125 lines
3.7 KiB
C
125 lines
3.7 KiB
C
/*---------------------------------------------------------------------------*\
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FILE........: fdmdv_mod.c
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AUTHOR......: David Rowe
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DATE CREATED: April 28 2012
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Given an input file of bits outputs a raw file (8kHz, 16 bit shorts)
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of FDMDV modem samples ready to send over a HF radio channel. The
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input file is assumed to be arranged as codec frames of 56 bits (7
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bytes) which we send as two 28 bit modem frames.
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\*---------------------------------------------------------------------------*/
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/*
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Copyright (C) 2012 David Rowe
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All rights reserved.
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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 Lesser General Public License version 2, as
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published by the Free Software Foundation. This program is
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distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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License for more details.
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You should have received a copy of the GNU Lesser 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 <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include <errno.h>
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#include "fdmdv.h"
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#define BITS_PER_CODEC_FRAME (2*FDMDV_BITS_PER_FRAME)
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#define BYTES_PER_CODEC_FRAME (BITS_PER_CODEC_FRAME/8)
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int main(int argc, char *argv[])
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{
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FILE *fin, *fout;
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struct FDMDV *fdmdv;
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char packed_bits[BYTES_PER_CODEC_FRAME];
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int tx_bits[2*FDMDV_BITS_PER_FRAME];
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COMP tx_fdm[2*FDMDV_NOM_SAMPLES_PER_FRAME];
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short tx_fdm_scaled[2*FDMDV_NOM_SAMPLES_PER_FRAME];
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int frames;
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int i, bit, byte;
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int sync_bit;
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if (argc < 3) {
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printf("usage: %s InputBitFile OutputModemRawFile\n", argv[0]);
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printf("e.g %s hts1a.c2 hts1a_fdmdv.raw\n", argv[0]);
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exit(1);
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}
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if (strcmp(argv[1], "-") == 0) fin = stdin;
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else if ( (fin = fopen(argv[1],"rb")) == NULL ) {
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fprintf(stderr, "Error opening input bit file: %s: %s.\n",
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argv[1], strerror(errno));
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exit(1);
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}
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if (strcmp(argv[2], "-") == 0) fout = stdout;
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else if ( (fout = fopen(argv[2],"wb")) == NULL ) {
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fprintf(stderr, "Error opening output modem sample file: %s: %s.\n",
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argv[2], strerror(errno));
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exit(1);
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}
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fdmdv = fdmdv_create();
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frames = 0;
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while(fread(packed_bits, sizeof(char), BYTES_PER_CODEC_FRAME, fin) == BYTES_PER_CODEC_FRAME) {
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frames++;
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/* unpack bits, MSB first */
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bit = 7; byte = 0;
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for(i=0; i<BITS_PER_CODEC_FRAME; i++) {
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tx_bits[i] = (packed_bits[byte] >> bit) & 0x1;
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bit--;
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if (bit < 0) {
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bit = 7;
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byte++;
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}
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}
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assert(byte == BYTES_PER_CODEC_FRAME);
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/* modulate even and odd frames */
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fdmdv_mod(fdmdv, tx_fdm, tx_bits, &sync_bit);
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assert(sync_bit == 1);
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fdmdv_mod(fdmdv, &tx_fdm[FDMDV_NOM_SAMPLES_PER_FRAME], &tx_bits[FDMDV_BITS_PER_FRAME], &sync_bit);
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assert(sync_bit == 0);
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/* scale and save to disk as shorts */
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for(i=0; i<2*FDMDV_NOM_SAMPLES_PER_FRAME; i++)
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tx_fdm_scaled[i] = FDMDV_SCALE * tx_fdm[i].real;
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fwrite(tx_fdm_scaled, sizeof(short), 2*FDMDV_NOM_SAMPLES_PER_FRAME, fout);
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/* if this is in a pipeline, we probably don't want the usual
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buffering to occur */
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if (fout == stdout) fflush(stdout);
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if (fin == stdin) fflush(stdin);
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}
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//fdmdv_dump_osc_mags(fdmdv);
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fclose(fin);
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fclose(fout);
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fdmdv_destroy(fdmdv);
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return 0;
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}
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