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added FIR LPF, HPF and BPF

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Ahmet Inan 2019-01-03 21:13:56 +01:00
commit 00501fa433
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README.md
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@ -21,6 +21,13 @@ Implemented are the follwing [Window functions](https://en.wikipedia.org/wiki/Wi
* [Gaussian window](https://en.wikipedia.org/wiki/Window_function#Gaussian_window)
* [Kaiser window](https://en.wikipedia.org/wiki/Window_function#Kaiser_window)
### [filter.hh](filter.hh)
Implemented are the following [finite impulse response](https://en.wikipedia.org/wiki/Finite_impulse_response) [filters](https://en.wikipedia.org/wiki/Filter_(signal_processing)):
* [low-pass filter](https://en.wikipedia.org/wiki/Low-pass_filter)
* [high-pass filter](https://en.wikipedia.org/wiki/High-pass_filter)
* [band-pass filter](https://en.wikipedia.org/wiki/Band-pass_filter)
### [const.hh](const.hh)
Some constants we need

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filter.hh Normal file
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@ -0,0 +1,61 @@
/*
Some finite impulse response filter functions
Copyright 2018 Ahmet Inan <inan@aicodix.de>
*/
#ifndef FILTER_HH
#define FILTER_HH
#include "const.hh"
#include "utils.hh"
#include "coeffs.hh"
namespace DSP {
template <typename TYPE>
class LowPass : public CoeffsFunc<TYPE>
{
TYPE f;
public:
LowPass(TYPE cutoff) : f(TYPE(2) * cutoff) {}
TYPE operator () (int n, int N)
{
TYPE x = TYPE(n) - TYPE(0.5) * TYPE(N - 1);
return f * sinc(f * x);
}
};
template <typename TYPE>
class HighPass : public CoeffsFunc<TYPE>
{
TYPE f;
public:
HighPass(TYPE cutoff) : f(TYPE(2) * cutoff) {}
TYPE operator () (int n, int N)
{
TYPE x = TYPE(n) - TYPE(0.5) * TYPE(N - 1);
// if (N%1) return delta(x) - f * sinc(f * x);
return sinc(x) - f * sinc(f * x);
}
};
template <typename TYPE>
class BandPass : public CoeffsFunc<TYPE>
{
TYPE f0, f1;
public:
BandPass(TYPE cutoff0, TYPE cutoff1) :
f0(TYPE(2) * cutoff0), f1(TYPE(2) * cutoff1) {}
TYPE operator () (int n, int N)
{
TYPE x = TYPE(n) - TYPE(0.5) * TYPE(N - 1);
return f1 * sinc(f1 * x) - f0 * sinc(f0 * x);
}
};
}
#endif