a Layer of Path Diversity and Link Availability Introduction to Satellite Communications Presented by Sally Sheridan
  • SATELLITE SYSTEMS PERFORM EFFECTIVELY WHEN: • Terrestrial infrastructure is damaged, destroyed, or overloaded interconnecting widely distributed networks. • Providing interoperability between disparate systems and networks. • Providing broadcasting services over very wide areas such as a country, region, or entire hemisphere providing connectivity for the “last mile” in cases where fiber networks are simply not available. • Providing mobile/transportable wideband and narrow-band communications. • Natural disasters or terrorist attacks occur. • Satellites are the best and most reliable platform for communications in such situations fiber networks or even terrestrial wireless can be disrupted by tsunamis, earthquakes, or hurricanes. Satellites are instant communications infrastructure. Introduction to Satellite Communications Presented by Sally Sheridan
  • • Ubiquitous Coverage: A group of satellites can cover virtually all of the Earth’s surface. • Instant Infrastructure: Satellite service can be offered in areas where there is no terrestrial infrastructure and the costs of deploying a fiber or microwave network are prohibitive. It can also support services in areas where existing infrastructure is outdated, insufficient, or damaged. • Independent Of Terrestrial Infrastructure: Satellite service can provide additional bandwidth to divert traffic from congested areas, provide over flow during peak usage periods, and provide redundancy in the case of terrestrial network outages. • Temporary Network Solutions: For applications such as news gathering, homeland security, or military activities, satellite can often provide the only practical, short-term solution for getting necessary information in and out. • Rapid Provisioning Of Services: Since satellite solutions can be set up quickly, communications networks and new services can be quickly recovered And reconfigured. In addition, you can expand services electronic all without traditional terrestrial networks. • As a result, you can achieve a high level of communications rapidly without high budget expenditures. Introduction to Satellite Communications Presented by Sally Sheridan
  • CAPABILITIES • FIXED-TO-FIXED FIXED-TO-MOBILE • Mobile to mobile POINT-TO-MULTIPOINT Introduction to Satellite Communications Presented by Sally Sheridan
  • INTEROPERABILITY • • Satellite communications can interconnect with any other communications solution (i.e. LMR, Cellular, WiFi, etc.) via generic crossbanding equipment. Introduction to Satellite Communications Presented by Sally Sheridan
  • VOICE •Mobile Satellite Service (MSS) uses portable satellite phones and terminals. •MSS terminals May be mounted on a ship, an airplane, truck, or an automobile. •MSS terminals may even be carried by an individual. •The most promising applications are portable, satellite telephones and broadband Terminals that enable global service. •In addition, emerging mobile communication networks will also offer voice, video and data services via “smart”chips Inserted in handheld devices ( i.e. cellphones, LMR’s, PDA’s, laptops, etc.) that integrate cellular and satellite technology. MSS APPLICATIONS: Mobile Telephony Push to Talk Radio Emergency Response Coordination Dispatch Coordination Communications On The Move Asset Tracking Data Transfer Lone Worker Protection Environmental Monitoring Event Reporting Messaging Introduction to Satellite Communications Presented by Sally Sheridan
  • VIDEO/DATA • • Fixed Satellite Service (FSS) has traditionally referred to a satellite service that uses terrestrial terminals communicating with satellites in geosynchronous orbit. New technologies allow FSS to communicate with mobile platforms. FSS APPLICATIONS: Cellular Restoration Wi-Fi Restoral Emergency Phone Bank Communications On The Move PSTN Backhaul Voice-over-IP Broadband Internet Access Live Video Telemedicine Video Conferencing FSS APPLICATIONS: Introduction to Satellite Communications Presented by Sally Sheridan
  • Broadband Connectivity SATELLITE VSAT NETWORKS: A satellite Very Small Aperture Terminal (VSAT) network consists of a pre-positioned, fixed, or transportable VSAT that connects to a hub station to provide broadband communications to hospitals, command posts, emergency field operations and other sites. VSAT(s) are low-cost, 2 to 4 foot antennas equipped with a fixed mount that can be made survivable to over 100 mph winds. There are also variants of VSATs that are transportable which can be on-the-air within 30 minutes and require no special Tools or test equipment for installation. Remote FSS VSAT equipment requires standard AC power for operation, but comes equipped with lightweight, 1 and 2KW, highly efficient, and selfcontained power generator equipment for continuous operation, regardless of local power availability. Turnkey FSS communications packages can be provided with satellite bandwidth and ground equipment fully integrated. Internet access and Internet applications (i.e. VoIP) are supported through the remote VSAT back through the FSS provider teleport location which is connected to the PSTN and/or the Internet. A typical VSAT used by a first responder may have full two-way connectivity up to several Mbps for any desired combination of voice, data, video, and Internet service capability. VSATs are also capable of supporting higher bandwidth requirements of up to 4 Mbps outbound and up to 10+ Mbps inbound. The FSS network topology consists of remote point-to-multi-point and two-way satellite IP connectivity. Delivered bandwidth can support a substantial number of phone lines (i.e. phone bank). Transportable FSS VSATs providing high-speed Internet, data, voice, and/or video access with automatic set-up and simple operation. Introduction to Satellite Communications Presented by Sally Sheridan
  • VIDEO/DATA Network Restoration TERRESTRIAL BROADBAND, LMR, CELLULAR, OR WIMAX AND WIFI INFRASTRUCTURE RESTORATION: VSAT networks are able to provide high-speed, two-way emergency communications restoration in the wake of a natural or man-made disaster when all other forms of high-speed communication are unavailable. VSAT networks provide connectivity for restoral and contingency communications, providing for higher volume VoIP telephony, data, video and Internet access, thereby connecting remote locations to the rest of the world in a time of crisis. Introduction to Satellite Communications Presented by Sally Sheridan
  • APPLICATIONS SUPPORTED: Telco Terrestrial and WiMAX/WiFi Infrastructure Restoration VSAT networks provide for restoration of the Public Switched Telephone Network (PSTN) and Internet access to meet emergency communications demand, with high-speed connections that are independent of the local Telco ground system infrastructure to re-establish voice, data, and video connectivity. VSAT networks equally provide for restoration of wireless cellular nodes and WiMAX (Worldwide Interoperability for Microwave Access) WAN (Wide Area Network) networks to be re-established for private First Responder networks or to reconstitute local Telcos and Internet Service Providers (ISPs). Wireless Handheld Interoperability FSS VSAT networks are fully compliant to support IP based Ethernet data to/ from P25 wireless handheld radio systems. FSS VSAT networks may provide for IP phone signaling, acting as a redundant link between remote fire, rescue and other first responder’s operations centers to support any radio system with IP connectivity,[i.e.700 MHz]. Introduction to Satellite Communications Presented by Sally Sheridan
  • Communications On The Move (COTM) MOBILE COMMAND AND CONTROL COMMUNICATIONS: FSS and MSS COTM solutions can provide fully mobile IP data and voice services to vehicles on the move up to 60 mph. The comprehensive FSS COTM offering includes the terminal, teleport, and satellite capacity to provide high performance COTM IP connectivity. TYPICAL APPLICATIONS SUPPORTED: Any vehicle can also serve as a mobile command post while in-route and as a fixed command access point for personnel upon arrival at the designated location when local Telco terrestrial and wireless infrastructure are not available. A full 10 Mbps downlink channel is delivered via FSS to the vehicle and 512 Kbps uplink channel transmitted from the vehicle to the Internet using IP support for voice, video and data simultaneously. Support for 802.11x wireless access allows vehicle to function as wireless hot spot access point for a First Responder convoy while in-route or a fixed hot spot for personnel upon arrival. Introduction to Satellite Communications Presented by Sally Sheridan
  • Types of Satellites • • • • • • • Weather Satellites Communications Satellites Observation Satellites Navigation / GPS Satellites Military Satellites Nanosatellites / Microsatellites Remote Sensing Satellites Introduction to Satellite Communications Presented by Sally Sheridan
  • Types of Orbits • Geostationary orbit is when the satellite or spacecraft is stationary in a single position relative to the Earth • Polar Orbit is an orbit in which your spacecraft or your satellite crosses the orbits in a longitudinal fashion. • In a polar orbit, you can circle the Earth several times during one day. • Highly Elliptical Orbit: When the satellite passes Earth quickly and stays away from Earth fixed in a distant location. Introduction to Satellite Communications Presented by Sally Sheridan
  • Geostationary Orbit (GEO) • Satellite has to be placed approximately 22,000 miles (36,000 km) away from the surface of the Earth in order to remain in a GEO orbit • In GEO, the satellite will be on the equator and it will remain stationary since it will have a period of 24 hours Introduction to Satellite Communications Presented by Sally Sheridan
  • Geosynchronous Orbit • Geosynchronous orbit is like a geostationary orbit in the sense that it has a period of 24 hours. • However, unlike a GEO, it doesn’t have to be exactly above the equator, as it can have an angle relative to Earth and the orbit doesn’t have to be fully circular Introduction to Satellite Communications Presented by Sally Sheridan
  • Geosynchronous/Geostationary Orbit • By positioning a satellite so that it has infinite dwell time over one spot on the Earth, we can constantly monitor the weather in one location, provide reliable telecommunications service, and even beam television signals directly to your home • The down side of a geosynchronous orbit is that it is more expensive to put something that high up, and not possible to repair it from the shuttle • So you only put something in GEO if you really need to have it in the same location in the sky at all times. Introduction to Satellite Communications Presented by Sally Sheridan
  • Polar Orbit • These orbits have an inclination near 90 degrees. This allows the satellite to see virtually every part of the Earth as the Earth rotates underneath it. It takes approximately 90 minutes for the satellite to complete one orbit. Introduction to Satellite Communications Presented by Sally Sheridan
  • Polar / Geostationary Orbit Introduction to Satellite Communications Presented by Sally Sheridan
  • Heliosynchronous Orbit • These orbits allows a satellite to pass over a section of the Earth at the same time of day. • Since there are 365 days in a year and 360 degrees in a circle, it means that the satellite has to shift its orbit by approximately one degree per day. These satellites orbit at an altitude between 700 to 800 km • These orbits are used for satellites that need a constant amount of sunlight Introduction to Satellite Communications Presented by Sally Sheridan
  • Highly Elliptical Orbit • An object in orbit about Earth moves much faster when it is close to Earth than when it is further away. • If the orbit is very elliptical, the satellite will spend most of its time near apogee (the furthest point in its orbit) where it moves very slowly. Introduction to Satellite Communications Presented by Sally Sheridan
  • Various Satellite Orbits Introduction to Satellite Communications Presented by Sally Sheridan
  • LEO • LEO is Low Earth orbit and it is considered as 160 km to 500 km of altitude. Technically, in Low Earth orbit, the drag effects will always hinder operations. • For example, ISS is in LEO (around 386 km – 460 km) and it needs its orbit readjusted by the Space Shuttle or by its own thrusters every 6 months or it will fall down • Satellites in LEO will have very high speeds around 18,000 miles per hour Introduction to Satellite Communications Presented by Sally Sheridan
  • Low Earth Orbit Disadvantages • The first disadvantage is that there is still some atmospheric drag. Even though the amount of atmosphere is far too little to breath, there is enough to place a small amount of drag on the satellite or other object. As a result, over time these objects slow down and their orbits slowly decay. • The second disadvantage has to do with how quickly a satellite in LEO goes around the Earth. As you can imagine, a satellite traveling 18,000 miles per hour or faster does not spend very long over any one part of the Earth at a given time Introduction to Satellite Communications Presented by Sally Sheridan
  • MEO • MEO is Middle Earth Orbit is a special orbit that is beyond LEO. • MEO is usually defined as 500 Km – 1000 Km in most literature. However, previously it was defined as high as 10,000 km Introduction to Satellite Communications Presented by Sally Sheridan
  • HEO • HEO is High Earth orbit • HEO is defined as orbit above 1000 km in most literature. It extends to 40,000 km altitude. • Mostly in HEO, the drag effects would be non existent. Hence, HEO will have a more stable orbit free from atmospheric effects, but also it will require much more energy to put there Introduction to Satellite Communications Presented by Sally Sheridan
  • Introduction to Satellite Communications Presented by Sally Sheridan
  • Station Keeping in GEO • Most GEO satellites are required to remain within a box of +/0.05 degrees, so that it can be kept within operational parameters. • Usually with an interval of two weeks, first E-W corrections are made and then after another two weeks N-S corrections are made. Hence, this is repeated monthly to station keep the satellite. Introduction to Satellite Communications Presented by Sally Sheridan
  • Satellite Communication Applications Introduction to Satellite Communications Presented by Sally Sheridan
  • T V . Broadcasting • One of the main uses of communications satellite s is for TV broadcasting. This way, the TV signal can be transmitted to a large geographical region without detailed land transmitters or repeaters. • Also for a live broadcasting, it is best to use a satellite for sending a live signal from anywhere on Earth • DBS is Direct Broadcast Satellite for home viewing systems Introduction to Satellite Communications Presented by Sally Sheridan
  • D B S System • The satellite is the space segment of the DBS (Direct Broadcast System), the Earth segment consists of the satellite dish as well as the LNB (LOW NOISE BLOCK) and the satellite receiver Introduction to Satellite Communications Presented by Sally Sheridan
  • Outdoor Unit of a DBS System • The outdoor unit consists of a receiving antenna and a low noise amplifier / convertor. • For the antenna, parabolic or offset reflector is used. The antenna is designed so that the focus will be in directly front of the reflector • Usually 0.6 m to 1.3 m dishes are enough in the Ku band but for C band 2-3 m recommended Introduction to Satellite Communications Presented by Sally Sheridan
  • Outdoor Unit of a DBS System (LNB) • LNB is the Low Noise Block which is the combination unit consisting of a low noise amplifier followed by a convertor. • The LNB provides gain for the broadband 12 Ghz signal and then converts the signal to a lower frequency range so that low cost coaxial cable can be used as feeder to the indoor unit Introduction to Satellite Communications Presented by Sally Sheridan
  • Indoor Unit • The indoor unit consists of coaxial cabling as well as the satellite DBS receiver. • It will demodulate the signals and convert it into a form applicable for TV (PAL/SECAM/NTSC) Introduction to Satellite Communications Presented by Sally Sheridan
  • Bit Rates and Compression for Broadcasting TV Signals via Satellite • Before transmission, all broadcasting signals must be converted to digital, compressed and time division multiplexed signals. • The compressed bit rate and hence the number of channels depends on the type of the program material. • Talk shows where there is little movement require the lowest bit rate, while sports channels with lots of movement requires larger bit rates. Introduction to Satellite Communications Presented by Sally Sheridan
  • MPEG • MPEG compression standards are used to define standards for transmissions as well as for storage of moving pictures and sound. • MPEG covers bit rate, picture resolution, time frames for audio, and the packet details for transmission. • In DBS systems, MPEG – 2 is used for video compression while MPEG -1 is used for only audio transmission via DBS. MPEG 2 can also contain multi channel audio with stereo. Introduction to Satellite Communications Presented by Sally Sheridan
  • Satellite Mobile Services • For communications purposes, satellites are very useful for providing telephone coverage at any point in the world. • Satellites provide full coverage for phone, fax and internet connection • Some global satellite mobile services include: - Asian Cellular System - Thuraya Global System - MSAT (for North American coverage) Introduction to Satellite Communications Presented by Sally Sheridan
  • Thuraya • Thuraya satellite system serves an area between 20W and 100E longitude to 60 N and 2S latitude. System covers more then 110 countries with a combined population of 2.3 billion. It spans Europe, North and Central Africa and some parts of Southern Africa • Network capacity is about 13,750 telephone channels. Introduction to Satellite Communications Presented by Sally Sheridan
  • Iridium Satellite Network • Iridium satellite systems are special communications satellites for telephony that uses 66 satellites grouped in 6 orbital planes with each containing 11 satellites. Introduction to Satellite Communications Presented by Sally Sheridan
  • Iridium and Thuraya Orbits Iridium Orbit Thuraya Orbit Introduction to Satellite Communications Presented by Sally Sheridan
  • Large Scale Communications Network Introduction to Satellite Communications Presented by Sally Sheridan
  • VSAT • VSAT stands for Very Small Aperture System • In essence a VSAT terminal will be very small and it is used to create a two way communication between that point and the satellite Introduction to Satellite Communications Presented by Sally Sheridan
  • Applications of VSAT • There are various different applications of VSAT. These include: - Remote ATM locations - Internet Connectivity in Remote Regions - Network Connectivity in Remote Regions Introduction to Satellite Communications Presented by Sally Sheridan
  • G P S Satellites • GPS stands for Global Positioning Satellite System. • It consists of 24 satellites that circle the Earth. • By receiving signal from at least three/four of these satellites, the receiver position consisting of latitude, longitude and altitude can be determined accurately. Introduction to Satellite Communications Presented by Sally Sheridan
  • G P S Usage • Four satellites are used for latitude, longitude, altitude and for time marking. • GPS system uses one way transmission from satellites to users so the user requires only a GPS receiver Introduction to Satellite Communications Presented by Sally Sheridan
  • Remote Sensing & Imaging Satellites • Remote Sensing and Imaging satellites are an important part of our world as full coverage and mapping of the Earth has been done. • Google Earth is a good representation of this as the whole world has been imaged and mapped at your fingertips Introduction to Satellite Communications Presented by Sally Sheridan
  • Satellite & Internet Communications • Satellite links have been part of Internet’s connectivity since its beginning. • Satellite internet connection is used for satellite direct to home links as well as in creating a communications path between continents and major nodes. Inter-satellite links are also used for internet connectivity • There is a delay of 0.532 s in GEO satellites. The delay is less in MEO and LEO but since they are not stationary, 24h coverage is not possible. Introduction to Satellite Communications Presented by Sally Sheridan
  • Satellite & Internet Communications Data Transmission model: Introduction to Satellite Communications Presented by Sally Sheridan
  • GLOSSARY ANTENNA A device for transmitting and receiving signals. An antenna is part of an Earth Station. BACKHAUL A terrestrial communications channel linking an earth station antenna to a local switching network or population center. BANDWIDTH A measure of spectrum (frequency) use or capacity. For instance, a voice transmission by telephone requires a bandwidth of about 3000 cycles per second (3KHz). CHANNEL A frequency band in which a specific broadcast signal is transmitted. Channel frequencies are specified in the United States by the Federal Communications Commission. DOWNLINK The link from the satellite down to the Earth Station. EARTH STATION The buildings, hardware, software and antennas used to communicate with a satellite. FDMA Frequency Division Multiple Access. A way of sharing a channel by assigning different frequencies to different users. FOOTPRINT The area of the Earth’s surface from which an Earth Station can transmit to or receive from a particular satellite. FREQUENCY BANDS Internationally, frequencies are divided into well-defined bands. For satellites, the relevant bands are: L-Band As defined by IEEE std . 521, the frequency range from 1 to 2 GHz. The L-band term is also used to refer to the 950 to 1450MHz frequency range used for mobile communications. L-band is used for Mobile Satellite Services and offers Good penetration through adverse weather conditions and foliage. C-Band The frequency range from 3.7 to 6.2 GHz. Transmissions are less affected by atmospheric conditions such as snow and rain. However, C-band transmissions have low power, so Earth Stations must be rather large to compensate dish size. Applications include public switched networks and Internet trunking. X-Band The frequency range from 8.0 – 12.0 GHz. The X-band frequency enables high power operations with very small terminals. Applications Include COTM, manpacks, emergency communications and airborne and shipboard platforms. X-band is also less vulnerable to rain fade and adjacent satellite side lobe Interference than Other frequencies. Ku-Band The frequency range from 11.7 to 14.5GHz. Ku-band has higher power than C-band allowing for smaller dishes to be used. However, the higher frequency of Ku-band makes it more susceptible to adverse weather conditions than C-band. Applications include VSAT, rural telephony, satellite news gathering, videoconferencing, and multimedia. Ka-Band The frequency range from 17.7 to 21.2 GHz. Has a higher power than Kuband allowing for smaller dishes to be used and therefore, will be used for high-bandwidth interactive services such as high-speed Internet, videoconferencing, and multimedia applications. Ka-band transmissions are more sensitive to poor weather conditions than Ku-band. Introduction to Satellite Communications Presented by Sally Sheridan
  • HUB The master station through which all communications, to, from and between terminals must flow. KBPS Kilobits per second. Refers to transmission speed of 1,000 bits per second. KHZ KiloHertz. One KiloHertz is the equivalent of one thousand Hertz, or one thousand cycles per second. Used to measure frequency and bandwidth. LAN Local Area Network. A geographically localized network. MHZ Megahertz. One Megahertz is equivalent of one million Hertz, or one million cycles per second. Used to measure frequency and bandwidth. SPOT BEAM A satellite beam with concentrated geographic coverage. TDMA Time Division Multiple Access. A way of sharing a channel by assigning different time slots to different users. TERMINAL One of the communications stations that receives, processes, and transmits signals between itself and a satellite. TRANSPONDER A device located on board the satellite which receives signals uplinked from an earth station and transmits them back to earth on a different frequency. UPLINK The link from the earth station up to the satellite. VSAT Very small aperture terminal. Refers to small earth stations, with antennas usually in the 1.2 to 2.4 meter range. Small aperture terminals under 0.5 meter are sometimes referred to Ultra Small Aperture Terminals (USAT’s) WIFI Wireless Fidelity - A brand originally licensed by the Wi-Fi Alliance to describe the underlying technology of wireless local area networks based on the IEEE 802.11 specifications. A person with a Wi-Fi device, such as a computer, telephone, or personal digital assistant (PDA) can connect to the Internet when in proximity of an access point. The region covered by one or several access points is called a hotspot. WIMAX WiMAX is a wireless communications technology that provides highthroughput broadband connections for considerably longer distances than that offered via WiFi (Wireless Fidelity) LAN (Local Area Network). LMR Land Mobile radio is a term that denotes a wireless communications system intended for use by terrestrial users in vehicles (mobiles) or on foot (portables). Such systems are used by emergency first responder organizations, public works organizations, or companies with large vehicle fleets or numerous field staff. PDA PDA stands for Personal Digital Assistant. A Personal Digital Assistant is a hand-held device that performs many functions like a digital address book and organizer. Introduction to Satellite Communications Presented by Sally Sheridan
  • Thank you for your invaluable time and attention. Introduction to Satellite Communications Presented by Sally Sheridan
  • Credits Brief Introduction to Satellite Communications Presented ,edited, and compilated By: Eng. Sally Sheridan Bensimon, Zichron Yaakov, Israel September 2013 For: Gilat Satellite Networks References http://www.navymars.org/national/training/nmo_courses/nmoc/module17/14189_ch4.pdf http://www.escus.info/images/book4_sample.pdf http://www.etecenter.com/GVF/BR-8_GVF520.pdf http://www.mu.ac.in/myweb_test/Satelight%20Comm..pdf http://www.intelsat.com/wp-content/uploads/2013/01/5941-SatellitePrimer-2010.pdf http://www.tu-ilmenau.de/fileadmin/public/iks/files/lehre/UMTS/02_Mobicom-basics-ws12.pdf http://transition.fcc.gov/pshs/docs-basic/SIA_FirstRespondersGuide07.pdf http://www.near.aero/nearweb/documents/Voice%20Over%20Internet%20Protocol%20Communication%20System%20for%20Use%20in%20%20Air%20Traffic%20C ontrol.pdf http://www.near.aero/nearweb/documents/Voice%20Over%20Internet%20Protocol%20Communication%20System%20for%20Use%20in%20%20Air%20Traffic%20C ontrol.pdf http://www.eolss.net/Sample-Chapters/C05/E6-108-10-00.pdf http://epubs.surrey.ac.uk/741313/1/SIP%20Signalling%20and%20QoS%20for%20VoIP%20over%20IPv6%20DVB-RCS%20Satellite%20Networks.pdf Introduction to Satellite Communications Presented by Sally Sheridan