MMDVM/AX25RX.cpp

349 lines
6.0 KiB
C++

/*
* Copyright (C) 2020 by Jonathan Naylor G4KLX
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "Config.h"
#include "Globals.h"
#include "AX25RX.h"
// 1200Hz = -12dB, 2200Hz = 0dB; 3381Hz cutoff; cosine.
q15_t dB12[] = {
176,
-812,
-3916,
-7586,
23536,
-7586,
-3916,
-812,
176
};
// 1200Hz = -11dB, 2200Hz = 0dB; 3258Hz cutoff; cosine.
q15_t dB11[] = {
121,
-957,
-3959,
-7383,
23871,
-7383,
-3959,
-957,
121
};
// 1200Hz = -10dB, 2200Hz = 0dB; 3118Hz cutoff; cosine.
q15_t dB10[] = {
56,
-1110,
-3987,
-7141,
24254,
-7141,
-3987,
-1110,
56
};
// 1200Hz = -9dB, 2200Hz = 0dB; 2959Hz cutoff; cosine.
q15_t dB9[] = {
-19,
-1268,
-3994,
-6856,
24688,
-6856,
-3994,
-1268,
-19
};
// 1200Hz = -8dB, 2200Hz = 0dB; 2778Hz cutoff; cosine.
q15_t dB8[] = {
-104,
-1424,
-3968,
-6516,
25182,
-6516,
-3968,
-1424,
-104
};
// 1200Hz = -7dB, 2200Hz = 0dB; 2573Hz cutoff; cosine.
q15_t dB7[] = {
-196,
-1565,
-3896,
-6114,
25742,
-6114,
-3896,
-1565,
-196
};
// 1200Hz = -6dB, 2200Hz = 0dB; 2343Hz cutoff; cosine.
q15_t dB6[] = {
-288,
-1676,
-3761,
-5642,
26370,
-5642,
-3761,
-1676,
-288
};
// 1200Hz = -5dB, 2200Hz = 0dB; 2085Hz cutoff; cosine.
q15_t dB5[] = {
-370,
-1735,
-3545,
-5088,
27075,
-5088,
-3545,
-1735,
-370
};
// 1200Hz = -4dB, 2200Hz = 0dB; 1790Hz cutoff; cosine.
q15_t dB4[] = {
-432,
-1715,
-3220,
-4427,
27880,
-4427,
-3220,
-1715,
-432
};
// 1200Hz = -3dB, 2200Hz = 0dB; 1456Hz cutoff; cosine.
q15_t dB3[] = {
-452,
-1582,
-2759,
-3646,
28792,
-3646,
-2759,
-1582,
-452
};
// 1200Hz = -2dB, 2200Hz = 0dB; 1070Hz cutoff; cosine.
q15_t dB2[] = {
-408,
-1295,
-2123,
-2710,
29846,
-2710,
-2123,
-1295,
-408
};
// 1200Hz = -1dB, 2200Hz = 0dB; 605Hz cutoff; cosine.
q15_t dB1[] = {
-268,
-795,
-1244,
-1546,
31116,
-1546,
-1244,
-795,
-268
};
q15_t dB0[] = {
0,
0,
0,
0,
32767,
0,
0,
0,
0,
};
// 1200Hz = 0dB, 2200Hz = -1dB; 4130Hz cutoff; cosine.
q15_t dB_1[] = {
-419,
-177,
3316,
8650,
11278,
8650,
3316,
-177,
-419
};
// 1200Hz = 0dB, 2200Hz = -2dB; 3190Hz cutoff; cosine.
q15_t dB_2[] = {
-90,
1033,
3975,
7267,
8711,
7267,
3975,
1033,
-90
};
// 1200Hz = 0dB, 2200Hz = -3dB; 2330Hz cutoff; cosine.
q15_t dB_3[] = {
292,
1680,
3752,
5615,
6362,
5615,
3752,
1680,
292
};
// 1200Hz = 0dB, 2200Hz = -4dB; 2657Hz cutoff; boxcar.
q15_t dB_4[] = {
917,
3024,
5131,
6684,
7255,
6684,
5131,
3024,
917
};
// 1200Hz = 0dB, 2200Hz = -5dB; 2360Hz cutoff; boxcar.
q15_t dB_5[] = {
1620,
3339,
4925,
6042,
6444,
6042,
4925,
3339,
1620
};
// 1200Hz = 0dB, 2200Hz = -6dB; 2067Hz cutoff; boxcar.
q15_t dB_6[] = {
2161,
3472,
4605,
5373,
5644,
5373,
4605,
3472,
2161
};
/*
* Generated with Scipy Filter, 152 coefficients, 1100-2300Hz bandpass,
* Hann window, starting and ending 0 value coefficients removed.
*
* np.array(
* firwin2(152,
* [
* 0.0,
* 1000.0/(sample_rate/2),
* 1100.0/(sample_rate/2),
* 2350.0/(sample_rate/2),
* 2500.0/(sample_rate/2),
* 1.0
* ],
* [0,0,1,1,0,0],
* antisymmetric = False,
* window='hann') * 32768,
* dtype=int)[10:-10]
*/
const uint32_t FILTER_LEN = 132;
q15_t FILTER_COEFFS[] = {
0, 5, 12, 18, 21, 19, 11, -2, -15, -25,
-27, -21, -11, -3, -5, -19, -43, -69, -83, -73,
-35, 27, 98, 155, 180, 163, 109, 39, -20, -45,
-26, 23, 74, 89, 39, -81, -247, -407, -501, -480,
-334, -92, 175, 388, 479, 429, 275, 99, 5, 68,
298, 626, 913, 994, 740, 115, -791, -1770, -2544, -2847,
-2509, -1527, -76, 1518, 2875, 3653, 3653, 2875, 1518, -76,
-1527, -2509, -2847, -2544, -1770, -791, 115, 740, 994, 913,
626, 298, 68, 5, 99, 275, 429, 479, 388, 175,
-92, -334, -480, -501, -407, -247, -81, 39, 89, 74,
23, -26, -45, -20, 39, 109, 163, 180, 155, 98,
27, -35, -73, -83, -69, -43, -19, -5, -3, -11,
-21, -27, -25, -15, -2, 11, 19, 21, 18, 12,
5, 0
};
CAX25RX::CAX25RX() :
m_filter(),
m_state(),
m_demod1(dB3, 9U),
m_demod2(dB6, 9U),
m_demod3(dB9, 9U),
m_lastFCS(0U)
{
m_filter.numTaps = FILTER_LEN;
m_filter.pState = m_state;
m_filter.pCoeffs = FILTER_COEFFS;
}
void CAX25RX::samples(q15_t* samples, uint8_t length)
{
q15_t output[RX_BLOCK_SIZE];
::arm_fir_fast_q15(&m_filter, samples, output, RX_BLOCK_SIZE);
m_lastFCS = 0U;
CAX25Frame frame;
bool ret = m_demod1.process(output, length, frame);
if (ret && frame.m_fcs != m_lastFCS) {
DEBUG1("Decoder 1 reported");
m_lastFCS = frame.m_fcs;
serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
}
ret = m_demod2.process(output, length, frame);
if (ret && frame.m_fcs != m_lastFCS) {
DEBUG1("Decoder 2 reported");
m_lastFCS = frame.m_fcs;
serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
}
ret = m_demod3.process(output, length, frame);
if (ret && frame.m_fcs != m_lastFCS) {
DEBUG1("Decoder 3 reported");
m_lastFCS = frame.m_fcs;
serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
}
}