Need help in designing a filter which removes all 1 Hz frequencies.

 I have white noise from this white noise i want to remove all 1 Hz frequencies using LPF 
In matlab how can be design a LPF with 1Hz cutoff freq

Answer 1

[Wayne King]

There are many ways. You have not told us your sampling frequency. Let me assume it is 60-Hz.

   d = fdesign.lowpass('Fp,Fst,Ap,Ast',1,3,0.5,40,60);
   Hd = design(d);
   % View filter magntidue response
   fvtool(Hd)
   % to filter data
   output = filter(Hd,inputdata);

[suresh]

sir, what if my sampling frequency is 0.0333 Hz

my cutoff frequency is 1Hz

output = filter(Hd,inputdata);

above equation will remove all 1Hz frequencies from input data

pls help

Answer 2

[Wayne King]

I answered this in your other post. If your sampling frequency is 0.0333 Hz, then you cannot resolve 1 Hz.

[Wayne King]

http://www.mathworks.com/matlabcentral/answers/39619-need-to-design-a-fir-lpf-with-cuff-frequency-at-1-hz