example_processing_static_presence.c

example_processing_static_presence.c Example program that shows how the spread of the phase values can be used to determine if there is a static object in front of the radar.In this example we use the the ratio of the coherent average to the noncoherent average to calculate the spread and determine if the phase values are aligned or not. It is also possible to measure the spread in other way, for example by calculating the standard deviation of the phase values.

Note that this example is mainly intended for detecting the precense of static objects in front of the radar sensor, while Acconeer's presence detector detects objects that moves or vibrates sligtly, ignoring static objects.

// Copyright (c) Acconeer AB, 2023-2025
// 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.
/** \example example_processing_static_presence.c
* @brief example_processing_static_presence.c
* Example program that shows how the spread of the phase values can be used
* to determine if there is a static object in front of the radar.
*
* In this example we use the the ratio of the coherent average to the noncoherent
* average to calculate the spread and determine if the phase values are aligned or
* not. It is also possible to measure the spread in other way, for example by
* calculating the standard deviation of the phase values.
*
* Note that this example is mainly intended for detecting the precense of static
* objects in front of the radar sensor, while Acconeer's presence detector detects
* objects that moves or vibrates sligtly, ignoring static objects.
*/
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include "acc_config.h"
#include "acc_hal_definitions_a121.h"
#include "acc_hal_integration_a121.h"
#include "acc_integration_log.h"
#include "acc_rss_a121.h"
#include "acc_version.h"
#include "acc_processing_helpers.h"
#define SENSOR_ID (1U)
#define SWEEPS_PER_FRAME 16
#define PHASE_SPREAD_TRESHOLD (0.01f)
static void update_configuration(acc_config_t *config);
int acconeer_main(int argc, char *argv[]);
int acconeer_main(int argc, char *argv[])
{
(void)argc;
(void)argv;
acc_control_helper_t control_helper_state = {0};
printf("Acconeer software version %s\n", acc_version_get());
const acc_hal_a121_t *hal = acc_hal_rss_integration_get_implementation();
if (!acc_rss_hal_register(hal))
{
return EXIT_FAILURE;
}
bool res = acc_control_helper_create(&control_helper_state, SENSOR_ID);
if (!res)
{
printf("acc_control_helper_create() failed\n");
return EXIT_FAILURE;
}
update_configuration(control_helper_state.config);
res = acc_control_helper_activate(&control_helper_state);
if (!res)
{
printf("acc_control_helper_activate() failed\n");
acc_control_helper_destroy(&control_helper_state);
return EXIT_FAILURE;
}
uint32_t sweep_data_length = control_helper_state.proc_meta.sweep_data_length;
uint32_t point_vector_length = SWEEPS_PER_FRAME;
acc_vector_float_t *phase_spread = acc_vector_float_alloc(sweep_data_length);
acc_vector_iq_t *point_vector = acc_vector_iq_alloc(point_vector_length);
bool mem_ok = (phase_spread != NULL) && (point_vector != NULL);
if (!mem_ok)
{
printf("Memory allocation for vectors failed\n");
goto clean_up;
}
uint32_t iterations = 5U;
for (uint32_t i = 0U; i < iterations; i++)
{
res = acc_control_helper_get_next(&control_helper_state);
if (!res)
{
printf("acc_control_helper_get_next() failed\n");
break;
}
for (uint32_t p = 0U; p < sweep_data_length; p++)
{
acc_get_iq_point_vector(&control_helper_state, p, point_vector);
// The ratio of the coherent average to the noncoherent average is used to determine
// the amount of phase spread. When the phases of the values in the array are similar,
// the coherent average approaches the noncoherent average. However, if the phase
// values are uniformly distributed around the unit circle and have the same
// amplitudes, they cancel out, resulting in a coherent average of 0, while the
// noncoherent average is still the average of the amplitudes.
// As a result, when there is an object in front of the radar and the spread is low,
// the ratio is close to 1. When there is no object in front of the radar and the
// phase values are random, the ratio is closer to 0.
// We set the phase spread to be 1 minus the ratio.
float coherent_mean = acc_vector_iq_coherent_mean_amplitude(point_vector);
float noncoherent_mean = acc_vector_iq_noncoherent_mean_amplitude(point_vector);
phase_spread->data[p] = 1 - coherent_mean / noncoherent_mean;
}
// Print a line with a dot or star for each distance point. A star ('*') means that there
// is an object in front of the radar at the distance point and a dot ('.') means that
// there is no object in front of the radar.
for (uint32_t p = 0U; p < sweep_data_length; p++)
{
printf("%c", phase_spread->data[p] > PHASE_SPREAD_TRESHOLD ? '.' : '*');
}
printf("\n");
}
clean_up:
acc_vector_iq_free(point_vector);
acc_vector_float_free(phase_spread);
acc_control_helper_destroy(&control_helper_state);
if (res && mem_ok)
{
printf("Application finished OK\n");
return EXIT_SUCCESS;
}
else
{
return EXIT_FAILURE;
}
}
static void update_configuration(acc_config_t *config)
{
int32_t start_point = 100; // start at 250 mm
uint16_t step_length = 24; // 24*2.5 mm = 60 mm
uint16_t num_points = 20; // range length 20*24*2.5 mm = 1200 mm
acc_config_start_point_set(config, start_point);
acc_config_num_points_set(config, num_points);
acc_config_step_length_set(config, step_length);
acc_config_profile_set(config, ACC_CONFIG_PROFILE_3);
acc_config_hwaas_set(config, 30);
// The processing in this example assumes that sweeps_per_frame > 1
acc_config_sweeps_per_frame_set(config, SWEEPS_PER_FRAME);
acc_config_prf_set(config, ACC_CONFIG_PRF_13_0_MHZ);
}
acc_config_start_point_set
void acc_config_start_point_set(acc_config_t *config, int32_t start_point)
Set the starting point of the sweep.
SENSOR_ID
#define SENSOR_ID
Definition: example_processing_static_presence.c:35
acc_control_helper_create
bool acc_control_helper_create(acc_control_helper_t *radar, acc_sensor_id_t sensor_id)
Create a helper instance.
Definition: acc_control_helper.c:41
acc_rss_a121.h
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_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_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
acconeer_main
int acconeer_main(int argc, char *argv[])
Assembly test example.
Definition: example_processing_static_presence.c:44
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_t::config
acc_config_t * config
Definition: acc_control_helper.h:25
PHASE_SPREAD_TRESHOLD
#define PHASE_SPREAD_TRESHOLD
Definition: example_processing_static_presence.c:38
acc_version.h
acc_config_profile_set
void acc_config_profile_set(acc_config_t *config, acc_config_profile_t profile)
Set a profile.
acc_config_sweeps_per_frame_set
void acc_config_sweeps_per_frame_set(acc_config_t *config, uint16_t sweeps)
Set sweeps per frame.
acc_vector_float_t::data
float * data
Definition: acc_processing_helpers.h:36
acc_control_helper_destroy
void acc_control_helper_destroy(acc_control_helper_t *radar)
Destroy a helper instance.
Definition: acc_control_helper.c:50
config
cargo_config_t config
Definition: i2c_example_cargo.c:34
acc_hal_rss_integration_get_implementation
const acc_hal_a121_t * acc_hal_rss_integration_get_implementation(void)
Get hal implementation reference.
Definition: acc_hal_integration_stm32cube_xm.c:152
acc_vector_iq_t
Definition: acc_processing_helpers.h:27
acc_hal_a121_t
Definition: acc_hal_definitions_a121.h:82
acc_control_helper_t::proc_meta
acc_processing_metadata_t proc_meta
Definition: acc_control_helper.h:32
acc_rss_hal_register
bool acc_rss_hal_register(const acc_hal_a121_t *hal)
Register an integration.
acc_config_hwaas_set
void acc_config_hwaas_set(acc_config_t *config, uint16_t hwaas)
Set the hardware accelerated average samples (HWAAS)
acc_processing_metadata_t::sweep_data_length
uint16_t sweep_data_length
Definition: acc_processing.h:41
update_configuration
static void update_configuration(acc_config_t *config)
Definition: example_processing_static_presence.c:152
acc_hal_integration_a121.h
acc_version_get
const char * acc_version_get(void)
Get the version of the Acconeer software.
acc_config_t
struct acc_config acc_config_t
Definition: acc_config.h:24
printf
#define printf
Definition: printf.h:60
acc_config_step_length_set
void acc_config_step_length_set(acc_config_t *config, uint16_t step_length)
Set the step length in a sweep.
acc_config_num_points_set
void acc_config_num_points_set(acc_config_t *config, uint16_t num_points)
Set the number of data points to measure.
acc_hal_definitions_a121.h
acc_processing_helpers.h
acc_vector_float_t
Definition: acc_processing_helpers.h:33
acc_integration_log.h
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_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
SWEEPS_PER_FRAME
#define SWEEPS_PER_FRAME
Definition: example_processing_static_presence.c:37
acc_control_helper_t
Definition: acc_control_helper.h:23
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_control_helper_activate
bool acc_control_helper_activate(acc_control_helper_t *radar)
Activate the sensor.
Definition: acc_control_helper.c:81
acc_config_prf_set
void acc_config_prf_set(acc_config_t *config, acc_config_prf_t prf)
Set Pulse Repetition Frequency.
ACC_CONFIG_PRF_13_0_MHZ
@ ACC_CONFIG_PRF_13_0_MHZ
Definition: acc_definitions_a121.h:118
acc_config.h
acc_control_helper_get_next
bool acc_control_helper_get_next(acc_control_helper_t *radar)
Perform a radar measurement and wait for the result.
Definition: acc_control_helper.c:157
ACC_CONFIG_PROFILE_3
@ ACC_CONFIG_PROFILE_3
Definition: acc_definitions_a121.h:54