# GCHEBWIN

## Purpose:

Generates a Dolph-Chebyshev
Window.

## Syntax:

GCHEBWIN(N, spacing, attn)

N |
- |
An integer, the number of points to generate. |

spacing |
- |
A real, the spacing (delta x) between points. |

attn |
- |
Optional. A real, the sidelobe attenuation
from the mainlobe in dB. Defaults to -100. |

## Returns:

A series.

## Example:

gchebwin(100,.01)

Creates a 100-point Dolph-Chebyshev
window with points spaced
at an interval of 0.01. The
sidelobe attenuation is
-100 dB.

## Example:

gchebwin(100,.01, -65)

Creates a 100-point Dolph-Chebyshev
window with points spaced
at an interval of 0.01. The
sidelobe attenuation is -65 dB.

## Example:

W1: gchebwin(100, 1, -60)

W2: magspec(w1, 8192);20*log10(curr/max(curr));

W1 Creates a 100 point Dolph-Chebyshev window where the sidelobe
attenuation is -60 dB. W2 displays the normalized frequency
response.

## Remarks:

The frequency response of an *N*^{th
}order Dolph-Chebyshev window with an attenuation
of **attn** decibels is given by:

The time domain response is determined by computing the inverse Fourier
transform and scaling the result to a unitary maximum.

The Dolph-Chebyshev windows minimizes the Chebyshev norm
of the
sidelobes for a given mainlobe width.

The Dolph-Chebyshev window can be regarded as the impulse
response of an optimal Chebyshev lowpass filter having a zero-width
passband.

Because the Dolph-Chebyshev window yields equiripple constant
magnitude sidelobes, impulses may result at the end points of the time
domain response.

Use CHEBWIN to automatically create and multiply
a Dolph-Chebyshev window with a series. For example:

chebwin(w2, 0, -60)

multiplies Window 2 with a Dolph-Chebyshev window with
an attenuation of -60 dB.

See GTAYLORWIN to generate a Taylor window.

## See Also:

CHEBWIN

FFT

GHAMMING

GKAISER

GTAYLORWIN

PSD

SPECTRUM