Satellite Link Design: Basic Transmission Theory & Noise Temperature
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This document discusses the basic transmission theory and calculations for satellite link design. It covers parameters like transmitted power, antenna gains, free space path loss, and the Friis transmission equation. It then discusses practical losses in the atmosphere and antennas. Thermal noise power and noise figure are defined. The concepts of system noise temperature and noise properties of cascaded stages are explained. References for further reading on satellite communication are provided.
![Basic Transmission Theory
Objective: Calculate the amount of power received by
Earth station from satellite
Assumption: [i] Free-space propagation
[ii] Source in free-space is isotropic
[iii] Transmitting antenna is lossless
[iv] Receiving antenna is highly directive
4/21/2020 2Arpan Deyasi RCCIIT MCE203A](https://image.slidesharecdn.com/satellitelinkdesignpart-i-200421114439/85/Satellite-Link-Design-Basic-Transmission-Theory-Noise-Temperature-2-320.jpg)
Satellite Link Design: Basic Transmission Theory & Noise Temperature
- 1. Arpan Deyasi Dept of ECE, RCCIIT, Kolkata, India Course: MCE203A Satellite Link Design: Part-I 4/21/2020 1Arpan Deyasi RCCIIT MCE203A
- 2. Basic Transmission Theory Objective: Calculate the amount of power received by Earth station from satellite Assumption: [i] Free-space propagation [ii] Source in free-space is isotropic [iii] Transmitting antenna is lossless [iv] Receiving antenna is highly directive 4/21/2020 2Arpan Deyasi RCCIIT MCE203A
- 3. Basic Transmission Theory 4/21/2020 3Arpan Deyasi RCCIIT MCE203A
- 4. Parameters for Mathematical Calculation R: distance between transmitter and receiver Basic Transmission Theory PT: radiated power from antenna GT: gain of transmitting antenna AR: aperture of receiving antenna GR: gain of receiving antenna 4/21/2020 4Arpan Deyasi RCCIIT MCE203A
- 5. Basic Transmission Theory Flux density at a distance ‘R’ from transmitting antenna 2 4 T TP G F Rπ = Considering aperture of receiving antenna, received power 2 4 T T R R P G P A Rπ = PTGT is called Effective Isotropic Radiated Power (EIRP) 4/21/2020 5Arpan Deyasi RCCIIT MCE203A
- 6. Basic Transmission Theory Receiving antenna gain is defined as 2 4 R R A G π λ = T T R R P P G G P L = 2 2 4 Rπ λ LP is called free space path loss, defined as Friis Transmission Equation 4/21/2020 6Arpan Deyasi RCCIIT MCE203A
- 7. Basic Transmission Theory From Friis equation 10logPR = 10logPT + 10logGT + 10logGR - 10logLP PR (in dBW) = EIRP (in dBW) + GR (in dB) – LP (in dB) 4/21/2020 7Arpan Deyasi RCCIIT MCE203A
- 8. Basic Transmission Theory Introducing practical losses PR (in dBW) = EIRP (in dBW) + GR (in dB) – LP (in dB) - LA (in dB) - LTA (in dB)- LRA (in dB) LA: losses in atmosphere LTA: losses associated with transmitting antenna LRA: losses associated with receiving antenna 4/21/2020 8Arpan Deyasi RCCIIT MCE203A
- 9. Thermal Noise Thermal Noise Power Pn = kBTB At room temperature (T=290 K) Pn = -174 + 10logB Thermal Noise Power Spectral Density Pno = kBT 4/21/2020 9Arpan Deyasi RCCIIT MCE203A
- 10. Noise Figure Noise Figure: It is the ratio of input SNR to output SNR 0 0 / / i iS N NF S N = 0 1 i N NF N G = G is called power gain over specified bandwidth 4/21/2020 10Arpan Deyasi RCCIIT MCE203A
- 11. System Noise Temperature Ni = kBTiB Ti: ambient temperature 0 B i N NF Gk T B = ΔN: noise power introduced by real amplifier N0 = GkBTiB + ΔN 1 B i N NF Gk T B ∆ = + 4/21/2020 11Arpan Deyasi RCCIIT MCE203A
- 12. System Noise Temperature It is the temperature of a resistance that would generate the Same noise power at the output of a noiseless device which is also produced by the actual device terminated at its input by noiseless resistance ΔN = GkBTeB Te: system noise temperature 1 e i T NF T = + 4/21/2020 12Arpan Deyasi RCCIIT MCE203A
- 13. System Noise Temperature L: loss factor 1 G L = N0 = GkBTiB + GkBTeB ( )0 B i B e 1 k TB + k T BN L = 4/21/2020 13Arpan Deyasi RCCIIT MCE203A
- 14. System Noise Temperature If attenuator is considered at ambient temperature N0 = kBTiB ( )B i B e 1 k TB + k T BB ik T B L = Te = Ti(L-1) 4/21/2020 14Arpan Deyasi RCCIIT MCE203A
- 15. Noise Properties of Cascaded Stages Consider a cascaded arrangement of ‘n’ no of communication blocks 4/21/2020 15Arpan Deyasi RCCIIT MCE203A
- 16. Noise Properties of Cascaded Stages Total noise power at the output 1 1 1 2 1 1... ..TO n B n n n B n n n BN G k T B G G k T B G G G G k T B− − −= + + + 2 1 2 1 1 1 1 2 1 .. ... .. n TO n n B n TT N G G G G k B T G G G G − − + + + 4/21/2020 16Arpan Deyasi RCCIIT MCE203A
- 17. Noise Properties of Cascaded Stages Te: effective input noise temperature of the cascaded arrangement 1 2 1..TO n n B eN G G G G k T B−= 2 1 1 1 2 1 ... .. n e n TT T T G G G G − = + + + 4/21/2020 17Arpan Deyasi RCCIIT MCE203A
- 18. Noise Properties of Cascaded Stages In terms of noise figure 2 1 1 1 2 1 11 ... .. n n NFNF NF NF G G G G − −− = + + + 4/21/2020 18Arpan Deyasi RCCIIT MCE203A
- 19. https://www.tutorialspoint.com/satellite_communication/satellite_ communication_link_budget.htm https://www.ieee.li/pdf/viewgraphs/fundamentals_satellite_com munication_part-2.pdf References 4/21/2020 19Arpan Deyasi RCCIIT MCE203A T. Pratt, C. Bostian, J. Allnutt, “Satellite Communications”, John Wiley & Sons, 2nd Ed., 2003 A. K. Maini, V. Agarawal, “Satellite Communications”, Wiley, 1st Ed., 2019 S. Katiyar, “Satellite Communication”, S. K. Kataria & Sons, 1st Ed., 2007