196 lines
7.8 KiB
C
196 lines
7.8 KiB
C
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/*---------------------------------------------------------------------------*\
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FILE........: fdmdv_internal.h
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AUTHOR......: David Rowe
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DATE CREATED: April 16 2012
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Header file for FDMDV internal functions, exposed via this header
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file for testing.
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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_INTERNAL__
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#define __FDMDV_INTERNAL__
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#include "comp.h"
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#include "codec2_fdmdv.h"
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#include "codec2_fft.h"
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/*---------------------------------------------------------------------------*\
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DEFINES
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\*---------------------------------------------------------------------------*/
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#ifndef PI
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#define PI 3.141592654
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#endif
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#define FS 8000 /* sample rate in Hz */
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#define T (1.0/FS) /* sample period in seconds */
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#define RS 50 /* symbol rate in Hz */
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#define NC 20 /* max number of data carriers (plus one pilot in the centre) */
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#define NB 2 /* Bits/symbol for QPSK modulation */
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#define RB (NC*RS*NB) /* bit rate */
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#define M_FAC (FS/RS) /* oversampling factor */
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#define NSYM 6 /* number of symbols to filter over */
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#define NFILTER (NSYM*M_FAC) /* size of tx/rx filters at sample rate M */
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#define FSEP 75 /* Default separation between carriers (Hz) */
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#define NT 5 /* number of symbols we estimate timing over */
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#define P 4 /* oversample factor used for initial rx symbol filtering output */
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#define Q (M_FAC/4) /* oversample factor used for initial rx symbol filtering input */
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#define NRXDEC 31 /* number of taps in the rx decimation filter */
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#define NPILOT_LUT (4*M_FAC) /* number of pilot look up table samples */
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#define NPILOTCOEFF 30 /* number of FIR filter coeffs in LP filter */
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#define NPILOTBASEBAND (NPILOTCOEFF+M_FAC+M_FAC/P) /* number of pilot baseband samples reqd for pilot LPF */
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#define NPILOTLPF (4*M_FAC) /* number of samples we DFT pilot over, pilot est window */
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#define MPILOTFFT 256
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#define NSYNC_MEM 6
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#define NRX_FDM_MEM (NFILTER+M_FAC+M_FAC/P) /* size of rx filter memory */
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#define NRXDECMEM (NRXDEC+M_FAC+M_FAC/P) /* size of rx decimation filter memory */
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/* averaging filter coeffs */
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#define TRACK_COEFF 0.5
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#define SNR_COEFF 0.9 /* SNR est averaging filter coeff */
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/*---------------------------------------------------------------------------*\
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STRUCT for States
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\*---------------------------------------------------------------------------*/
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struct FDMDV {
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int Nc;
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float fsep;
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/* test data (test frame) states */
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int ntest_bits;
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int current_test_bit;
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int *rx_test_bits_mem;
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/* Modulator */
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int old_qpsk_mapping;
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int tx_pilot_bit;
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COMP prev_tx_symbols[NC+1];
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COMP tx_filter_memory[NC+1][NSYM];
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COMP phase_tx[NC+1];
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COMP freq[NC+1];
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float freq_pol[NC+1];
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/* Pilot generation at demodulator */
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COMP pilot_lut[NPILOT_LUT];
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int pilot_lut_index;
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int prev_pilot_lut_index;
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/* freq offset estimation states */
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codec2_fft_cfg fft_pilot_cfg;
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COMP pilot_baseband1[NPILOTBASEBAND];
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COMP pilot_baseband2[NPILOTBASEBAND];
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COMP pilot_lpf1[NPILOTLPF];
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COMP pilot_lpf2[NPILOTLPF];
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COMP S1[MPILOTFFT];
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COMP S2[MPILOTFFT];
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/* baseband to low IF carrier states */
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COMP fbb_rect;
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float fbb_pol;
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COMP fbb_phase_tx;
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COMP fbb_phase_rx;
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/* freq offset correction states */
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float foff;
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COMP foff_phase_rect;
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float foff_filt;
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/* Demodulator */
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COMP rxdec_lpf_mem[NRXDECMEM];
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COMP rx_fdm_mem[NRX_FDM_MEM];
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COMP phase_rx[NC+1];
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COMP rx_filter_mem_timing[NC+1][NT*P];
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float rx_timing;
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COMP phase_difference[NC+1];
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COMP prev_rx_symbols[NC+1];
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/* sync state machine */
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int sync_mem[NSYNC_MEM];
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int fest_state;
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int sync;
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int timer;
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/* SNR estimation states */
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float sig_est[NC+1];
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float noise_est[NC+1];
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/* channel simulation */
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float sig_pwr_av;
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};
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/*---------------------------------------------------------------------------*\
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FUNCTION PROTOTYPES
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\*---------------------------------------------------------------------------*/
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void bits_to_dqpsk_symbols(COMP tx_symbols[], int Nc, COMP prev_tx_symbols[], int tx_bits[], int *pilot_bit, int old_qpsk_mapping);
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void tx_filter(COMP tx_baseband[NC+1][M_FAC], int Nc, COMP tx_symbols[], COMP tx_filter_memory[NC+1][NSYM]);
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void fdm_upconvert(COMP tx_fdm[], int Nc, COMP tx_baseband[NC+1][M_FAC], COMP phase_tx[], COMP freq_tx[],
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COMP *fbb_phase, COMP fbb_rect);
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void tx_filter_and_upconvert(COMP tx_fdm[], int Nc, COMP tx_symbols[],
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COMP tx_filter_memory[NC+1][NSYM],
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COMP phase_tx[], COMP freq[], COMP *fbb_phase, COMP fbb_rect);
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void generate_pilot_fdm(COMP *pilot_fdm, int *bit, float *symbol, float *filter_mem, COMP *phase, COMP *freq);
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void generate_pilot_lut(COMP pilot_lut[], COMP *pilot_freq);
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float rx_est_freq_offset(struct FDMDV *f, COMP rx_fdm[], int nin, int do_fft);
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void lpf_peak_pick(float *foff, float *max, COMP pilot_baseband[], COMP pilot_lpf[], codec2_fft_cfg fft_pilot_cfg, COMP S[], int nin, int do_fft);
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void fdm_downconvert(COMP rx_baseband[NC+1][M_FAC+M_FAC/P], int Nc, COMP rx_fdm[], COMP phase_rx[], COMP freq[], int nin);
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void rxdec_filter(COMP rx_fdm_filter[], COMP rx_fdm[], COMP rxdec_lpf_mem[], int nin);
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void rx_filter(COMP rx_filt[NC+1][P+1], int Nc, COMP rx_baseband[NC+1][M_FAC+M_FAC/P], COMP rx_filter_memory[NC+1][NFILTER], int nin);
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void down_convert_and_rx_filter(COMP rx_filt[NC+1][P+1], int Nc, COMP rx_fdm[],
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COMP rx_fdm_mem[], COMP phase_rx[], COMP freq[],
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float freq_pol[], int nin, int dec_rate);
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float rx_est_timing(COMP rx_symbols[], int Nc,
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COMP rx_filt[NC+1][P+1],
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COMP rx_filter_mem_timing[NC+1][NT*P],
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float env[],
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int nin,
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int m);
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float qpsk_to_bits(int rx_bits[], int *sync_bit, int Nc, COMP phase_difference[], COMP prev_rx_symbols[], COMP rx_symbols[], int old_qpsk_mapping);
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void snr_update(float sig_est[], float noise_est[], int Nc, COMP phase_difference[]);
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int freq_state(int *reliable_sync_bit, int sync_bit, int *state, int *timer, int *sync_mem);
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float calc_snr(int Nc, float sig_est[], float noise_est[]);
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#endif
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