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Utility for interpolation of calibration parameters

This commit is contained in:
Silvano Seva 2020-12-04 18:13:24 +01:00
parent aa0e1f479e
commit 0931f1b588
2 changed files with 96 additions and 0 deletions
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45
openrtx/include/calibration/calibUtils.h Normal file
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/***************************************************************************
* Copyright (C) 2020 by Federico Amedeo Izzo IU2NUO, *
* Niccolò Izzo IU2KIN, *
* Silvano Seva IU2KWO *
* *
* 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 3 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, see <http://www.gnu.org/licenses/> *
***************************************************************************/
#ifndef CALIB_UTILS_H
#define CALIB_UTILS_H
#include <datatypes.h>
#include <stdint.h>
/**
* This function allows to obtain the value of a given calibration parameter for
* frequencies outside the calibration points. It works by searching the two
* calibration points containing the target frequency and then by linearly
* interpolating the calibration parameter among these two points.
* @param freq: target frequency for which a calibration value has to be
* computed.
* @param calPoints: pointer to the vector containing the frequencies of the
* calibration points.
* @param param: pointer to the vector containing the values for the calibration
* parameter, it must have the same length of the one containing the frequencies
* of calibration points.
* @param elems: number of elements of both the vectors for calibration parameter
* and frequencies.
* @return value for the calibration parameter at the given frequency point.
*/
uint8_t interpCalParameter(freq_t freq, freq_t *calPoints, uint8_t *param,
uint8_t elems);
#endif /* CALIB_UTILS_H */

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openrtx/src/calibUtils.c Normal file
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/***************************************************************************
* Copyright (C) 2020 by Federico Amedeo Izzo IU2NUO, *
* Niccolò Izzo IU2KIN, *
* Silvano Seva IU2KWO *
* *
* 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 3 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, see <http://www.gnu.org/licenses/> *
***************************************************************************/
#include <calibUtils.h>
uint8_t interpCalParameter(freq_t freq, freq_t *calPoints, uint8_t *param,
uint8_t elems)
{
if(freq <= calPoints[0]) return param[0];
if(freq >= calPoints[elems - 1]) return param[elems - 1];
/* Find calibration point nearest to target frequency */
uint8_t pos = 0;
for(; pos < elems; pos++)
{
if(calPoints[pos] >= freq) break;
}
uint8_t interpValue = 0;
freq_t delta = calPoints[pos] - calPoints[pos - 1];
if(param[pos - 1] < param[pos])
{
interpValue = param[pos - 1] + ((freq - calPoints[pos - 1]) *
(param[pos] - param[pos - 1]))/delta;
}
else
{
interpValue = param[pos - 1] - ((freq - calPoints[pos - 1]) *
(param[pos - 1] - param[pos]))/delta;
}
return interpValue;
}