acc_processing_helpers.c

This is a collection of helper functions for processing of the sparse IQ data that is generated by Acconeer's A121 radar sensor. The functions are used by Acconeer's processing examples to show common processing steps when working on sparse IQ data. The purpose of the helper functions is to increase the readability of the example programs. The helper functions do not provide optimized implementations of the processing steps.

// Copyright (c) Acconeer AB, 2022
// All rights reserved
// This file is subject to the terms and conditions defined in the file
// 'LICENSES/license_acconeer.txt', (BSD 3-Clause License) which is part
// of this source code package.
#include <assert.h>
#include <complex.h>
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "acc_control_helper.h"
#include "acc_processing_helpers.h"
#include "acc_integration_log.h"
#define MAX_DATA_ENTRY_LEN_IQ 87
#define MAX_DATA_ENTRY_LEN_FLOAT 44
acc_vector_iq_t *acc_vector_iq_alloc(uint32_t data_length)
{
acc_vector_iq_t *vector_iq = malloc(sizeof(acc_vector_iq_t));
if (vector_iq == NULL)
{
return NULL;
}
vector_iq->data = malloc(data_length * sizeof(float complex));
if (vector_iq->data == NULL)
{
free(vector_iq);
return NULL;
}
vector_iq->data_length = data_length;
return vector_iq;
}
acc_vector_float_t *acc_vector_float_alloc(uint32_t data_length)
{
acc_vector_float_t *vector_float = malloc(sizeof(acc_vector_float_t));
if (vector_float == NULL)
{
return NULL;
}
vector_float->data = malloc(data_length * sizeof(float));
if (vector_float->data == NULL)
{
free(vector_float);
return NULL;
}
vector_float->data_length = data_length;
return vector_float;
}
void acc_vector_iq_free(acc_vector_iq_t *vector)
{
if (vector == NULL)
{
return;
}
free(vector->data);
free(vector);
}
void acc_vector_float_free(acc_vector_float_t *vector)
{
if (vector == NULL)
{
return;
}
free(vector->data);
free(vector);
}
float acc_processing_helper_tc_to_sf(float time_constant_s, float update_rate_hz)
{
if (time_constant_s <= 0.0f)
{
return 0.0f;
}
else
{
return expf(-1.0f / (time_constant_s * update_rate_hz));
}
}
float acc_processing_helper_dynamic_sf(float static_sf, uint32_t update_count)
{
return fminf(static_sf, 1.0f - 1.0f / (1.0f + update_count));
}
void acc_vector_iq_update_exponential_average(const acc_vector_iq_t *current, acc_vector_iq_t *averaged_data, float sf)
{
assert(current->data_length == averaged_data->data_length);
for (uint32_t i = 0; i < current->data_length; i++)
{
averaged_data->data[i] = sf * averaged_data->data[i] + (1.0f - sf) * current->data[i];
}
}
void acc_vector_float_update_exponential_average(const acc_vector_float_t *current, acc_vector_float_t *averaged_data, float sf)
{
assert(current->data_length == averaged_data->data_length);
for (uint32_t i = 0; i < current->data_length; i++)
{
averaged_data->data[i] = sf * averaged_data->data[i] + (1.0f - sf) * current->data[i];
}
}
void acc_get_iq_sweep_vector(const acc_control_helper_t *control_helper_state, acc_vector_iq_t *vector_out)
{
uint32_t data_length = control_helper_state->proc_meta.sweep_data_length;
assert(data_length == vector_out->data_length);
for (uint32_t i = 0; i < data_length; i++)
{
acc_int16_complex_t iq = control_helper_state->proc_result.frame[i];
vector_out->data[i] = iq.real + iq.imag * I;
}
}
void acc_get_iq_point_vector(const acc_control_helper_t *control_helper_state, uint32_t point, acc_vector_iq_t *vector_out)
{
assert(point < control_helper_state->proc_meta.sweep_data_length);
assert(vector_out->data_length == (control_helper_state->proc_meta.frame_data_length / control_helper_state->proc_meta.sweep_data_length));
for (uint32_t i = 0; i < vector_out->data_length; i++)
{
acc_int16_complex_t iq = control_helper_state->proc_result.frame[point + i * control_helper_state->proc_meta.sweep_data_length];
vector_out->data[i] = iq.real + iq.imag * I;
}
}
uint32_t acc_processing_helper_get_filter_length(uint32_t peak_width_points, uint32_t step_length)
{
return (peak_width_points / step_length) | 1;
}
void acc_vector_float_create_depth_filter_vector(acc_vector_float_t *vector_out)
{
uint32_t data_length = vector_out->data_length;
assert(data_length % 2 == 1);
uint32_t mid_offset = (data_length + 1) / 2;
float sum = 0.0f;
for (uint32_t i = 0; i < data_length; i++)
{
if (i < mid_offset)
{
vector_out->data[i] = (float)i + 1;
}
else
{
vector_out->data[i] = (float)(data_length - i);
}
sum += vector_out->data[i];
}
// Normalize
for (uint32_t i = 0; i < data_length; i++)
{
vector_out->data[i] /= sum;
}
}
void acc_vector_iq_apply_filter(const acc_vector_iq_t *vector_a, acc_vector_float_t *filter_vector, acc_vector_iq_t *vector_out)
{
assert(vector_a->data_length == vector_out->data_length);
assert(filter_vector->data_length % 2 == 1); // Filter length must be odd
uint32_t offset = filter_vector->data_length / 2;
for (uint32_t i = 0; i < vector_out->data_length; i++)
{
vector_out->data[i] = 0.0f;
for (uint32_t j = 0; j < filter_vector->data_length; j++)
{
int32_t a_index = i + j - offset;
if (a_index >= 0 && (uint32_t)a_index < vector_a->data_length)
{
vector_out->data[i] += vector_a->data[a_index] * filter_vector->data[j];
}
}
}
}
void acc_vector_iq_copy(const acc_vector_iq_t *vector_a, acc_vector_iq_t *vector_out)
{
assert(vector_a->data_length == vector_out->data_length);
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_out->data[i] = vector_a->data[i];
}
}
void acc_vector_iq_add(const acc_vector_iq_t *vector_a, const acc_vector_iq_t *vector_b, acc_vector_iq_t *vector_out)
{
assert(vector_a->data_length == vector_b->data_length);
assert(vector_a->data_length == vector_out->data_length);
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_out->data[i] = vector_a->data[i] + vector_b->data[i];
}
}
void acc_vector_iq_subtract(const acc_vector_iq_t *vector_a, const acc_vector_iq_t *vector_b, acc_vector_iq_t *vector_out)
{
assert(vector_a->data_length == vector_b->data_length);
assert(vector_a->data_length == vector_out->data_length);
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_out->data[i] = vector_a->data[i] - vector_b->data[i];
}
}
void acc_vector_iq_mult(const acc_vector_iq_t *vector_a, const acc_vector_iq_t *vector_b, acc_vector_iq_t *vector_out)
{
assert(vector_a->data_length == vector_b->data_length);
assert(vector_a->data_length == vector_out->data_length);
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_out->data[i] = vector_a->data[i] * vector_b->data[i];
}
}
void acc_vector_iq_mult_conj(const acc_vector_iq_t *vector_a, const acc_vector_iq_t *vector_b, acc_vector_iq_t *vector_out)
{
assert(vector_a->data_length == vector_b->data_length);
assert(vector_a->data_length == vector_out->data_length);
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_out->data[i] = vector_a->data[i] * conjf(vector_b->data[i]);
}
}
void acc_vector_iq_rotate_phase_inline(acc_vector_iq_t *vector_a, float radians)
{
float complex rotated_unit_vector = cexpf(radians*I);
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_a->data[i] *= rotated_unit_vector;
}
}
void acc_vector_iq_conj_inline(acc_vector_iq_t *vector_a)
{
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_a->data[i] = conjf(vector_a->data[i]);
}
}
void acc_vector_iq_amplitude(const acc_vector_iq_t *vector_a, acc_vector_float_t *vector_out)
{
assert(vector_a->data_length == vector_out->data_length);
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_out->data[i] = cabsf(vector_a->data[i]);
}
}
float acc_vector_iq_coherent_mean_amplitude(const acc_vector_iq_t *vector_a)
{
assert(vector_a->data_length > 0);
float complex coherent_mean = 0;
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
coherent_mean += vector_a->data[i];
}
return cabsf(coherent_mean / vector_a->data_length);
}
float acc_vector_iq_noncoherent_mean_amplitude(const acc_vector_iq_t *vector_a)
{
assert(vector_a->data_length > 0);
float noncoherent_mean_amplitude = 0;
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
noncoherent_mean_amplitude += cabsf(vector_a->data[i]);
}
return noncoherent_mean_amplitude / vector_a->data_length;
}
void acc_vector_iq_phase(const acc_vector_iq_t *vector_a, acc_vector_float_t *vector_out)
{
assert(vector_a->data_length == vector_out->data_length);
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
vector_out->data[i] = cargf(vector_a->data[i]);
}
}
uint32_t acc_vector_float_argmax(acc_vector_float_t *vector_a)
{
float max = -INFINITY;
int max_index = -1;
for (uint32_t i = 0; i < vector_a->data_length; i++)
{
if (vector_a->data[i] > max)
{
max = vector_a->data[i];
max_index = i;
}
}
return max_index;
}
uint32_t acc_vector_float_argmax_skip_edges(acc_vector_float_t *vector_a, uint32_t elemets_to_skip)
{
float max = -INFINITY;
int max_index = -1;
assert(elemets_to_skip < vector_a->data_length - elemets_to_skip);
for (uint32_t i = elemets_to_skip; i < (vector_a->data_length - elemets_to_skip); i++)
{
if (vector_a->data[i] > max)
{
max = vector_a->data[i];
max_index = i;
}
}
return max_index;
}
float acc_processing_helper_interpolate_peak_position(float y1, float y2, float y3)
{
return (y1 - y3) / (2.0f * y1 - 4.0f * y2 + 2.0f * y3);
}
void acc_vector_float_print(const char *label, acc_vector_float_t *vector_a)
{
printf("%s:\n", label);
char buffer[MAX_DATA_ENTRY_LEN_FLOAT];
for (uint16_t i = 0; i < vector_a->data_length; i++)
{
if ((i > 0) && ((i % 8) == 0))
{
printf("\n");
}
snprintf(buffer, sizeof(buffer), "%" PRIfloat " ", ACC_LOG_FLOAT_TO_INTEGER(vector_a->data[i]));
printf("%14s ", buffer);
}
printf("\n");
}
void acc_vector_iq_print(const char *label, acc_vector_iq_t *vector_a)
{
printf("%s: ", label);
char buffer[MAX_DATA_ENTRY_LEN_IQ];
for (uint16_t i = 0; i < vector_a->data_length; i++)
{
if ((i > 0) && ((i % 8) == 0))
{
printf("\n");
}
snprintf(buffer, sizeof(buffer), "%" PRIfloat "+%" PRIfloat "i",
ACC_LOG_FLOAT_TO_INTEGER(crealf(vector_a->data[i])),
ACC_LOG_FLOAT_TO_INTEGER(cimagf(vector_a->data[i])));
printf("%14s ", buffer);
}
printf("\n");
}
acc_processing_helper_dynamic_sf
float acc_processing_helper_dynamic_sf(float static_sf, uint32_t update_count)
Calculate a dynamic smoothing factor.
Definition: acc_processing_helpers.c:110
acc_vector_iq_apply_filter
void acc_vector_iq_apply_filter(const acc_vector_iq_t *vector_a, acc_vector_float_t *filter_vector, acc_vector_iq_t *vector_out)
Apply a FIR filter to an IQ vector.
Definition: acc_processing_helpers.c:203
acc_vector_iq_amplitude
void acc_vector_iq_amplitude(const acc_vector_iq_t *vector_a, acc_vector_float_t *vector_out)
Amplitude of an IQ vector.
Definition: acc_processing_helpers.c:305
acc_vector_iq_mult
void acc_vector_iq_mult(const acc_vector_iq_t *vector_a, const acc_vector_iq_t *vector_b, acc_vector_iq_t *vector_out)
Multiply two IQ vectors.
Definition: acc_processing_helpers.c:261
buffer
void * buffer
Definition: i2c_example_cargo.c:40
MAX_DATA_ENTRY_LEN_IQ
#define MAX_DATA_ENTRY_LEN_IQ
Definition: acc_processing_helpers.c:23
acc_int16_complex_t
Data type for interger-based representation of complex numbers.
Definition: acc_definitions_common.h:40
acc_vector_iq_rotate_phase_inline
void acc_vector_iq_rotate_phase_inline(acc_vector_iq_t *vector_a, float radians)
Rotate the phase of elements in an IQ vector.
Definition: acc_processing_helpers.c:285
acc_vector_iq_update_exponential_average
void acc_vector_iq_update_exponential_average(const acc_vector_iq_t *current, acc_vector_iq_t *averaged_data, float sf)
Update the exponential average of an IQ vector.
Definition: acc_processing_helpers.c:116
acc_vector_float_create_depth_filter_vector
void acc_vector_float_create_depth_filter_vector(acc_vector_float_t *vector_out)
Create a distance filter vector.
Definition: acc_processing_helpers.c:172
acc_vector_float_update_exponential_average
void acc_vector_float_update_exponential_average(const acc_vector_float_t *current, acc_vector_float_t *averaged_data, float sf)
Update the exponential average of a float vector.
Definition: acc_processing_helpers.c:127
acc_vector_iq_t::data
float complex * data
Definition: acc_processing_helpers.h:30
acc_vector_float_t::data
float * data
Definition: acc_processing_helpers.h:36
acc_get_iq_point_vector
void acc_get_iq_point_vector(const acc_control_helper_t *control_helper_state, uint32_t point, acc_vector_iq_t *vector_out)
Extract an IQ vector with sweep data for a specific point from a newly captured IQ frame with multipl...
Definition: acc_processing_helpers.c:152
acc_get_iq_sweep_vector
void acc_get_iq_sweep_vector(const acc_control_helper_t *control_helper_state, acc_vector_iq_t *vector_out)
Converts a newly captured IQ frame with one sweep to an IQ vector.
Definition: acc_processing_helpers.c:138
acc_vector_iq_mult_conj
void acc_vector_iq_mult_conj(const acc_vector_iq_t *vector_a, const acc_vector_iq_t *vector_b, acc_vector_iq_t *vector_out)
Multiply first IQ vector with conjugate of second IQ vector.
Definition: acc_processing_helpers.c:273
acc_vector_iq_alloc
acc_vector_iq_t * acc_vector_iq_alloc(uint32_t data_length)
Allocate storage for an IQ vector.
Definition: acc_processing_helpers.c:27
acc_vector_iq_t
Definition: acc_processing_helpers.h:27
acc_vector_float_print
void acc_vector_float_print(const char *label, acc_vector_float_t *vector_a)
Print float vector.
Definition: acc_processing_helpers.c:401
acc_vector_float_argmax
uint32_t acc_vector_float_argmax(acc_vector_float_t *vector_a)
Index of element with maximum value in a float vector.
Definition: acc_processing_helpers.c:357
acc_processing_helper_tc_to_sf
float acc_processing_helper_tc_to_sf(float time_constant_s, float update_rate_hz)
Convert time constant to smoothing factor.
Definition: acc_processing_helpers.c:97
acc_control_helper_t::proc_meta
acc_processing_metadata_t proc_meta
Definition: acc_control_helper.h:32
acc_vector_iq_noncoherent_mean_amplitude
float acc_vector_iq_noncoherent_mean_amplitude(const acc_vector_iq_t *vector_a)
Non-coherent mean amplitude of IQ vector.
Definition: acc_processing_helpers.c:331
acc_vector_iq_add
void acc_vector_iq_add(const acc_vector_iq_t *vector_a, const acc_vector_iq_t *vector_b, acc_vector_iq_t *vector_out)
Add two IQ vectors.
Definition: acc_processing_helpers.c:237
acc_vector_iq_coherent_mean_amplitude
float acc_vector_iq_coherent_mean_amplitude(const acc_vector_iq_t *vector_a)
Coherent mean amplitude of IQ vector.
Definition: acc_processing_helpers.c:316
acc_processing_metadata_t::sweep_data_length
uint16_t sweep_data_length
Definition: acc_processing.h:41
acc_vector_iq_subtract
void acc_vector_iq_subtract(const acc_vector_iq_t *vector_a, const acc_vector_iq_t *vector_b, acc_vector_iq_t *vector_out)
Subtract two IQ vectors.
Definition: acc_processing_helpers.c:249
acc_vector_iq_free
void acc_vector_iq_free(acc_vector_iq_t *vector)
Free storage of data elements in an IQ vector.
Definition: acc_processing_helpers.c:73
acc_control_helper.h
acc_vector_float_alloc
acc_vector_float_t * acc_vector_float_alloc(uint32_t data_length)
Allocate storage for a float vector.
Definition: acc_processing_helpers.c:50
acc_processing_metadata_t::frame_data_length
uint16_t frame_data_length
Definition: acc_processing.h:39
acc_int16_complex_t::real
int16_t real
Definition: acc_definitions_common.h:42
printf
#define printf
Definition: printf.h:60
acc_processing_helper_interpolate_peak_position
float acc_processing_helper_interpolate_peak_position(float y1, float y2, float y3)
Interpolate peak position.
Definition: acc_processing_helpers.c:395
snprintf
#define snprintf
Definition: printf.h:84
acc_vector_iq_phase
void acc_vector_iq_phase(const acc_vector_iq_t *vector_a, acc_vector_float_t *vector_out)
Phase of an IQ vector.
Definition: acc_processing_helpers.c:346
acc_processing_helpers.h
acc_processing_result_t::frame
acc_int16_complex_t * frame
Definition: acc_processing.h:91
acc_vector_float_t
Definition: acc_processing_helpers.h:33
acc_integration_log.h
ACC_LOG_FLOAT_TO_INTEGER
#define ACC_LOG_FLOAT_TO_INTEGER(a)
Definition: acc_integration_log.h:26
acc_vector_float_t::data_length
uint32_t data_length
Definition: acc_processing_helpers.h:35
acc_control_helper_t
Definition: acc_control_helper.h:23
acc_vector_iq_t::data_length
uint32_t data_length
Definition: acc_processing_helpers.h:29
acc_int16_complex_t::imag
int16_t imag
Definition: acc_definitions_common.h:43
acc_vector_iq_print
void acc_vector_iq_print(const char *label, acc_vector_iq_t *vector_a)
Print IQ vector.
Definition: acc_processing_helpers.c:423
acc_vector_float_free
void acc_vector_float_free(acc_vector_float_t *vector)
Free storage of data elements in a float vector.
Definition: acc_processing_helpers.c:85
acc_vector_iq_copy
void acc_vector_iq_copy(const acc_vector_iq_t *vector_a, acc_vector_iq_t *vector_out)
Copy an IQ vector.
Definition: acc_processing_helpers.c:226
acc_processing_helper_get_filter_length
uint32_t acc_processing_helper_get_filter_length(uint32_t peak_width_points, uint32_t step_length)
Calculate filter vector length.
Definition: acc_processing_helpers.c:166
PRIfloat
#define PRIfloat
Specifier for printing float type using integers.
Definition: acc_integration_log.h:31
acc_vector_float_argmax_skip_edges
uint32_t acc_vector_float_argmax_skip_edges(acc_vector_float_t *vector_a, uint32_t elemets_to_skip)
Index of element with maximum value in a float vector disregarding edge elements.
Definition: acc_processing_helpers.c:375
MAX_DATA_ENTRY_LEN_FLOAT
#define MAX_DATA_ENTRY_LEN_FLOAT
Definition: acc_processing_helpers.c:24
acc_control_helper_t::proc_result
acc_processing_result_t proc_result
Definition: acc_control_helper.h:33
acc_vector_iq_conj_inline
void acc_vector_iq_conj_inline(acc_vector_iq_t *vector_a)
Update an IQ vector with its conjugate.
Definition: acc_processing_helpers.c:296