I am making a 9th order digital bandpass filter with lower and upper corners of 200 kHz and 40 MHz respectively. I am using this filter to filter a 1D time domain signal which is 64k samples long sampled at a frequency of 150MHz.
I have done some digital filtering before in university, so I know what to expect, but it's been a while.
I have used this site: http://www-users.cs.york.ac.uk/~fisher/mkfilter/trad.html to generate the filter coefficients and the gain, and I can see how the code works, my question is this:
I start with the value of X, then to calculate the value of Y I need values for Y[-1] ... Y[-18] and x[-1] ... X[-18].
I know these do not exist, so I think (from what I remember from university) that I pad with zeros, however, doing a bit or reading I heard it mentioned that padding with zeros changes the sampling frequency.
So how do I go about calculating this new sampling frequency (if indeed required..)?