Filter.h

// -*- C++ -*-
// -*- coding: utf-8 -*-
//
// Author: Heresh Fattahi, Bryan Riel
// Copyright 2018-
//
 
#pragma once
 
#include "forward.h"
 
#include <cmath>
#include <valarray>
 
#include <isce3/core/Constants.h>
#include <isce3/io/Raster.h>
#include <isce3/core/LUT1d.h>
#include "Signal.h"
 
// Declaration
namespace isce3 { namespace signal {
    void fftfreq(double dt, std::valarray<double> &freq);
}}
 
template<class T>
class isce3::signal::Filter {
    public:
 
        Filter() {};
 
        ~Filter() {};

        void initiateRangeFilter(std::valarray<std::complex<T>> &signal,
                                std::valarray<std::complex<T>> &spectrum,
                                size_t ncols,
                                size_t nrows);

        void initiateAzimuthFilter(std::valarray<std::complex<T>> &signal,
                                std::valarray<std::complex<T>> &spectrum,
                                size_t ncols,
                                size_t nrows);

        //void setFilter(std::valarray<std::complex<T>>);

        void constructRangeBandpassFilter(double rangeSamplingFrequency,
                                        std::valarray<double> subBandCenterFrequencies,
                                        std::valarray<double> subBandBandwidths,
                                        std::valarray<std::complex<T>> &signal,
                                        std::valarray<std::complex<T>> &spectrum,
                                        size_t ncols,
                                        size_t nrows,
                                        std::string filterType);
 
        void constructRangeBandpassFilter(double rangeSamplingFrequency,
                                        std::valarray<double> subBandCenterFrequencies,
                                        std::valarray<double> subBandBandwidths,
                                        size_t ncols,
                                        size_t nrows,
                                        std::string filterType);

        void constructRangeBandpassBoxcar(std::valarray<double> subBandCenterFrequencies,
                                       std::valarray<double> subBandBandwidths,
                                       double dt,
                                       int fft_size,
                                       std::valarray<std::complex<T>> &_filter1D);
 
        void constructRangeBandpassCosine(std::valarray<double> subBandCenterFrequencies,
                             std::valarray<double> subBandBandwidths,
                             double dt,
                             std::valarray<double>& frequency,
                             double beta,
                             std::valarray<std::complex<T>>& _filter1D);
 
        //T constructRangeCommonbandFilter();

        void constructAzimuthCommonbandFilter(const isce3::core::LUT1d<double> & refDoppler,
                                const isce3::core::LUT1d<double> & secDoppler,
                                double bandwidth,
                                double prf,
                                double beta,
                                std::valarray<std::complex<T>> &signal,
                                std::valarray<std::complex<T>> &spectrum,
                                size_t ncols,
                                size_t nrows);

        void filter(std::valarray<std::complex<T>> &signal,
                std::valarray<std::complex<T>> &spectrum);

        static void indexOfFrequency(double dt, int N, double f, int& n);
 
        void writeFilter(size_t ncols, size_t nrows);
 
    private:
        isce3::signal::Signal<T> _signal;
        std::valarray<std::complex<T>> _filter;
 
};