"ghazale " <ghazale.boroumand@gmail.com> wrote in message <l38j39$1m1$1@newscl01ah.mathworks.com>...
> In MATLAB I have to pass cutoff frequency for designing a filter. But this Cutoff frequency is in radianspersample. How do I convert my analog Cut off frequency in Hz, into the required radianspersample for MATLAB?
If you know the frequency in Hz and the sampling frequency you can do it easily.
Assume that T = 1/(sampling frequency), in other words, T is the sampling interval.
To convert your frequency in Hz to radians/sample
f*(2*pi*T)
The above gives you the frequency in radians/sample. For example, assume the sampling frequency is 1000 Hz and the frequency you want to convert is 100 Hz.
The equivalent frequency in radians/sample is
100*(2*pi*0.001)
Note that in designing filters, MATLAB often uses normalized frequency where a factor of pi is factored out, so that 1 is actually pi.
That means that the above would actually be:
(100*2*pi*0.001)/pi
