kopia lustrzana https://github.com/mobilinkd/tnc3-firmware
77 wiersze
2.3 KiB
C++
77 wiersze
2.3 KiB
C++
// Copyright 2015-2019 Mobilinkd LLC <rob@mobilinkd.com>
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// All rights reserved.
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#ifndef MOBILINKD__AFSK_DEMODULATOR_HPP_
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#define MOBILINKD__AFSK_DEMODULATOR_HPP_
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#include <arm_math.h>
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#include "DelayLine.hpp"
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#include "AudioInput.hpp"
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#include "DigitalPLL.hpp"
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#include "HdlcDecoder.hpp"
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#include "Hysteresis.hpp"
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#include "FirFilter.hpp"
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#include "NRZI.hpp"
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#include <algorithm>
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#include <functional>
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namespace mobilinkd { namespace tnc { namespace afsk1200 {
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const size_t LPF_FILTER_LEN = 96;
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const q15_t lpf_coeffs[] = {
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0, 1, 3, 5, 8, 11, 14, 17, 19, 20, 18, 14,
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7, -2, -16, -33, -53, -76, -101, -126, -151, -174, -194, -208,
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-215, -212, -199, -173, -133, -79, -10, 74, 173, 287, 413, 549,
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693, 842, 993, 1142, 1287, 1423, 1547, 1656, 1747, 1817, 1865, 1889,
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1889, 1865, 1817, 1747, 1656, 1547, 1423, 1287, 1142, 993, 842, 693,
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549, 413, 287, 173, 74, -10, -79, -133, -173, -199, -212, -215,
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-208, -194, -174, -151, -126, -101, -76, -53, -33, -16, -2, 7,
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14, 18, 20, 19, 17, 14, 11, 8, 5, 3, 1, 0,
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};
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static constexpr uint32_t ADC_BUFFER_SIZE = 88;
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typedef FirFilter<ADC_BUFFER_SIZE, 9> emphasis_filter_type;
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struct Demodulator {
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typedef float float_type;
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typedef std::function<float_type(float_type)> filter_function_type;
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static const size_t SYMBOL_RATE = 1200;
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typedef BaseDigitalPLL<float_type> DPLL;
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size_t sample_rate_;
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emphasis_filter_type& audio_filter_;
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libafsk::FixedDelayLine<40> delay_line_;
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DPLL pll_;
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Q15FirFilter<ADC_BUFFER_SIZE, LPF_FILTER_LEN> lpf_filter_;
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libafsk::NRZI nrzi_;
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hdlc::NewDecoder hdlc_decoder_;
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bool locked_;
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q15_t buffer_[ADC_BUFFER_SIZE];
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Demodulator(size_t sample_rate, emphasis_filter_type& c)
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: sample_rate_(sample_rate)
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, audio_filter_(c)
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, delay_line_(sample_rate, 0.000448)
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, pll_(sample_rate, SYMBOL_RATE)
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, nrzi_(), hdlc_decoder_(false), locked_(false)
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{
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lpf_filter_.init(lpf_coeffs);
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}
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hdlc::IoFrame* operator()(q15_t* samples, size_t len);
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bool locked() const {return locked_;}
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};
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}}} // mobilinkd::tnc::afsk1200
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#endif // MOBILINKD__AFSK_DEMODULATOR_HPP_
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