BEST Local GUI
BEST
User’s Manual
40
4.4
Frequency Analysis Tool
The “Frequency Analysis Tool” window, which is accessible from
Tools->Frequency
Analysis Tool,
allows the user to perform a dynamical frequency analysis of the
system by determining its Bode plots (phase and amplitude).
The Bode plot is
a
graph
of the
frequency response
of a system. It is usually a combination of a Bode
magnitude plot, expressing the magnitude of the transfer function (in [m]/[V]), and
a Bode phase plot, expressing the
phase shift (in degrees)
. Both axis in the Bode
magnitude plot are in logarithmic scale, while only the x-axis in the Bode phase plot
is in logarithmic scale.
We follow the established, classic approach: a sinusoidal stimulus of constant
amplitude generated by the
PreDAC
is swept through a pre-defined frequency
range and, in parallel, the system response is read by the
TetrAMM
and analyzed
by
the
Central
Unit.
The
Frequency
Analysis
Tool
uses
the
I/Q
modulation/demodulation principle to extract magnitude and phase of the system
response.
We provide a very simple graphical interface allowing the user to:
Set the start and stop frequency of the test;
Set the spacing and the number of points for the frequency analysis;
Set the
PreDAC
output channel to use as frequency signal stimulus;
Set the
TetrAMM
input channel for the I/Q demodulation; this allows
studying both direct correlation (i.e.: stimulus and response applied and read
on the same variable, either X or Y) and cross-correlations (e.g.: stimulus on X
Vs. response on Y);
Set the fixed amplitude of the sinusoidal stimulus in Volts p-p.
The acquired data can be exported in .csv format for further analysis.