135 lines
4.4 KiB
C
135 lines
4.4 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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#include "simulation.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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void 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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/*
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DEBUG_PRINTN(" [emulated adc buf] ");
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for (size_t i=0; i<FMEAS_FFT_LEN; i++)
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DEBUG_PRINTN("%5d, ", adc_buf[i]);
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DEBUG_PRINTN("\n");
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*/
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//DEBUG_PRINT("Applying window function");
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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 - 0.5) * fmeas_fft_window_table[i];
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//DEBUG_PRINT("Running FFT");
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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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*out = NAN;
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return rc;
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}
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/*
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DEBUG_PRINTN(" [input] ");
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for (size_t i=0; i<FMEAS_FFT_LEN; i++)
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DEBUG_PRINTN("%010f, ", in_buf[i]);
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DEBUG_PRINTN("\n");
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*/
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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_HZ 30.0f
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#define FMEAS_FFT_WINDOW_MAX_F_HZ 70.0f
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const float binsize_hz = (float)FMEAS_ADC_SAMPLING_RATE / FMEAS_FFT_LEN;
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const size_t first_bin = (int)(FMEAS_FFT_WINDOW_MIN_F_HZ / binsize_hz);
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const size_t last_bin = (int)(FMEAS_FFT_WINDOW_MAX_F_HZ / binsize_hz + 0.5f);
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const size_t nbins = last_bin - first_bin + 1;
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DEBUG_PRINT("binsize_hz=%f first_bin=%zd last_bin=%zd nbins=%zd", binsize_hz, first_bin, last_bin, nbins);
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DEBUG_PRINTN(" [bins real] ");
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for (size_t i=0; i<FMEAS_FFT_LEN/2; i+=2)
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DEBUG_PRINTN("%010f, ", out_buf[i]);
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DEBUG_PRINTN("\n [bins imag] ");
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for (size_t i=1; i<FMEAS_FFT_LEN/2; i+=2)
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DEBUG_PRINTN("%010f, ", out_buf[i]);
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DEBUG_PRINT("\n");
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DEBUG_PRINT("Repacking FFT results");
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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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float real = out_buf[2 * (first_bin + i)];
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float imag = out_buf[2 * (first_bin + i) + 1];
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out_buf[i] = sqrtf(real*real + imag*imag);
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}
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DEBUG_PRINT("Running Levenberg-Marquardt");
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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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DEBUG_PRINT(" par_pre={%010f, %010f, %010f}", par[0], par[1], par[2]);
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if (levmarq(3, par, nbins, out_buf, NULL, func_gauss, func_gauss_grad, NULL, &lmstat) < 0) {
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*out = NAN;
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return -1;
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}
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DEBUG_PRINT(" par_post={%010f, %010f, %010f}", par[0], par[1], par[2]);
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DEBUG_PRINT("done.");
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*out = (par[1] + first_bin) * binsize_hz;
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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], b = params[1], c = params[2];
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float n = x-b;
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return a*expf(-n*n / (2.0f* c*c));
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}
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void 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], b = params[1], c = params[2];
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float n = x-b;
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float e = expf(-n*n / (2.0f * c*c));
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/* d/da */
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out[0] = e;
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/* d/db */
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out[1] = a*n/(c*c) * e;
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/* d/dc */
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out[2] = a*n*n/(c*c*c) * e;
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}
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