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vicliu
278 lines
9.6 KiB
C
278 lines
9.6 KiB
C
/*---------------------------------------------------------------------------*\
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FILE........: ofdm_internal.h
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AUTHORS.....: David Rowe & Steve Sampson
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DATE CREATED: June 2017
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OFDM Internal definitions.
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\*---------------------------------------------------------------------------*/
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/*
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Copyright (C) 2017 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 OFDM_INTERNAL_H
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#define OFDM_INTERNAL_H
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#include <complex.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include "codec2_ofdm.h"
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#include "filter.h"
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#ifdef __cplusplus
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extern "C"
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{
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#endif
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#ifndef M_PI
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#define M_PI 3.14159265358979323846f
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#endif
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#define TAU (2.0f * M_PI)
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#define ROT45 (M_PI / 4.0f)
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#define MAX_UW_BITS 64
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#define cmplx(value) (cosf(value) + sinf(value) * I)
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#define cmplxconj(value) (cosf(value) + sinf(value) * -I)
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/* modem state machine states */
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typedef enum {
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search,
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trial,
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synced
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} State;
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typedef enum {
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unsync, /* force sync state machine to lose sync, and search for new sync */
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autosync, /* falls out of sync automatically */
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manualsync /* fall out of sync only under operator control */
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} Sync;
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/* phase estimator bandwidth options */
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typedef enum {
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low_bw, /* can only track a narrow freq offset, but accurate */
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high_bw /* can track wider freq offset, but less accurate at low SNR */
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} PhaseEstBandwidth;
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/*
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* User-defined configuration for OFDM modem. Used to set up
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* constants at init time, e.g. for different bit rate modems.
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*/
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struct OFDM_CONFIG {
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float tx_centre; /* TX Centre Audio Frequency */
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float rx_centre; /* RX Centre Audio Frequency */
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float fs; /* Sample Frequency */
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float rs; /* Symbol Rate */
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float ts; /* symbol duration */
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float tcp; /* Cyclic Prefix duration */
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float timing_mx_thresh;
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int nc; /* Number of carriers */
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int ns; /* Number of Symbol frames */
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int np; /* number of modem frames per packet */
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int bps; /* Bits per Symbol */
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int txtbits; /* number of auxiliary data bits */
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int nuwbits; /* number of unique word bits */
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int bad_uw_errors;
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int ftwindowwidth;
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int edge_pilots;
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char *state_machine; /* name of sync state machine used for this mode */
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char *codename; /* name of LDPC code used with this mode */
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uint8_t tx_uw[MAX_UW_BITS]; /* user defined unique word */
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int amp_est_mode;
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bool tx_bpf_en; /* default tx (mod) hilbert clipper BPF enable */
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bool rx_bpf_en; /* default rx (demod) input BPF enable */
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bool foff_limiter; /* tames freq offset updates in low SNR */
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float amp_scale; /* used to scale Tx waveform to approx FREEDV_PEAK with clipper off */
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float clip_gain1; /* gain we apply to Tx signal before clipping to control PAPR*/
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float clip_gain2; /* gain we apply to Tx signal after clipping and BBF to control peak level */
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bool clip_en;
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char mode[16]; /* OFDM mode in string form */
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char *data_mode;
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float fmin;
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float fmax;
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};
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struct OFDM {
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struct OFDM_CONFIG config;
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char mode[16]; /* mode in string form */
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/*
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* See 700D Part 4 Acquisition blog post and ofdm_dev.m routines
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* for how this was set
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*/
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float timing_mx_thresh;
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int nc;
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int ns; /* NS-1 = data symbols between pilots */
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int bps; /* Bits per symbol */
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int m; /* duration of each symbol in samples */
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int ncp; /* duration of CP in samples */
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int np; /* number of modem frames per packet. In some modes we want */
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/* the total packet of data to span multiple modem frames, e.g. HF data */
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/* and/or when the FEC codeword is larger than the one */
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/* modem frame. In other modes (e.g. 700D/2020) Np=1, ie the modem frame */
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/* is the same length as the packet/FEC frame. */
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int ftwindowwidth;
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int bitsperframe; /* total bits in all data symbols in modem frame */
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int bitsperpacket; /* total bits in all data symbols in a packet */
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int rowsperframe;
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int samplespersymbol;
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int samplesperframe;
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int nrxbufhistory; /* extra storage at start of rxbuf to allow us to step back in time */
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int nrxbufmin; /* min number of samples we need in rxbuf to process a modem frame */
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int rxbufst; /* start of rxbuf window used for demod of current rx frame */
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int pre, post; /* pre-amble and post-amble detections */
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int max_samplesperframe;
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int nuwframes;
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int nrxbuf;
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int ntxtbits; /* reserve bits/frame for aux text information */
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int nuwbits; /* number of unique word bits used to achieve packet frame sync */
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int bad_uw_errors; /* threshold for UW detection check */
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int uw_fails; /* number of times we exceeded bad_uw_errors and dropped sync */
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int edge_pilots; /* insert pilots at 1 and Nc+2, to support low bandwidth phase est */
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char *data_mode; /* "", "streaming", "burst" */
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int packetsperburst; /* for OFDM data modes, how many packets before we reset state machine */
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int amp_est_mode; /* amplitude estimtor algorithm */
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float amp_scale;
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float clip_gain1;
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float clip_gain2;
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bool clip_en;
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float tx_centre; /* TX Center frequency */
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float rx_centre; /* RX Center frequency */
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float fs; /* Sample rate */
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float ts; /* Symbol cycle time */
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float rs; /* Symbol rate */
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float tcp; /* Cyclic prefix duration */
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float tpacket; /* time for one packet in ms */
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float inv_m; /* 1/m */
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float tx_nlower; /* TX lowest carrier freq */
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float rx_nlower; /* RX lowest carrier freq */
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float doc; /* division of radian circle */
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float fmin;
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float fmax;
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// Pointers
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struct quisk_cfFilter *tx_bpf;
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struct quisk_cfFilter *rx_bpf;
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complex float *pilot_samples;
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complex float *rxbuf;
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complex float *pilots;
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complex float **rx_sym;
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complex float *rx_np;
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complex float *tx_uw_syms;
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COMP *tx_preamble;
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COMP *tx_postamble;
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float *rx_amp;
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float *aphase_est_pilot_log;
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uint8_t tx_uw[MAX_UW_BITS];
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int *uw_ind;
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int *uw_ind_sym;
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// State enums
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State sync_state;
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State last_sync_state;
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// Sync enums
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Sync sync_mode;
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// Phase enums
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PhaseEstBandwidth phase_est_bandwidth;
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int phase_est_bandwidth_mode;
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// Complex
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complex float foff_metric;
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// Float
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float foff_est_gain;
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bool foff_limiter;
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float foff_est_hz;
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float timing_mx;
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float coarse_foff_est_hz;
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float timing_norm;
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float mean_amp;
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// Integer
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int clock_offset_counter;
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int verbose;
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int sample_point;
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int timing_est;
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int timing_valid;
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int ct_est;
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int nin;
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int uw_errors;
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int sync_counter;
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int frame_count; /* general purpose counter of modem frames */
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int packet_count; /* data mode: number of packets received so far */
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int modem_frame; /* increments for every modem frame in packet */
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// Boolean
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bool sync_start;
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bool sync_end;
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bool timing_en;
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bool foff_est_en;
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bool phase_est_en;
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bool tx_bpf_en;
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bool rx_bpf_en;
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bool dpsk_en;
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bool postambledetectoren; /* allows us to optionally disable the postamble detector */
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char *codename;
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char *state_machine;
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};
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/* Prototypes */
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complex float qpsk_mod(int *);
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complex float qam16_mod(int *);
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void qpsk_demod(complex float, int *);
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void qam16_demod(complex float, int *);
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void ofdm_txframe(struct OFDM *, complex float *, complex float []);
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void ofdm_assemble_qpsk_modem_packet(struct OFDM *, uint8_t [], uint8_t [], uint8_t []);
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void ofdm_assemble_qpsk_modem_packet_symbols(struct OFDM *, complex float [], COMP [], uint8_t []);
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void ofdm_disassemble_qpsk_modem_packet(struct OFDM *, complex float rx_syms[], float rx_amps[], COMP [], float [], short []);
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void ofdm_disassemble_qpsk_modem_packet_with_text_amps(struct OFDM *, complex float rx_syms[], float rx_amps[], COMP [], float [], short [], int*);
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void ofdm_extract_uw(struct OFDM *ofdm, complex float rx_syms[], float rx_amps[], uint8_t rx_uw[]);
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void ofdm_rand(uint16_t [], int);
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void ofdm_rand_seed(uint16_t r[], int n, uint64_t seed) ;
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void ofdm_generate_payload_data_bits(uint8_t data_bits[], int n);
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void ofdm_generate_preamble(struct OFDM *ofdm, COMP *tx_preamble, int seed);
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int ofdm_get_phase_est_bandwidth_mode(struct OFDM *);
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void ofdm_set_phase_est_bandwidth_mode(struct OFDM *, int);
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void ofdm_clip(complex float tx[], float clip_thresh, int n);
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void ofdm_hilbert_clipper(struct OFDM *ofdm, complex float *tx, size_t n);
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float ofdm_esno_est_calc(complex float *rx_sym, int nsym);
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float ofdm_snr_from_esno(struct OFDM *ofdm, float EsNodB);
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void ofdm_get_demod_stats(struct OFDM *ofdm, struct MODEM_STATS *stats, complex float *rx_syms, int Nsymsperpacket);
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#ifdef __cplusplus
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}
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#endif
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#endif
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