115 lines
4.6 KiB
C
115 lines
4.6 KiB
C
/*---------------------------------------------------------------------------*\
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FILE........: fdmdv.h
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AUTHOR......: David Rowe
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DATE CREATED: April 14 2012
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A 1400 bit/s Frequency Division Multiplexed Digital Voice (FDMDV)
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modem. Used for digital audio over HF SSB. See README_fdmdv.txt for
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more information, and fdmdv_mod.c and fdmdv_demod.c for example
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usage.
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References:
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[1] http://n1su.com/fdmdv/FDMDV_Docs_Rel_1_4b.pdf
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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 2.1, 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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#ifndef __FDMDV__
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#define __FDMDV__
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* set up the calling convention for DLL function import/export for
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WIN32 cross compiling */
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#ifdef __CODEC2_WIN32__
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#ifdef __CODEC2_BUILDING_DLL__
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#define CODEC2_WIN32SUPPORT __declspec(dllexport) __stdcall
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#else
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#define CODEC2_WIN32SUPPORT __declspec(dllimport) __stdcall
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#endif
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#else
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#define CODEC2_WIN32SUPPORT
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#endif
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#include "comp.h"
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#define FDMDV_BITS_PER_FRAME 28 /* 20ms frames, 1400 bit/s */
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#define FDMDV_NOM_SAMPLES_PER_FRAME 160 /* modulator output samples/frame and nominal demod samples/frame */
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/* at 8000 Hz sample rate */
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#define FDMDV_MAX_SAMPLES_PER_FRAME 200 /* max demod samples/frame, use this to allocate storage */
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#define FDMDV_SCALE 1000 /* suggested scaling for 16 bit shorts */
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#define FDMDV_NSYM 15
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#define FDMDV_FCENTRE 1500 /* Centre frequency, Nc/2 carriers below this, Nc/2 carriers above (Hz) */
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/* 8 to 48 kHz sample rate conversion */
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#define FDMDV_OS 6 /* oversampling rate */
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#define FDMDV_OS_TAPS 48 /* number of OS filter taps */
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/* FFT points */
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#define FDMDV_NSPEC 512
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#define FDMDV_MAX_F_HZ 4000
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/* FDMDV states and stats structures */
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struct FDMDV;
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struct FDMDV_STATS {
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float snr_est; /* estimated SNR of rx signal in dB (3 kHz noise BW) */
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COMP rx_symbols[FDMDV_NSYM]; /* latest received symbols, for scatter plot */
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int fest_coarse_fine; /* freq est state, 0-coarse 1-fine */
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float foff; /* estimated freq offset in Hz */
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float rx_timing; /* estimated optimum timing offset in samples */
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float clock_offset; /* Estimated tx/rx sample clock offset in ppm */
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};
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struct FDMDV * CODEC2_WIN32SUPPORT fdmdv_create(void);
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void CODEC2_WIN32SUPPORT fdmdv_destroy(struct FDMDV *fdmdv_state);
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void CODEC2_WIN32SUPPORT fdmdv_mod(struct FDMDV *fdmdv_state, COMP tx_fdm[], int tx_bits[], int *sync_bit);
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void CODEC2_WIN32SUPPORT fdmdv_demod(struct FDMDV *fdmdv_state, int rx_bits[], int *sync_bit, COMP rx_fdm[], int *nin);
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void CODEC2_WIN32SUPPORT fdmdv_get_test_bits(struct FDMDV *fdmdv_state, int tx_bits[]);
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void CODEC2_WIN32SUPPORT fdmdv_put_test_bits(struct FDMDV *f, int *sync, int *bit_errors, int *ntest_bits, int rx_bits[]);
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void CODEC2_WIN32SUPPORT fdmdv_get_demod_stats(struct FDMDV *fdmdv_state, struct FDMDV_STATS *fdmdv_stats);
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void CODEC2_WIN32SUPPORT fdmdv_get_rx_spectrum(struct FDMDV *fdmdv_state, float mag_dB[], COMP rx_fdm[], int nin);
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void CODEC2_WIN32SUPPORT fdmdv_8_to_48(float out48k[], float in8k[], int n);
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void CODEC2_WIN32SUPPORT fdmdv_48_to_8(float out8k[], float in48k[], int n);
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void CODEC2_WIN32SUPPORT fdmdv_freq_shift(COMP rx_fdm_fcorr[], COMP rx_fdm[], float foff, COMP *foff_rect, COMP *foff_phase_rect, int nin);
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/* debug/development function(s) */
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void CODEC2_WIN32SUPPORT fdmdv_dump_osc_mags(struct FDMDV *f);
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#ifdef __cplusplus
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}
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#endif
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#endif
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