111 lines
3.5 KiB
C
111 lines
3.5 KiB
C
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/*---------------------------------------------------------------------------*\
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FILE........: fmfsk.h
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AUTHOR......: Brady O'Brien
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DATE CREATED: 6 February 2016
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C Implementation of 2FSK+Manchester over FM modulator/demodulator, based
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on mancyfsk.m and fmfsk.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 __C2FMFSK_H
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#define __C2FMFSK_H
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#include <stdint.h>
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#include "comp.h"
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#include "modem_stats.h"
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#define FMFSK_SCALE 16383
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/*
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* fm-me-2fsk state
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*/
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struct FMFSK{
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/* Static fmfsk parameters */
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int Rb; /* Manchester-encoded bitrate */
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int Rs; /* Raw modem symbol rate */
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int Fs; /* Sample rate */
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int Ts; /* Samples-per-symbol */
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int N; /* Sample processing buffer size */
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int nsym; /* Number of raw modem symbols processed per demod call */
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int nbit; /* Number of bits spit out per demod call */
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int nmem; /* Number of samples kept around between demod calls */
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/* State kept by demod */
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int nin; /* Number of samples to be demod-ed the next cycle */
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int lodd; /* Last integrated sample for odd bitstream generation */
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float * oldsamps; /* Memory of old samples to make clock-offset-tolerance possible */
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/* Stats generated by demod */
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float norm_rx_timing; /* RX Timing, used to calculate clock offset */
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int ppm; /* Clock offset in parts-per-million */
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float snr_mean;
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/* Modem stat structure */
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struct MODEM_STATS * stats;
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};
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/*
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* Create a new fmfsk modem instance.
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*
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* int Fs - sample rate
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* int Rb - non-manchester bitrate
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* returns - new struct FMFSK on sucess, NULL on failure
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*/
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struct FMFSK * fmfsk_create(int Fs,int Rb);
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/*
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* Destroys an fmfsk modem and deallocates memory
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*/
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void fmfsk_destroy(struct FMFSK *fmfsk);
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/*
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* Deposit demod statistics into a MODEM_STATS struct
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*/
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void fmfsk_get_demod_stats(struct FMFSK *fmfsk,struct MODEM_STATS *stats);
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/*
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* Returns the number of samples that must be fed to fmfsk_demod the next
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* cycle
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*/
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uint32_t fmfsk_nin(struct FMFSK *fmfsk);
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/*
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* Modulates nbit bits into N samples to be sent through an FM radio
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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 mod_out[] - Buffer for N samples of modulated FMFSK
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* uint8_t tx_bits[] - Buffer containing Nbits unpacked bits
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*/
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void fmfsk_mod(struct FMFSK *fmfsk, float fmfsk_out[],uint8_t bits_in[]);
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/*
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* Demodulate some number of FMFSK samples. The number of samples to be
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* demodulated can be found by calling fmfsk_nin().
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*
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* struct FMFSK *fsk - FMFSK config/state struct, set up by fsk_create
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* uint8_t rx_bits[] - Buffer for nbit unpacked bits to be written
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* float fsk_in[] - nin samples of modualted FMFSK from an FM radio
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*/
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void fmfsk_demod(struct FMFSK *fmfsk, uint8_t rx_bits[],float fmfsk_in[]);
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#endif
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