Order Power Spectrum

Order power spectrum is also called the half spectrum—magnitudes are calculated from a single sensor rather than a sensor pair.

When analyzing machinery sound and vibration, you typically compute an order power spectrum after displaying the spectral map. After you identify a certain block of a signal as the signal of interest on the spectral map, you can compute an order power spectrum on this signal block to get more detailed order information. You can identify the characteristic order components, form a quantitative spectrum measurement of the orders, and compare the amplitudes of different orders. The following figure shows a typical order power spectrum for a gearbox.

You can identify the significant orders, like the 48th and 72nd orders, measure the amplitude of the orders, and compare different orders in this plot.