mirror of
https://github.com/radio95-rnt/fm95.git
synced 2026-02-26 19:23:51 +01:00
dcf77 encoder
This commit is contained in:
2
.vscode/.server-controller-port.log
vendored
2
.vscode/.server-controller-port.log
vendored
@@ -1,5 +1,5 @@
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{
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"port": 13452,
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"time": 1741509228803,
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"time": 1741524942188,
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"version": "0.0.3"
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}
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421
src/dcf95.c
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421
src/dcf95.c
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@@ -0,0 +1,421 @@
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#include <stdio.h>
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#include <stdlib.h>
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#include <getopt.h>
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#include <time.h>
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#include <signal.h>
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#include <string.h>
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#define buffer_maxlength 2048
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#define buffer_tlength_fragsize 2048
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#define buffer_prebuf 32
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#include "../lib/constants.h"
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#include "../lib/oscillator.h"
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#define FREQ 77500.0f // DCF77 frequency is 77.5 kHz
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#define SAMPLE_RATE 192000 // Higher sample rate for the carrier
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#define OUTPUT_DEVICE "alsa_output.platform-soc_sound.stereo-fallback"
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#define BUFFER_SIZE 512
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#include <pulse/simple.h>
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#include <pulse/error.h>
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#define MASTER_VOLUME 0.5f // Volume
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#define OFFSET 0 // Offset in seconds
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// DCF77 specific parameters
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#define PULSE_0_DURATION 100 // 100ms for binary 0
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#define PULSE_1_DURATION 200 // 200ms for binary 1
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#define REDUCED_AMPLITUDE 0.15f // Reduced to 15% of normal amplitude during pulses
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#define BIT_LENGTH 1000 // 1 second per bit
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volatile sig_atomic_t to_run = 1;
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volatile sig_atomic_t transmitting = 0;
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volatile int bit_position = 0;
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volatile int test_mode = 0; // 0 = normal, 1 = test mode
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// DCF77 bits array (59 bits, indexed 0-58)
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volatile int dcf77_bits[60]; // 60th position is for the 1-second pause
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static void stop(int signum) {
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(void)signum;
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printf("\nReceived stop signal.\n");
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to_run = 0;
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}
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int is_timezone_change_soon() {
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time_t now, in_an_hour;
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struct tm local_now, local_later;
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// Get current time
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time(&now);
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local_now = *localtime(&now);
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// Get time an hour from now
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in_an_hour = now + 3600; // 3600 seconds = 1 hour
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local_later = *localtime(&in_an_hour);
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// Return 1 if a time zone change is about to happen, otherwise 0
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return local_now.tm_isdst != local_later.tm_isdst;
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}
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// Function to calculate DCF77 bits based on current time
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void calculate_dcf77_bits(time_t now, int *bits) {
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struct tm *t = localtime(&now); // Use local time instead of UTC
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// Initialize all bits to 0
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memset(bits, 0, 60 * sizeof(int));
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//bit[15] = 0; // Helper antenna
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bits[16] = is_timezone_change_soon();
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if(t->tm_isdst) {
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bits[17] = 1;
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} else {
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bits[18] = 1;
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}
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bits[20] = 1;
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// Bits 20-27: Minutes (BCD encoded)
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int minutes = t->tm_min;
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bits[21] = (minutes % 10) & 0x01;
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bits[22] = ((minutes % 10) >> 1) & 0x01;
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bits[23] = ((minutes % 10) >> 2) & 0x01;
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bits[24] = ((minutes % 10) >> 3) & 0x01;
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bits[25] = ((minutes / 10) & 0x01);
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bits[26] = ((minutes / 10) >> 1) & 0x01;
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bits[27] = ((minutes / 10) >> 2) & 0x01;
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// Bit 28: Even parity for minutes
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int parity = 0;
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for (int i = 21; i <= 27; i++) {
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parity ^= bits[i];
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}
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bits[28] = parity;
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// Bits 29-34: Hours (BCD encoded)
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int hours = t->tm_hour;
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bits[29] = (hours % 10) & 0x01;
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bits[30] = ((hours % 10) >> 1) & 0x01;
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bits[31] = ((hours % 10) >> 2) & 0x01;
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bits[32] = ((hours % 10) >> 3) & 0x01;
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bits[33] = ((hours / 10) & 0x01);
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bits[34] = ((hours / 10) >> 1) & 0x01;
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// Bit 35: Even parity for hours
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parity = 0;
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for (int i = 29; i <= 34; i++) {
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parity ^= bits[i];
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}
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bits[35] = parity;
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// Bits 36-41: Day of month (1-31, BCD encoded)
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int day = t->tm_mday;
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bits[36] = (day % 10) & 0x01;
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bits[37] = ((day % 10) >> 1) & 0x01;
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bits[38] = ((day % 10) >> 2) & 0x01;
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bits[39] = ((day % 10) >> 3) & 0x01;
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bits[40] = ((day / 10) & 0x01);
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bits[41] = ((day / 10) >> 1) & 0x01;
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// Bits 42-44: Day of week (1=Monday, 7=Sunday)
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int dow = t->tm_wday == 0 ? 7 : t->tm_wday; // Convert Sunday from 0 to 7
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bits[42] = dow & 0x01;
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bits[43] = (dow >> 1) & 0x01;
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bits[44] = (dow >> 2) & 0x01;
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// Bits 45-49: Month (1-12, BCD encoded)
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int month = t->tm_mon + 1; // tm_mon is 0-11
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bits[45] = (month % 10) & 0x01;
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bits[46] = ((month % 10) >> 1) & 0x01;
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bits[47] = ((month % 10) >> 2) & 0x01;
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bits[48] = ((month % 10) >> 3) & 0x01;
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bits[49] = (month / 10) & 0x01;
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// Bits 50-57: Year within century (0-99, BCD encoded)
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int year = t->tm_year % 100; // Get last two digits of year
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bits[50] = (year % 10) & 0x01;
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bits[51] = ((year % 10) >> 1) & 0x01;
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bits[52] = ((year % 10) >> 2) & 0x01;
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bits[53] = ((year % 10) >> 3) & 0x01;
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bits[54] = ((year / 10) & 0x01);
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bits[55] = ((year / 10) >> 1) & 0x01;
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bits[56] = ((year / 10) >> 2) & 0x01;
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bits[57] = ((year / 10) >> 3) & 0x01;
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// Bit 58: Even parity for date bits
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parity = 0;
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for (int i = 36; i <= 57; i++) {
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parity ^= bits[i];
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}
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bits[58] = parity;
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// Bit 59: Always 0 (no pulse during minute marker)
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bits[59] = 0;
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}
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// Print the current DCF77 bit pattern (for debugging)
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void print_dcf77_bits(const int *bits) {
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printf("DCF77 Bit Pattern: ");
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for (int i = 0; i < 60; i++) {
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printf("%d", bits[i]);
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if ((i+1) % 10 == 0) printf(" "); // Space every 10 bits
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}
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printf("\n");
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}
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void show_version() {
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printf("dcf95 (DCF77 time signal encoder by radio95) version 1.0\n");
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}
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void show_help(char *name) {
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printf(
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"Usage: %s\n"
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" -o,--output Override output device [default: %s]\n"
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" -F,--frequency DCF77 Frequency [default: %.1f Hz]\n"
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" -s,--samplerate Output Samplerate [default: %d]\n"
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" -v,--volume Output volume [default: %.2f]\n"
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" -t,--offset Time Offset [default: %d s]\n"
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" -T,--test Enable test mode (continuously generates signal)\n"
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,name
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,OUTPUT_DEVICE
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,FREQ
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,SAMPLE_RATE
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,MASTER_VOLUME
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,OFFSET
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);
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}
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int main(int argc, char **argv) {
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show_version();
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pa_simple *output_device;
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char audio_output_device[64] = OUTPUT_DEVICE;
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float master_volume = MASTER_VOLUME;
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float freq = FREQ;
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int sample_rate = SAMPLE_RATE;
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int offset = OFFSET;
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int test_mode = 0; // Test mode flag
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// #region Parse Arguments
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int opt;
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const char *short_opt = "o:F:s:v:t:Th";
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struct option long_opt[] =
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{
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{"output", required_argument, NULL, 'o'},
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{"frequency", required_argument, NULL, 'F'},
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{"samplerate", required_argument, NULL, 's'},
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{"volume", required_argument, NULL, 'v'},
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{"offset", required_argument, NULL, 't'},
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{"test", no_argument, NULL, 'T'},
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{"help", no_argument, NULL, 'h'},
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{0, 0, 0, 0}
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};
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while((opt = getopt_long(argc, argv, short_opt, long_opt, NULL)) != -1) {
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switch(opt) {
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case 'o': // Output Device
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memcpy(audio_output_device, optarg, 63);
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audio_output_device[63] = '\0'; // Ensure null-termination
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break;
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case 'F': // Frequency
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freq = strtof(optarg, NULL);
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break;
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case 's': // Sample rate
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sample_rate = strtol(optarg, NULL, 10);
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break;
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case 'v': // Volume
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master_volume = strtof(optarg, NULL);
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break;
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case 't': // Offset
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offset = strtol(optarg, NULL, 10);
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break;
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case 'T': // Test mode
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test_mode = 1;
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break;
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case 'h':
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show_help(argv[0]);
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return 0;
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}
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}
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// #endregion
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if(test_mode) {
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time_t now = time(NULL) + offset;
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calculate_dcf77_bits(now, (int *)dcf77_bits);
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print_dcf77_bits((int *)dcf77_bits);
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return 0;
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}
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printf("Configuration:\n");
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printf(" Output device: %s\n", audio_output_device);
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printf(" Frequency: %.1f Hz\n", freq);
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printf(" Sample rate: %d Hz\n", sample_rate);
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printf(" Volume: %.2f\n", master_volume);
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printf(" Time offset: %d seconds\n", offset);
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// #region Setup devices
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pa_sample_spec mono_format = {
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.format = PA_SAMPLE_FLOAT32NE,
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.channels = 1,
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.rate = sample_rate
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};
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pa_buffer_attr input_buffer_atr = {
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.maxlength = buffer_maxlength,
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.fragsize = buffer_tlength_fragsize
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};
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pa_buffer_attr output_buffer_atr = {
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.maxlength = buffer_maxlength,
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.tlength = buffer_tlength_fragsize,
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.prebuf = buffer_prebuf
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};
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int opentime_pulse_error;
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printf("Connecting to output device... (%s)\n", audio_output_device);
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output_device = pa_simple_new(
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NULL,
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"dcf95",
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PA_STREAM_PLAYBACK,
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audio_output_device,
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"DCF77 Output",
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&mono_format,
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NULL,
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&output_buffer_atr,
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&opentime_pulse_error
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);
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if (!output_device) {
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fprintf(stderr, "Error: cannot open output device: %s\n", pa_strerror(opentime_pulse_error));
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return 1;
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}
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// #endregion
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// #region Setup Oscillator
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Oscillator osc;
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init_oscillator(&osc, freq, sample_rate);
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// #endregion
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signal(SIGINT, stop);
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signal(SIGTERM, stop);
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int pulse_error;
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float output[BUFFER_SIZE]; // Output buffer
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// DCF77 parameters
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int elapsed_samples = 0;
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int current_second = -1;
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int ms_within_second = 0;
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int last_bit = -1;
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// Pre-calculate samples for different durations
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int bit_samples = (int)((BIT_LENGTH / 1000.0) * sample_rate);
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int pulse_0_samples = (int)((PULSE_0_DURATION / 1000.0) * sample_rate);
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int pulse_1_samples = (int)((PULSE_1_DURATION / 1000.0) * sample_rate);
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printf("DCF77 encoder ready.\n");
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printf("Will transmit time signal continuously.\n");
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// Main loop
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while (to_run) {
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// Clear the output buffer
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memset(output, 0, sizeof(output));
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// Get current time
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time_t now = time(NULL) + offset;
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struct tm *t = gmtime(&now);
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int second = t->tm_sec;
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// Check if we're at the start of a new minute
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if (second == 0 && current_second != 0) {
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// Calculate the DCF77 bits for the new minute
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calculate_dcf77_bits(now, (int *)dcf77_bits);
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print_dcf77_bits((int *)dcf77_bits);
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// Reset counters for the new minute
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bit_position = 0;
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elapsed_samples = 0;
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transmitting = 1;
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printf("Starting new DCF77 transmission for %02d:%02d:%02d UTC\n",
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t->tm_hour, t->tm_min, t->tm_sec);
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}
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// Update the current second if it has changed
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if (second != current_second) {
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current_second = second;
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// Update the bit position at the start of each second
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if (transmitting) {
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if (bit_position < 59) {
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printf("Bit %2d: %d\n", bit_position, dcf77_bits[bit_position]);
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bit_position++;
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} else {
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// End of minute (59 bits + 1 second pause)
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bit_position = 0;
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printf("End of minute, restarting bit sequence.\n");
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}
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}
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// Reset sample counter at the start of each second
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elapsed_samples = 0;
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}
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// Generate the DCF77 signal
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for (int i = 0; i < BUFFER_SIZE; i++) {
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// Get base carrier signal
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float carrier = get_oscillator_sin_sample(&osc);
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// Process in test mode or normal mode
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if (test_mode) {
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// In test mode, generate a repeating pattern regardless of time
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int cycle_position = elapsed_samples % bit_samples;
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int test_bit = (elapsed_samples / bit_samples) % 2; // Alternate 0 and 1
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if ((test_bit == 0 && cycle_position < pulse_0_samples) ||
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(test_bit == 1 && cycle_position < pulse_1_samples)) {
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// Reduced amplitude during pulse
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output[i] = carrier * master_volume * REDUCED_AMPLITUDE;
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} else {
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// Full amplitude otherwise
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output[i] = carrier * master_volume;
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}
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} else if (transmitting) {
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// Calculate milliseconds within the current second
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ms_within_second = (int)((elapsed_samples * 1000.0) / sample_rate);
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// Get the current bit (between 0-58)
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int current_bit = bit_position > 0 ? bit_position - 1 : 59;
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// Determine if we should output reduced amplitude
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if ((dcf77_bits[current_bit] == 0 && ms_within_second < PULSE_0_DURATION) ||
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(dcf77_bits[current_bit] == 1 && ms_within_second < PULSE_1_DURATION)) {
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// Reduced amplitude during pulse
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output[i] = carrier * master_volume * REDUCED_AMPLITUDE;
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} else {
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// Full amplitude otherwise
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output[i] = carrier * master_volume;
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}
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} else {
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// Not transmitting (should not happen in normal operation)
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output[i] = carrier * master_volume;
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}
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elapsed_samples++;
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}
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// Output the audio buffer
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if (pa_simple_write(output_device, output, sizeof(output), &pulse_error) < 0) {
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fprintf(stderr, "Error writing to output device: %s\n", pa_strerror(pulse_error));
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to_run = 0;
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break;
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}
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}
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printf("Cleaning up...\n");
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pa_simple_free(output_device);
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return 0;
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}
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