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210 lines
6.7 KiB
C++
210 lines
6.7 KiB
C++
/*---------------------------------------------------------------------------*\
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FILE........: fsk.h
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AUTHOR......: Brady O'Brien
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DATE CREATED: 6 January 2016
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C Implementation of 2FSK/4FSK modulator/demodulator, based on octave/fsk_horus.m
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\*---------------------------------------------------------------------------*/
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/*
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Copyright (C) 2016 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 __C2FSK_H
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#define __C2FSK_H
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#include <stdint.h>
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#include "codec2/comp.h"
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#include "kiss_fftr.h"
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#include "modem_stats.h"
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#define MODE_2FSK 2
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#define MODE_4FSK 4
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#define MODE_M_MAX 4
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#define FSK_SCALE 16383
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namespace FreeDV
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{
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struct FSK {
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/* Static parameters set up by fsk_init */
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int Ndft; /* buffer size for freq offset est fft */
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int Fs; /* sample freq */
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int N; /* processing buffer size */
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int Rs; /* symbol rate */
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int Ts; /* samples per symbol */
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int Nmem; /* size of extra mem for timing adj */
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int P; /* oversample rate for timing est/adj */
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int Nsym; /* Number of symbols spat out in a processing frame */
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int Nbits; /* Number of bits spat out in a processing frame */
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int f1_tx; /* f1 for modulator */
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int fs_tx; /* Space between TX freqs for modulatosr */
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int mode; /* 2FSK or 4FSK */
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int est_min; /* Minimum frequency for freq. estimator */
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int est_max; /* Maximum frequency for freq. estimaotr */
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int est_space; /* Minimum frequency spacing for freq. estimator */
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float* hann_table; /* Precomputed or runtime computed hann window table */
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/* Parameters used by demod */
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COMP phi_c[MODE_M_MAX];
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kiss_fft_cfg fft_cfg; /* Config for KISS FFT, used in freq est */
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float norm_rx_timing; /* Normalized RX timing */
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COMP* samp_old; /* Tail end of last batch of samples */
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int nstash; /* How many elements are in there */
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float* fft_est; /* Freq est FFT magnitude */
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/* Memory used by demod but not important between demod frames */
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/* Parameters used by mod */
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COMP tx_phase_c; /* TX phase, but complex */
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/* Statistics generated by demod */
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float EbNodB; /* Estimated EbNo in dB */
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float f_est[MODE_M_MAX];/* Estimated frequencies */
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float ppm; /* Estimated PPM clock offset */
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/* Parameters used by mod/demod and driving code */
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int nin; /* Number of samples to feed the next demod cycle */
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int burst_mode; /* enables/disables 'burst' mode */
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/* modem statistic struct */
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struct MODEM_STATS *stats;
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int normalise_eye; /* enables/disables normalisation of eye diagram */
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};
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/*
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* Create an FSK config/state struct from a set of config parameters
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*
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* int Fs - Sample frequency
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* int Rs - Symbol rate
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* int tx_f1 - '0' frequency
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* int tx_fs - frequency spacing
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*/
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struct FSK * fsk_create(int Fs, int Rs, int M, int tx_f1, int tx_fs);
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/*
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* Create an FSK config/state struct from a set of config parameters
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*
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* int Fs - Sample frequency
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* int Rs - Symbol rate
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* int tx_f1 - '0' frequency
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* int tx_fs - frequency spacing
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*/
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struct FSK * fsk_create_hbr(int Fs, int Rs, int P, int M, int tx_f1, int tx_fs);
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/*
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* Set a new number of symbols per processing frame
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*/
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void fsk_set_nsym(struct FSK *fsk,int nsym);
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/*
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* Set the minimum and maximum frequencies at which the freq. estimator can find tones
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*/
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void fsk_set_est_limits(struct FSK *fsk,int fmin, int fmax);
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/*
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* Clear the estimator states
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*/
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void fsk_clear_estimators(struct FSK *fsk);
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/*
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* Fills MODEM_STATS struct with demod statistics
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*/
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void fsk_get_demod_stats(struct FSK *fsk, struct MODEM_STATS *stats);
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/*
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* Destroy an FSK state struct and free it's memory
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*
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* struct FSK *fsk - FSK config/state struct to be destroyed
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*/
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void fsk_destroy(struct FSK *fsk);
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/*
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* Modulates Nsym bits into N samples
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*
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* struct FSK *fsk - FSK config/state struct, set up by fsk_create
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* float fsk_out[] - Buffer for N samples of modulated FSK
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* uint8_t tx_bits[] - Buffer containing Nbits unpacked bits
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*/
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void fsk_mod(struct FSK *fsk, float fsk_out[], uint8_t tx_bits[]);
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/*
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* Modulates Nsym bits into N samples
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*
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* struct FSK *fsk - FSK config/state struct, set up by fsk_create
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* float fsk_out[] - Buffer for N samples of "voltage" used to modulate an external VCO
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* uint8_t tx_bits[] - Buffer containing Nbits unpacked bits
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*/
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void fsk_mod_ext_vco(struct FSK *fsk, float vco_out[], uint8_t tx_bits[]);
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/*
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* Modulates Nsym bits into N complex samples
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*
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* struct FSK *fsk - FSK config/state struct, set up by fsk_create
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* comp fsk_out[] - Buffer for N samples of modulated FSK
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* uint8_t tx_bits[] - Buffer containing Nbits unpacked bits
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*/
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void fsk_mod_c(struct FSK *fsk, COMP fsk_out[], uint8_t tx_bits[]);
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/*
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* Returns the number of samples needed for the next fsk_demod() cycle
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*
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* struct FSK *fsk - FSK config/state struct, set up by fsk_create
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* returns - number of samples to be fed into fsk_demod next cycle
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*/
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uint32_t fsk_nin(struct FSK *fsk);
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/*
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* Demodulate some number of FSK samples. The number of samples to be
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* demodulated can be found by calling fsk_nin().
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*
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* struct FSK *fsk - FSK config/state struct, set up by fsk_create
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* uint8_t rx_bits[] - Buffer for Nbits unpacked bits to be written
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* float fsk_in[] - nin samples of modualted FSK
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*/
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void fsk_demod(struct FSK *fsk, uint8_t rx_bits[],COMP fsk_in[]);
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/*
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* Demodulate some number of FSK samples. The number of samples to be
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* demodulated can be found by calling fsk_nin().
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*
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* struct FSK *fsk - FSK config/state struct, set up by fsk_create
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* float rx_bits[] - Buffer for Nbits soft decision bits to be written
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* float fsk_in[] - nin samples of modualted FSK
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*/
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void fsk_demod_sd(struct FSK *fsk, float rx_bits[],COMP fsk_in[]);
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/* enables/disables normalisation of eye diagram samples */
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void fsk_stats_normalise_eye(struct FSK *fsk, int normalise_enable);
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/* Set the FSK modem into burst demod mode */
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void fsk_enable_burst_mode(struct FSK *fsk,int nsyms);
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} // FreeSV
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#endif
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