HP 54750A, User Manual, Page: 286 / 478

General Purpose Oscilloscope Menus
FFT Menu
Computation of dBV
Another common unit of amplitude is dB V . A 0 dB V signal is dened as
a 1 Vrms signal. Y ou can convert a dBm reading to a dB V reading by
subtracting 13 dB .
dB V = 20 l og
0: 707107 2 V
p
1 V
Which gives us:
dB V = 20 l og
V
p
0: 316228 V
+ 20 l og
0: 707107 2 0: 316228 V
1V
Therefore:
dB V = dB m v al ue 0 13: 01 dB
dc value
F or eciency reasons , the FFT computation produces a dc value that is
incorrect.
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