radar_signal.h

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// SPDX-License-Identifier: GPL-2.0-only
//
// Copyright (c) 2006-2008 Marc Brooker and Michael Inggs
// Copyright (c) 2008-present FERS Contributors (see AUTHORS.md).
//
// See the GNU GPLv2 LICENSE file in the FERS project root for more information.
 
/**
 * @file radar_signal.h
 * @brief Classes for handling radar waveforms and signals.
 */
 
#pragma once
 
#include <memory>
#include <optional>
#include <span>
#include <string>
#include <tuple>
#include <vector>
 
#include "core/config.h"
 
namespace interp
{
    struct InterpPoint;
}
 
namespace fers_signal
{
    /**
     * @class Signal
     * @brief Class for handling radar waveform signal data.
     */
    class Signal
    {
    public:
        virtual ~Signal() = default;
 
        Signal() = default;
 
        Signal(const Signal&) = delete;
 
        Signal& operator=(const Signal&) = delete;
 
        Signal(Signal&&) = default;
 
        Signal& operator=(Signal&&) = default;
 
        /**
         * @brief Clears the internal signal data.
         */
        void clear() noexcept;
 
        /**
         * @brief Loads complex radar waveform data.
         *
         * @param inData The input span of complex signal data.
         * @param samples The number of samples in the input data.
         * @param sampleRate The sample rate of the input data.
         */
        void load(std::span<const ComplexType> inData, unsigned samples, RealType sampleRate);
 
        /**
         * @brief Gets the sample rate of the signal.
         *
         * @return The sample rate of the signal.
         */
        [[nodiscard]] RealType getRate() const noexcept { return _rate; }
 
        /**
         * @brief Renders the signal data based on interpolation points.
         *
         * @param points A vector of interpolation points used to render the signal.
         * @param size Reference to store the size of the rendered data.
         * @param fracWinDelay Fractional window delay to apply during rendering.
         * @return A vector of rendered complex signal data.
         */
        virtual std::vector<ComplexType> render(const std::vector<interp::InterpPoint>& points, unsigned& size,
                                                double fracWinDelay) const;
 
    private:
        std::vector<ComplexType> _data; ///< The complex signal data.
        unsigned _size{0}; ///< The size of the signal data.
        RealType _rate{0}; ///< The sample rate of the signal.
 
        /**
         * @brief Calculates weights and delays for rendering.
         *
         * @param iter Iterator pointing to the current interpolation point.
         * @param next Iterator pointing to the next interpolation point.
         * @param sampleTime Current sample time.
         * @param idelay Integer delay value.
         * @param fracWinDelay Fractional window delay to apply.
         * @return A tuple containing amplitude, phase, fractional delay, and sample unwrap index.
         */
        [[nodiscard]] constexpr std::tuple<double, double, double, int>
        calculateWeightsAndDelays(std::vector<interp::InterpPoint>::const_iterator iter,
                                  std::vector<interp::InterpPoint>::const_iterator next, double sampleTime,
                                  double idelay, double fracWinDelay) const noexcept;
 
        /**
         * @brief Performs convolution with a filter.
         *
         * @param i Index of the current sample.
         * @param filt Pointer to the filter coefficients.
         * @param filtLength Length of the filter.
         * @param amplitude Amplitude scaling factor.
         * @param iSampleUnwrap Unwrapped sample index for the convolution.
         * @return The result of the convolution for the given sample.
         */
        ComplexType performConvolution(int i, const double* filt, int filtLength, double amplitude,
                                       int iSampleUnwrap) const noexcept;
    };
 
    /**
     * @class RadarSignal
     * @brief Class representing a radar signal with associated properties.
     */
    class RadarSignal
    {
    public:
        /**
         * @brief Constructs a RadarSignal object.
         *
         * @param name The name of the radar signal.
         * @param power The power of the radar signal.
         * @param carrierfreq The carrier frequency of the radar signal.
         * @param length The length of the radar signal.
         * @param signal A unique pointer to the `Signal` object containing the waveform data.
         * @throws std::runtime_error if the signal is null.
         */
        RadarSignal(std::string name, RealType power, RealType carrierfreq, RealType length,
                    std::unique_ptr<Signal> signal);
 
        ~RadarSignal() = default;
 
        RadarSignal(const RadarSignal&) noexcept = delete;
 
        RadarSignal& operator=(const RadarSignal&) noexcept = delete;
 
        RadarSignal(RadarSignal&&) noexcept = delete;
 
        RadarSignal& operator=(RadarSignal&&) noexcept = delete;
 
        /**
         * @brief Sets the filename associated with this signal.
         * @param filename The source filename.
         */
        void setFilename(const std::string& filename) noexcept { _filename = filename; }
 
        /**
         * @brief Gets the filename associated with this signal.
         * @return The source filename, if one was set.
         */
        [[nodiscard]] const std::optional<std::string>& getFilename() const noexcept { return _filename; }
 
        /**
         * @brief Gets the power of the radar signal.
         *
         * @return The power of the radar signal.
         */
        [[nodiscard]] RealType getPower() const noexcept { return _power; }
 
        /**
         * @brief Gets the carrier frequency of the radar signal.
         *
         * @return The carrier frequency of the radar signal.
         */
        [[nodiscard]] RealType getCarrier() const noexcept { return _carrierfreq; }
 
        /**
         * @brief Gets the name of the radar signal.
         *
         * @return The name of the radar signal.
         */
        [[nodiscard]] const std::string& getName() const noexcept { return _name; }
 
        /**
         * @brief Gets the sample rate of the radar signal.
         *
         * @return The sample rate of the radar signal.
         */
        [[nodiscard]] RealType getRate() const noexcept { return _signal->getRate(); }
 
        /**
         * @brief Gets the length of the radar signal.
         *
         * @return The length of the radar signal.
         */
        [[nodiscard]] RealType getLength() const noexcept { return _length; }
 
        /**
         * @brief Gets the underlying signal object.
         * @return A const pointer to the Signal object.
         */
        [[nodiscard]] const Signal* getSignal() const noexcept { return _signal.get(); }
 
        /**
         * @brief Renders the radar signal.
         *
         * @param points A vector of interpolation points.
         * @param size Reference to store the size of the rendered data.
         * @param fracWinDelay Fractional window delay to apply during rendering.
         * @return A vector of rendered complex radar signal data.
         */
        std::vector<ComplexType> render(const std::vector<interp::InterpPoint>& points, unsigned& size,
                                        RealType fracWinDelay) const;
 
    private:
        std::string _name; ///< The name of the radar signal.
        RealType _power; ///< The power of the radar signal.
        RealType _carrierfreq; ///< The carrier frequency of the radar signal.
        RealType _length; ///< The length of the radar signal.
        std::unique_ptr<Signal> _signal; ///< The `Signal` object containing the radar signal data.
        std::optional<std::string> _filename; ///< The original filename for file-based signals.
    };
 
    class CwSignal final : public Signal
    {
    public:
        CwSignal() = default;
 
        ~CwSignal() override = default;
 
        CwSignal(const CwSignal&) noexcept = delete;
 
        CwSignal& operator=(const CwSignal&) noexcept = delete;
 
        CwSignal(CwSignal&&) noexcept = delete;
 
        CwSignal& operator=(CwSignal&&) noexcept = delete;
 
        /**
         * @brief Renders the signal data. For CW signals, this is a no-op.
         * @return An empty vector of complex signal data.
         */
        std::vector<ComplexType> render(const std::vector<interp::InterpPoint>& points, unsigned& size,
                                        RealType fracWinDelay) const override;
    };
}