mirror of https://github.com/g4klx/MMDVM.git
144 lines
4.4 KiB
C++
144 lines
4.4 KiB
C++
/*
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* Copyright (C) 2020 by Jonathan Naylor G4KLX
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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 of the License, or
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* (at your option) 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; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "Config.h"
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#include "Globals.h"
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#include "AX25RX.h"
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// XXX There are for the wrong sample rate
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// 1200Hz = -9dB, 2200Hz = 0dB; 3252Hz cutoff, 3.7 gain; cosine.
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float32_t dB9[] = {
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-0.00232554104135,
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-0.142858725752,
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-0.449053780255,
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-0.770264863826,
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2.77651146344,
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-0.770264863826,
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-0.449053780255,
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-0.142858725752,
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-0.00232554104135};
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// 1200Hz = -6dB, 2200Hz = 0dB; 2640Hz cutoff, 2.59 gain; cosine.
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float32_t dB6[] = {
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-0.0209448226653,
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-0.130107651829,
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-0.299004731072,
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-0.45336946386,
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2.0629448761,
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-0.45336946386,
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-0.299004731072,
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-0.130107651829,
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-0.0209448226653};
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// 1200Hz = -3dB, 2200Hz = 0dB; 1700Hz cutoff, 1.68 gain; cosine.
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float32_t dB3[] = {
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-0.0231416146776,
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-0.0833375337803,
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-0.147937602401,
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-0.197411259519,
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1.46066084756,
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-0.197411259519,
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-0.147937602401,
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-0.0833375337803,
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-0.0231416146776};
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/*
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* Generated with Scipy Filter, 152 coefficients, 1100-2300Hz bandpass,
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* Hann window, starting and ending 0 value coefficients removed.
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*
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* np.array(
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* firwin2(152,
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* [
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* 0.0,
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* 1000.0/(sample_rate/2),
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* 1100.0/(sample_rate/2),
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* 2350.0/(sample_rate/2),
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* 2500.0/(sample_rate/2),
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* 1.0
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* ],
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* [0,0,1,1,0,0],
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* antisymmetric = False,
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* window='hann') * 32768,
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* dtype=int)[10:-10]
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*/
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const uint32_t FILTER_LEN = 132U;
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// XXX This is for the wrong sample rate
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q15_t FILTER_COEFFS[] = {
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4, 0, -5, -10, -13, -12, -9, -4, -2, -4, -12, -26,
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-41, -52, -51, -35, -3, 39, 83, 117, 131, 118, 83, 36,
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-6, -32, -30, -3, 36, 67, 66, 19, -74, -199, -323, -408,
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-421, -344, -187, 17, 218, 364, 417, 369, 247, 106, 14, 26,
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166, 407, 676, 865, 866, 605, 68, -675, -1484, -2171, -2547, -2471,
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-1895, -882, 394, 1692, 2747, 3337, 3337, 2747, 1692, 394, -882, -1895,
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-2471, -2547, -2171, -1484, -675, 68, 605, 866, 865, 676, 407, 166,
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26, 14, 106, 247, 369, 417, 364, 218, 17, -187, -344, -421,
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-408, -323, -199, -74, 19, 66, 67, 36, -3, -30, -32, -6,
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36, 83, 118, 131, 117, 83, 39, -3, -35, -51, -52, -41,
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-26, -12, -4, -2, -4, -9, -12, -13, -10, -5, 0, 4};
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CAX25RX::CAX25RX() :
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m_filter(),
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m_state(),
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m_demod1(dB3, 9U),
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m_demod2(dB6, 9U),
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m_demod3(dB9, 9U),
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m_lastFCS(0U)
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{
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m_filter.numTaps = FILTER_LEN;
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m_filter.pState = m_state;
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m_filter.pCoeffs = FILTER_COEFFS;
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}
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void CAX25RX::samples(q15_t* samples, uint8_t length)
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{
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q15_t output[RX_BLOCK_SIZE];
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::arm_fir_fast_q15(&m_filter, samples, output, RX_BLOCK_SIZE);
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CAX25Frame frame;
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bool ret = m_demod1.process(output, length, frame);
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if (ret && frame.m_length > 10U) {
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if (m_lastFCS != frame.m_fcs) {
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DEBUG1("Decoder 1 reported");
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m_lastFCS = frame.m_fcs;
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serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
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}
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}
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ret = m_demod2.process(output, length, frame);
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if (ret && frame.m_length > 10U) {
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if (m_lastFCS != frame.m_fcs) {
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DEBUG1("Decoder 2 reported");
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m_lastFCS = frame.m_fcs;
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serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
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}
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}
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ret = m_demod3.process(output, length, frame);
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if (ret && frame.m_length > 10U) {
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if (m_lastFCS != frame.m_fcs) {
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DEBUG1("Decoder 3 reported");
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m_lastFCS = frame.m_fcs;
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serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
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}
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}
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}
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