gsignal (version 0.3-1)

chebwin: Chebyshev window

Description

Return the filter coefficients of a Dolph-Chebyshev window.

Usage

chebwin(n, at = 100)

Arguments

n

Window length, specified as a positive integer.

at

Stop-band attenuation in dB. Default: 100.

Value

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

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

# NOT RUN {
cw <- chebwin(64)
plot (cw, type = "l", xlab = "Samples", ylab =" Amplitude")


# }