gsignal (version 0.3-7)

chebwin: Chebyshev window

Description

Return the filter coefficients of a Dolph-Chebyshev window.

Usage

chebwin(n, at = 100)

Value

Chebyshev window, returned as a vector. If you specify a one-point window (n = 1), the value 1 is returned.

Arguments

n

Window length, specified as a positive integer.

at

Stop-band attenuation in dB. Default: 100.

Author

André Carezia, .
Conversion to R by Geert van Boxtel, .

Details

The window is described in frequency domain by the expression:

                Cheb(m - 1, Beta * cos(\pi * k / m))
         W(k) = ------------------------------------
                       Cheb(m - 1, Beta)

with

  Beta = cosh(1 / (m - 1) * acosh(10^(at / 20))

and and $Cheb(m,x)$ denoting the $m$-th order Chebyshev polynomial calculated at the point $x$.

Note that the denominator in W(k) above is not computed, and after the inverse Fourier transform the window is scaled by making its maximum value unitary.

Examples

cw <- chebwin(64)
plot (cw, type = "l", xlab = "Samples", ylab =" Amplitude")