The next sections describe common stepz operation with adaptive and multirate filters. For more input options and for information about using stepz with discrete-time filters, refer to stepz in Signal Processing Toolbox documentation.

Adaptive Filters

For adaptive filters, stepz returns the instantaneous zero-phase response based on the current filter coefficients.

[h,t] = stepz(ha) returns the step response h of the multirate filter ha. The length of column vector h is the length of the impulse response of ha. Returned vector t contains the time samples at which stepz evaluated the step response. stepz returns h as a matrix when ha is a vector of filters. Each column of the matrix corresponds to one filter in the vector.

stepz(ha) displays the filter step response in the Filter Visualization Tool (FVTool).

Multirate Filters

[h,t] = stepz(hm) returns the step response h of the multirate filter hm. The length of column vector h is the length of the impulse response of hm. The vector t contains the time samples at which stepz evaluated the step response. stepz returns h as a matrix when hm is a vector of filters. Each column of the matrix corresponds to one filter in the vector.

stepz(hm) displays the step response in the Filter Visualization Tool (FVTool).

Note that the response is computed relative to the rate at which the filter is running. If a sampling frequency is specified, it is assumed that the filter is running at that rate.

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

For multistage cascades, stepz 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. stepz 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 two-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. stepz uses the equivalent filter for the analysis. If you specify a sampling frequency fs as an input argument to stepz, the function interprets fs as the rate at which the equivalent filter is running.

stepz - Step response for filter

Syntax

Description

Adaptive Filters

Multirate Filters

See Also