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nicam728.h
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nicam728.h
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/* hacktv - Analogue video transmitter for the HackRF */
/*=======================================================================*/
/* Copyright 2017 Philip Heron <[email protected]> */
/* */
/* This program is free software: you can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation, either version 3 of the License, or */
/* (at your option) any later version. */
/* */
/* 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 General Public License */
/* along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef _NICAM_H
#define _NICAM_H
#include <stdint.h>
#include "common.h"
/* NICAM bit and symbol rates */
#define NICAM_BIT_RATE 728000
#define NICAM_SYMBOL_RATE (NICAM_BIT_RATE / 2)
/* Audio sample rate for NICAM */
#define NICAM_AUDIO_RATE 32000
/* Length of a NICAM frame in bits, bytes and symbols */
#define NICAM_FRAME_BITS 728
#define NICAM_FRAME_BYTES (NICAM_FRAME_BITS / 8)
#define NICAM_FRAME_SYMS (NICAM_FRAME_BITS / 2)
/* Length of a NICAM frame in audio samples */
#define NICAM_AUDIO_LEN (NICAM_AUDIO_RATE / 1000)
/* Frame alignment word (0b01001110) */
#define NICAM_FAW 0x4E
/* Modes of operation */
#define NICAM_MODE_STEREO 0x00 /* Single stereo audio signal */
#define NICAM_MODE_DUAL_MONO 0x02 /* Two independent mono audio signals */
#define NICAM_MODE_MONO_DATA 0x04 /* One mono audio signal and one data channel */
#define NICAM_MODE_DATA 0x06 /* One data channel */
/* Taps in J.17 pre-emphasis filter */
#define _J17_NTAPS 83
typedef struct {
uint8_t mode;
uint8_t reserve;
unsigned int frame;
uint8_t prn[NICAM_FRAME_BYTES - 1];
int fir_p;
int16_t fir_l[_J17_NTAPS];
int16_t fir_r[_J17_NTAPS];
} nicam_enc_t;
typedef struct {
nicam_enc_t enc;
int16_t audio[NICAM_AUDIO_LEN * 2];
int ntaps;
int16_t *taps;
int16_t *hist;
int dsym; /* Differential symbol */
cint16_t *bb;
cint16_t *bb_start;
cint16_t *bb_end;
int bb_len;
int sps;
int ds;
int dsl;
int decimation;
cint16_t *cc;
cint16_t *cc_start;
cint16_t *cc_end;
uint8_t frame[NICAM_FRAME_BYTES];
int frame_bit;
} nicam_mod_t;
extern void nicam_encode_init(nicam_enc_t *s, uint8_t mode, uint8_t reserve);
extern void nicam_encode_frame(nicam_enc_t *s, uint8_t frame[NICAM_FRAME_BYTES], const int16_t audio[NICAM_AUDIO_LEN * 2]);
extern void nicam_encode_mac_packet(nicam_enc_t *s, uint8_t pkt[91], const int16_t audio[NICAM_AUDIO_LEN * 2]);
extern int nicam_mod_init(nicam_mod_t *s, uint8_t mode, uint8_t reserve, unsigned int sample_rate, unsigned int frequency, double beta, double level);
extern void nicam_mod_input(nicam_mod_t *s, const int16_t audio[NICAM_AUDIO_LEN * 2]);
extern int nicam_mod_output(nicam_mod_t *s, int16_t *iq, size_t samples);
extern int nicam_mod_free(nicam_mod_t *s);
#endif