Butterworth filter

ROOT
1

I have time-domain digitizer traces that I would like to run through a low-pass Butterworth filter. Are there any signal processing classes within root that can do this?

EDIT: Seriously people, someone has to have done this before in root! I don’t really want to switch to matlab…

2

I don’t think ROOT has any signal processing functions. What you can do though is use python to access your ROOT data and then use the scipy/numpy python packages for filtering.

Adam

3

That had been my backup plan. As there seemed to be no solution in root, I ended up using the scipy.signal.butter() method. I am now filled with a profound sadness. If anyone needs help for something similar, hit me up.

4

OK. I implemented Butterworth filter transfer function as a RooAbsReal class. You can see it here. You could use it by convolving it with your input. There may be not enough documentation now but I will fix this soon. Any suggestion and/or correction would be appreciated.

2 Likes
5

If you consider using an external DSP library, this one has also Butterworth filters:

6

Hello @ferhue,

I have managed to build KFR with clang 10. (and the C API library too)
Right know I am facing some additional issue when I try to compile with rootcling.

          ^
In file included from input_line_9:5:
In file included from /home/marcomeyer/Software/escalade/src/lib/UMO/include/UMO/TSignal.h:28:
In file included from /home/marcomeyer/Software/kfr/4.2.1/include/kfr/dft.hpp:25:
In file included from /home/marcomeyer/Software/kfr/4.2.1/include/kfr/base.hpp:25:
In file included from /home/marcomeyer/Software/kfr/4.2.1/include/kfr/math.hpp:25:
In file included from /home/marcomeyer/Software/kfr/4.2.1/include/kfr/simd.hpp:25:
In file included from /home/marcomeyer/Software/kfr/4.2.1/include/kfr/simd/comparison.hpp:28:
In file included from /home/marcomeyer/Software/kfr/4.2.1/include/kfr/simd/constants.hpp:28:
/home/marcomeyer/Software/kfr/4.2.1/include/kfr/simd/types.hpp:404:48: error: reference to 'is_same' is ambiguous
    is_same<T, float> || is_same<T, double> || is_same<T, signed char> || is_same<T, unsigned char> ||
                                               ^
/home/marcomeyer/Software/kfr/4.2.1/include/kfr/simd/../cometa.hpp:181:23: note: candidate found by name lookup is 'cometa::is_same'
constexpr inline bool is_same = std::is_same<T1, T2>::value;
                      ^
/usr/include/c++/9/type_traits:1285:12: note: candidate found by name lookup is 'std::is_same'
    struct is_same
           ^

Any help from ROOT expert would be very welcome too :slight_smile:
I have remove “using namespace std;” I though this was the reason I get this issue.

7

Hmm maybe try adding cometa:: before every occurrence of is_same in the header.

8

Hi, thanks for the reply !

I was hoping not to modify KFR, but well…
I think I have fix the issue adding the proper namespace to remove ambiguities.

9

For those who are passing by this thread.
There is an unmerged branch that is fixing the issues.

In my case GNU C++ was detected first by cmake. This was working at first.
I could compute my FFT forward and backward, but an issue raised when I started to use more advanced methods. For instance, I edited some example programs available in the repository, by combining windows & fft. And these were breaking, due to some seg. faults.
So please, if you want KFR to properly work remember perhaps to use Clang++ compiler. (-DCMAKE_CXX_COMPILER=clang++)

There is no community and the core team is not very active, but all in all this is a good library so far for 1D(only) signal processing.

1 Like