Envelope spectrum

The sample illustrates a calculation implementation for an envelope spectrum with the function block FB_CMA_EnvelopeSpectrum. The input signal is generated with a function generator. It corresponds to the superposition of two sine waves with 120 Hz and 230 Hz. For a better illustration of the result, the scope is limited to the frequency range from 0 Hz to 300 Hz.

The sample is available for download from here:
EnvelopeSpectrum_Sample.zip

Block diagram

Envelope spectrum 1:

Program parameters

The table below shows a list with important configuration parameters for the function block for calculating the envelope spectrum.

FFT length envelope

2048

FFT length spectrum

2048

Window size

2048

Conversion to decibels

FALSE

Window type

eCM_HannWindow

Scaling type

eCM_RMS

Requirements

Development environment

Target system type

PLC libraries to include

TwinCAT v3.1.4013

PC or CX (x86, x64)

Tc3_CM, Tc3_CM_Base, Tc3_MultiArray