I have a simple FIR filter that should eliminate all lower frequencies:
H = zeros(60,1);
H(30:end) = 1+1i;
H = [H;conj(flipud(H(2:end)))]; % double sided
Then I assign a sample time to generate a time vector:
dT = 0.002;
Tspan = dT*length(h);
dF = 1/Tspan;
Here my nyquist is 250Hz. So the filter should eliminate everything below 125Hz.
I generate a signal at 15Hz, and convolve it with the filter coefficients.
t = 0:dT:5; x = cos(2*pi*15*t);
But, I get an output signal that clearly does not have the 15Hz eliminated:
Does it look like my convolution algorithm is incorrect? Or am I misunderstanding something?
Any help is appreciated!