Tutorial
81150A and 81160A User’s Guide 635
Attributes of AC Signals Crest Factor
If an average-reading voltmeter is used to measure the “DC voltage” of a
waveform, the reading may not agree with the DC Offset setting of the
function generator. This is because the waveform may have a non-zero
average value that would be added to the DC Offset.
You may occasionally see ac levels specified in “decibels relative to 1
milliwatt” (dBm). Since dBm represents a power level, you will need to
know the signal’s RMS voltage and the load resistance in order to make the
calculation.
dBm = 10 x log
10
(P / 0.001)
where
For a sine wave into a 50 load, the following table relates dBm to voltage.
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