homework4b_solution

homework4b_solution - 3. Losses: There is the 40 dB loss to...

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ECE 5325/6325 Fall 2009: Homework 4(b) Solution (4b) For the sensor network example from the lecture 7 notes, what would the range be if the fade margin was zero? In that case, how would the range increase if we used a better RFIC that had a sensitivity of -99 dBm (reduced by 1 dB)? Solution : - 98(dBm) = S/N + P N (dBm) = P t (dBm) + s dB Gains - s dB Losses (1) 1. P t (dBm) = 0 dBm. 2. Gains: Two antennas at 3 dBi (the units are e±ectively dB), so the total gains are 6 dB.
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Unformatted text preview: 3. Losses: There is the 40 dB loss to 1 m, then an additional 10(3 . 0) log 10 d dB. So-98(dBm) = 0(dBm) + 6(dB)-40(dB)-30 log 10 ( d/ 1m) (2) Solving for d , we have . d = (1m)10 64 / 30 = 136m . (3) For part two of this question, now the -98 is reduced to -99 dBm. Eectively, the LHS of (2) becomes one lower. This increases the 64 on the RHS of (3) to 65, and so d = (1m)10 65 / 30 = 147m....
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