Stepped-frequency continuous-wave signal implementation. More...

#include "radar_signal.h"

Inheritance diagram for fers_signal::SteppedFrequencySignal:

Collaboration diagram for fers_signal::SteppedFrequencySignal:

Classes
struct	StepState
	Active SFCW dwell selected for one local waveform time. More...

Public Member Functions
	SteppedFrequencySignal (RealType start_frequency_offset, RealType step_size, std::size_t step_count, RealType dwell_time, RealType step_period, std::optional< std::size_t > sweep_count=std::nullopt)
	Constructs a uniform stepped-frequency CW signal.

	~SteppedFrequencySignal () override=default

	SteppedFrequencySignal (const SteppedFrequencySignal &) noexcept=delete

SteppedFrequencySignal &	operator= (const SteppedFrequencySignal &) noexcept=delete

	SteppedFrequencySignal (SteppedFrequencySignal &&) noexcept=delete

SteppedFrequencySignal &	operator= (SteppedFrequencySignal &&) noexcept=delete

RealType	getStartFrequencyOffset () const noexcept
	Gets the first-step offset from carrier in hertz.

RealType	getStepSize () const noexcept
	Gets the uniform frequency step in hertz.

std::size_t	getStepCount () const noexcept
	Gets the number of steps per sweep.

RealType	getDwellTime () const noexcept
	Gets active dwell time per step in seconds.

RealType	getStepPeriod () const noexcept
	Gets step repetition period in seconds.

const std::optional< std::size_t > &	getSweepCount () const noexcept
	Gets optional finite sweep count.

RealType	getSweepPeriod () const noexcept
	Gets full sweep period in seconds.

RealType	firstFrequency (RealType carrier_frequency) const noexcept
	Gets first-step RF frequency in hertz.

RealType	lastFrequency (RealType carrier_frequency) const noexcept
	Gets final-step RF frequency in hertz.

RealType	frequencySpan () const noexcept
	Gets first-to-last absolute span in hertz.

RealType	effectiveBandwidth () const noexcept
	Gets DFT-convention effective bandwidth in hertz.

std::optional< RealType >	totalDuration () const noexcept
	Gets finite waveform duration, if sweep_count is configured.

std::optional< StepState >	activeStepAt (RealType time_since_segment_start, RealType carrier_frequency) const noexcept
	Returns the active step for a time since the segment start.

std::vector< ComplexType >	render (const std::vector< interp::InterpPoint > &points, unsigned &size, RealType fracWinDelay) const override
	Renders the signal data. For SFCW signals, this is a no-op.

void	clear () noexcept
	Clears the internal signal data.

void	load (std::span< const ComplexType > inData, unsigned samples, RealType sampleRate)
	Loads complex radar waveform data.

RealType	getRate () const noexcept
	Gets the sample rate of the signal.

unsigned	getSampleCount () const noexcept
	Gets the number of native samples held by this signal.

virtual std::vector< ComplexType >	renderSlice (const std::vector< interp::InterpPoint > &points, RealType outputStartTime, RealType outputSampleRate, std::size_t sampleCount, RealType fracWinDelay) const
	Renders a bounded absolute-time slice on the requested output grid.

virtual bool	isFmcwFamily () const noexcept
	Returns true when this signal belongs to the FMCW waveform family.

Detailed Description

Stepped-frequency continuous-wave signal implementation.

Definition at line 313 of file radar_signal.h.

Constructor & Destructor Documentation

◆ SteppedFrequencySignal() [1/3]

fers_signal::SteppedFrequencySignal::SteppedFrequencySignal	(	RealType	start_frequency_offset,
		RealType	step_size,
		std::size_t	step_count,
		RealType	dwell_time,
		RealType	step_period,
		std::optional< std::size_t >	sweep_count = `std::nullopt`
	)

Constructs a uniform stepped-frequency CW signal.

Definition at line 55 of file radar_signal.cpp.

                                                                                                                   :
        _start_frequency_offset(start_frequency_offset), _step_size(step_size), _step_count(step_count),
        _dwell_time(dwell_time), _step_period(step_period), _sweep_count(sweep_count)
    {
    }

◆ ~SteppedFrequencySignal()

fers_signal::SteppedFrequencySignal::~SteppedFrequencySignal ( )

overridedefault

◆ SteppedFrequencySignal() [2/3]

fers_signal::SteppedFrequencySignal::SteppedFrequencySignal ( const SteppedFrequencySignal & )

deletenoexcept

◆ SteppedFrequencySignal() [3/3]

fers_signal::SteppedFrequencySignal::SteppedFrequencySignal ( SteppedFrequencySignal && )

deletenoexcept

Member Function Documentation

◆ activeStepAt()

std::optional< SteppedFrequencySignal::StepState > fers_signal::SteppedFrequencySignal::activeStepAt	(	RealType	time_since_segment_start,
		RealType	carrier_frequency
	)		const

noexcept

Returns the active step for a time since the segment start.

Definition at line 101 of file radar_signal.cpp.

    {
        if (time_since_segment_start < 0.0 || _step_count == 0 || _step_period <= 0.0 || _dwell_time <= 0.0)
        {
            return std::nullopt;
        }
 
        const RealType sweep_period = getSweepPeriod();
        const auto sweep_index = static_cast<std::size_t>(std::floor(time_since_segment_start / sweep_period));
        if (_sweep_count.has_value() && sweep_index >= *_sweep_count)
        {
            return std::nullopt;
        }
 
        const RealType local_sweep_time = time_since_segment_start - static_cast<RealType>(sweep_index) * sweep_period;
        const auto step_index = static_cast<std::size_t>(std::floor(local_sweep_time / _step_period));
        if (step_index >= _step_count)
        {
            return std::nullopt;
        }
 
        const RealType step_start_time =
            static_cast<RealType>(sweep_index) * sweep_period + static_cast<RealType>(step_index) * _step_period;
        const RealType local_step_time = time_since_segment_start - step_start_time;
        if (local_step_time < 0.0 || local_step_time >= _dwell_time)
        {
            return std::nullopt;
        }
 
        return StepState{.step_index = step_index,
                         .sweep_index = sweep_index,
                         .step_start_time = step_start_time,
                         .dwell_end_time = step_start_time + _dwell_time,
                         .step_end_time = step_start_time + _step_period,
                         .rf_frequency =
                             firstFrequency(carrier_frequency) + static_cast<RealType>(step_index) * _step_size};
    }

References max, and fers_signal::SteppedFrequencySignal::StepState::step_index.

◆ clear()

void fers_signal::Signal::clear ( )

noexceptinherited

Clears the internal signal data.

Definition at line 334 of file radar_signal.cpp.

    {
        _size = 0;
        _rate = 0;
    }

Referenced by fers_signal::Signal::load().

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◆ effectiveBandwidth()

RealType fers_signal::SteppedFrequencySignal::effectiveBandwidth ( ) const

noexcept

Gets DFT-convention effective bandwidth in hertz.

Definition at line 86 of file radar_signal.cpp.

    {
        return static_cast<RealType>(_step_count) * std::abs(_step_size);
    }

◆ firstFrequency()

RealType fers_signal::SteppedFrequencySignal::firstFrequency ( RealType carrier_frequency ) const

noexcept

Gets first-step RF frequency in hertz.

Definition at line 63 of file radar_signal.cpp.

    {
        return carrier_frequency + _start_frequency_offset;
    }

◆ frequencySpan()

RealType fers_signal::SteppedFrequencySignal::frequencySpan ( ) const

noexcept

Gets first-to-last absolute span in hertz.

Definition at line 77 of file radar_signal.cpp.

    {
        if (_step_count == 0)
        {
            return 0.0;
        }
        return std::abs(static_cast<RealType>(_step_count - 1U) * _step_size);
    }

◆ getDwellTime()

RealType fers_signal::SteppedFrequencySignal::getDwellTime ( ) const

noexcept

Gets active dwell time per step in seconds.

Definition at line 352 of file radar_signal.h.

352{ return _dwell_time; }

◆ getRate()

RealType fers_signal::Signal::getRate ( ) const

noexceptinherited

Gets the sample rate of the signal.

Returns: The sample rate of the signal.

Definition at line 86 of file radar_signal.h.

86{ return _rate; }

◆ getSampleCount()

unsigned fers_signal::Signal::getSampleCount ( ) const

noexceptinherited

Gets the number of native samples held by this signal.

Definition at line 89 of file radar_signal.h.

89{ return _size; }

◆ getStartFrequencyOffset()

RealType fers_signal::SteppedFrequencySignal::getStartFrequencyOffset ( ) const

noexcept

Gets the first-step offset from carrier in hertz.

Definition at line 343 of file radar_signal.h.

343{ return _start_frequency_offset; }

◆ getStepCount()

std::size_t fers_signal::SteppedFrequencySignal::getStepCount ( ) const

noexcept

Gets the number of steps per sweep.

Definition at line 349 of file radar_signal.h.

349{ return _step_count; }

◆ getStepPeriod()

RealType fers_signal::SteppedFrequencySignal::getStepPeriod ( ) const

noexcept

Gets step repetition period in seconds.

Definition at line 355 of file radar_signal.h.

355{ return _step_period; }

◆ getStepSize()

RealType fers_signal::SteppedFrequencySignal::getStepSize ( ) const

noexcept

Gets the uniform frequency step in hertz.

Definition at line 346 of file radar_signal.h.

346{ return _step_size; }

◆ getSweepCount()

const std::optional< std::size_t > & fers_signal::SteppedFrequencySignal::getSweepCount ( ) const

noexcept

Gets optional finite sweep count.

Definition at line 358 of file radar_signal.h.

358{ return _sweep_count; }

◆ getSweepPeriod()

RealType fers_signal::SteppedFrequencySignal::getSweepPeriod ( ) const

noexcept

Gets full sweep period in seconds.

Definition at line 361 of file radar_signal.h.

        {
            return static_cast<RealType>(_step_count) * _step_period;
        }

Referenced by totalDuration().

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◆ isFmcwFamily()

virtual bool fers_signal::Signal::isFmcwFamily ( ) const

virtualnoexceptinherited

Returns true when this signal belongs to the FMCW waveform family.

Reimplemented in fers_signal::FmcwChirpSignal, and fers_signal::FmcwTriangleSignal.

Definition at line 109 of file radar_signal.h.

109{ return false; }

◆ lastFrequency()

RealType fers_signal::SteppedFrequencySignal::lastFrequency ( RealType carrier_frequency ) const

noexcept

Gets final-step RF frequency in hertz.

Definition at line 68 of file radar_signal.cpp.

    {
        if (_step_count == 0)
        {
            return firstFrequency(carrier_frequency);
        }
        return firstFrequency(carrier_frequency) + static_cast<RealType>(_step_count - 1U) * _step_size;
    }

◆ load()

void fers_signal::Signal::load	(	std::span< const ComplexType >	inData,
		unsigned	samples,
		RealType	sampleRate
	)

inherited

Loads complex radar waveform data.

Parameters

inData	The input span of complex signal data.
samples	The number of samples in the input data.
sampleRate	The sample rate of the input data.

Definition at line 340 of file radar_signal.cpp.

    {
        clear();
        const unsigned ratio = params::oversampleRatio();
        const auto oversampled_samples = static_cast<std::size_t>(samples) * static_cast<std::size_t>(ratio);
        if (oversampled_samples > std::numeric_limits<unsigned>::max())
        {
            throw std::overflow_error("Oversampled signal sample count exceeds unsigned range");
        }
        _data.resize(oversampled_samples);
        _size = static_cast<unsigned>(oversampled_samples);
        _rate = sampleRate * static_cast<RealType>(ratio);
 
        if (ratio == 1)
        {
            std::ranges::copy(inData, _data.begin());
        }
        else
        {
            upsample(inData, samples, _data);
        }
    }

References fers_signal::Signal::clear(), max, params::oversampleRatio(), and fers_signal::upsample().

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◆ operator=() [1/2]

SteppedFrequencySignal & fers_signal::SteppedFrequencySignal::operator= ( const SteppedFrequencySignal & )

deletenoexcept

◆ operator=() [2/2]

SteppedFrequencySignal & fers_signal::SteppedFrequencySignal::operator= ( SteppedFrequencySignal && )

deletenoexcept

◆ render()

std::vector< ComplexType > fers_signal::SteppedFrequencySignal::render	(	const std::vector< interp::InterpPoint > &	points,
		unsigned &	size,
		RealType	fracWinDelay
	)		const

overridevirtual

Renders the signal data. For SFCW signals, this is a no-op.

Reimplemented from fers_signal::Signal.

Definition at line 140 of file radar_signal.cpp.

    {
        size = 0;
        return {};
    }

References max.

◆ renderSlice()

std::vector< ComplexType > fers_signal::Signal::renderSlice	(	const std::vector< interp::InterpPoint > &	points,
		RealType	outputStartTime,
		RealType	outputSampleRate,
		std::size_t	sampleCount,
		RealType	fracWinDelay
	)		const

virtualinherited

Renders a bounded absolute-time slice on the requested output grid.

Definition at line 374 of file radar_signal.cpp.

    {
        auto out = std::vector<ComplexType>(sampleCount);
        if (_size == 0 || _rate <= 0.0 || outputSampleRate <= 0.0 || points.empty())
        {
            return out;
        }
 
        const RealType timestep = 1.0 / outputSampleRate;
        const int filt_length = static_cast<int>(params::renderFilterLength());
        const auto& interp = interp::InterpFilter::getInstance();
 
        auto iter = points.begin();
        auto next = points.size() > 1 ? std::next(iter) : iter;
        const RealType idelay = std::round(_rate * iter->delay);
        RealType sample_time = outputStartTime;
 
        for (std::size_t i = 0; i < sampleCount; ++i)
        {
            while (sample_time > next->time && next != iter)
            {
                iter = next;
                if (std::next(next) != points.end())
                {
                    ++next;
                }
                else
                {
                    break;
                }
            }
 
            auto [amplitude, phase, fdelay, i_sample_unwrap] =
                calculateWeightsAndDelays(iter, next, sample_time, idelay, fracWinDelay);
            const RealType native_position = (sample_time - points.front().time) * _rate;
            const auto source_index = static_cast<int>(std::floor(native_position));
            RealType source_fraction = native_position - static_cast<RealType>(source_index);
            if (source_fraction < 0.0 && source_fraction > -1.0e-12)
            {
                source_fraction = 0.0;
            }
 
            const RealType combined_delay = fdelay + source_fraction;
            const auto delay_unwrap = static_cast<int>(std::floor(combined_delay));
            fdelay = combined_delay - static_cast<RealType>(delay_unwrap);
            i_sample_unwrap += delay_unwrap;
 
            const auto& filt = interp.getFilter(fdelay);
            const ComplexType accum =
                performConvolution(source_index, filt.data(), filt_length, amplitude, i_sample_unwrap);
            out[i] = std::exp(ComplexType(0.0, 1.0) * phase) * accum;
 
            sample_time += timestep;
        }
 
        return out;
    }

References interp::InterpFilter::getInstance(), max, and params::renderFilterLength().

Referenced by fers_signal::Signal::render().

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◆ totalDuration()

std::optional< RealType > fers_signal::SteppedFrequencySignal::totalDuration ( ) const

noexcept

Gets finite waveform duration, if sweep_count is configured.

Definition at line 91 of file radar_signal.cpp.

    {
        if (!_sweep_count.has_value())
        {
            return std::nullopt;
        }
        return static_cast<RealType>(*_sweep_count) * getSweepPeriod();
    }

References getSweepPeriod().

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The documentation for this class was generated from the following files:

packages/libfers/src/signal/radar_signal.h
packages/libfers/src/signal/radar_signal.cpp

Classes

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ SteppedFrequencySignal() [1/3]

◆ ~SteppedFrequencySignal()

◆ SteppedFrequencySignal() [2/3]

◆ SteppedFrequencySignal() [3/3]

Member Function Documentation

◆ activeStepAt()

◆ clear()

◆ effectiveBandwidth()

◆ firstFrequency()

◆ frequencySpan()

◆ getDwellTime()

◆ getRate()

◆ getSampleCount()

◆ getStartFrequencyOffset()

◆ getStepCount()

◆ getStepPeriod()

◆ getStepSize()

◆ getSweepCount()

◆ getSweepPeriod()

◆ isFmcwFamily()

◆ lastFrequency()

◆ load()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ render()

◆ renderSlice()

◆ totalDuration()