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Unformatted text preview: RMS ) dB mW = dB m = 20 Log 10 PR V 2 Where P =  or V = PR R Vmeasured Vmeasured dB m = 20 Log 10 = 20 Log 10  (50 ) ( 1 mW) (.05) Vmeasured dB m = 20 Log 10  = 20 Log 10 ( 4.472) V M 0.223606 Then, if V M = 1 V RMS dB m = 20 Log 10 (4.472) (1) dB m = 20 (0.65) = 13.01004 Therefore, if you measure the dBVs from the oscilloscope/FFT you add 13.01 to that value to get the equivalent in dB m , or simply: dB m = dBV + 13.01004 from oscilloscope to spectrum analyzer, dBV = dB m13.01004 from spectrum analyzer to oscilloscope, dB mV = dB m + 46.98996 from milliwatts to millvolts. R. Cockrum 06/24/08...
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This note was uploaded on 11/28/2010 for the course ECE 405L taught by Professor Cockrum during the Fall '10 term at Cal Poly Pomona.
 Fall '10
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