SEMBODAI RUKMANI VARATHARAJAN ENGINEERING COLLEGE SATELLITE COMMUNICATION PREVIOUS YEAR UNIVERSITY QUESTION PAPERS

Transcription

1 SEMBODAI RUKMANI VARATHARAJAN ENGINEERING COLLEGE DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING SATELLITE COMMUNICATION PREVIOUS YEAR UNIVERSITY QUESTION PAPERS PREPARED BY G.SUNDAR M.Tech.,MISTE., ASSISTANT PROFESS/ECE

2 B.E/B.Tech. DEGREE EXAMINATION, NOV/DEC 2007 Eighth semester ELECTRONICS AND COMMUNICATION ENGINEERING EC048 SATELLITE COMMUNICATION Time: Three hours maximum: 100 marks Answer ALL questions PART A-(10 x 2= 20 marks) 1. What are the conditions required for an orbit to be Geostationary? 2. Define Sun Transit outage. 3. What do you mean by a satellite Transponder? 4. Mention the effect of rain on the satellite service in C and Ku bands. 5. Distinguish single access and multiple accesses. 6. Compare the use of data compression and encryption in satellite communication. 7. What is Cassegrain antenna popular for large earth stations? 8. Why is G/T ratio a useful parameter to characterize earth stations? 9. What are the major short comings of present day VAST system? 10. Compare LEO, GEO and MEO satellite. PART B(5x16=80) 11.A. i. State the kepler s laws. Discuss its importance in satellite communications. ii. Explain satellite launching and the types of launch vehicles. B.i. Discuss the effect of non spherical earth atmospheric drag on the satellite orbit. ii. Explain how station keeping helps to keep a geostationary satellite in its correct Orbital slot. 12.A. i. Explain the difference types of transmission losses in satellite communication with necessary expression. Write the link power budget equation.

3 ii. Discuss the different types of noise and their significance in the design of a satellitelink with necessary expression. B. i. Explain the following: input backoff, output backoff, earth station HPA andcombined uplink and downlink. C/N ratio. ii. For a satellite circuit the individual link carrier-to-noise spectral density ratios are:uplink 100 db Hz; Downlink: 87 db Hz. Calculate the combined U/No ratio. 13.A. i. Compare pre-assigned FDMA and demand-assigned FDMA. ii. Explain the following with respect to TDMA: Reference burst, preamble andpostamble and carrier recovery. B. i. Compare the uplink power requirements of FDMA and TDMA. ii. Explain principles of Code-Division multiple Access. 14.A. Write short notes on:i. Community antenna TV system ii. TVRO system B. Explain the major test equipments required at an earth station. 15.A. i. Explain with the neat diagram the indoor and outdoor units of DBS home receiver. ii. Discuss the satellite mobile services. B. Explain the following satellite applications. i. GPS. ii. Satellite Navigational system.

4 B.E/B.Tech. DEGREE EXAMINATION, NOV/DEC 2007 Seventh semester Information Technology EC1015- SATELLITE COMMUNICATION Time: Three hours maximum: 100 marks Answer ALL questions PART A-(10 x 2= 20 marks) 1. Define satellite orbit and satellite axes. 2. What is the difference between geosynchronous and a geostationary satellite? 3. What is footprint? What does it depends upon? 4. What is eclipse of the satellite? 5. What is scintillation? 6. Define backoff in a power amplifier? 7. Define multiple accesses. 8. What are called syllabic companders? 9. Name some mobile satellite system. 10. What are the advantages and is disadvantages of forward error correction? PART B(5 x16=80 marks) 11.A.i. Explain the interpretation of kepler s laws. ii. Satellite is orbiting in a geosynchronous orbit of radius 42500km. find the velocity and time of orbit. What will be the change in velocity if the radius reduces to 36000km.if go= km3s2. B. i. If a satellite has an orbiting time of 23 hrs 56 min. calculate orbiting distance. Assume suitable data if required. ii. A satellite is orbiting round the earth at 4212km. The earth station is looking at this satellite at an elevation angle of 35degree. Calculate slant range. Make suitable assumption. 12.A. i. With a neat sketch explain launching mechanism. ii. Explain wideband receiver operation with neat diagram.b. i. Explain thermal control system. ii. With a neat sketch, explain Telemetry, Tracking and command subsystem.

5 13.A. i. Explain with neat diagram, the community antenna TV system. ii. Explain about the feeder losses and antenna misalignment losses. B. i. Derive link power budget equation. ii. Explain about the downlink and uplink rain fade margin. 14.A. i. Explain about the pre-assigned FDMA with neat diagram. ii. With aid of a diagram explain demand assigned FDMA. B. i. Explain the on-board signal processing for TDMA operation. ii. Explain the acquisition and tracking mechanism for CDMA techniques. 15.A. Write note on: i. Bit rate for digital television. ii. MPEG compression standards. B.i. Explain detail about the VSAT. ii. With neat sketch explain Global Positioning satellite System.

6 B.E/B.Tech. DEGREE EXAMINATION, APR/MAY 2008 Eighth semester ELECTRONICS AND COMMUNICATION ENGINEERING EC1015- SATELLITE COMMUNICATION (Common to VII Semester B.Tech. Information Technology and VII Semester Part-Time B.E.(ECE) ) Time: Three hours maximum: 100 marks Answer ALL questions PART A-(10 x 2= 20 marks) 1.A satellite is orbiting in the equatorial plane with a period from perigee to perigee of 12hours. Given that the eccentricity is 0.002, calculate the semimajor axis. The earth s equatorial radius is Km. 2.What are polar orbiting satellites? 3.Determine the angle of tilt required for a polar mount used with an earth station at latitude 49 degree north. Assume a spherical earth of mean radius 6371 Km and ignore earth station altitude. 4.What is a transponder? 5.A satellite downlink at 12 GHz operates with a transmit power of 6 W and an antennagain of 48.2dB. Calculate the EIRP in dbw. 6.What is intermodulation noise? 7.What is a SPADE system? 8.What is CDMA? 9.What is the orbital spacing of satellites? 10.What are VSTs? PART B-(5x16=80) 11.A. i. State kepler s three laws planetary motion. Explain their relevance to artificial satellites orbiting the earth. (8) ii. Define universal time and sidereal time. (4)

7 iii. The cosmos 1675 satellite has an apogee height of Km and a perigee heigh tof 613 Km. Determine the semi major axis and the eccentricity of its orbit. Assume a mean earth radius of 6371 Km. (4) B. i. Discuss about frequency allocations for satellite services. (8) ii. What are the effects of non spherical earth on the orbital mechanics of a satellite? (4) iii. Calculate the radius of a circular orbit for which the periods is 1 day. (4) 12.A. i. Discuss about near geostationary orbits. ii. Determine the limits of visibility for an earth station situated at mean sea level, at latitude degree north and longitude degree west. Assume a minimum angle of elevation of 5.9 degree. iii. Discuss about sun transit outage. B.i. Discuss in detail about attitude control of a satellite. ii. What is the chief advantage of the TWTA used aboard satellite compared to other types of high power amplifiers? What are the main disadvantages of TWTA? iii. What is thermal control? Why is it required? (4) 13.A. i. With the aid of a block diagram, describe the functioning of the indoor receiving unit of a satellite TV/FM receiving system intended for home reception. ii. In most satellite TV receivers, the first IF band is converted to a second, fixed IF. Why is this second frequency conversion required? iii. Discuss about antenna misalignment losses with relevant, figures. (6) B. i. An antenna has a noise temperature of 35 K and is matched into a receiver which has a noise temperature of 100 K. Calculate the noise power for a band of 36MHz. (4) ii. What is input backoff? Describe it. Also substantiate the reason behind employing it. (6) iii. Derive the link power budget equation. (6) 14.A. i. Discuss in detail about direct sequence spread spectrum. (8)

8 ii. In a TDMA network the reference burst and the preamble each requires 5GO bites and the nominal guard interval between bursts is equivalent to 120 bits. Given that there are eight traffic bursts and one reference burst per frame and the frame length I equivalent to bits, calculate the frame efficiency. (4) iii. Distinguish between pre assigned and demand assigned traffic in relation to a satellite communication network. (4) B. i. Discuss in detail about satellite links find TCP. (10) ii. Explain what is meant by satellite asymmetric channels- Describe how asymmetric channels may be incorporated in internet connections via satellites. 15.A. i. For a 24 MHz bandwidth transponder and allowing for a roll off factor of 0.2, what is the symbol rate? ii. Discuss in detail about MPEG compression standards. iii. The EIRP of a 240W transponder is 57dBW. Calculated the approximate gain of the antennas. Suppose if this transponder is switched to 120W. what will be the new EIRP, Given the same antenna is used? B. i. Discuss in detail about global positioning satellite system.ii. Write brief notes on the advantages and disadvantages of using satellite in LEOs,MEOs and GEOs for mobile satellite communications.

9 B.E/B.Tech. DEGREE EXAMINATION, APRIL/MAY 2008 Eighth semester ELECTRONICS AND COMMUNICATION ENGINEERING EC1015 SATELLITE COMMUNICATION (Regulation 2004) Time: Three hours maximum: 100 marks Answer ALL questions PART A-(10 x 2= 20 marks) 1.List out the frequency bands used for satellite services. 2.State Kepler s second law of planetary motion. 3.What is meant by momentum wheel stabilization? 4.What are geostationary satellites? 5.What is meant by input back off of a transponder? 6.Give the formulae to compute the uplink carrier to noise ratio. 7.What are the limitations of FDMA-satellite access? 8.Distinguish between pre-assigned and demand-assigned TDMA satellite access. 9.Give the application of satellites. 10.What are the various compressions standards used inn satellite applications? PART B(5x16=80 marks) 11.A. What are orbital elements? Derive the six orbital elements of satellite from Newton slaw of motion. B. How the satellite positions are estimated using the sub-satellite points? 12.A. What are look angles and derive the expressions for azimuth and elevation?

10 B. With a neat block diagram, explain the attitude and orbit control system present in the space segment. 13.A. With a neat sketch, explain the power budget for a satellite link considering back off and rain fade margin. B. How does the system noise temperature affect the performance? Derive the expression for overall system noise temperature at the receiving earth station. 14.A. With a neat block diagram, explain the functioning of a SPADE system. B. Explain the TDMA burst and frame structure of satellite system. Draw the necessary diagrams. 15.A. In detail, give an account of various compression standards used in the satellite context. B. What is meant by DTH? What are the design issues to be considered for launching DTH systems?

11 B.E/B.Tech. DEGREE EXAMINATION, APR/MAY 2008 Eighth semester ELECTRONICS AND COMMUNICATION ENGINEERING EC048 SATELLITE COMMUNICATION Time: Three hours maximum: 100 marks 1.What is meant by perigee? 2.Define geostationary orbit. Answer ALL questions PART A-(10 x 2= 20 marks) 3.Why is noise temperature an important parameter in communication receivers? 4.What are the main fund ions of TTC sub system? 5.What are the basic problems in satellite digital transmission? 6.Define encryption. 7.List the earth station parameters affecting the C/N ratio. 8.What is the relationship between EIRP and antenna gain? 9.Which kinds of communication can be accommodated by the network structure of MSAT? 10.Write the applications of INSAT. PART B-(5x16=80 marks) 11.A. Explain how Kepler s and Newton s laws are useful to describe the orbit. B. i. A satellite is moving in a highly eccentric Malniya orbit having the farthest and the closest points as 3500km and 500km and 500km respectively from earth surface. Determine the orbital time period time period time period and the velocity at apogee and perigee points. (Assume earth s radius = 6360km).

12 ii. The semi-major axis and the semi-minor axis of an elliptical satellite orbit are20,000km and 16,000km respectively. Determine the apogee and perigee distances. 12.A. i. Consider the receiver side of an earth station. The antenna gain is 65 db and it noise contribution in 60 K. The wave guide Ions is 0.5 db. Find the equivalent noise temperature of LNA assuming that the noise contribution by the down converter is negligible and earth station G/T is 40 db. K. (To=300K) ii. What are the factors contributing to noise in an earth station receiving channel? Explain. B. From system noise temperature calculation, prove that C/N ratio is directly proportional to G/T ratio. 13.A. i. Distinguish between TDMA, FDMA and CDMA techniques. B.i. Explain the properties of maximum length sequences. ii. Discuss briefly on analog voice transmission. 14.A. i. Explain in detail about TVRO systems. ii. Explain how the gain of large antenna van be optimized. B. i. The continental united states (48 contiguous states) subtend on angle of approximately 6º x 3º when viewed from geostationary orbit. What dimension must a reflector antenna have to illuminate half this area with a circular beam 3º in diameter at11 GHz? What gain would the antenna have? Can a reflector be used to produce a 6º x 3ºbeam?ii. The earth subtends an angle of 17 º when viewed from geostationary orbit. What are the dimensions and gain of a horn antenna that will provide global coverage at 4 GHz? 15.A. i. Discuss briefly on DAB system. ii. With a neat block diagram explain (lie outdoor unit for an OUS home receiver. B. Explain all the types of INTELSAT satellite with respect to basic space craft characteristics and the vehicle type.

13 B.E./B. Tech DEGREE EXAMINAION, MAY/JUNE 2009 Eigth Semester (Regulation 2004) Electronics and Communication Engineering EC SATELLITE COMMUNICATION (Common to VII Semester B.Tech. Information Technology and VII Semester Part-Time B.E. (ECE)) Time : Three hours Maximum: 100 marks Answer ALL questions PART A- (10 x 2=20 marks) 1. A satellite is orbiting in the equatorial plane with a period from perigee to perigee of 12hours. Given that the eccentricity is 0.002, calculate the semimajor axis. The earth's equatorial radius is Km. 2. What are polar orbiting satellites? 3. Determine the angle of tilt required for a polar mount used with an earth station at latitude49 degrees north. Assume a spherical earth of mean radius 6371 Km and ignore earth station altitude. 4. What is a transponder? 5. A satellite downlink at 12 GHz operates with a transmit power of 6 W and an antenna gain of 48.2 db. Calculate the EIRP in dbw. 6. What is intermodulation noise? 7. What is a SPADE system? 8. What is CDMA? 9. What is the orbital spacing of satellites? 10. What are VSATs? PART B (5 x 16=80 marks) 11.(a)(i) State Kepler's three laws of planetary motion. Explain their relevance to artificial satellites orbiting the earth. [Marks 8] (ii) Define Universal time and sidereal time. [Marks 4]

14 (iii) The cosmos 1675 satellite has an apogee height of Km and a Perigee height of 613Km. Determine the semi major axis and the eccentricity of its orbit. Assume a mean earth radius of 6371 Km. [Marks 4] Or 11.(b)(i) Discuss about frequency allocations for satellite services. [Marks 8] (ii) What are the effects of a non spherical earth on the orbital mechanics of a satellite? [Marks4] (iii) Calculate the radius of circular orbit for which the period is 1 day. [Marks 4] 12.(a)(i) Discuss about near Geostationary orbits. [Marks 6] (ii) Determine the limits of visibility for an earth station situated at mean sea level, at latitude degrees north and longitude degrees West. Assume a minimum angle of elevation of 5 degrees. [Marks 6] (iii) Discuss about sun transit outage. [Marks 4] 12.(b)(i) Discuss in detail about attitude control of a satellite. [Marks 8] Or (ii) What is the chief advantage of the TWTA used aboard satellites compared to other types of high power amplifiers? What are the main disadvantages of TWTA? [Marks 4] (iii) What is thermal control? Why is it required? [Marks 4] 13.(a)(i) With the aid of a block diagram, describe the functioning of the indoor receiving unit of a satellite TV/FM receiving system intended for home reception. [Marks 8] (ii) In most satellites TV receivers, the first IF band is converted to a second, fixed IF. Why is this second frequency conversion required? [Marks 2] (iii) Discuss about antenna misalignment losses with relevant figures. [Marks 6] Or 13.(b)(i) An antenna has a noise temperature of 35 K and is matched into a receiver which has a noise temperature of 100 K. Calculate the noise power density and the noise power for a bandwidth of 36 MHz. [Marks 4] (ii) What is input backoff? Describe it. Also substantiate the reason behind employing it.[marks 6] (iii) Derive the link power budget equation. [Marks 6]

15 14.(a)(i) Discuss in detail about direct sequence spread spectrum. [Marks 8] (ii) In a TDMA network the reference burst and the preamble each requires 560 bits and the nominal guard interval between burats is equivalent to 120 bits.given that there are eight traffic bursts and one reference burst per frame and the total frame length is equivalent to40800 bits, Calculate the frame efficiency. [Marks 4] (iii) Distinguish between preassigned and demand assigned traffic in relation to a satellite communications network. [Marks 4] 14.(b)(i) Discuss in detail about satellite links and TCP. [Marks 10] Or (ii) Explain what is meant by asymmetric channels. Describe how asymmetric channels may be incorporated in internet connections via satellites.[marks 6] 15.(a)(i) For a 24 MHz bandwidth transponder and allowing for a roll off factor of 0.2, what is symbol rate? [Marks 2] (ii) Discuss in detail about MPEG compression standards. [Marks 10] (iii) The EIRP of a 240 W transponder is 57 dbw. Calculate the approximate gain of the antenna. Suppose if this transponder is switched to 120 W.What will be the new EIRP, given the same antenna is used? [Marks 4] Or 15.(b)(i) Discuss in detail about Global Positioning satellite System. [Marks 10] (ii) Write brief notes on the advantages and disadvantages of using satellites in LEOs, MEOs and GEOs for mobile satellite communications. [Marks 6]

16 B.E/B.Tech. DEGREE EXAMINATION, APR/MAY 2010 Eighth semester ELECTRONICS AND COMMUNICATION ENGINEERING EC1008 SATELLITE COMMUNICATION (Regulation 2007) Time: Three hours maximum: 100 marks Answer ALL questions PART A-(10 x 2= 20 marks) 1.Distinguish mean anomaly and true anomaly 2.What is meant by Julian zero time reference? 3.Distinguish geostationary and geosynchronous satellite. 4.What is meant by Hohmann transfer orbit? 5.The range between a ground station and satellite is 42,000 km. Calculate the free space loss at a frequency of 6 GHz. 6.A LNA is connected to a receiver which has a noise figure of 12 db. The gain LNA is 30dB and its noise temperature is 12k. Calculate the overall noise temperature referred to the LNA input. 7.Define space division multiple access. 8.Compare centrally controlled and distributed control random access techniques. 9.Determine the symbol rate that can be carried in a 24 MHz transponder. Assume a rolloff factor of Give the application of orbeomm. PART B(5x16=80 marks) 11.A. i. Discuss the effects non spherical earth and atmosphere drag on satellite Communication. ii. State and explain Kepler s laws.

17 B. i. Explain topocentric horizon and geocentric equatorial coordinate systems. ii. Explain the determination of sub satellite point. 12.A. i. Explain the attitude control of a satellite with necessary diagrams. ii. Write a brief note on TT and C subsystem. B. i. Discuss in detail various units of a transponder. ii. Discuss with a neat diagram the Anik-E C band transponder. 13.A. i. Explain in detail transmit receive earth stations. ii. A satellite TV signals occupies the full transponder bandwidth of 36 MHz, and it must provide a C/N ratio of 22 db the destination losses are 200 db and the destination earth station G/T ratio is 31dB/K, Calculate the satellite required. B. i. Explain the effected of rain on satellite communication system. ii. Explain the intermodulation noise in satellite communication systems. 14.A. i. Explain satellite switched TDMA. ii. Discuss the on board signal processing for FDMA/TDMA operation. B. i. Discuss the principles of CDMA. Explain the application of CDMA in satellite communication. ii. Give a brief account of split TCP connections. 15.A. i. Give a brief account of MPEG compression standards. ii. Write a block diagram explain home receiver indoor unit. B. Write a short notes on i. VSAT ii. Radarsat iii. GPS System

18 B.E/B.Tech. DEGREE EXAMINATION, November/December 2010 Seventh semester ELECTRONICS AND COMMUNICATION ENGINEERING EC1008 SATELLITE COMMUNICATION (Regulation 2007) Time: Three hours maximum: 100 marks Answer ALL questions PART A-(10 x 2= 20 marks) 1.What is meant by apogee and perigee heights? 2.Define universal time. 3.What is meant by polar mount antenna? 4.Define transponder. 5.What is intermodulation noise? 6.A satellite downlink at 12 GHz operates with a transmit power of 6 W and an antennagain of 48.2 db. Calculate the EIRP in dbw. 7.Distinguish between pre-assigned and demand assigned TDMA satellite access. 8.Define space division multiple access. 9.What are the components of GIS? 10.List out the image enhancement techniques. PART B-(5x16=80 marks) 11.A. i. Discuss the effects of non spherical earth and atmospheric drag on satellite communications. (10) ii. State and explain kepler s laws. (6) B. Explain how satellite positions are estimated using sub-satellite. (16) 12.A. i. What are look angles and derive the expressions for azimuth and elevation? (16) B. i. Discuss with a neat diagram the Anik-E C band transponder. (8) ii. Explain the attitude control of a satellite with necessary diagrams. (8)

19 13.A. i. Explain in detail transmit receive earth stations. (10) ii. An antenna has a noise temperature of 35K and is matched into a receiver which has a noise temperature of 100K. Calculate the noise power density and the noise power for a bandwidth of 36 MHz (6) B. With a neat sketch, explain the power budget for a satellite link considering back off and rain fade margin.(16) 14.A. i. Explain the principle behind spectrum spreading and dispreading and how this is used to minimize interference in a CDMA system. Also determine the throughput efficiency of the system. (16) B. Explain the TDMA burst frame structure of satellite system with necessary diagrams.(16) 15.A. i. Explain about data input hardware of GIS. (8) ii. Explain about output hardware of GIS. (8) B. i. How GIS is integrated with remote sensing? (8) ii. Briefly discuss about watershed management and resource information systems. (8)

20 B.E/B.Tech. DEGREE EXAMINATION, APR/MAY 2011 Eighth semester ELECTRONICS AND COMMUNICATION ENGINEERING EC1015 SATELLITE COMMUNICATION (Regulation 2004) (Common to B.E. (Part-Time) Seventh Semester, Electronics and Communication Engineering,Regulation 2005) Time: Three hours maximum: 100 marks Answer ALL questions PART A-(10 x 2= 20 marks) 1.Distinguish direct and retrograde orbits. 2.What is the impact of atmospheric drag on satellite systems? 3.Define polar mount antenna. 4.What is meant by station keeping? 5.Calculate the gain in db of a 5 meter paraboloidal antenna operating at 12GHz. Assumean aperture efficiency of The range between a ground station and a satellite is 42,000km. Calculate the free spaceloss at a frequency of 4 GHz. 7.Define false detection probability. 8.What are the applications of Teledesic satellite network? 9.Write the objectives of Radarsat program. 10.Give the services offered by Globalstar. PART B-(5 x 16 = 80 marks) 11.A. i. Discuss the effect of non spherical earth on satellite communication.(8)ii. Explain the determination of sub satellite point. (8) B. Give a brief account of i. Theory and application of geocentric equatorial coordinate systems. (8) ii. Orbital elements. (4) iii. Orbital plane. (4) 12.A. i. Explain the attitude control of satellite with necessary diagram. (10)

21 ii. Write a brief note on satellite wideband receiver. (6) B. i. Explain the antenna subsystem. (8) ii. Discuss launching orbits in detail. (8) 13.A. i. Explain in detail transmit receive earth stations. (10) ii. What is the effect of a rain on the uplink and downlink of satellite systems? (6) B. i. Explain the different types of noise to be considered in the design of satellite communication system. (8) ii. Explain the calculation of combined uplink and downlink C/N ratio. (8) 14.A.i. Explain pre assigned and demand assigned TDMA systems. (8) ii. Discuss the operation of SPADE communication system. (8) B. i. Discuss the principles of CDMA. Explain the applications of CDMA in satellite communication. (8) ii. Give a brief account of asymmetric channels in satellite links using TCP connections. (8) 15.A. i. With a block diagram explain home receiver indoor and outdoor units. (10) ii. Give a brief account of VSAT systems. (6) B. Explain the objectives, principles and applications of i. Orbcomm. (8) ii. GPS system. (8)

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