Documentation |
Filter impulse response
[h,t]
= impz(hfilt)
[h,t]
= impz(hfilt,n)
[h,t]
= impz(hfilt,n,fs)
[h,t]
= impz(hfilt,[],fs)
impz(hfilt)
[h,t]
= impz(hs)
[h,t] =
impz(hs,Name,Value)
impz(hs)
impz returns the impulse response based on the current filter coefficients. This section describes common impz operation with adaptive filters, discrete-time filters, multirate filters, and filter System objects. For more input options, refer to impz in Signal Processing Toolbox™ documentation.
[h,t] = impz(hfilt) returns the impulse response h and the corresponding time points w at which the impulse response of hfilt is computed. The impulse response is evaluated at 10 1-second intervals—(0:9)'.
[h,t] = impz(hfilt,n) returns the impulse response evaluated at floor(n) 1-second intervals—(0:floor(n)-1)'.
[h,t] = impz(hfilt,n,fs) returns the impulse response evaluated at floor(n) 1/fs-second intervals—(0:floor(n)-1)'/fs.
[h,t] = impz(hfilt,[],fs) returns the impulse response evaluated at 10 1/fs-second intervals—(0:9)'/fs.
impz(hfilt) uses FVTool to plot the impulse response of the filter. You can also provide the optional input arguments n and fs with this syntax.
[h,t] = impz(hs) returns the impulse response for the filter System object™ hs. The impulse response is evaluated at 10 1-second intervals—(0:9)'. You can also provide the optional input arguments n and fs with this syntax.
[h,t] = impz(hs,Name,Value) returns an impulse response with additional options specified by one or more Name,Value pair arguments.
impz(hs) uses FVTool to plot the impulse response of the filter System object hs.
h |
Complex, n-element impulse response vector. If hfilt is a vector of filters, h is a complex, length(hfilt)-by-n matrix of impulse response vectors corresponding to each filter in hfilt. If n is not specified, the function uses a default value of 8192. For adaptive filters, h is the instantaneous impulse response. |
t |
Time vector of length n, in seconds. t consists of n points equally spaced from 0 to floor(n)/fs. If n is not specified, the function uses a default value of 10. If fs is not specified, the function uses a default value of 1. |
Create a discrete-time filter for a fourth-order, lowpass elliptic filter with a cutoff frequency of 0.4 times the Nyquist frequency. Use a second-order sections structure to resist quantization errors. Plot the first 50 samples of the impulse response, along with the reference impulse response.
d = fdesign.lowpass(.4,.5,1,80); % Create a design object for the prototype filter.
Use ellip to design a minimum order discrete-time filter in second-order section form.
hd=design(d,'ellip');
Convert hd to fixed-point, and plot the impulse response:
impz(hd); axis([1 75 -0.2 0.35])