SATELLITE COMMUNICATION AND IT'S APPLICATION IN GPS
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SATELLITE COMMUNICATION AND IT'S APPLICATION IN GPS
- 1. Satellite Communication & Its Application In GPS Presented by: •Suchishmita Datta •Kakali Das •Arkaprava Jana
- 2. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 3. Introduction • A communication satellite is a station in space that is used for telecommunication, radio and television signals.
- 4. Kepler’s Law 1st Law : “The orbit of every planet is an 2nd Law: :A line joining a planet and the Sun sweeps out equal ellipse areasthe Sun equal intervals of time." with during at one of the two foci." 3rd law: "The square of the orbital period of a planet is 2 2 0.5 directly proportional e=(sthe )cube of the semi- to –r /s major axis of its orbit." where s & r are the major & minor axis of elliptical path respectively, e = T2=aD3 [a=orbital constant] eccentricity,
- 5. Pioneers in Satellite Communication • Konstantin Tsiolkovsky • Hermann Noordung • Arthur C. Clarke
- 6. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 7. Types of Satellite Orbits • Based on the inclination(i): – Equatorial Orbit (i=0°) – Polar Orbit (i=90°) – Other orbits (0°<i<90°) • Based on Eccentricity: – Circular with centre at the earth’s centre – Elliptical with one foci at earth’s centre
- 8. Based on Altitude: • Low Earth Orbit (LEO). • Geostationary Earth Orbit (GEO). • Medium Earth Orbit (MEO). • Highly Eccentric Orbit (HEO).
- 9. LEO (Low Earth Orbit) • Circular/slightly elliptical orbit, 2000km • Orbit period: 1.5 -2 km • Diameter of coverage: 8000 km • Signal propagation delay: <20 ms • Maximum satellite visible time:20 min • Atmospheric drag results in orbital deterioration.
- 10. MEO (Medium Earth Orbit) • Circular orbit: 2000-36000km • Orbit period: 2-12hrs • Diameter of coverage: 10,000-15,000km • Signal propagation delay: <50ms • GPS
- 11. GEO(Geostationary Earth Orbit) • Circular , 36,000 km • Orbital velocity:3 km/s • Orbital period : 1436 min or 23.93 hrs • High coverage area, stationary footprint • Good for broadcasting TV • Theoretically 3 geostationary satellites provides 100% earth coverage.(120 degree)
- 12. HEO(Highly Elliptical Orbit) •Elliptic orbit with a low-altitude perigee and a high-altitude apogee(over 35,786 kilometres) •i = 63.4° •All traffic must be periodically transferred from the “setting” satellite to the “rising” satellite (Satellite Handover)
- 13. Other Orbits • Molniya Orbit Satellites: • High Altitude Platform (HAP): i=63.4, orbital period = half sidereal day Solar powered aerial platforms Used by in quasi-stationary Operates Russia for decades. position, alt. : 22km Airship, Aircraftis an elliptical orbit. The satellite remains in a nearly fixed Molniya Orbit HAPs would have very small eight hours. but would have position relative to earth for coverage area, aA series of three Molniya satellites can act like a GEO satellite. comparatively strong signal. Cheaper to put polar regions would require a lot of them Useful in near in position, but in a network Altitude selection above normal air traffic
- 14. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 15. Types of Satellite • Passive Satellite: - Works as a reflector • Active Satellite: - Works as a retransmitter
- 16. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 17. Satellite Sub-systems • Altitude and Orbit control subsystem (AOCS) • Telemetry, Tracking, Command and monitoring Subsystem (TTC&M) • Power Subsystem • Structural Subsystem • Thermal Control Subsystem
- 18. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 19. Satellite Systems Types:-- S1 ES2 • Ground to ground system. ES1 S2 S1 • Ground cross link ground system. ES1 ES1 S1 • Ground to relay platform system. ES Relay Platfrom
- 21. Ground Segment •User , Terrestrial system •Earth station
- 22. Space Segment • Satellite Launching Phase , Transfer Orbit Phase , Deployment. • Operation • TT&C -Telemetry,Tracking and Command Station • SCC - Satellite Control Center, a.k.a.: • OCC - Operations Control Center • SCF - Satellite Control Facility • Retirement Phase
- 23. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 24. Frequency Coordination Choice of frequency bands depends on: • System Considerations(MSS and FSS). • Organization level frequency planning • Orbit frequency planning and coordination(INSAT).
- 25. Frequency Planning • Primary Frequency Allocation. • Secondary Frequency Allocation. • Footnote Allocation.
- 26. Frequency Bands Band Uplink Downlink Uses L–Band 1GHz 2GHz MSS S-Band 2GHz 4GHz MSS, NASA, Deep space research. C-Band 4GHz 8GHz FSS. X-Band 8GHz 12.5GHz FSS and in terrestrial imaging, [Ex: military and meteorological satellites].
- 27. Frequency Bands Band Uplink Downlink Uses Ku–Band 12.5GHz 18GHz FSS and BSS (DBS). K-Band 18GHz 26.5GHz FSS and BSS. Ka-Band 26.5GHz 40GHz FSS. Millimeter 40GHz 300GHz -------
- 28. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 29. Satellite Link Uplink Downlink Transponder
- 30. Types of Link
- 31. Satellite Link Design • The weight of satellite. • The choice frequency band. • Atmospheric propagation effects. • Multiple access technique.
- 32. Design (Downlink Received Power) Pr = EIRP + Gr - Lp - La - Lta - Lra dBW Where: EIRP(Equivalent isotropically radiated power)=10log10(PtGt)Dbw Gr =10log10(4πAe/λ2)dB Path Loss Lp =10log10[(4πR/λ)2]= 20log10[4πR/λ]dB La =Attenuation in the atmosphere Lta =Losses associated with transmitting antenna Lra =Losses associated with receiving antenna
- 33. Design (Downlink Noise Power) Pn=kTsBn watts. N=k+Ts+Bn dBW Where, K is Boltzmann's constant (-228.6 dBW/K/Hz) Ts is the system noise temperature in dBK Bn is the noise Bandwidth of the receiver in dBHz
- 34. Design (Uplink Received Power) Prxp=Pt+Gt+Gr-Lp-Lup dBW
- 35. Design (Uplink Noise Power) Nxp=K+Txp+Bn dBW
- 36. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 37. Capacity Allocation • TDMA Tf/N = b/R • FDMA DAMA µ = R/(N*b) FAMA • CDMA • ALOHA
- 38. Outline • Introduction • Orbit • Types of Satellite • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Satellite subsystems • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 39. VSAT •VERY SMALL APERTURE TERMINAL •Low or medium traffic •Antenna diameter – 1 to 3.7 meter •Star topology
- 40. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 41. Revolution of Satellites • 1957 – October 4 : - First satellite Sputnik – Sputnik 02 • 1958 – Project Score • 1960 – First successful passive satellite: Echo 1
- 42. Revolution of Satellite • 1962 – First active satellite Telstar • 1964 – INTELSAT – Syncom 3 • 1974 − ATS-6
- 43. INDIAN Satellite • 1975 - Aryabhata • 2003 - INSAT-3A • 2007 - INSAT-4B • 2012 - Megha-Tropiques
- 44. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 45. Application • SAT-PHONE •• INTERNET radio Amateur •• GPS DSCS • Fixed Service Satellite(FSS) • Direct Broadcast Satellite
- 46. GPS • Global Positioning System • Network of 24 satellites • Developed by DoD • Operational 24 hours/day • Available worldwide • Land, sea and air • Works in all weather conditions
- 47. GPS Satellite • Weighs approximately 2,000 lbs • Travels 7,000 mph • 17 feet across with solar panels extended • Orbit 12,500 miles above Earth • Circle the Earth twice daily
- 48. How Does GPS Work? HALDIA KOLKATA ITME DIAMOND HARBOUR
- 49. Determining GPS Position + Satellite A + Satellite B
- 50. Determining GPS Position + Satellite A + Satellite C + Satellite B
- 51. How do we decide which one is our true location? + Satellite A + Satellite C + Satellite B
- 52. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 53. Advantages •Satellite can be used for broadcast purpose ( one to many) within the large covered area. •Satellites are capable of handling very high bandwidth. •It is possible to provide large coverage using satellite •Satellite can provide signal to terrestrial uncovered pockets like valleys and mountainous regions. •The cost of transmitting information through satellite is independent of distance involved.
- 54. Disadvantages • Launching satellites into orbit is costly. • Satellite bandwidth is gradually becoming used up. • There is a larger propagation delay and noise interference in satellite communication • Impossibility to repair and maintain
- 55. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 56. CONCLUSION • The use of satellite technology, particularly in the use of communications satellites has grown rapidly in the past thirty years. Each day more and more uses for the satellites are being discovered. Feeding this is the rapid advancement of technology that allows the quick implementation of these uses. • Satellites remain the best utilization used for communications due to their speed and other advantages mentioned in this presentation.
- 57. Outline • Introduction • Orbit • Types of Satellite • Satellite subsystems • System Design • Choice of carrier • Satellite link • Capacity allocation • VSAT • Revolution • Application • Advantage & Disadvantage • Conclusion • Acknowledgement
- 58. Acknowledgement
Editor's Notes
- The dot pattern shows that as the planet is closest the sun, the planet is moving fastest and as the planet is farthest from the sun, it is moving slowest. Nonetheless, the imaginary line joining the center of the planet to the center of the sun sweeps out the same amount of area in each equal interval of time.
- In 1903, Konstantin Tsiolkovsky (1857–1935) published Means of Reaction Devices (in Russian: ???????????? ??????? ??????????? ??????????? ?????????), which is the first academic treatise on the use of rocketry to launch spacecraft. He calculated the orbital speed required for a minimal orbit around the Earth at 8 km/s, and that a multi-stage rocket fueled by liquid propellants could be used to achieve this. He proposed the use of liquid hydrogen and liquid oxygen, though other combinations can be used.In 1928 Slovenian Herman Potocnik (1892–1929) published his sole book, The Problem of Space Travel — The Rocket Motor (German: Das Problem der Befahrung des Weltraums — der Raketen-Motor), a plan for a breakthrough into space and a permanent human presence there. He conceived of a space station in detail and calculated its geostationary orbit. He described the use of orbiting spacecraft for detailed peaceful and military observation of the ground and described how the special conditions of space could be useful for scientific experiments. The book described geostationary satellites (first put forward by Tsiolkovsky) and discussed communication between them and the ground using radio, but fell short of the idea of using satellites for mass broadcasting and as telecommunications relays.In a 1945 Wireless World article the English science fiction writer Arthur C. Clarke (1917–2008) described in detail the possible use of communications satellites for mass communications.[3] Clarke examined the logistics of satellite launch, possible orbits and other aspects of the creation of a network of world-circling satellites, pointing to the benefits of high-speed global communications. He also suggested that three geostationary satellites would provide coverage over the entire planet.
- A low Earth orbit (LEO) is generally defined as an orbit below an altitude of approximately 2,000 kilometers (1,200 mi). Given the rapid orbital decay of objects below approximately 200 kilometers (120 mi), the commonly accepted definition for LEO is between 160 kilometers (99 mi) and 2,000 kilometers (1,200 mi) above the Earth's surface.[1][2] With the exception of the lunar flights of the Apollo program, all human spaceflights have taken place in LEO (or were suborbital). The altitude record for a human spaceflight in LEO was Gemini 11 with an apogee of 1,374.1 kilometers (853.8 mi). All manned space stations to date, as well as the majority of artificial satellites, have been in LEOOrbit period ranges from 1.5 to 2 hours.Diameter of coverage is about 8000 km.Round-trip signal propagation delay less than 20 ms.Maximum satellite visible time up to 20 min.Atmospheric drag results in orbital deterioration.
- Medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), is the region of space around the Earth above low Earth orbit (altitude of 2,000 kilometres (1,243 mi)) and below geostationary orbit (altitude of 35,786 kilometres (22,236 mi)).[3]The most common use for satellites in this region is for navigation, communication, and geodetic/space environment science.[3] The most common altitude is approximately 20,200 kilometres (12,552 mi)), which yields an orbital period of 12 hours, as used, for example, by the Global Positioning System(GPS).[3] Communications satellites that cover the North and South Pole are also put in MEO.[4]
- A geostationary orbit, or Geostationary Earth Orbit (GEO), is a circular orbit 35,786 kilometres (22,236 mi) above the Earth's equator and following the direction of the Earth's rotation. An object in such an orbit has an orbital period equal to the Earth's rotational period (one sidereal day), and thus appears motionless, at a fixed position in the sky, to ground observers. Communications satellites and weather satellites are often given geostationary orbits, so that the satellite antennas that communicate with them do not have to move to track them, but can be pointed permanently at the position in the sky where they stay. A geostationary orbit is a particular type of geosynchronous orbit.A geostationary orbit can only be achieved at an altitude very close to 35,786 km (22,236 mi), and directly above the Equator. This equates to an orbital velocity of 3.07 km/s (1.91 mi/s) or a period of 1,436 minutes, which equates to almost exactly one sidereal day or 23.934461223 hours. This ensures that the satellite is locked to the Earth's rotational period and has a stationary footprint on the ground. All geostationary satellites have to be located on this ring.Satellites in geostationary orbits are far enough away from Earth that communication latency becomes significant — about a quarter of a second for a trip from one ground-based transmitter to the satellite and back to another ground-based transmitter; close to half a second for a round-trip communication from one Earth station to another and then back to the first.
- . In satellite communications it is the process of transferring satellite control responsibility from one earth station to another without loss or interruption of service.
- Molniya orbit is a type of highly elliptical orbit with an inclination of 63.4 degrees, an argument of perigee of −90 degrees and an orbital period of one half of a sidereal day. Molniya orbits are named after a series ofSoviet/Russian Molniya (Russian: "Lightning") communications satellites which have been using this type of orbit since the mid-1960s.A satellite in a highly eccentric orbit spends most of its time in the neighborhood of apogee which for a Molniya orbit is over the northern hemisphere, the sub-satellite point at apogee having a latitude of 63.4 degrees North. As the apogee altitude is as high as 40,000 km, it will therefore, for a considerable period around apogee, have an excellent visibility from the Northern hemisphere, from Russia but also from northern Europe, Greenland and Canada.Much of the area of the former Soviet Union, and Russia in particular, is located at high latitudes. To broadcast to these latitudes from a geostationary orbit would require considerable power due to the low elevation angles. A satellite in a Molniya orbit is better suited to communications in these regions because it looks directly down on them.An additional advantage is that considerably less launch energy is needed to place a spacecraft into a Molniya orbit than into a geostationary orbit. Disadvantages are that, as opposed to a spacecraft in a geostationary orbit, the ground station needs a steerable antenna to track the spacecraft and that the spacecraft will pass the Van Allen belt four times per day.It is necessary to have at least three spacecraft if permanent high elevation coverage is needed for a large area like the whole of Russia where some parts are as far south as 45° N. If three spacecraft are used, each spacecraft is active for periods of eight hours per orbit centered at apogee