AEMC OX 7102 III, User Manual

Page: 124 / 226

Harmonic Analysis Mode - The « Horizontal » Menu
V - 124 SCOPIX
Harmonic Analysis Mode (cont'd)
The "Horiz" Menu
Fundamental freq: AUTO
Fundamental freq: ~50Hz
Fundamental freq: ~60Hz
Fundamental freq:
~400Hz
In "Automatic fundamental frequency search" mode, the instrument
analysis the signal on the range
[40Hz 1kHz].
If this search is not successful, you can indicate one of three
frequencies proposed to the instrument. The instrument will then
search for the fundamental based on this central frequency.
In particular, the manual indication (approximate) of the signal
frequency, allows the analysis of its harmonic composition, for which
the fundamental one is not the highest row of amplitude (e.g.: systems
of control of engine by variations of frequency.
No averaging
Averaging coeff.: 2
Averaging coeff.: 4
Averaging coeff.: 16
Averaging coeff.: 64
An averaging coefficient can be used to improve the display.
When this coefficient is selected, it attenuates the random noise
observed on a signal.
The calculation is performed using the following formula:
Pixel
N
= Sample * 1/Averaging Coeff. + Pixel
N-1
(1-1/Averaging Coeff.)
with:
•
Sample: value of new sample acquired at abscissa t
•
Pixel N: ordinate of the pixel with abscissa t on the screen at
instant N
•
Pixel N-1: ordinate of the pixel with abscissa t on the screen at
instant N-1
The "
"
symbol indicates the averaging coefficient selected.
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