phasedelay

Phase delay response of discrete-time filter System object

Syntax

[phi,w] = phasedelay(sysobj)
[phi,w] = phasedelay(sysobj,n)
[phi,w] = phasedelay(sysobj,Name,Value)
phasedelay(sysobj)


Description

[phi,w] = phasedelay(sysobj) returns the phase delay phi of the filter System object™, sysobj, based on the current filter coefficients. The vector w contains the frequencies (in radians) at which the phase delay is evaluated.

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

[phi,w] = phasedelay(sysobj,n) returns the phase delay of the filter System object at n points equally spaced around the upper half of the unit circle.

[phi,w] = phasedelay(sysobj,Name,Value) returns the phase delay with additional options specified by one or more Name,Value pair arguments.

phasedelay(sysobj) plots the phase delay of the filter System object sysobj in the fvtool.

For information on more input options, refer to phasedelay in Signal Processing Toolbox™ documentation.

Examples

Phase Delay of a Discrete-Time Filter

Fs = 8000; Fcutoff = 2000;
FIRFilt = dsp.FIRFilter('Numerator', fir1(130,Fcutoff/(Fs/2)));

phasedelay computes the phase delay of the filter and displays it using fvtool

phasedelay(FIRFilt);

Input Arguments

sysobj

Filter System object. The following Filter System objects are supported by this analysis function: Filter System objects dsp.AllpassFilter dsp.AllpoleFilter dsp.BiquadFilter dsp.Channelizer dsp.CICCompensationDecimator dsp.CICCompensationInterpolator dsp.CICDecimator dsp.CICInterpolator dsp.CoupledAllpassFilter dsp.FarrowRateConverter dsp.FilterCascade dsp.FIRDecimator dsp.FIRFilter dsp.FIRHalfbandDecimator dsp.FIRHalfbandInterpolator dsp.FIRInterpolator dsp.FIRRateConverter dsp.HighpassFilter dsp.IIRFilter dsp.IIRHalfbandDecimator dsp.IIRHalfbandInterpolator dsp.LowpassFilter dsp.NotchPeakFilter dsp.VariableBandwidthFIRFilter dsp.VariableBandwidthIIRFilter

n

Number of samples. For an FIR filter where n is a power of two, the computation is done faster using FFTs. Default: 8192

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

'Arithmetic' — Value types:

'double' | 'single' | 'fixed'

Specify the arithmetic used during analysis. When you specify 'double' or 'single', the function performs double- or single-precision analysis. When you specify 'fixed' , the arithmetic changes depending on the setting of the CoefficientDataType property and whether the System object is locked or unlocked.

 Details for Fixed-Point Arithmetic

System Object State	Coefficient Data Type	Rule
Unlocked	'Same as input'	The function assumes that the coefficient data type is signed, 16 bit, and autoscaled. The function performs fixed-point analysis based on this assumption.
Unlocked	'Custom'	The function performs fixed-point analysis based on the setting of the CustomCoefficientsDataType property.
Locked	'Same as input'	When the input data type is 'double' or 'fixed', the function assumes that the coefficient data type is signed, 16-bit, and autoscaled. The function performs fixed-point analysis based on this assumption.
Locked	'Custom'	The function performs fixed-point analysis based on the setting of the CustomCoefficientsDataType property.

When you do not specify the arithmetic for non-CIC structures, the function uses double-precision arithmetic if the filter System object is in an unlocked state. If the System object is locked, the function performs analysis based on the locked input data type. CIC structures only support fixed-point arithmetic.

Output Arguments

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

Algorithms

You can provide fs, the sampling frequency, as an input as well. phasedelay uses fs to calculate the delay response and plots the response to fs/2.