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grpdelay

Group delay response of discrete-time filter System object

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Syntax

[gd,w] = grpdelay(sysobj)
[gd,w] = grpdelay(sysobj,n)
[gd,w] = grpdelay(sysobj,Arithmetic=arithType)
grpdelay(sysobj)

Description

[gd,w] = grpdelay(sysobj) returns the group delay gd of the filter System object™, sysobj, based on the current filter coefficients. The vector w contains the frequencies (in radians) at which the group delay is evaluated. The group delay is defined as:

−ddw(angle(w))

The group delay is evaluated at 8192 points equally spaced around the upper half of the unit circle.

[gd,w] = grpdelay(sysobj,n) returns the group delay of the filter System object and the corresponding frequencies at n points equally spaced around the upper half of the unit circle.

[gd,w] = grpdelay(sysobj,Arithmetic=arithType) computes the group delay of the filter System object, based on the arithmetic specified in arithType, using either of the previous syntaxes.

grpdelay(sysobj) plots the group delay of the filter System object.

For more input options, see grpdelay in Signal Processing Toolbox™.

example

Examples

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Open Live Script
CICComp = dsp.CICCompensationDecimator;

grpdelay computes and plots the group delay of the filter.

grpdelay(CICComp);

Figure contains an axes object. The axes object with title Group Delay, xlabel Normalized Frequency ( times pi blank rad/sample), ylabel Group delay (samples) contains an object of type line.

Input Arguments

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Number of samples, specified as a positive integer. For an FIR filter where n is a power of two, the computation is done faster using FFTs.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Arithmetic used in the filter analysis, specified as 'double', 'single', or 'Fixed'. When the arithmetic input is not specified and the filter System object is unlocked, the analysis tool assumes a double-precision filter. When the arithmetic input is not specified and the System object is locked, the function performs the analysis based on the data type of the locked input.

The 'Fixed' value applies to filter System objects with fixed-point properties only.

When the 'Arithmetic' input argument is specified as 'Fixed' and the filter object has the data type of the coefficients set to 'Same word length as input', the arithmetic analysis depends on whether the System object is unlocked or locked.

  • unlocked –– The analysis object function cannot determine the coefficients data type. The function assumes that the coefficients data type is signed, has a 16-bit word length, and is auto scaled. The function performs fixed-point analysis based on this assumption.

  • locked –– When the input data type is 'double' or 'single', the analysis object function cannot determine the coefficients data type. The function assumes that the data type of the coefficients is signed, has a 16-bit word length, and is auto scaled. The function performs fixed-point analysis based on this assumption.

To check if the System object is locked or unlocked, use the isLocked function.

When the arithmetic input is specified as 'Fixed' and the filter object has the data type of the coefficients set to a custom numeric type, the object function performs fixed-point analysis based on the custom numeric data type.

Output Arguments

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Group delay vector of length n. If n is not specified, the function uses a default value of 8192.

Data Types: double

Frequency vector of length n, in radians/sample. w consists of n points equally spaced around the upper half of the unit circle (from 0 to π radians/sample). If n is not specified, the function uses a default value of 8192.

Data Types: double

Version History

Introduced in R2011a

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See Also

Functions

Topics