81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
/* AFC (Automatic Frequency Correction) Implementation */
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/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
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* (C) 2011 by Andreas Eversberg <jolly@eversberg.eu>
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*
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* All Rights Reserved
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*
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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 General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <stdint.h>
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#include <stdio.h>
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#include <debug.h>
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#include <osmocom/gsm/gsm_utils.h>
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#include <layer1/toa.h>
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#include <layer1/avg.h>
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#include <layer1/sync.h>
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/* Over how many TDMA frames do we want to average? */
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#define TOA_PERIOD 250
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/* How many of our measurements have to be valid? */
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#define TOA_MIN_MUN_VALID 125
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// FIXME:
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#define TOA_SNR_THRESHOLD 2560 /* 2.5 dB in fx6.10 */
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struct toa_state {
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struct running_avg ravg; /* running average */
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};
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static void toa_ravg_output(struct running_avg *ravg, int32_t avg);
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static struct toa_state toa_state = {
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.ravg = {
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.outfn = &toa_ravg_output,
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.period = TOA_PERIOD,
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.min_valid = TOA_MIN_MUN_VALID,
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},
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};
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void toa_input(int32_t offset, uint32_t snr)
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{
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int valid = 1;
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if (snr < TOA_SNR_THRESHOLD || offset < 0 || offset >31)
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valid = 0;
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runavg_input(&toa_state.ravg, offset, valid);
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runavg_check_output(&toa_state.ravg);
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}
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void toa_reset(void)
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{
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toa_state.ravg.num_samples = toa_state.ravg.num_samples_valid = 0;
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toa_state.ravg.acc_val = 0;
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}
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/* callback function for runavg */
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static void toa_ravg_output(struct running_avg *ravg, int32_t avg)
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{
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if (avg != 16) {
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printf("TOA AVG is not 16 qbits, correcting (got %ld)\n", avg);
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l1s.tpu_offset_correction = avg - 16;
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}
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}
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