586 lines
16 KiB
C
586 lines
16 KiB
C
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/* implementation of DCF77 transmitter and receiver
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*
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* (C) 2022 by Andreas Eversberg <jolly@eversberg.eu>
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* All Rights Reserved
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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 3 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, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdint.h>
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#include <inttypes.h>
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#include <stdlib.h>
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#include <math.h>
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#include "../libdebug/debug.h"
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#include "dcf77.h"
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double get_time(void);
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#define CARRIER_FREQUENCY 77500
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#define TEST_FREQUENCY 1000
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#define CARRIER_BANDWIDTH 10.0
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#define SAMPLE_CLOCK 1000
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#define CLOCK_1S 1.0
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#define CLOCK_BANDWIDTH 0.1
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#define REDUCTION_FACTOR 0.15
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#define REDUCTION_TH 0.575
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#define TX_LEVEL 0.9
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#define level2db(level) (20 * log10(level))
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static int fast_math = 0;
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static float *sin_tab = NULL, *cos_tab = NULL;
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const char *time_zone[4] = { "???", "CEST", "CET", "???" };
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const char *week_day[8] = { "???", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };
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const char *month_name[13] = { "???", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
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/* global init */
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int dcf77_init(int _fast_math)
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{
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fast_math = _fast_math;
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if (fast_math) {
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int i;
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sin_tab = calloc(65536+16384, sizeof(*sin_tab));
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if (!sin_tab) {
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fprintf(stderr, "No mem!\n");
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return -ENOMEM;
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}
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cos_tab = sin_tab + 16384;
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/* generate sine and cosine */
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for (i = 0; i < 65536+16384; i++)
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sin_tab[i] = sin(2.0 * M_PI * (double)i / 65536.0);
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}
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return 0;
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}
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/* global exit */
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void dcf77_exit(void)
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{
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if (sin_tab) {
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free(sin_tab);
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sin_tab = cos_tab = NULL;
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}
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}
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dcf77_t *dcf77_create(int samplerate, int use_tx, int use_rx, int test_tone)
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{
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dcf77_t *dcf77 = NULL;
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dcf77_tx_t *tx;
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dcf77_rx_t *rx;
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dcf77 = calloc(1, sizeof(*dcf77));
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if (!dcf77) {
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PDEBUG(DDCF77, DEBUG_ERROR, "No mem!\n");
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return NULL;
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}
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tx = &dcf77->tx;
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rx = &dcf77->rx;
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/* measurement */
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display_wave_init(&dcf77->dispwav, (double)samplerate, "DCF77");
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display_measurements_init(&dcf77->dispmeas, samplerate, "DCF77");
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/* prepare tx */
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if (use_tx) {
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tx->enable = 1;
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if (fast_math)
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tx->phase_360 = 65536.0;
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else
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tx->phase_360 = 2.0 * M_PI;
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/* carrier generation */
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tx->carrier_phase_step = tx->phase_360 * (double)CARRIER_FREQUENCY / ((double)samplerate);
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tx->test_phase_step = tx->phase_360 * (double)TEST_FREQUENCY / ((double)samplerate);
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tx->waves_0 = CARRIER_FREQUENCY / 10;
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tx->waves_1 = CARRIER_FREQUENCY / 5;
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tx->waves_sec = CARRIER_FREQUENCY;
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tx->test_tone = test_tone;
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}
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/* prepare rx */
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if (use_rx) {
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rx->enable = 1;
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if (fast_math)
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rx->phase_360 = 65536.0;
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else
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rx->phase_360 = 2.0 * M_PI;
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/* carrier filter */
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rx->carrier_phase_step = rx->phase_360 * (double)CARRIER_FREQUENCY / ((double)samplerate);
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/* use fourth order (2 iter) filter, since it is as fast as second order (1 iter) filter */
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iir_lowpass_init(&rx->carrier_lp[0], CARRIER_BANDWIDTH, (double)samplerate, 2);
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iir_lowpass_init(&rx->carrier_lp[1], CARRIER_BANDWIDTH, (double)samplerate, 2);
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/* signal rate */
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rx->sample_step = (double)SAMPLE_CLOCK / (double)samplerate;
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/* delay buffer */
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rx->delay_size = ceil((double)SAMPLE_CLOCK * 0.1);
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rx->delay_buffer = calloc(rx->delay_size, sizeof(*rx->delay_buffer));
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if (!rx->delay_buffer) {
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PDEBUG(DDCF77, DEBUG_ERROR, "No mem!\n");
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return NULL;
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}
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/* count clock signal */
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rx->clock_count = -1;
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/* measurement parameters */
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dcf77->dmp_input_level = display_measurements_add(&dcf77->dispmeas, "Input Level", "%.0f dB", DISPLAY_MEAS_AVG, DISPLAY_MEAS_LEFT, -100.0, 0.0, -INFINITY);
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dcf77->dmp_signal_level = display_measurements_add(&dcf77->dispmeas, "Signal Level", "%.0f dB", DISPLAY_MEAS_AVG, DISPLAY_MEAS_LEFT, -100.0, 0.0, -INFINITY);
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dcf77->dmp_signal_quality = display_measurements_add(&dcf77->dispmeas, "Signal Qualtiy", "%.0f %%", DISPLAY_MEAS_LAST, DISPLAY_MEAS_LEFT, 0.0, 100.0, -INFINITY);
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}
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if (tx->enable)
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PDEBUG(DDCF77, DEBUG_INFO, "DCF77 transmitter has been created.\n");
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if (rx->enable)
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PDEBUG(DDCF77, DEBUG_INFO, "DCF77 receiver has been created.\n");
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return dcf77;
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}
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void dcf77_destroy(dcf77_t *dcf77)
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{
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if (dcf77) {
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dcf77_rx_t *rx = &dcf77->rx;
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free(rx->delay_buffer);
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free(dcf77);
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}
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PDEBUG(DDCF77, DEBUG_INFO, "DCF77 has been destroyed.\n");
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}
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/* set inital time stamp at the moment the stream starts */
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void dcf77_tx_start(dcf77_t *dcf77, time_t timestamp)
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{
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dcf77_tx_t *tx = &dcf77->tx;
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double now;
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time_t t;
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/* get time stamp */
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if (timestamp < 0)
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now = get_time();
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else
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now = timestamp;
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t = floor(now);
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/* current second within minute */
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tx->second = t % 60;
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/* time stamp of next minute */
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tx->timestamp = t - tx->second + 60;
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/* wave within current second */
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tx->wave = floor(fmod(now, 1.0) * (double)tx->waves_sec);
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/* silence until next second begins */
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tx->symbol = 'm'; tx->level = 0;
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}
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static char tx_symbol(dcf77_t *dcf77, time_t timestamp, int second)
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{
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dcf77_tx_t *tx = &dcf77->tx;
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char symbol;
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/* generate frame */
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if (second == 0 || !tx->data_frame) {
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struct tm *tm;
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int isdst_next_hour, wday, zone;
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uint64_t frame = 0, p;
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timestamp += 3600;
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tm = localtime(×tamp);
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timestamp -= 3600;
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if (!tm) {
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error_tm:
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PDEBUG(DDCF77, DEBUG_ERROR, "Failed to get local time of time stamp!\n");
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return 'm';
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}
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isdst_next_hour = tm->tm_isdst;
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tm = localtime(×tamp);
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if (!tm)
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goto error_tm;
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if (tm->tm_wday > 0)
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wday = tm->tm_wday;
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else
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wday = 7;
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if (tm->tm_isdst > 0)
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zone = 1;
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else
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zone = 2;
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PDEBUG(DDCF77, DEBUG_NOTICE, "The time transmitting: %s %s %d %02d:%02d:00 %s %02d\n", week_day[wday], month_name[tm->tm_mon + 1], tm->tm_mday, tm->tm_hour, tm->tm_min, time_zone[zone], tm->tm_year + 1900);
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if ((tm->tm_isdst > 0) != (isdst_next_hour > 0))
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frame |= (uint64_t)1 << 16;
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if (tm->tm_isdst > 0)
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frame |= (uint64_t)1 << 17;
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else
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frame |= (uint64_t)2 << 17;
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frame |= 1 << 20;
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frame |= (uint64_t)(tm->tm_min % 10) << 21;
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frame |= (uint64_t)(tm->tm_min / 10) << 25;
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p = (frame >> 21) & 0x7f;
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p = p ^ (p >> 4);
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p = p ^ (p >> 2);
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p = p ^ (p >> 1);
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frame |= (uint64_t)(p & 1) << 28;
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frame |= (uint64_t)(tm->tm_hour % 10) << 29;
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frame |= (uint64_t)(tm->tm_hour / 10) << 33;
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p = (frame >> 29) & 0x3f;
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p = p ^ (p >> 4);
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p = p ^ (p >> 2);
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p = p ^ (p >> 1);
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frame |= (uint64_t)(p & 1) << 35;
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frame |= (uint64_t)(tm->tm_mday % 10) << 36;
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frame |= (uint64_t)(tm->tm_mday / 10) << 40;
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frame |= (uint64_t)(wday) << 42;
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frame |= (uint64_t)((tm->tm_mon + 1) % 10) << 45;
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frame |= (uint64_t)((tm->tm_mon + 1) / 10) << 49;
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frame |= (uint64_t)(tm->tm_year % 10) << 50;
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frame |= (uint64_t)((tm->tm_year / 10) % 10) << 54;
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p = (frame >> 36) & 0x3fffff;
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p = p ^ (p >> 16);
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p = p ^ (p >> 8);
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p = p ^ (p >> 4);
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p = p ^ (p >> 2);
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p = p ^ (p >> 1);
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frame |= (uint64_t)(p & 1) << 58;
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tx->data_frame = frame;
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}
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if (second == 59)
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symbol = 'm';
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else symbol = ((tx->data_frame >> second) & 1) + '0';
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PDEBUG(DDSP, DEBUG_DEBUG, "Trasmitting symbol '%c' (Bit %d)\n", symbol, second);
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return symbol;
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}
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void dcf77_encode(dcf77_t *dcf77, sample_t *samples, int length)
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{
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dcf77_tx_t *tx = &dcf77->tx;
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double carrier_phase, test_phase;
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int i;
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if (!tx->enable) {
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memset(samples, 0, sizeof(*samples) * length);
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return;
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}
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carrier_phase = tx->carrier_phase;
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test_phase = tx->test_phase;
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for (i = 0; i < length; i++) {
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if (fast_math)
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samples[i] = sin_tab[(uint16_t)carrier_phase] * tx->level;
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else
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samples[i] = sin(carrier_phase) * tx->level;
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carrier_phase += tx->carrier_phase_step;
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if (carrier_phase >= tx->phase_360) {
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carrier_phase -= tx->phase_360;
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tx->wave++;
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if (tx->wave >= tx->waves_sec) {
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tx->wave -= tx->waves_sec;
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if (++tx->second == 60) {
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tx->second = 0;
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tx->timestamp += 60;
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}
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tx->symbol = tx_symbol(dcf77, tx->timestamp, tx->second);
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}
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switch (tx->symbol) {
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case '0':
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if (tx->wave < tx->waves_0)
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tx->level = TX_LEVEL * REDUCTION_FACTOR;
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else
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tx->level = TX_LEVEL;
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break;
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case '1':
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if (tx->wave < tx->waves_1)
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tx->level = TX_LEVEL * REDUCTION_FACTOR;
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else
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tx->level = TX_LEVEL;
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break;
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case 'm':
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tx->level = TX_LEVEL;
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break;
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}
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if (tx->test_tone)
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tx->level *= 0.9; /* 90 % */
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}
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if (tx->test_tone) {
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if (fast_math)
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samples[i] += sin_tab[(uint16_t)test_phase] * tx->level / 10.0; /* 10 % */
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else
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samples[i] += sin(test_phase) * tx->level / 10.0; /* 10 % */
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if (test_phase >= tx->phase_360)
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test_phase -= tx->phase_360;
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test_phase += tx->test_phase_step;
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}
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}
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tx->carrier_phase = carrier_phase;
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tx->test_phase = test_phase;
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}
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static void rx_frame(uint64_t frame)
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{
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int zone;
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int minute_one, minute_ten, minute = -1;
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int hour_one, hour_ten, hour = -1;
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int day_one, day_ten, day = -1;
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int wday = -1;
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int month_one, month_ten, month = -1;
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int year_one, year_ten, year = -1;
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uint64_t p;
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PDEBUG(DFRAME, DEBUG_INFO, "Bit 0 is '0'? : %s\n", ((frame >> 0) & 1) ? "no" : "yes");
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PDEBUG(DFRAME, DEBUG_INFO, "Bits 1..14 : 0x%04x\n", (int)(frame >> 1) & 0x3fff);
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PDEBUG(DFRAME, DEBUG_INFO, "Call Bit : %d\n", (int)(frame >> 15) & 1);
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PDEBUG(DFRAME, DEBUG_INFO, "Change Time Zone : %s\n", ((frame >> 16) & 1) ? "yes" : "no");
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zone = ((frame >> 17) & 3);
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PDEBUG(DFRAME, DEBUG_INFO, "Time Zone : %s\n", time_zone[zone]);
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PDEBUG(DFRAME, DEBUG_INFO, "Add Leap Second : %s\n", ((frame >> 19) & 1) ? "yes" : "no");
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PDEBUG(DFRAME, DEBUG_INFO, "Bit 20 is '1'? : %s\n", ((frame >> 20) & 1) ? "yes" : "no");
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minute_one = (frame >> 21 & 0xf);
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minute_ten = ((frame >> 25) & 0x7);
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p = (frame >> 21) & 0xff;
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p = p ^ (p >> 4);
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p = p ^ (p >> 2);
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p = p ^ (p >> 1);
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if (minute_one > 9 || minute_ten > 5 || (p & 1))
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PDEBUG(DFRAME, DEBUG_INFO, "Minute : ???\n");
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else {
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minute = minute_ten * 10 + minute_one;
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PDEBUG(DFRAME, DEBUG_INFO, "Minute : %02d\n", minute);
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}
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hour_one = (frame >> 29 & 0xf);
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hour_ten = ((frame >> 33) & 0x3);
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p = (frame >> 29) & 0x7f;
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p = p ^ (p >> 4);
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p = p ^ (p >> 2);
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p = p ^ (p >> 1);
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if (hour_one > 9 || hour_ten > 2 || (hour_ten == 2 && hour_one > 3) || (p & 1))
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PDEBUG(DFRAME, DEBUG_INFO, "Hour : ???\n");
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else {
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hour = hour_ten * 10 + hour_one;
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PDEBUG(DFRAME, DEBUG_INFO, "Hour : %02d\n", hour);
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}
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day_one = (frame >> 36 & 0xf);
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day_ten = ((frame >> 40) & 0x3);
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wday = (frame >> 42 & 0x7);
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month_one = (frame >> 45 & 0xf);
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month_ten = ((frame >> 49) & 0x1);
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year_one = (frame >> 50 & 0xf);
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year_ten = ((frame >> 54) & 0xf);
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p = (frame >> 36) & 0x7fffff;
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p = p ^ (p >> 16);
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p = p ^ (p >> 8);
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p = p ^ (p >> 4);
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p = p ^ (p >> 2);
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p = p ^ (p >> 1);
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if (day_one > 9 || day_ten > 3 || (day_ten == 3 && day_one > 1) || (day_ten == 0 && day_one == 0) || (p & 1))
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PDEBUG(DFRAME, DEBUG_INFO, "Day : ???\n");
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else {
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day = day_ten * 10 + day_one;
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PDEBUG(DFRAME, DEBUG_INFO, "Day : %d\n", day);
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}
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if (wday < 1 || wday > 7 || (p & 1)) {
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PDEBUG(DFRAME, DEBUG_INFO, "Week Day : ???\n");
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wday = -1;
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} else
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PDEBUG(DFRAME, DEBUG_INFO, "Week Day : %s\n", week_day[wday]);
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if (month_one > 9 || month_ten > 1 || (month_ten == 1 && month_one > 2) || (month_ten == 0 && month_one == 0) || (p & 1))
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PDEBUG(DFRAME, DEBUG_INFO, "Month : ???\n");
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else {
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month = month_ten * 10 + month_one;
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PDEBUG(DFRAME, DEBUG_INFO, "Month : %d\n", month);
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}
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if (year_one > 9 || year_ten > 9 || (p & 1))
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PDEBUG(DFRAME, DEBUG_INFO, "Year : ???\n");
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else {
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year = year_ten * 10 + year_one;
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PDEBUG(DFRAME, DEBUG_INFO, "Year : %02d\n", year);
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}
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if (minute >= 0 && hour >= 0 && day >= 0 && wday >= 0 && month >= 0 && year >= 0)
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PDEBUG(DDCF77, DEBUG_NOTICE, "The received time is: %s %s %d %02d:%02d:00 %s 20%02d\n", week_day[wday], month_name[month], day, hour, minute, time_zone[zone], year);
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else
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PDEBUG(DDCF77, DEBUG_NOTICE, "The received time is invalid!\n");
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}
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static void rx_symbol(dcf77_t *dcf77, char symbol)
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{
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dcf77_rx_t *rx = &dcf77->rx;
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PDEBUG(DDSP, DEBUG_DEBUG, "Received symbol '%c'\n", symbol);
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if (!rx->data_receive) {
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if (symbol == 'm') {
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PDEBUG(DDSP, DEBUG_INFO, "Reception of frame has started\n");
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rx->data_receive = 1;
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rx->data_index = 0;
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}
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} else {
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if (symbol == 'm') {
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if (rx->data_index == 59) {
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rx->data_string[rx->data_index] = '\0';
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rx->data_index = 0;
|
|
PDEBUG(DDSP, DEBUG_INFO, "Received complete frame: %s (0x%016" PRIx64 ")\n", rx->data_string, rx->data_frame);
|
|
rx_frame(rx->data_frame);
|
|
} else {
|
|
PDEBUG(DDSP, DEBUG_INFO, "Short read, frame too short\n");
|
|
rx->data_index = 0;
|
|
}
|
|
} else {
|
|
if (rx->data_index == 59) {
|
|
PDEBUG(DDSP, DEBUG_INFO, "Long read, frame too long\n");
|
|
rx->data_receive = 0;
|
|
} else {
|
|
rx->data_string[rx->data_index++] = symbol;
|
|
rx->data_frame >>= 1;
|
|
rx->data_frame |= (uint64_t)(symbol & 1) << 58;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//#define DEBUG_SAMPLE
|
|
|
|
void dcf77_decode(dcf77_t *dcf77, sample_t *samples, int length)
|
|
{
|
|
dcf77_rx_t *rx = &dcf77->rx;
|
|
sample_t I[length], Q[length];
|
|
double phase, level, delayed_level, reduction, quality;
|
|
int i;
|
|
|
|
display_wave(&dcf77->dispwav, samples, length, 1.0);
|
|
|
|
if (!rx->enable)
|
|
return;
|
|
|
|
/* rotate spectrum */
|
|
phase = rx->carrier_phase;
|
|
for (i = 0; i < length; i++) {
|
|
/* mix with carrier frequency */
|
|
if (fast_math) {
|
|
I[i] = cos_tab[(uint16_t)phase] * samples[i];
|
|
Q[i] = sin_tab[(uint16_t)phase] * samples[i];
|
|
} else {
|
|
I[i] = cos(phase) * samples[i];
|
|
Q[i] = sin(phase) * samples[i];
|
|
}
|
|
phase += rx->carrier_phase_step;
|
|
if (phase >= rx->phase_360)
|
|
phase -= rx->phase_360;
|
|
}
|
|
rx->carrier_phase = phase;
|
|
|
|
level = sqrt(I[0] * I[0] + Q[0] * Q[0]);
|
|
if (level > 0.0) // don't average with level of 0.0 (-inf dB)
|
|
display_measurements_update(dcf77->dmp_input_level, level2db(level), 0.0);
|
|
|
|
/* filter carrier */
|
|
iir_process(&rx->carrier_lp[0], I, length);
|
|
iir_process(&rx->carrier_lp[1], Q, length);
|
|
|
|
for (i = 0; i < length; i++) {
|
|
rx->sample_counter += rx->sample_step;
|
|
if (rx->sample_counter >= 1.0) {
|
|
rx->sample_counter -= 1.0;
|
|
/* level */
|
|
level = sqrt(I[i] * I[i] + Q[i] * Q[i]);
|
|
if (level > 0.0) // don't average with level of 0.0 (-inf dB)
|
|
display_measurements_update(dcf77->dmp_signal_level, level2db(level), 0.0);
|
|
|
|
#ifdef DEBUG_SAMPLE
|
|
printf("%s amplitude= %.6f\n", debug_amplitude(level/rx->value_level), level/rx->value_level);
|
|
#endif
|
|
|
|
/* delay sample */
|
|
delayed_level = rx->delay_buffer[rx->delay_index];
|
|
rx->delay_buffer[rx->delay_index] = level;
|
|
if (++rx->delay_index == rx->delay_size)
|
|
rx->delay_index = 0;
|
|
|
|
if (rx->clock_count < 0 || rx->clock_count > 900) {
|
|
if (level / delayed_level < REDUCTION_TH)
|
|
rx->clock_count = 0;
|
|
}
|
|
if (rx->clock_count >= 0) {
|
|
if (rx->clock_count == 0) {
|
|
#ifdef DEBUG_SAMPLE
|
|
puts("got clock");
|
|
#endif
|
|
rx->value_level = delayed_level;
|
|
}
|
|
if (rx->clock_count == 50) {
|
|
#ifdef DEBUG_SAMPLE
|
|
puts("*short*");
|
|
#endif
|
|
rx->value_short = level;
|
|
reduction = rx->value_short / rx->value_level;
|
|
if (reduction < REDUCTION_TH) {
|
|
#ifdef DEBUG_SAMPLE
|
|
printf("reduction is %.3f\n", reduction);
|
|
#endif
|
|
if (reduction < REDUCTION_FACTOR)
|
|
reduction = REDUCTION_FACTOR;
|
|
quality = 1.0 - (reduction - REDUCTION_FACTOR) / (REDUCTION_TH - REDUCTION_FACTOR);
|
|
display_measurements_update(dcf77->dmp_signal_quality, quality * 100.0, 0.0);
|
|
}
|
|
}
|
|
if (rx->clock_count == 150) {
|
|
#ifdef DEBUG_SAMPLE
|
|
puts("*long*");
|
|
#endif
|
|
rx->value_long = level;
|
|
if (rx->value_long / rx->value_level < REDUCTION_TH)
|
|
rx_symbol(dcf77, '1');
|
|
else
|
|
rx_symbol(dcf77, '0');
|
|
}
|
|
if (rx->clock_count == 1100) {
|
|
#ifdef DEBUG_SAMPLE
|
|
puts("*missing clock*");
|
|
#endif
|
|
rx->clock_count = -1;
|
|
rx_symbol(dcf77, 'm');
|
|
}
|
|
}
|
|
if (rx->clock_count >= 0)
|
|
rx->clock_count++;
|
|
|
|
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|