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comparison ringing/genring.c @ 9:b875c8edd54f

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ringing: generate North American ringing signal
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 07 Apr 2024 19:05:18 +0000
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8:d5bcfb378049 9:b875c8edd54f
1 /*
2 * This program computes the waveform for the North American precise tone plan
3 * ringing signal, specifically the 2 s long ON phase, and writes it into a
4 * "robe" PCM16 file.
5 */
6
7 #include <math.h>
8 #include <stdio.h>
9 #include <stdint.h>
10 #include <stdlib.h>
11
12 #define FREQ_LOW (M_PI * 440.0 / 4000.0)
13 #define FREQ_HIGH (M_PI * 480.0 / 4000.0)
14
15 #define AMPL_PEAK 2552.329f /* -19 dBm0 */
16
17 #define TOTAL_SAMPLES 16000
18
19 main(argc, argv)
20 char **argv;
21 {
22 FILE *outf;
23 float angle_low, angle_high;
24 unsigned nsamp;
25 int sample;
26 unsigned sample_out;
27
28 if (argc != 2) {
29 fprintf(stderr, "usage: %s outfile\n", argv[0]);
30 exit(1);
31 }
32 outf = fopen(argv[1], "w");
33 if (!outf) {
34 perror(argv[1]);
35 exit(1);
36 }
37 angle_low = 0;
38 angle_high = 0;
39 for (nsamp = 0; nsamp < TOTAL_SAMPLES; nsamp++) {
40 sample = (sinf(angle_low) + sinf(angle_high)) * AMPL_PEAK;
41 sample_out = sample & 0xFFFF;
42 putc(sample_out >> 8, outf);
43 putc(sample_out & 0xFF, outf);
44 angle_low += FREQ_LOW;
45 angle_high += FREQ_HIGH;
46 }
47 exit(0);
48 }