mirror of https://github.com/g4klx/MMDVM.git
110 lines
3.4 KiB
C++
110 lines
3.4 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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/*
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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 = 132;
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q15_t FILTER_COEFFS[] = {
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0, 5, 12, 18, 21, 19, 11, -2, -15, -25,
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-27, -21, -11, -3, -5, -19, -43, -69, -83, -73,
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-35, 27, 98, 155, 180, 163, 109, 39, -20, -45,
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-26, 23, 74, 89, 39, -81, -247, -407, -501, -480,
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-334, -92, 175, 388, 479, 429, 275, 99, 5, 68,
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298, 626, 913, 994, 740, 115, -791, -1770, -2544, -2847,
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-2509, -1527, -76, 1518, 2875, 3653, 3653, 2875, 1518, -76,
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-1527, -2509, -2847, -2544, -1770, -791, 115, 740, 994, 913,
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626, 298, 68, 5, 99, 275, 429, 479, 388, 175,
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-92, -334, -480, -501, -407, -247, -81, 39, 89, 74,
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23, -26, -45, -20, 39, 109, 163, 180, 155, 98,
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27, -35, -73, -83, -69, -43, -19, -5, -3, -11,
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-21, -27, -25, -15, -2, 11, 19, 21, 18, 12,
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5, 0
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};
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CAX25RX::CAX25RX() :
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m_filter(),
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m_state(),
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m_demod1(3),
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m_demod2(6),
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m_demod3(9),
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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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m_lastFCS = 0U;
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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_fcs != m_lastFCS) {
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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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ret = m_demod2.process(output, length, frame);
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if (ret && frame.m_fcs != m_lastFCS) {
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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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ret = m_demod3.process(output, length, frame);
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if (ret && frame.m_fcs != m_lastFCS) {
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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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void CAX25RX::setParams(int8_t twist)
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{
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m_demod1.setTwist(twist - 3);
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m_demod2.setTwist(twist);
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m_demod3.setTwist(twist + 3);
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}
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