Crest Factor
(continued)
You can estimate the measurement error due to signal crest factor as
shown below:
Total Error = Error (sine) + Error (crest factor) + Error (bandwidth)
Error (sine): error for sinewave as shown in chapter 8.
Error (crest factor): crest factor additional error as shown in chapter 8.
Error (bandwidth): estimated bandwidth error as shown below.
Example Calculate the approximate measurement error for a pulse train input
with a crest factor of 3 and a fundamental frequency of 20 kHz. For this
example, assume the multimeter’s 90-day accuracy specifications:
± (0.05% + 0.03%).
Total Error = 0.08% + 0.15% + 1.4% = 1.6%
Bandwidth Error =
– C.F.
2
x F
4 π x BW
C.F. = signal crest factor
F = input fundamental frequency
BW = multimeter’s
–3 dB bandwidth
( 1 MHz for the HP 34401A )
Chapter 7 Measurement Tutorial
Crest Factor Errors (non-sinusoidal inputs)
208
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