92 lines
3.1 KiB
C++
92 lines
3.1 KiB
C++
/*
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* Copyright (C) 2016 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __OOK_HPP__
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#define __OOK_HPP__
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#include "phase_detector.hpp"
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#include "phase_accumulator.hpp"
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#include <cstdint>
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#include <complex>
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#include <algorithm>
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#include <cmath>
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class OOKSlicerMagSquaredInt {
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public:
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using symbol_t = bool;
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constexpr OOKSlicerMagSquaredInt(
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const float samples_per_symbol)
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: mag2_threshold_leak_factor{
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static_cast<uint32_t>(
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factor_sq(-1.0f / (8.0f * samples_per_symbol)) * float(1ULL << 32))} {
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}
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symbol_t operator()(const std::complex<int16_t> in) {
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const uint32_t real2 = in.real() * in.real();
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const uint32_t imag2 = in.imag() * in.imag();
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const uint32_t mag2 = real2 + imag2;
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const uint32_t mag2_attenuated = mag2 >> 3; // Approximation of (-4.5dB)^2
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mag2_threshold = (uint64_t(mag2_threshold) * uint64_t(mag2_threshold_leak_factor)) >> 32;
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mag2_threshold = std::max(mag2_threshold, mag2_attenuated);
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const bool symbol = (mag2 > mag2_threshold);
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return symbol;
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}
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private:
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const uint32_t mag2_threshold_leak_factor;
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uint32_t mag2_threshold = 0;
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constexpr float factor_sq(float db) {
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return std::pow(10.0f, db / (10.0f / 2));
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}
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};
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class OOKClockRecovery {
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public:
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constexpr OOKClockRecovery(
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const float samples_per_symbol)
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: symbol_phase_inc_nominal{static_cast<uint32_t>(std::round((1ULL << 32) / samples_per_symbol))},
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symbol_phase_inc_k{static_cast<uint32_t>(std::round(symbol_phase_inc_nominal * (2.0f / 8.0f) / samples_per_symbol))},
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phase_detector{static_cast<size_t>(std::round(samples_per_symbol))},
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phase_accumulator{symbol_phase_inc_nominal} {
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}
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template <typename SymbolHandler>
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void operator()(const uint32_t slicer_history, SymbolHandler symbol_handler) {
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if (phase_accumulator()) {
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const auto detector_result = phase_detector(slicer_history);
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phase_accumulator.set_inc(symbol_phase_inc_nominal + detector_result.error * symbol_phase_inc_k);
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symbol_handler(detector_result.symbol);
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}
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}
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private:
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const uint32_t symbol_phase_inc_nominal;
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const uint32_t symbol_phase_inc_k;
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PhaseDetectorEarlyLateGate phase_detector;
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PhaseAccumulator phase_accumulator;
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};
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#endif /*__OOK_HPP__*/
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