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 (bandwi dth)
Error (sine): error fo r si newave as shown in cha pter 8.
Error (crest factor): crest f actor additional error as shown in chapter 8.
Error (bandwidth): estimated bandwidth error as shown below.
Example Calculate the approximate measurement error for a pulse tra in in pu t
with a crest factor of 3 and a fundamental frequency of 20 kHz. For this
example, assume the multimeter’s 90-day accurac y 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 th e Agilent 34401A )
Chapter 7 Measurement Tutorial
Crest Factor Errors (non-sinusoidal inputs)
208