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lecture21 - EE455/591 EE455/591 Terrestrial Link Power...

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Unformatted text preview: EE455/591 EE455/591 Terrestrial Link Power Budgets Terrestrial Link Power Budgets Reading: Focus on these notes. Reading: Focus on these notes. Details in text pp. 674-689 Details in text pp. 674-689 Review: GEO Satellite Link Power Budget Example Review: GEO Satellite Link Power Budget Example Topics: Topics: 1. 1. Terrestrial Wireless Communications Terrestrial Wireless Communications 2. 2. Shadow Fading Shadow Fading 3. 3. Rayleigh and Ricean Fading Rayleigh and Ricean Fading Review Power Link Budget All in One Formula for received Power: P R (dBW) = P T (dBW) + G T (dB) + G R (dB) L R (dB)-L A (dB) Transmitter gain relative to omni-directional antenna is given Receiver gain for a dish antenna: Distance loss given by Absorption loss depends on the absorption medium (e.g. rain) and the path length in medium (e.g. a 0.2dB/km loss through a rain cloud of 10 km would produce a 2dB loss) 2 ) / 4 ( d G G P P R T T R = d L d 4 log 20 = 2 = D G R Review: Example of Link Power Budget Examples 7.7.2, 7.7.3. What is the received power ? Geosynchronous satellite (36,000 km above earth) 100W of power from nonlinear amplifier (20 dBW). Transmit antenna gain is 18 dB. Ground receiver is a 3-meter parabolic antenna. Transmission frequency f = 4 GHz or = 0.075 m. Link Power Budget: Start with high power amplifiers P T 20 dBW Transmit antenna gain G T (directional gain). + 18 dB Distance loss Ld = 10 log (4 d/ ) (-195 dB) -195 dB Receive antenna gain with =0.5 +39 dB Total = - 118.6 dBW = 25pW. Review: Calculating SNR and Max Data Rate For the satellite link, what data rate can be achieved, if we require SNR or E...
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lecture21 - EE455/591 EE455/591 Terrestrial Link Power...

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