Name:GTID:ECE 6390: Satellite Communications and Navigation SystemsTEST 2 (Fall 2004)• Please read all instructions before continuing with the test.• This is a closed notes, closed book, closed friend, open mind test. On your desk you shouldonly have writing instruments and a calculator.• Show all work. (It helps me to give partial credit.) Work all problems in the spaces below theproblem statement. If you need more room, use the back of the page. DO NOT use or attachextra sheets of paper for work.• Work intelligently – read through the exam and do the easiest problems first. Save the hardones for last.• All necessary mathematical formulas are included either in the problem statements or the lastpage of this test.• You have 50 minutes to complete this examination. When the proctor announces a “last call”for examination papers, he will leave the room in 5 minutes. The fact that the proctor doesnot have your examination in hand will not stop him.• I will not grade your examination if you fail to 1) put your name and GTID number in theupper left-hand blanks on this page or 2) sign the blank below acknowledging the terms of thistest and the honor code policy.• Have a nice day!Pledge Signature:I acknowledge the above terms for taking this examination. I have neither given nor received unau-thorized help on this test. I have followed the Georgia Tech honor code in preparing and submittingthe test.11. Short Answer Section (20 points)(a)For a satellite that uses Answer multiple access, the average power of multiple signalsmust be backed-off from the peak amplifier output to avoid non-linear operation.(b)(True or False) If you double the C/N at the receiver, you will double the Shannon chan-nel capacity.(c) (1) (2) (3)Name three types of error correction codes.(d)A Answer filter is the optimal method for detecting a digital symbol.(e)Rayleigh fading is a special case of Rician fading when K = Answer .(f)A digital signal has a symbol period of 100 ns. Each symbol is used on in-phase andquadrature channels to code 32 discrete states. If the real data rate is 25 Mbits/sec, thenAnswer percent of the signal bits represent redundant error-correction coding.(g)(True or False) TDMA is best-suited for analog signals.(h) Check the boxes below for scenarios that do not lead to Rician fading in a radio link.A satellite mobile phone moves through an environment filled with nearby scatterers.The output amplifier of a bent-pipe transponder operates in saturation (nonlinearinput-output relation).Another TDMA packet collides with the data packet that an ES was trying to send.A 30 GHz ES points towards a GEO satellite during a storm.22. Digital Transmissions: A digital alien signal is received from outer space which uses thefollowing (bizarre) signal constellation and symbol shape.11100100TSSymbolShapeSignalConstellation(a) In the two graphs below, make a rough sketch of the in-phase and quadrature signals thatwould be sent into the alien’s IQ-modulator for the following data sequence: 10000111(16 points)90PhaseShifteroModulatedRFSignalOscillatorcos(2 )pf tCS++ttVoltageVoltageIn-PhaseQuadrature(b) What might be one of the drawbacks in using a symbol with this type of pulse shape? (9points)33. Video Over Satellite: A 14 GHz geostationary satellite is used to transmit a video signalto earth using one of three proposed methods. Assume a link distance of 36,000 km and anearth station that operates with 50 K of system noise temperature.• Method A: An analog video signal will be sent using VSB-AM with total bandwidth of 6MHz. Signal fidelity requirements demand a carrier-to-noise ratio of at least 40 dB.• Method B: The same analog video signal in Method A will be sent with FM, occupying afinal RF bandwidth of 30 MHz. Assume a pre-emphasis/de-emphasis gain of 7 dB.• Method C: The video signal will be digitized, compressed, and sent using the MPEG-2protocol, which operates at an average data rate of 28.2 Mbits/sec. This digital transmis-sion will occupy a total RF bandwidth of 43.2 MHz and will employ the World’s GreatestPossible Error Correction Code (WGPECC).Answer the following questions based on this scenario.(a) How much more/less transmit power in dB is required for Method B to maintain thesame effective C/N as Method A? (Do not include the subjective gain factor Q in thiscalculation.) (15 points)(b) How much more/less transmit power in dB is required for Method C compared to MethodA for maintaining the digital link? (15 points)4(c) If the maximum tolerable BER is 10−5for Method C, how much coding gain did WG-PEECG provide the link when compared to an uncoded QPSK signal? (use Q-functiongraph on last page to assist your calculation) (10 points)(d) If you were told that Method C uses BPSK for its digital modulation with a raised cosinepulse, what would the roll-off factor be? (5 points)(e) Other than transmit power, what are some of the engineering trade-offs in choosing oneof the 3 methods? (10 points)5Cheat Sheetλf = c c = 3 × 108m/sPR= PT+ GT+ GR− 20 log10µ4πλ¶− 20 log10(r) − Additional Loss in dBPN= kT B k = 1.3807 × 10−23J K−1FM SNR (in dB) =µCN¶dB+ 10 log10µBRFfmax¶+ 20 log10µfpeakfmax¶+ 1.8 + PBFM= 2(fmax+ fpeak) Channel Capacity = B log2µ1 +CN¶BER for QPSK: = QÃr2CN!Raised Cosine BW = (1 +