phasez - Unwrapped phase response for filter

Syntax

phasez(ha)
[phi,w] = phasez(ha,n)
[phi,w] = phasez(...,f)
phasez(hd)
[phi,w] = phasez(hd,n)
[phi,w] = phasez(...,f)phasez(hm)
[phi,w] = phasez(hm,n)
[phi,w] = phasez(...,f)
[phi,w] = phasez(...,fs)

Description

The following sections describe phasez operation for adaptive filters, discrete-time filters, and multirate filters. For more information about optional input arguments for phasez, refer to phasez in Signal Processing Toolbox documentation.

Adaptive Filters

For adaptive filters, phasez returns the instantaneous unwrapped phase response based on the current filter coefficients.

phasez(ha) displays the phase response of ha in the Filter Visualization Tool (FVTool).

[phi,w]=phasez(ha,n) returns vectors phi and w containing the instantaneous phase response of the adaptive filter ha, and the frequencies in radians at which it is evaluated. The phase response is evaluated at n points equally spaced around the upper half of the unit circle. When you do not specify n, it defaults to 8192.

If ha is a vector of filter objects, phasez returns phi as a matrix. Each column of phi corresponds to one filter in the vector. If you provide a row vector of frequency points f as an input argument, each row of phi corresponds to each filter in the vector.

Discrete-Time Filters

phasez(hd) displays the phase response of hd in the Filter Visualization Tool (FVTool).

[phi,w]=phasez(hd,n) returns vectors phi and w containing the instantaneous phase response of the adaptive filter hd, and the frequencies in radians at which it is evaluated. The phase response is evaluated at n points equally spaced around the upper half of the unit circle. When you do not specify n, it defaults to 8192.

If hd is a vector of filter objects, phasez returns phi as a matrix. Each column of phi corresponds to one filter in the vector. If you provide a row vector of frequency points f as an input argument, each row of phi corresponds to each filter in the vector.

Multirate Filters

phasez(hm) displays the phase response of hm in the Filter Visualization Tool (FVTool).

[phi,w]=phasez(hm,n) returns vectors phi and w containing the instantaneous phase response of the adaptive filter hm, and the frequencies in radians at which it is evaluated. The phase response is evaluated at n points equally spaced around the upper half of the unit circle. When you do not specify n, it defaults to 8192.

If hm is a vector of filter objects, phasez returns phi as a matrix. Each column of phi corresponds to one filter in the vector. If you provide a row vector of frequency points f as an input argument, each row of phi corresponds to each filter in the vector.

Note that the multirate filter response is computed relative to the rate at which the filter is running. When you specify fs (the sampling rate) as an input argument, phasez assumes the filter is running at that rate.

For multistage cascades, phasez forms a single-stage multirate filter that is equivalent to the cascade and computes the response relative to the rate at which the equivalent filter is running. phasez does not support all multistage cascades. Only cascades for which it is possible to derive an equivalent single-stage filter are allowed for analysis.

As an example, consider a 2-stage interpolator where the first stage has an interpolation factor of 2 and the second stage has an interpolation factor of 4. An equivalent single-stage filter with an overall interpolation factor of 8 can be found. phasez uses the equivalent filter for the analysis. If a sampling frequency fs is specified as an input argument to phasez, the function interprets fs as the rate at which the equivalent filter is running.