94 lines
3.2 KiB
C
94 lines
3.2 KiB
C
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#include <unistd.h>
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#include <math.h>
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#include <arm_math.h>
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#include <levmarq.h>
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#include "freq_meas.h"
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#include "sr_global.h"
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/* FTT window lookup table defined in generated/fmeas_fft_window.c */
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extern const float * const fmeas_fft_window_table;
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/* jury-rig some definitions for these functions since the ARM headers only export an over-generalized variable bin size
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* variant. */
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extern arm_status arm_rfft_32_fast_init_f32(arm_rfft_fast_instance_f32 * S);
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extern arm_status arm_rfft_64_fast_init_f32(arm_rfft_fast_instance_f32 * S);
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extern arm_status arm_rfft_128_fast_init_f32(arm_rfft_fast_instance_f32 * S);
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extern arm_status arm_rfft_256_fast_init_f32(arm_rfft_fast_instance_f32 * S);
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extern arm_status arm_rfft_512_fast_init_f32(arm_rfft_fast_instance_f32 * S);
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extern arm_status arm_rfft_1024_fast_init_f32(arm_rfft_fast_instance_f32 * S);
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extern arm_status arm_rfft_2048_fast_init_f32(arm_rfft_fast_instance_f32 * S);
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extern arm_status arm_rfft_4096_fast_init_f32(arm_rfft_fast_instance_f32 * S);
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#define CONCAT(A, B, C) A ## B ## C
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#define arm_rfft_init_name(nbits) CONCAT(arm_rfft_, nbits, _fast_init_f32)
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float func_gauss_grad(float *out, float *params, int x, void *userdata);
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float func_gauss(float *params, int x, void *userdata);
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int adc_buf_measure_freq(uint16_t adc_buf[FMEAS_FFT_LEN], float *out) {
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int rc;
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float in_buf[FMEAS_FFT_LEN];
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float out_buf[FMEAS_FFT_LEN];
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for (size_t i=0; i<FMEAS_FFT_LEN; i++)
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in_buf[i] = (float)adc_buf[i] / (float)FMEAS_ADC_MAX * fmeas_fft_window_table[i];
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arm_rfft_fast_instance_f32 fft_inst;
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if ((rc = arm_rfft_init_name(FMEAS_FFT_LEN)(&fft_inst)) != ARM_MATH_SUCCESS)
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return rc;
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arm_rfft_fast_f32(&fft_inst, in_buf, out_buf, 0);
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#define FMEAS_FFT_WINDOW_MIN_F 30.0f
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#define FMEAS_FFT_WINDOW_MAX_F 70.0f
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const float binsize = (float)FMEAS_ADC_SAMPLING_RATE / FMEAS_FFT_LEN;
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const int first_bin = (int)(FMEAS_FFT_WINDOW_MIN_F / binsize);
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const int last_bin = (int)(FMEAS_FFT_WINDOW_MAX_F / binsize + 0.5f);
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const int nbins = last_bin - first_bin + 1;
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/* Copy real values of target data to front of output buffer */
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for (size_t i=0; i<nbins; i++)
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out_buf[i] = out_buf[2 * (first_bin + i)];
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LMstat lmstat;
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levmarq_init(&lmstat);
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float a_max = 0.0f;
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int i_max = 0;
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for (size_t i=0; i<nbins; i++) {
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if (out_buf[i] > a_max) {
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a_max = out_buf[i];
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i_max = i;
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}
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}
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float par[3] = {
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a_max, i_max, 1.0f
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};
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if (levmarq(3, ¶ms, nbins, out_buf, NULL, func_gauss, func_gauss_grad, NULL, &lmstat))
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return -1;
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*out = (params[1] + first_bin) * binsize;
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return 0;
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}
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float func_gauss(float *params, int x, void *userdata) {
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UNUSED(userdata);
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float a = params[0];
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float mu = params[1];
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float sigma = params[2];
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return a*expf(-arm_power_f32((x-mu), 2.0f/(2.0f*(sigma*sigma))));
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}
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float func_gauss_grad(float *out, float *params, int x, void *userdata) {
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UNUSED(userdata);
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float a = params[0];
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float mu = params[1];
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float sigma = params[2];
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return -(x-mu) / ( sigma*sigma*sigma * 2.5066282746310002f) * a*expf(-arm_power_f32((x-mu), 2.0f/(2.0f*(sigma*sigma))));
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}
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