Filter in MATLAB

stay matlab When we need to generate a filter , have access to matlab Tools included in the .

stay matlab Input in the command window filterDesigner, The following window appears . 

  Here, you can design the filter you need according to your needs .

After designing the filter, if we want to use our filter in a functional way , Then we can save the designed filter as a function .

Save it to the directory where we need to use the filter , You can use filters like functions . 

 

When using filters ：

h=lowpass_filter;
yy=filter(h,y);

  You can get the filtered signal .

If we want to save the parameters of the filter ：

 

  It can be saved in the desired format as needed

for example , We save the parameters of the filter as mat file , If we need to use filters in the program , So first of all mat File import , And then assign a value .

load coef_lpf.mat;
h=Num;% there Num Is the name of the call parameter in the above , It is recommended to use the same name as the filter 

Introduce several kinds of matlab Frequently used functions

filter One dimensional filter .

In the form of ：y=filter(b,a,x)

  this MATLAB function Use the numerator and denominator coefficients b and a Defined rational transfer function For input data x Filtering .

firls: Least squares linear phase FIR Filter design .firls A linear phase is designed FIR filter , The filter can minimize the weighted integral square error between the ideal piecewise linear function and the amplitude response of the filter in a set of required frequency bands .

b=firls(n,f,a)

for example ：

h=firls(N,[0,0.2,0.25,1],[1,1,0,0]);% Design filters 
fvtool(h)% Display filter 

  The transition zone is located in 0.2 and Between .