Weighting Modes

When performing RMS or vector spectrum averaging, you can apply either linear or exponential weighting modes.

  • Linear weighting—Weights each individual spectrum by the same amount in the averaged spectrum. Use linear weighting for analysis purposes.
  • Exponential weighting—Weights the most recent spectrum more than the previous spectra, which makes the averaged spectrum more responsive to changes in the input signal. This responsiveness makes exponential weighting ideal for the configuration phase of a measurement. Exponential weighting also is useful for monitoring applications because the averaged spectrum responds to a singular event. A linearly averaged spectrum might not respond noticeably to a singular event, especially with a large number of averages.

Weighting is applied according to the following equation:

Y i = N − 1 N Y i − 1 + 1 N X i

where

Xi is the result of the analysis performed on the ith block.

Yi is the result of the averaging process from X to X1i.

N = i for linear weighting.

N is a constant for exponential weighting with N = 1 for i = 1.