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Link Budget Calculation

Link Budget Calculation. Introduction. A satellite communication link is defined as an Earth station - satellite - Earth station connection . The Earth station - satellite segment is called the uplink . The satellite - Earth station segment is called the downlink. Introduction.

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Link Budget Calculation

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  1. Link Budget Calculation

  2. Introduction • A satellite communication link is defined as an Earth station - satellite - Earth station connection. • The Earth station - satellite segment is called the uplink. • The satellite - Earth station segment is called the downlink.

  3. Introduction • The Earth station design consists of the Transmission Link Design (Link Budget) and the Transmission System Design. • Link Budget establishes the resources needed for a given service to achieve the performance objectives.

  4. Link Budget Calculation betweenthe VINASAT satellite and the Earth Station at Tam Ky, Quang Nam

  5. LinkParameters * Operation Bandwidth Link design at Ku-Band, using frequency of 14GHz for the uplink and 11GHz for the downlink.

  6. LinkParameters * Earth Station - Located at 15,20N latitude and 108,30E longitude. - The diameter of the antenna (D) is 13m, the aperture efficiency (η) is 65% - Transmission power of Earth Station is 300W. - Earth station antenna height of 7m above sea level.

  7. LinkParameters * Satellite - Located at 1320E longtitude. - EIRPs = 50dBW. - Transponder Bandwidth is 36MHz. - Receiver noise figure F = 4dB. - Receiver figure of merit (G/T)s = 1dB/0K

  8. LinkParameters * Other suppositions - Feeder loss LF = 1dB - Polarization mismatch loss LPOL = 0.5dB - Antenna misalignment loss 0.9dB - Rain loss figure ɣ= 3.96dB/km, rain height hR = 3.208Km - Tropospheric loss figure 0.02dB/Km - Ambient temperature TX = 3000K

  9. Link Budget - Slant range distance is where + Earth station latitudeat Tam Ky= 15.20 N + Ls = 1320E , Le = 108.30N → Difference in longitude between the earth station and the satellite is ΔLe = 1320 – 108.30 = 23,70 → → β0 = 27.920

  10. Link Budget Distance between VINASAT satellite and Earth station at Tam Ky is d=36629.4 km - Elevation angle of satellite from the Earth station θe where Re = 6378 [km] r = 35768 + 6378 = 42146 [km] → tgθe = 1.565 →θe = 57.420

  11. Link Budget • Azimuth of the satellite φa → A = -59.150 → φa = 1800 – (–59.150) = 239.150 - Earth station transmit antenna gain where η= 0.65 ; D = 20m ; fU= 14GHz ; c=3.108m/s → GTe =67.473 [dB]

  12. Uplink Budget - Earth station transmit power (300W) in dB is PTe = 24.77 [dBW] - Equivalent Isotropic Radiated Power of the transmitting Earth station is EIRPe = GTe+ PTe = 92.244 [dBW] - Uplink total loss is LU = LSPU + LFU + LOU

  13. Uplink Budget + Free-space loss is + Rain loss is (LR)U = ɣU.LS [dB] where LS is the effective path length of the signal through the rain At 15,20N latitude, rain height (adapted from CCIR Recommendation 564) is hR = 3+ 0.028 =3,028 [km] hS = 7m = 0,007km ; sinθe = sin57.420

  14. Uplink Budget → Ls = 3.585km ɣU = 3.96dB/km → Uplink rain loss is (LR)U= 14.197dB + Antenna misalignment losses are LTe = 0.9dB ; LRs = 0.9dB +Polarization mismatch loss is LPOL = 0.5dB + Loss due to tropospheric effects is Ltr=0.02 x 15 = 0.3[dB/Km] (assuming troposphere height at Tam Ky is 15km)

  15. Uplink Budget Hence, uplink total loss is LU = LSPU + LFU + LOU = LSPU + LFU + (LRU + LTe + LRs + LPOL + Ltr) = 206.641 + 1 + (14.197 + 0.9 + 0.9 + 0.5 + 0.3) = 224.438 [dB] - Satellite receiver noise temperature với F = 4dB ; T0 = 2900K → TRS = 4380K

  16. Uplink Budget - Uplink noise temperature is TU = TRS + TAS where TRS = 4380K ; TAS = 2900K → TU = 4380 + 2900 = 7280K - Satellite receive antenna gain is GRS= (G/T)S + 10lgTU [dB] where (G/T)S = 1 dB/0K → GRS= 1 + 10lg728 = 29.62 [dB]

  17. Uplink Budget - Satellite received carrier power is CRS = EIRPe – LU + GRS= - 102.574 [dBW] - Uplink noise power is NU = 10lgkTUB where k is Boltzmann’s constant (1,38.10-23 [J/K]) TU equivalent noise temperature (7280K) B is the noise bandwidth of the carrier 36MHz → NU = - 124.4 [dBW] - Uplink carrier-to-noise ratio (C/N)U = - 102.574 + 124.4 = 21.826 [dBW]

  18. Downlink budget - Downlink total loss LD + Free-space loss is (Ltd)D= 20lg(4πfDd) – 20lgc = 20lg(4πx11.109x36629.4x103)-20lg3.108 = 204.55 dB + Downlink rain loss is (LR)D= 14.197dB + Polarization mismatch loss is LPOL= 0.5 dB + Antenna misalignment losses are LTs = 0.9 dB ; LRe = 0.9 dB

  19. Downlink budget → Downlink total loss is LD = (Ltd)D + (LR)D + LPOL+ LTs + LRe = 204.55 + 14.197 + 0.5 + 0.9 + 0.9 = 221.05 dB - Earth station receive antenna gain is where η= 0.65; D = 20m; fD= 11GHz; c=3.108m/s → GRe =65.38 dB

  20. Downlink budget * Downlink noise calculation - Space noise temperature is TS = 52.760K - Rain noise temperature TM Wave attenuation caused by rain is →

  21. Downlink budget - Noise temperature introduced by the loss of the feeder line is - Receiver noise temperature TR ~T1 ,where T1 is noise temperature of the first module of earth station receiver Let’s give TR = 150oK - System noise temperature = 4720K

  22. Downlink budget - System noise power - Downlink carrier-to-noise ratio (C/N)D →

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