Order tracking

Order Analysis

The Order tracking Order tracking facility is the natural analysis method applied to spectral maps. It consists in extracting order curves from the spectral map in a 2D display. Such curves can show potential resonances in the system.

As the sampling of the original signal is a fixed time step method, order curves in the spectral map do not correspond to a spectral lines (lines corresponding to a fixed frequency). The order curves pass through the spectral map following the X, Y relation : X = order * Y with X and Y using similar unit (Hz or RPM). Thus the order 1 curve passes by the point (X = 100 Hz, Y = 6000 RPM), the order 2 curve passes by (X = 100 Hz, Y = 3000 RPM), as illustrated by the following figure.

Figure 29: Order axes on a spectral map

The fixed time sampling of the original curve results in a loss of spectral energy. Each point of the order curve corresponds to the frequency RMS of the FFT over a specified interval. The length of this interval corresponds to the Bandwidth parameter.