# Blackman-Harris Window

- A weighting that is applied in the time domain to reduce leakage within a Fourier Transform analysis.
- The Blackman-Harris windows are a family of three and four term windows. The variations on the coefficients allow a trade between main-lobe width and side-lobe level.

**3 term -67dB side-lobe**- where
*w(t)*= weighting as a function of time*t*= time*N*= total length of window

**3 term -61dB side-lobe**

**4 term -92dB side-lobe**- The Blackman-Harris window has much the same performance as the Kaiser-Bessel window, except that it suppreses the sidelobes more than 92dB at a cost of an 11% wider noise bandwidth.

- In the time domain this function is shown below:

- The frequency response of this window is shown along with that of a rectangular window for comparison:

**4 term -74dB side-lobe**

**See also: **Bohman Window, Cauchy Window, Hamming Window, Rectangular Window, Windowing.

**Subjects: ** Noise & Vibration Signal Processing