- #1
jensel
- 22
- 0
Hello,
Please help me with the following problem.
Given a measured signal which has to be smoothed. A lowpass filter has to be applied. The signal is available as measured data (a data file on the hard disk, numerical, not real-time) ( it has to be applied in C or C++). The filter frequency where "the cut-off" should apply is well-known. It is a real signal and has constant delta t.
I have no serious background in frequency data analysis so I will order my questions in a way of most urgency (sorry if one of the points is "easy to see" or wrong):
- if the signal is given as a series f(n), the converted signal is (depending from the order of the filter)
f_filtered(n)=f(n-k)*a_(-k)+f(n-k+1)*a_(-k+1)+...+f(n)*a_0+...+f(n+k)*a_(k+1)
under the condition that we have a kernel in the integration which is, let us say Butterworth (as far I understand the problem).
If this is right, how are the coefficients calculated? (for example with Matlab or in a different way)
- which free C/C++ library can be included to be more flexible to exactly solve this problem (it is not needed to be the universal library with all sorts of filtering - easy to use is priority)
Thanks a lot for helping me with this issue.
Jens
Please help me with the following problem.
Given a measured signal which has to be smoothed. A lowpass filter has to be applied. The signal is available as measured data (a data file on the hard disk, numerical, not real-time) ( it has to be applied in C or C++). The filter frequency where "the cut-off" should apply is well-known. It is a real signal and has constant delta t.
I have no serious background in frequency data analysis so I will order my questions in a way of most urgency (sorry if one of the points is "easy to see" or wrong):
- if the signal is given as a series f(n), the converted signal is (depending from the order of the filter)
f_filtered(n)=f(n-k)*a_(-k)+f(n-k+1)*a_(-k+1)+...+f(n)*a_0+...+f(n+k)*a_(k+1)
under the condition that we have a kernel in the integration which is, let us say Butterworth (as far I understand the problem).
If this is right, how are the coefficients calculated? (for example with Matlab or in a different way)
- which free C/C++ library can be included to be more flexible to exactly solve this problem (it is not needed to be the universal library with all sorts of filtering - easy to use is priority)
Thanks a lot for helping me with this issue.
Jens
