Angle of Arrival / Departure

Angle of Arrival / Departure.

Data Structures

struct  sl_rtl_clib_iq_sample_qa_antenna_data_t
 
struct  sl_rtl_clib_iq_sample_qa_dataset_t

Macros

#define SL_RTL_AOX_IQ_SAMPLE_QA_ALL_OK   0
 
#define SL_RTL_AOX_IQ_SAMPLE_QA_FAILURE   0xffffffff
 
#define SL_RTL_AOX_IQ_SAMPLE_QA_CLEAR_BIT(code, bit)   (code &= ~ (1UL << bit))
 
#define SL_RTL_AOX_IQ_SAMPLE_QA_SET_BIT(code, bit)   (code |= (1UL << bit))
 
#define SL_RTL_AOX_IQ_SAMPLE_QA_IS_SET(code, bit)   (code & (1UL << bit))

Typedefs

typedef void * sl_rtl_aox_libitem
 Angle of Arrival / Departure library item.

Enumerations

enum  sl_rtl_aox_array_type { SL_RTL_AOX_ARRAY_TYPE_4x4_URA = 0, SL_RTL_AOX_ARRAY_TYPE_3x3_URA, SL_RTL_AOX_ARRAY_TYPE_1x4_ULA, SL_RTL_AOX_ARRAY_TYPE_LAST }
 AoX antenna array type.
 
enum  sl_rtl_aox_mode {
  SL_RTL_AOX_MODE_ONE_SHOT_BASIC = 3, SL_RTL_AOX_MODE_ONE_SHOT_BASIC_LIGHTWEIGHT, SL_RTL_AOX_MODE_ONE_SHOT_FAST_RESPONSE, SL_RTL_AOX_MODE_ONE_SHOT_HIGH_ACCURACY,
  SL_RTL_AOX_MODE_ONE_SHOT_BASIC_AZIMUTH_ONLY, SL_RTL_AOX_MODE_ONE_SHOT_FAST_RESPONSE_AZIMUTH_ONLY, SL_RTL_AOX_MODE_ONE_SHOT_HIGH_ACCURACY_AZIMUTH_ONLY, SL_RTL_AOX_MODE_REAL_TIME_FAST_RESPONSE,
  SL_RTL_AOX_MODE_REAL_TIME_BASIC, SL_RTL_AOX_MODE_REAL_TIME_HIGH_ACCURACY, SL_RTL_AOX_MODE_LAST
}
 AoX estimator mode.
 
enum  sl_rtl_aox_constraint_type { SL_RTL_AOX_CONSTRAINT_TYPE_AZIMUTH = 0, SL_RTL_AOX_CONSTRAINT_TYPE_ELEVATION }
 
enum  sl_rtl_aox_switch_pattern_mode { SL_RTL_AOX_SWITCH_PATTERN_MODE_DEFAULT = 0, SL_RTL_AOX_SWITCH_PATTERN_MODE_RANDOM, SL_RTL_AOX_SWITCH_PATTERN_MODE_EXTERNAL }
 
enum  sl_rtl_slib_iq_sample_qa_result_t {
  SL_RTL_AOX_IQ_SAMPLE_QA_INVAL_REF = 0, SL_RTL_AOX_IQ_SAMPLE_QA_DCOFFSET = 2, SL_RTL_AOX_IQ_SAMPLE_QA_SNDR = 3, SL_RTL_AOX_IQ_SAMPLE_QA_ROTATING_ERROR = 4,
  SL_RTL_AOX_IQ_SAMPLE_QA_REF_ANT_PHASE_VALUE = 5, SL_RTL_AOX_IQ_SAMPLE_QA_REF_ANT_PHASE_JITTER = 6, SL_RTL_AOX_IQ_SAMPLE_QA_ANT_X_PHASE_JITTER = 7, SL_RTL_AOX_IQ_SAMPLE_QA_ALL_SAME_PHASE = 8,
  SL_RTL_AOX_IQ_SAMPLE_QA_SWICHING_JITTER = 9
}

Functions

enum sl_rtl_error_code sl_rtl_aox_init (sl_rtl_aox_libitem *item)
 
enum sl_rtl_error_code sl_rtl_aox_deinit (sl_rtl_aox_libitem *item)
 
enum sl_rtl_error_code sl_rtl_aox_set_num_snapshots (sl_rtl_aox_libitem *item, uint32_t num_snapshots)
 
enum sl_rtl_error_code sl_rtl_aox_set_array_type (sl_rtl_aox_libitem *item, enum sl_rtl_aox_array_type array_type)
 
enum sl_rtl_error_code sl_rtl_aox_set_mode (sl_rtl_aox_libitem *item, enum sl_rtl_aox_mode mode)
 
enum sl_rtl_error_code sl_rtl_aox_calculate_iq_sample_phase_rotation (sl_rtl_aox_libitem *item, float iq_data_downsampling_factor, float *i_samples, float *q_samples, uint32_t num_samples, float *phase_rotation_out)
 
enum sl_rtl_error_code sl_rtl_aox_set_iq_sample_phase_rotation (sl_rtl_aox_libitem *item, float phase_rotation)
 
enum sl_rtl_error_code sl_rtl_aox_add_constraint (sl_rtl_aox_libitem *item, enum sl_rtl_aox_constraint_type constraint_type, float min_value, float max_value)
 
enum sl_rtl_error_code sl_rtl_aox_set_sample_rate (sl_rtl_aox_libitem *item, float sampleRate)
 
enum sl_rtl_error_code sl_rtl_aox_set_num_radio_channels (sl_rtl_aox_libitem *item, uint32_t channels)
 
enum sl_rtl_error_code sl_rtl_aox_iq_sample_qa_configure (sl_rtl_aox_libitem *item)
 
uint32_t sl_rtl_aox_iq_sample_qa_get_results (sl_rtl_aox_libitem *item)
 
enum sl_rtl_error_code sl_rtl_aox_iq_sample_qa_get_details (sl_rtl_aox_libitem *item, sl_rtl_clib_iq_sample_qa_dataset_t *results, sl_rtl_clib_iq_sample_qa_antenna_data_t *antenna_data)
 
enum sl_rtl_error_code sl_rtl_aox_iq_sample_qa_get_channel_details (sl_rtl_aox_libitem *item, uint8_t channel, sl_rtl_clib_iq_sample_qa_dataset_t *results, sl_rtl_clib_iq_sample_qa_antenna_data_t *antenna_data)
 
enum sl_rtl_error_code sl_rtl_aox_create_estimator (sl_rtl_aox_libitem *item)
 
enum sl_rtl_error_code sl_rtl_aox_convert_raw_samples (sl_rtl_aox_libitem *item, uint32_t start_offset, float iq_data_downsampling_factor, float *raw_i_samples_in, float *raw_q_samples_in, uint32_t num_raw_samples_in, float **i_samples_out, float **q_samples_out, uint32_t num_snapshots_out)
 
enum sl_rtl_error_code sl_rtl_aox_calculate_number_of_snapshots (sl_rtl_aox_libitem *item, uint32_t num_raw_samples_in, uint32_t start_offset, float iq_data_downsampling_factor, uint32_t num_channels, uint32_t *num_snapshots_out)
 
enum sl_rtl_error_code sl_rtl_aox_set_switch_pattern_mode (sl_rtl_aox_libitem *item, enum sl_rtl_aox_switch_pattern_mode mode)
 
enum sl_rtl_error_code sl_rtl_aox_update_switch_pattern (sl_rtl_aox_libitem *item, uint32_t *switch_pattern_in, uint32_t **switch_pattern_out)
 
enum sl_rtl_error_code sl_rtl_aox_reset_estimator (sl_rtl_aox_libitem *item)
 
enum sl_rtl_error_code sl_rtl_aox_process (sl_rtl_aox_libitem *item, float **i_samples, float **q_samples, float tone_frequency, float *az_out, float *el_out)

Detailed Description

Angle of Arrival / Departure.

These functions are related to the calculation of the Angle of Arrival and Angle of Departure from I/Q samples. The angles can be calculated following these steps:

  1. Initialize a sl_rtl_aox_libitem instance.
  2. Setup the antenna array and angle calculation parameters.
  3. Create the estimator.
  4. Set the antenna switching pattern.
  5. Input the I/Q data into the libitem.
  6. Process the I/Q data into an angle.

Data Structure Documentation

◆ sl_rtl_clib_iq_sample_qa_antenna_data_t

struct sl_rtl_clib_iq_sample_qa_antenna_data_t
Data Fields
float level Antenna signal level, in decibels.
float snr Antenna level signal to noise ratio, in decibels.
float phase_value Antenna's average unrotated phase value in the packet, in radians.
float phase_jitter Phase variation of snapshots' data of an antenna in packet, in radians.

◆ sl_rtl_clib_iq_sample_qa_dataset_t

struct sl_rtl_clib_iq_sample_qa_dataset_t
Data Fields
bool data_available If false, all the antenna values are undefined.
uint32_t curr_channel Radio channel for the last packet.
float ref_freq Apparent suplemental tone frequency.
float ref_sndr Reference period signal to noise and distortion ratio.
float switching_jitter Estimated antenna switching clock jitter.

Macro Definition Documentation

◆ SL_RTL_AOX_IQ_SAMPLE_QA_ALL_OK

#define SL_RTL_AOX_IQ_SAMPLE_QA_ALL_OK   0

◆ SL_RTL_AOX_IQ_SAMPLE_QA_FAILURE

#define SL_RTL_AOX_IQ_SAMPLE_QA_FAILURE   0xffffffff

◆ SL_RTL_AOX_IQ_SAMPLE_QA_CLEAR_BIT

#define SL_RTL_AOX_IQ_SAMPLE_QA_CLEAR_BIT (   code,
  bit 
)    (code &= ~ (1UL << bit))

◆ SL_RTL_AOX_IQ_SAMPLE_QA_SET_BIT

#define SL_RTL_AOX_IQ_SAMPLE_QA_SET_BIT (   code,
  bit 
)    (code |= (1UL << bit))

◆ SL_RTL_AOX_IQ_SAMPLE_QA_IS_SET

#define SL_RTL_AOX_IQ_SAMPLE_QA_IS_SET (   code,
  bit 
)    (code & (1UL << bit))

Typedef Documentation

◆ sl_rtl_aox_libitem

typedef void* sl_rtl_aox_libitem

Angle of Arrival / Departure library item.

Enumeration Type Documentation

◆ sl_rtl_aox_array_type

enum sl_rtl_aox_array_type

AoX antenna array type.

Enumerator
SL_RTL_AOX_ARRAY_TYPE_4x4_URA 

Ref. 4x4 Uniform Rectangular Array.

SL_RTL_AOX_ARRAY_TYPE_3x3_URA 

Ref. 3x3 Uniform Rectangular Array.

SL_RTL_AOX_ARRAY_TYPE_1x4_ULA 

Ref. 1x4 Uniform Linear Array.

SL_RTL_AOX_ARRAY_TYPE_LAST 

Placeholder.

◆ sl_rtl_aox_mode

enum sl_rtl_aox_mode

AoX estimator mode.

Enumerator
SL_RTL_AOX_MODE_ONE_SHOT_BASIC 

Medium filtering, medium response. Returns 2D angle, requires 10 rounds. Most suitable for single shot measurement.

SL_RTL_AOX_MODE_ONE_SHOT_BASIC_LIGHTWEIGHT 

Medium filtering, medium response, low CPU cost & low elevation resolution. 2D angle, req. 10 rounds. Most suitable for single shot measurement.

SL_RTL_AOX_MODE_ONE_SHOT_FAST_RESPONSE 

Low filtering, fast response, low CPU cost & low elevation resolution. 2D angle, requires 2 rounds. Most suitable for single shot measurement.

SL_RTL_AOX_MODE_ONE_SHOT_HIGH_ACCURACY 

High filtering, slow response. 2D angle, requires 20 rounds. Most suitable for single shot measurement.

SL_RTL_AOX_MODE_ONE_SHOT_BASIC_AZIMUTH_ONLY 

Equivalent to ONE_SHOT_BASIC with low CPU cost and returns 1D angle. Most suitable for single shot measurement.

SL_RTL_AOX_MODE_ONE_SHOT_FAST_RESPONSE_AZIMUTH_ONLY 

Equivalent to ONE_SHOT_FAST_RESPONSE with low CPU cost, 1D angle. Most suitable for single shot measurement.

SL_RTL_AOX_MODE_ONE_SHOT_HIGH_ACCURACY_AZIMUTH_ONLY 

Equivalent to ONE_SHOT_HIGH_ACCURACY with low CPU cost, 1D angle. Most suitable for single shot measurement.

SL_RTL_AOX_MODE_REAL_TIME_FAST_RESPONSE 

Low filtering, fast response, lowest CPU cost, 2D angle, Most suitable for real-time tracking.

SL_RTL_AOX_MODE_REAL_TIME_BASIC 

Medium filtering, medium response, medium CPU cost, 2D angle, Most suitable for real-time tracking.

SL_RTL_AOX_MODE_REAL_TIME_HIGH_ACCURACY 

High filtering, slow response, highest CPU cost, 2D angle, Most suitable for real-time tracking.

SL_RTL_AOX_MODE_LAST 

Placeholder.

◆ sl_rtl_aox_constraint_type

enum sl_rtl_aox_constraint_type
Enumerator
SL_RTL_AOX_CONSTRAINT_TYPE_AZIMUTH 

Azimuth constraint in degrees.

SL_RTL_AOX_CONSTRAINT_TYPE_ELEVATION 

Elevation constraint in degrees.

◆ sl_rtl_aox_switch_pattern_mode

enum sl_rtl_aox_switch_pattern_mode
Enumerator
SL_RTL_AOX_SWITCH_PATTERN_MODE_DEFAULT 

Interally defined switch pattern: 0, 1, 2, ..., N-1, where N is the number of antennas.

SL_RTL_AOX_SWITCH_PATTERN_MODE_RANDOM 

Internally defined random switch pattern.

SL_RTL_AOX_SWITCH_PATTERN_MODE_EXTERNAL 

Switch pattern set externally by the user.

◆ sl_rtl_slib_iq_sample_qa_result_t

enum sl_rtl_slib_iq_sample_qa_result_t
Enumerator
SL_RTL_AOX_IQ_SAMPLE_QA_INVAL_REF 

Invalid refenrence period data.

SL_RTL_AOX_IQ_SAMPLE_QA_DCOFFSET 

DC offset too large.

SL_RTL_AOX_IQ_SAMPLE_QA_SNDR 

Reference period SNDR too large.

SL_RTL_AOX_IQ_SAMPLE_QA_ROTATING_ERROR 

Rotation error too large.

SL_RTL_AOX_IQ_SAMPLE_QA_REF_ANT_PHASE_VALUE 

Reference antenna phase value too big.

SL_RTL_AOX_IQ_SAMPLE_QA_REF_ANT_PHASE_JITTER 

Reference antenna phase jitter too large.

SL_RTL_AOX_IQ_SAMPLE_QA_ANT_X_PHASE_JITTER 

Antenna X phase jitter too large.

SL_RTL_AOX_IQ_SAMPLE_QA_ALL_SAME_PHASE 

All the antennas seen in the same phase.

SL_RTL_AOX_IQ_SAMPLE_QA_SWICHING_JITTER 

Switching jitter too large.

Function Documentation

◆ sl_rtl_aox_init()

enum sl_rtl_error_code sl_rtl_aox_init ( sl_rtl_aox_libitem *  item)

Initialize the AoX libitem instance.

Parameters
[in]itemPointer to the libitem to be initialized
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_deinit()

enum sl_rtl_error_code sl_rtl_aox_deinit ( sl_rtl_aox_libitem *  item)

Deinitialize a libitem instance of the AoX estimator.

Parameters
[in]itemPointer to the libitem to be deinitialized
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_set_num_snapshots()

enum sl_rtl_error_code sl_rtl_aox_set_num_snapshots ( sl_rtl_aox_libitem *  item,
uint32_t  num_snapshots 
)

Set the number of signal snapshots to be used in the angle estimation.

Parameters
[in]itemPointer to the initialized AoX libitem
[in]num_snapshotsNumber of snapshots as positive integer value
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_set_array_type()

enum sl_rtl_error_code sl_rtl_aox_set_array_type ( sl_rtl_aox_libitem *  item,
enum sl_rtl_aox_array_type  array_type 
)

Set the array type used with the estimator.

Parameters
[in]itemPointer to the initialized AoX libitem
[in]array_typeArray type as sl_rtl_aox_array_type
Returns
SL_RTL_ERROR_SUCCESS if successful

Set the array type used with the estimator. For example, the array type should be set to SL_RTL_AOX_ARRAY_TYPE_4x4_URA when using the reference 4x4 URA board.

◆ sl_rtl_aox_set_mode()

enum sl_rtl_error_code sl_rtl_aox_set_mode ( sl_rtl_aox_libitem *  item,
enum sl_rtl_aox_mode  mode 
)

Set the estimation mode.

Parameters
[in]itemPointer to the initialized AoX libitem
[in]modeEstimator mode as sl_rtl_aox_mode
Returns
SL_RTL_ERROR_SUCCESS if successful

Set the estimation mode. For example ::SL_RTL_AOX_MODE_BASIC sets medium filtering and estimates both azimuth and elevation. For further description of the modes, see the documentation of sl_rtl_aox_mode.

◆ sl_rtl_aox_calculate_iq_sample_phase_rotation()

enum sl_rtl_error_code sl_rtl_aox_calculate_iq_sample_phase_rotation ( sl_rtl_aox_libitem *  item,
float  iq_data_downsampling_factor,
float *  i_samples,
float *  q_samples,
uint32_t  num_samples,
float *  phase_rotation_out 
)

Estimate the I/Q-sample phase rotation error in degrees.

Parameters
[in]itemPointer to the initialized AoX libitem
[in]iq_data_downsampling_factorRatio between reference period IQ-data sampling rate and actual IQ-data (i.e. antenna array data) sampling rate. For example 1e6 / 500e3 = 2.0
[in]i_samplesFloat-array of the reference period I samples
[in]q_samplesFloat-array of the reference period Q samples
[in]num_samplesNumber of samples, or size of the I or Q sample array
[out]phase_rotation_outReturned phase rotation value as float in degrees
Returns
SL_RTL_ERROR_SUCCESS if successful

Estimate the I/Q-sample phase rotation error caused by switching and CTE frequency error based on I/Q samples from the reference period.

◆ sl_rtl_aox_set_iq_sample_phase_rotation()

enum sl_rtl_error_code sl_rtl_aox_set_iq_sample_phase_rotation ( sl_rtl_aox_libitem *  item,
float  phase_rotation 
)

Set a constant value of I/Q sample phase rotation in degrees.

Parameters
[in]itemPointer to the initialized AoX libitem
[in]phase_rotationFloat value of I/Q sample phase rotation in degrees
Returns
SL_RTL_ERROR_SUCCESS if successful

Set a constant value of I/Q sample phase rotation in degrees. The sample rotation can be used for correcting the switching and CTE frequency error.

Note
: This function should be called only after the estimator is created.

◆ sl_rtl_aox_add_constraint()

enum sl_rtl_error_code sl_rtl_aox_add_constraint ( sl_rtl_aox_libitem *  item,
enum sl_rtl_aox_constraint_type  constraint_type,
float  min_value,
float  max_value 
)

Add constraints for the estimator. Call before sl_rtl_aox_create_estimator.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]constraint_typeSelect which constraint should be added.
[in]min_valueStarting (minimum) value of the range including the min_value.
[in]max_valueEnding (maximum) value of the range including the max_value.
Returns
SL_RTL_ERROR_SUCCESS if successful

For example constraint for SL_RTL_AOX_CONSTRAINT_TYPE_AZIMUTH with min_value = 0 and max_value = 90 would mean that the angular range 0 to 90 degrees is excluded from the estimators internal processing range and angle estimated between that range are not considered as valid results. Setting constraints will help ruling out false multipath-detections when the locator is installed nearby a wall or a RF-reflective surface.

Note
: This function must called before the estimator is created.

◆ sl_rtl_aox_set_sample_rate()

enum sl_rtl_error_code sl_rtl_aox_set_sample_rate ( sl_rtl_aox_libitem *  item,
float  sampleRate 
)

Configure the IQ sampling sample rate for the library.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]sampleRateThe new sample rate.
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_set_num_radio_channels()

enum sl_rtl_error_code sl_rtl_aox_set_num_radio_channels ( sl_rtl_aox_libitem *  item,
uint32_t  channels 
)

Configure the number of radio channels.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]channelsThe new number of radio channels.
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_iq_sample_qa_configure()

enum sl_rtl_error_code sl_rtl_aox_iq_sample_qa_configure ( sl_rtl_aox_libitem *  item)

Configure the IQ sample quality analysis.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
Returns
SL_RTL_ERROR_SUCCESS if successful

The IQ sample quality analysis is not done by default, this function turns the functionality on.

◆ sl_rtl_aox_iq_sample_qa_get_results()

uint32_t sl_rtl_aox_iq_sample_qa_get_results ( sl_rtl_aox_libitem *  item)

Get the IQ sample quality analysis overal results.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
Returns
bitmask of found problems, zero means everything is OK

◆ sl_rtl_aox_iq_sample_qa_get_details()

enum sl_rtl_error_code sl_rtl_aox_iq_sample_qa_get_details ( sl_rtl_aox_libitem *  item,
sl_rtl_clib_iq_sample_qa_dataset_t *  results,
sl_rtl_clib_iq_sample_qa_antenna_data_t *  antenna_data 
)

Get the IQ sample quality analysis detailed results for the latest packet.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[out]resultsThe data structure with all the data related to the latest data packet
[out]antenna_dataThe array of antenna specific results
Returns
SL_RTL_ERROR_SUCCESS if successful

Fetch the results for the latest packet.

◆ sl_rtl_aox_iq_sample_qa_get_channel_details()

enum sl_rtl_error_code sl_rtl_aox_iq_sample_qa_get_channel_details ( sl_rtl_aox_libitem *  item,
uint8_t  channel,
sl_rtl_clib_iq_sample_qa_dataset_t *  results,
sl_rtl_clib_iq_sample_qa_antenna_data_t *  antenna_data 
)

Get the IQ sample quality analysis detailed results for the requested radio channel.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]channelRadio channel to show results for.
[out]resultsThe data structure with all the data related to the last data packet using the requested channel
[out]antenna_dataThe array of antenna specific results
Returns
SL_RTL_ERROR_SUCCESS if successful

Fetch the latest results for the given radio channel. That may be other than the latest packet received.

◆ sl_rtl_aox_create_estimator()

enum sl_rtl_error_code sl_rtl_aox_create_estimator ( sl_rtl_aox_libitem *  item)

Create the estimator after initializing the libitem and setting the parameters.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_convert_raw_samples()

enum sl_rtl_error_code sl_rtl_aox_convert_raw_samples ( sl_rtl_aox_libitem *  item,
uint32_t  start_offset,
float  iq_data_downsampling_factor,
float *  raw_i_samples_in,
float *  raw_q_samples_in,
uint32_t  num_raw_samples_in,
float **  i_samples_out,
float **  q_samples_out,
uint32_t  num_snapshots_out 
)

Convert data in RAW IQ-data buffers to downsampled IQ-data buffers.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]start_offsetThe start offset in the buffer (for example for skipping a reference period)
[in]iq_data_downsampling_factorRatio between chip IQ-data sampling rate and downsampled rate. For example 4.8e6 / 500e3 = 9.6
[in]raw_i_samples_inI-part sample buffer input
[in]raw_q_samples_inQ-part sample buffer input
[in]num_raw_samples_inNumber of IQ-sample pairs in the input buffers
[out]i_samples_outBuffer for the processed I-samples. Must be allocated by the user. Indexing: i_samples_out[snapshot][antenna]
[out]q_samples_outBuffer for the processed Q-samples. Must be allocated by the user. Indexing: q_samples_out[snapshot][antenna]
[in]num_snapshots_outNumber of snaphots allocated in the output buffers. This function will check if the given number of snaphots and calculated snapshots based on the length of RAW-data match
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_calculate_number_of_snapshots()

enum sl_rtl_error_code sl_rtl_aox_calculate_number_of_snapshots ( sl_rtl_aox_libitem *  item,
uint32_t  num_raw_samples_in,
uint32_t  start_offset,
float  iq_data_downsampling_factor,
uint32_t  num_channels,
uint32_t *  num_snapshots_out 
)

Calculate the number of downsampled snaphots in a RAW IQ-data buffer. This function can be used for getting the number of snaphots for allocating the i_samples and q_samples buffers for the process-function.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]num_raw_samples_inTotal number of RAW IQ-sample pairs
[in]start_offsetThe start offset in the buffer (for example for skipping a reference period)
[in]iq_data_downsampling_factorRatio between chip IQ-data sampling rate and downsampled rate. For example 4.8e6 / 500e3 = 9.6.
[in]num_channelsNumber of channels in the RAW data
[out]num_snapshots_outCalculated number of snaphots based on the input
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_set_switch_pattern_mode()

enum sl_rtl_error_code sl_rtl_aox_set_switch_pattern_mode ( sl_rtl_aox_libitem *  item,
enum sl_rtl_aox_switch_pattern_mode  mode 
)

Set switch pattern mode. Sets internal mode used by the library. See enum sl_rtl_aox_switch_pattern_mode for detailed description of the modes. In case this function has not been called, a default switch pattern of: 0, 1, 2, 3, ..., N-1 will be used, where N is the number of antennas. This function can be called run-time after initializing and creating the estimator.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]modeRequired mode
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_update_switch_pattern()

enum sl_rtl_error_code sl_rtl_aox_update_switch_pattern ( sl_rtl_aox_libitem *  item,
uint32_t *  switch_pattern_in,
uint32_t **  switch_pattern_out 
)

Update switch pattern. Calling this function updates switching pattern used by the estimator algorithm. This function must be called before calling function sl_rtl_aox_process. This function can be called run-time after initializing and creating the estimator.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]switch_pattern_inPointer to the switch pattern array. The pointer must point to a valid switch pattern when SL_RTL_AOX_SWITCH_PATTERN_MODE_EXTERNAL is used.
[out]switch_pattern_outPointer to the user defined uint32_t* variable. This pointer must be non-zero when using internally defined switch pattern modes, otherwise can be zero.
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_reset_estimator()

enum sl_rtl_error_code sl_rtl_aox_reset_estimator ( sl_rtl_aox_libitem *  item)

Reset estimator state. Calling this function causes the selected aox-mode to start from its initial state. This function can be called run-time after initializing and creating the estimator.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
Returns
SL_RTL_ERROR_SUCCESS if successful

◆ sl_rtl_aox_process()

enum sl_rtl_error_code sl_rtl_aox_process ( sl_rtl_aox_libitem *  item,
float **  i_samples,
float **  q_samples,
float  tone_frequency,
float *  az_out,
float *  el_out 
)

Calculate the angle estimate.

Parameters
[in]itemPointer to the initialized and configured AoX libitem
[in]i_samplesTwo-dimensional float-array of captured I samples as i_samples[snapshot][antenna]
[in]q_samplesTwo-dimensional float-array of captured Q samples as q_samples[snapshot][antenna], corresponding to the I samples array
[in]tone_frequencyThe frequency of the signal from which the I/Q data was captured from as float (e.g. 2.46e9f)
[out]az_outOutput azimuth angle
[out]el_outOutput elevation angle
Returns
SL_RTL_ERROR_SUCCESS if successful and SL_RTL_ERROR_ESTIMATION_IN_PROGRESS if estimate is not yet final and more I/Q data needs to be processed.

Calculate the angle estimate from the given I/Q samples captured at the given frequency. Needs to be called with new I/Q data as many times as indicated by the sl_rtl_aox_mode used by the estimator before the final estimate is output.