Spike Energy Spectrum

Block diagram

Program parameters

The table below shows a list of the important parameters for configuring the function blocks.

Explanations

The generated amplitude-modulated input signal is composed as follows: A shock (yellow) is modulated with a frequency of 200 Hz onto a fundamental oscillation (blue). The input signal of the function block thus corresponds to the curve below (green).

The input data are processed as follows: The signal components that are not relevant for the analysis (below 1 kHz) are filtered out by means of an IIR bandpass filter. In the case of exact arithmetic, this would correspond to the shock (yellow). The filtered signal is now transformed into a time-wave form in which the energy peaks are displayed in relation to the configured decay time (fDecayTime) ("peak to peak"). The following image shows the time-wave shape for the input data described above.

The frequency of the occurring peak values, i.e. the repetition rate of high-frequency components in the form of shocks in the original signal, is already recognizable in this representation. The distance between two consecutive peaks is 0.5 ms, i.e. 1 / 0.005 s = 200 Hz. This periodicity is represented by the calculation of a magnitude spectrum. This leads to the following visualization in the scope project of the sample:

In the resulting peak value spectrum, the component of the error frequency (f_defect) at 200 Hz and the associated harmonics is clearly recognizable. Furthermore, the frequency components of the fundamental vibration (f_carrier) and those of the shocks (f_shock) are eliminated by the bandpass filtering and transformation into the time-wave form.

The peak value below f_low is not meaningful because it lies below the resolution limit of cMinFrequency = cSampleRate/cWindowLength = 12,5 Hz.

Requirements