# welchwin: Welch window In gsignal: Signal Processing

 welchwin R Documentation

## Welch window

### Description

Return the filter coefficients of a Welch window of length `n`.

### Usage

```welchwin(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 Welch window is a polynomial window consisting of a single parabolic section:

w(k) = 1 - (k / N - 1)^2, n=0,1, ... n-1

. The optional argument specifies a "symmetric" window (the default) or a "periodic" window. A symmetric window has zero at each end and maximum in the middle, and the length must be an integer greater than 2. The variable `N` in the formula above is `(n-1)/2`. A periodic window wraps around the cyclic interval `0,1, ... m-1`, and is intended for use with the DFT. The length must be an integer greater than 1. The variable `N` in the formula above is `n/2`.

### Value

Welch window, returned as a vector.

### Author(s)

Muthiah Annamalai, muthiah.annamalai@uta.edu,
Mike Gross, mike@appl-tech.com,
Conversion to R by Geert van Boxtel, G.J.M.vanBoxtel@gmail.com.

### Examples

```
w <- welchwin(64)
plot (w, type = "l", xlab = "Samples", ylab =" Amplitude")

ws = welchwin(64,'symmetric')
wp = welchwin(63,'periodic')
plot (ws, type = "l", xlab = "Samples", ylab =" Amplitude")
lines(wp, col="red")

```

gsignal documentation built on May 15, 2022, 5:05 p.m.