Engee documentation

chebwin

Chebyshev’s window.

Library

EngeeDSP

Syntax

Function call

  • w = chebwin(L) — returns L- Chebyshev point window.

  • w = chebwin(L,r) — returns L-Chebyshev point window, using the amplitude coefficient of the side lobes r dB.

  • w = chebwin(___,typeName) — indicates the possibility of returning the window w with single or double precision.

Arguments

Input arguments

# L — window length

+ positive integer

Details

The window length specified as a positive integer.

If you set L as a non-integer, the function will round it to the nearest integer value.
Типы данных

Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64

# r — attenuation of the side lobes

+ 100 dB (by default) | positive real scalar

Details

The attenuation of the side lobes in dB, given as a positive integer. The Chebyshev window has the amplitude of the Fourier transform by r dB is below the amplitude of the main lobe.

Типы данных

Float32, Float64

# typeName — type of output data

+ Float64 (by default) | Float32

Details

The type of output data (class) specified in one of the following ways:

  • Float64 — use this value to return the output w with double precision.

  • Float32 — use this value to return the output w with single precision.

Типы данных

DataType

Output arguments

# w — Chebyshev’s window

+ column vector

Details

Chebyshev window, returned as a column vector.

If you set a single-point window (L = 1), the function will return the value 1.

Tips

An artifact of the equal-wave design method used in the function chebwin, is the presence of pulses at the ends of the time characteristic. These pulses are caused by side lobes of a constant level in the frequency domain. The magnitude of the pulses is of the order of magnitude of the spectral side lobes. If the side lobes are large, the effect at the ends can be significant. For more information about this effect, see [2].

The equivalent noise band of the Chebyshev window does not grow monotonically with increasing attenuation of the side lobes if it is less than approximately 45 dB. For spectral analysis, use large values of the attenuation of the side lobes or, if you need to work with small attenuations, use the Kaiser window.

Literature

  1. Digital Signal Processing Committee of the IEEE Acoustics, Speech, and Signal Processing Society, eds. Programs for Digital Signal Processing. New York: IEEE Press, 1979, program 5.2.

  2. Harris, Fredric J. Multirate Signal Processing for Communication Systems. Upper Saddle River, NJ: Prentice Hall PTR, 2004, pp. 60–64.