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/*---------------------------------------------------------------------------*\
FILE........: fdmdv_mod.c
AUTHOR......: David Rowe
DATE CREATED: April 28 2012
Given an input file of bits outputs a raw file (8kHz, 16 bit shorts)
of FDMDV modem samples ready to send over a HF radio channel. The
input file is assumed to be arranged as codec frames of 56 bits (7
bytes) which we send as two 28 bit modem frames.
\*---------------------------------------------------------------------------*/
/*
Copyright (C) 2012 David Rowe
All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License version 2.1, as
published by the Free Software Foundation. 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 Lesser General Public License
along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <errno.h>
#include "codec2_fdmdv.h"
int main(int argc, char *argv[])
{
FILE *fin, *fout;
struct FDMDV *fdmdv;
char *packed_bits;
int *tx_bits;
COMP tx_fdm[2*FDMDV_NOM_SAMPLES_PER_FRAME];
short tx_fdm_scaled[2*FDMDV_NOM_SAMPLES_PER_FRAME];
int i, bit, byte;
int sync_bit;
int bits_per_fdmdv_frame;
int bits_per_codec_frame;
int bytes_per_codec_frame;
int Nc;
#ifdef CHANNEL_SIM
COMP foff_phase_rect;
float foff;
#endif
if (argc < 3) {
printf("usage: %s InputBitFile OutputModemRawFile [Nc]\n", argv[0]);
printf("e.g %s hts1a.c2 hts1a_fdmdv.raw\n", argv[0]);
exit(1);
}
if (strcmp(argv[1], "-") == 0) fin = stdin;
else if ( (fin = fopen(argv[1],"rb")) == NULL ) {
fprintf(stderr, "Error opening input bit file: %s: %s.\n",
argv[1], strerror(errno));
exit(1);
}
if (strcmp(argv[2], "-") == 0) fout = stdout;
else if ( (fout = fopen(argv[2],"wb")) == NULL ) {
fprintf(stderr, "Error opening output modem sample file: %s: %s.\n",
argv[2], strerror(errno));
exit(1);
}
if (argc == 4) {
Nc = atoi(argv[3]);
if ((Nc < 2) || (Nc > FDMDV_NC_MAX) ) {
fprintf(stderr, "Error number of carriers must be between 2 and %d\n", FDMDV_NC_MAX);
exit(1);
}
}
else
Nc = FDMDV_NC;
fdmdv = fdmdv_create(Nc);
bits_per_fdmdv_frame = fdmdv_bits_per_frame(fdmdv);
bits_per_codec_frame = 2*fdmdv_bits_per_frame(fdmdv);
bytes_per_codec_frame = (bits_per_codec_frame+7)/8;
packed_bits = (char*)malloc(bytes_per_codec_frame);
assert(packed_bits != NULL);
tx_bits = (int*)malloc(sizeof(int)*bits_per_codec_frame);
assert(tx_bits != NULL);
#ifdef CHANNEL_SIM
foff = -100;
foff_phase_rect.real = 1.0; foff_phase_rect.imag = 0.0;
#endif
while(fread(packed_bits, sizeof(char), bytes_per_codec_frame, fin) == bytes_per_codec_frame) {
/* unpack bits, MSB first */
bit = 7; byte = 0;
for(i=0; i<bits_per_codec_frame; i++) {
tx_bits[i] = (packed_bits[byte] >> bit) & 0x1;
bit--;
if (bit < 0) {
bit = 7;
byte++;
}
}
/* modulate even and odd frames */
fdmdv_mod(fdmdv, tx_fdm, tx_bits, &sync_bit);
assert(sync_bit == 1);
fdmdv_mod(fdmdv, &tx_fdm[FDMDV_NOM_SAMPLES_PER_FRAME], &tx_bits[bits_per_fdmdv_frame], &sync_bit);
assert(sync_bit == 0);
#ifdef CHANNEL_SIM
/* optional freq shift and channel simulation */
fdmdv_freq_shift(tx_fdm, tx_fdm, foff, &foff_phase_rect, 2*FDMDV_NOM_SAMPLES_PER_FRAME);
fdmdv_simulate_channel(&sig_pwr_av, tx_fdm, 2*FDMDV_NOM_SAMPLES_PER_FRAME, 10.0);
#endif
/* scale and save to disk as shorts */
for(i=0; i<2*FDMDV_NOM_SAMPLES_PER_FRAME; i++)
tx_fdm_scaled[i] = FDMDV_SCALE * tx_fdm[i].real;
fwrite(tx_fdm_scaled, sizeof(short), 2*FDMDV_NOM_SAMPLES_PER_FRAME, fout);
/* if this is in a pipeline, we probably don't want the usual
buffering to occur */
if (fout == stdout) fflush(stdout);
}
//fdmdv_dump_osc_mags(fdmdv);
free(tx_bits);
free(packed_bits);
fclose(fin);
fclose(fout);
fdmdv_destroy(fdmdv);
return 0;
}
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