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