Designing a band pass filter for filtering a sinusoidal function with a known frequency from a signal with an unknown sampling rate

Hi,

I have a non-periodic signal which I do not know it's smapling frequency.Just a random signal with an nunkown sampling frequency.

R=rand(2000,1);

I need to filter a first a order fourier function: f(x) = a0 + a1*cos(x*w) + b1*sin(x*w) from singal R. So Filter f(x) from R.

I have all it's coefficents and I know the value for frequecy

a0 = -0.828e-06 ;

a1 = 7.8 ;

b1 = -460 ;

w = 0.00976 ;

the length of x is equal to size(R(1))=2000 points;

the value of the a1 and b1 are unkown .

I need to filter the non -periodic signal ( R) with the function f(x) .

I wnat to use a band pass filter to elimiante all the frequencies associated and close to sinusidoal wave (f(x)) .

Many thanks

Answer 1

[Agnish Dutta]

The signal processing toolbox will give you the necessary functionality to carry out filtering of signals.

The following will create a bandpass filter:

% To create an FIR filter:

Hd1 = designfilt('bandpassfir', ...
    'StopbandFrequency1',1/60,'PassbandFrequency1',1/40, ...
    'PassbandFrequency2',1/4 ,'StopbandFrequency2',1/2 , ...
    'StopbandAttenuation1',10,'PassbandRipple',1, ...
    'StopbandAttenuation2',10,'DesignMethod','equiripple','SampleRate',Fs);

% To create an IIR filter:

Hd2 = designfilt('bandpassiir', ...
    'StopbandFrequency1',1/60,'PassbandFrequency1',1/40, ...
    'PassbandFrequency2',1/4 ,'StopbandFrequency2',1/2 , ...
    'StopbandAttenuation1',10,'PassbandRipple',1, ...
    'StopbandAttenuation2',10,'DesignMethod','butter','SampleRate',Fs);

I believe you'll be able to set the parameters to their appropriate values as per your application.

To filter a signal using the above filters:

yfir = filter(Hd1,y);
yiir = filter(Hd2,y);

Links:

Filtering Data With Signal Processing Toolbox Software - https://www.mathworks.com/help/signal/ug/filtering-data-with-signal-processing-toolbox.html