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Telecommunications Design Work The AggieSat Lab

Telecommunications Design Work The AggieSat Lab. http://www.aggiesatweb.tamu.edu. Telecom Sizing Process Case Study of RFIC System Radio concept Download budget Link budget Case Study of AggieSat2 System overview Spacecraft antenna examples Ground station antennas References. Agenda.

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Telecommunications Design Work The AggieSat Lab

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  1. Telecommunications Design WorkThe AggieSat Lab http://www.aggiesatweb.tamu.edu

  2. Telecom Sizing Process Case Study of RFIC System Radio concept Download budget Link budget Case Study of AggieSat2 System overview Spacecraft antenna examples Ground station antennas References Agenda

  3. Telecom Sizing Process

  4. A 100 kbps UHF radio for small satellites Consists of a small RFIC chip (radio) and PIC18F4520 microcontroller (C&DH) Small “system” Case Study:RFIC Radio System

  5. System Concept cont. Selection of an RFIC chip Licensing Frequency agility/tuning (Doppler, thermal effects) Downlink performance Proximity link performance Additional practical considerations 4

  6. Radio Concept 5

  7. Download Budget (operations/processes) Data rate analysis (useful rate of the device) 6

  8. Download Budget (useful throughput) Data rate analysis (useful rate of the RF device) 7

  9. Download Budget (throughput with operational assumptions for total downlink capacity)

  10. Link Analysis (signal power) Link analysis – signal power 9

  11. Link Analysis (key equations) Link analysis Combination of signal power gains and penalties over noise power Basic path loss given by: Noise figure of receiver given by the relationship: Bandwidth, coupled to data rate, gives actual noise power Noise figure of environment given by Department of Commerce and SMAD models Noise added together via Friis formula where early “stages of system” dominate noise: 10

  12. Link Analysis (noise) Link analysis – noise estimates and ratios Receiver Environment and combined effect 11

  13. Link Analysis (total picture) Link analysis - Margin 12

  14. MHX425 UHF modem (1 Watt) Maxstream 2.4 GHz modem AggieSat2 Spacecraft

  15. AggieSat2 Spacecraft

  16. Monopole Antenna Pattern

  17. Patch Antenna

  18. AggieSat2 Ground Station

  19. Helical (array) Other Types • Quadrifillar Helix • Geometrical problem • Overall sizes driven by frequency • Cabling, elements sized by frequency and “electrical length”

  20. Important to get as much manufacturer data as possible Frequency, raw rate, vs. useful data rate Tuning capability Lead times/cost Modulation Davidoff, M., The Radio Amateur’s Satellite Handbook, The American Radio Relay League, Newington, CT, 2003, Chaps. 5, 9. Larson, W.J. (ed.), and Wertz, J.R. (ed.), Space Mission Analysis and Design, 3rd ed., Space Technology Library, Microcosm Press, El Segundo, 1999, Chaps. 8, 13. Walraven, D., “Understanding SWR by Example,” QST, Vol. 90, No. 11, 2006, pp. 37-41. Sklar, B., Digital Communications Fundamentals and Applications, 2nd ed., Prentice Hall PTR, New Jersey, 2001, Chaps. 4, 5, 9. References

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