flattopwin {gsignal}

Flat top window

Description

Return the filter coefficients of a flat top window.

Usage

flattopwin(n, method = c("symmetric", "periodic"))

Arguments

n

Window length, specified as a positive integer.

method

Character string. Window sampling method, specified as:

"symmetric"

(Default). Use this option when using windows for filter design.

"periodic"

This option is useful for spectral analysis because it enables a windowed signal to have the perfect periodic extension implicit in the discrete Fourier transform. When 'periodic' is specified, the function computes a window of length n + 1 and returns the first n points.

Details

The Flat Top window is defined by the function:

f(w) = 1 - 1.93 cos(2 \pi w) + 1.29 cos(4 \pi w) - 0.388 cos(6 \pi w) + 0.0322 cos(8 \pi w)

where w = i/(n-1) for i=0:n-1 for a symmetric window, or w = i/n for i=0:n-1 for a periodic window. The default is symmetric. The returned window is normalized to a peak of 1 at w = 0.5.

Flat top windows have very low passband ripple (< 0.01 dB) and are used primarily for calibration purposes. Their bandwidth is approximately 2.5 times wider than a Hann window.

Value

Flat top window, returned as a vector.

Author(s)

Paul Kienzle, [e-mail].
Conversion to R by Geert van Boxtel, [e-mail].

Examples

ft <- flattopwin(64)
plot (ft, type = "l", xlab = "Samples", ylab =" Amplitude")