![]() abs(h) is the magnitude responseĮdit : Does wn=0.34 corresponds to 42. Plot(f,20*log10(abs(h))) % we will use 20log10() for ploting the mag. X=fir1(N,wn,ftype,kaiser(N 1,beta)) % designing the corresponding fir filter ( note that fir1 takes an even filter order so we wrote N 1) , order of the filter, filter type and betta according to the design specs. This function will return the cuttoff freq. =kaiserord(fcuts,mags,devs,fs) % using kaiser window for designing the fir filter. 2 There are many possibilities: A) One way is to tell fvtool to normailize the output fvt fvtool (.) fvt. Mags= % The required filter amplitude in these bands (Absolute value not in dB)ĭevs= % Passband and stopband ripples (Absolute value not in dB) So what is wrong with my code? Here is the code (with the required filter specifications): fs=250 įcuts= % passband and stopband frequencies 2 Answers Sorted by: 2 You simply specify a 1 (because the denominator equals 1 ). My question is that when I plot the amplitude response, the -3dB point occurs at frequency above 100 Hz, which means that the cutoff frequency is not equal to 42.5 Hz. Doing this, the returned wn is equal to 0.34 (returned by kaiserord()), which when I convert it to Hertz it gives me 42.5 Hz as required. ![]() ![]() I need to plot the filter's magnitude and phase responses with the x-axis as frequency in Hertz instead of plotting them with the normalized angular frequency. To design the filters you have to first create the transfer function of the filter (ie: H(z)). you can do: h,f freqz (x,1, ,fs) If I just make that change to your code, the magnitude response plot shows the -3dB point where it should be. H, f freqz( obj, ind ) returns the frequency response of filters with indices corresponding to the elements in vector ind. 2 for Octave and Matlab version listings), and saveplot is a trivial compatibility wrapper for the print function, which saves the current plot to a disk file (. ![]() The corresponding magnitude for $\omega = 3\pi/4$ is not shown on the single-sided magnitude response plot above but you can see the asymptotic trend at $3\pi/4$.I am designing an FIR filter in Matlab using a Kaiser window. It can be used to get the frequency response of the filters. 1 Answer Sorted by: 1 freqz () has a form that takes a sample rate and returns the frequency sample points in Hz, instead of in radians, so instead of. In this example, freqz returns two arguments: the vector of frequency response values h at samples of the frequency domain given by w. ![]() The complex-valued frequency response is calculated. Below is the MATLAB code for the evaluation at the frequencies $\omega = 0, \pi/4, \pi/2, 3\pi/4, \text The freqz function calculates the frequency response for a filter from the filter transfer function Hq(z). For the evaluation only at specific frequencies, you need to specify the frequency vector with at least two frequencies in it (see MATLAB's freqz). ![]()
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