kopia lustrzana https://github.com/amedes/pico_tnc
215 wiersze
5.6 KiB
C
215 wiersze
5.6 KiB
C
/*
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Copyright (c) 2021, Kazuhisa Yokota, JN1DFF
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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* Neither the name of the <organization> nor the names of its contributors
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may be used to endorse or promote products derived from this software
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without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <math.h>
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//#include "timer.h"
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#include "filter.h"
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#include "tnc.h"
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int bell202_decode(tnc_t *tp, int adc)
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{
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int m;
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int sum;
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int val;
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//fprintf(stderr,"adc = %d\n");
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//val = input_bpf(adc);
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// Bandpass filter
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val = filter(&tp->bpf, adc) >> ADC_BIT;
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//val = adc;
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//printf("val = %d\n", val);
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m = val * tp->delayed[tp->delay_idx];
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//printf("val = %d, m = %d\n", val, m);
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//printf("%d\n", m);
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tp->delayed[tp->delay_idx] = val;
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if (++tp->delay_idx >= DELAYED_N) tp->delay_idx = 0;
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#if 0
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x[x_idx] = m >> 12;
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sum = 0;
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for (i = 0; i < FIR_LPF_N; i++) {
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sum += an[i] * x[(x_idx + i) % FIR_LPF_N];
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#if 0
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if (sum > (1 << 30)) printf("%d,", sum);
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else
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if (sum < -(1 << 30)) printf("%d,", sum);
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#endif
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}
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x_idx += FIR_LPF_N - 1;
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x_idx %= FIR_LPF_N;
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//printf("%d, %d, %d\n", adc, m >> 8, sum >> 8);
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#else
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sum = filter(&tp->lpf, m >> 16);
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//printf("%d, %d, %d, %d\n", adc, val, m, sum);
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#endif
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#ifdef LPF_FLOAT
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return sum * 65536;
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#else
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return sum;
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#endif
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}
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#ifdef BELL202_SYNC
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#define LOW_N SAMPLING_N
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#define HIGH_N (LOW_N * 6 / 11)
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static int16_t low_i_tab[LOW_N];
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static int16_t low_q_tab[LOW_N];
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static int16_t high_i_tab[HIGH_N];
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static int16_t high_q_tab[HIGH_N];
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static const int16_t low_tab[LOW_N] = {
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-15704,
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2338,
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19637,
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30701,
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32018,
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23170,
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6965,
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-11451,
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-26231,
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-32684,
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-28759,
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};
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static const int16_t high_tab[HIGH_N + 1] = {
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23170,
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-8481,
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-31650,
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-23170,
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8481,
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31650,
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23170,
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};
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// Synch decode
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int bell202_decode2(tnc_t *tp, int adc)
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{
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int m;
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int sum;
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int val;
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int i;
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values_t *vp;
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// Band pass filter
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#if ADC_BIT == 8
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//val = filter(&tp->bpf, adc) >> 8;
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val = filter(&tp->bpf, adc) >> 12;
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#else
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val = filter(&tp->bpf, adc) >> 12;
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#endif
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//printf("val = %d\n", val);
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vp = &tp->values[tp->values_idx];
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// subtract old values
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tp->sum_low_i -= vp->low_i;
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tp->sum_low_q -= vp->low_q;
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tp->sum_high_i -= vp->high_i;
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tp->sum_high_q -= vp->high_q;
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// add new values
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#if 0
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tp->sum_low_i += (vp->low_i = val * low_i_tab[tp->low_idx]);
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tp->sum_low_q += (vp->low_q = val * low_q_tab[tp->low_idx]);
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tp->sum_high_i += (vp->high_i = val * high_i_tab[tp->high_idx]);
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tp->sum_high_q += (vp->high_q = val * high_q_tab[tp->high_idx]);
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#endif
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tp->sum_low_i += (vp->low_i = val * low_tab[tp->low_idx]);
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tp->sum_low_q += (vp->low_q = val * low_tab[LOW_N - 1 - tp->low_idx]);
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tp->sum_high_i += (vp->high_i = val * high_tab[tp->high_idx]);
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tp->sum_high_q += (vp->high_q = val * high_tab[HIGH_N - tp->high_idx]);
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int sqr_li = tp->sum_low_i >> 16;
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int sqr_lq = tp->sum_low_q >> 16;
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int sqr_hi = tp->sum_high_i >> 16;
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int sqr_hq = tp->sum_high_q >> 16;
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// compare
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m = (sqr_li * sqr_li + sqr_lq * sqr_lq)
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- (sqr_hi * sqr_hi + sqr_hq * sqr_hq);
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// low pass filter
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sum = filter(&tp->lpf, m >> 16);
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//printf("%d, %d, %d, %d\n", adc, val, m, sum);
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// advance indexes
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if (++tp->values_idx >= SAMPLING_N) tp->values_idx = 0;
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if (++tp->low_idx >= LOW_N) tp->low_idx = 0;
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if (++tp->high_idx >= HIGH_N) tp->high_idx = 0;
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return sum;
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}
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#endif // BELL202_SYNC
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void bell202_init(void)
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{
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#ifdef BELL202_SYNC
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// initialize sin, cos table
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int i;
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#define AMP 32767
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//printf("bell202: I/Q tables\n");
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for (i = 0; i < LOW_N; i++) {
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float t = M_PI * 2 * i / LOW_N + M_PI / 4;
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low_i_tab[i] = cosf(t) * AMP + 0.5;
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low_q_tab[i] = sinf(t) * AMP + 0.5;
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printf("%d, %d, ", low_i_tab[i], low_q_tab[i]);
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if (i < HIGH_N) {
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t = M_PI * 2 * i / HIGH_N + M_PI / 4;
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high_i_tab[i] = cosf(t) * AMP + 0.5;
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high_q_tab[i] = sinf(t) * AMP + 0.5;
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//printf("%d, %d, ", high_i_tab[i], high_q_tab[i]);
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}
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//printf("\n");
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}
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#endif
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}
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