Advanced | SIMXSYMT

ABSOLUTE HARMONIC MAXIMUM – [SIMXSYMT]
Compute the absolute maximum amplitudes of the harmonic components in a window moving over time.

CATEGORY
Advanced

DESCRIPTION
This function allows to compute the absolute maximum amplitudes (modules) for the symmetric components of a harmonic in a window moving over time.

RESULT VARIABLES AND PARAMETERS

Module (m)	Absolute maximum of module (or amplitude) for the symmetric components of a harmonic. It is computed for each window moving over the signal. The maximum computed is then multiplied by the absolute value of the factor.
Phase (a)	Angle a (or phase) of the symmetric component sequence associated with the maximum module found. Value is between -180 and 180 degrees [°]. Since the module is multiplied by the absolute value of the factor, the phase is modified if the multiplying factor is negative. In this case, 180 degrees are added to the phase.
Phase 0-360 (a0)	Angle a0 (or phase) of the symmetric component sequence associated with the maximum module found. Value is between 0 and 360 degrees [°].
Real (r)	Real part r of the maximum module of the required symmetric component sequence (m * cos(a)).
Imaginary (i)	Imaginary part i of the maximum module of the required symmetric component sequence (m * sin(a)).
Signal_A	Symbolic name of first signal to analyze (phase A).
Signal_B	Symbolic name of second signal to analyze (phase B).
Signal_C	Symbolic name of third signal to analyze (phase C).
Freq:	Fundamental frequency of the signals in Hertz [Hz], normally computed with the sifreq function. This fundamental frequency in hertz serves to establish the length of time the window moves over the analyzed signal. In fact, this window is equal to one cycle (in number of samples). lfen = rate/ freq [samples]. If the number of samples to establish the length of a cycle is greater than the number of samples found between the begin_time and end_time of the sequence, then the length of the window used is equal to the number of samples between the begin_time and end_time (in other words end_time - begin_time).
Harmonic number	Number of harmonic to compute. 0: DC; 1: Fundamental; 2: 2nd harmonic; n: nth harmonic (max. 30).
Sequence	Sequence of symmetric components to compute. 0: zero sequence 1: positive sequence 2: negative sequence
Begin_time	Time at which the analysis of a signal must start. This time is expressed in milliseconds [ms]. This value must be greater than 0 and lower than the size of the acquisition buffer. The default value is 0.
End_time	Time at which the analysis of a signal must end. This time is expressed in milliseconds [ms]. The value of this time must be larger than the specified begin_time and smaller than the duration of the test. Use the “HUGE” value to specify the end of the test. The default value is HUGE. The begin_time and end_time specified for the calculation of the harmonics must be the same as those used in the sifreq sequences to compute the fundamental frequency.
Factor	Multiplying factor for the results generated by the function. The default value of the multiplying factor is 1.0 and has no effect on the results.

SYNTAX
[m, a, a0, r, i] = simxsymt(a, b, c, 60, 1, 1, 0, HUGE,1)

CHARACTERISTICS
Data type support
Double Floating point

EXAMPLE
In the following example, the function compute the absolute maximum of the positive sequence of the first harmonic.

The following diagram shows the window moving over a signal based on the time specified for the window.

The symmetric components are computed for each window from the start to the end of the limits and the function returns the maximum of the computed modules.

Let:

nbech= number of samples to analyze for the signal
lfen= number of samples in a window
nbfen= number of windows for which the calculations are made

Then:

nbfen=nbech-lfen+1

This set of points is used to find the maximum.

The following figure shows the formulas used to calculate the symmetric components.

Let:

m1	module of required harmonic for signal 1
m2	module of required harmonic for signal 2
m3	module of required harmonic for signal 3
a1	angle of required harmonic for signal 1
a2	angle of required harmonic for signal 2
a3	angle of required harmonic for signal 3