how yo use AOA mode 1us,in RX,it is set 2us AOA,how to change it?

[swz_nordic]

i use the zephyr 3.0.9.i use direction with nrf52833 or nrf5340 in RX.The tx is nrf52833 with nrf of NCS,ITversion is  zephyr 2.7.9.The default is 2us AOA. I want to use 1us,i change the configurarion in main.c.The xlot_durations is 0x2,i change iit,make it as 0x1.

#if defined(CONFIG_BT_DF_CTE_RX_AOA)
		.cte_types = BT_DF_CTE_TYPE_ALL,
		.slot_durations = 0x1,
		.num_ant_ids = ARRAY_SIZE(ant_patterns),
		.ant_ids = ant_patterns,
#else
		.cte_types = BT_DF_CTE_TYPE_AOD_1US | BT_DF_CTE_TYPE_AOD_2US,
#endif /* CONFIG_BT_DF_CTE_RX_AOA */

but it is 2us mode. it is strange.this is my putty output.

PER_ADV_SYNC[0]: [DEVICE]: 3C:D0:89:51:58:90 (random), tx_power 127, RSSI -67, CTE AOA, data length 0, data:

CTE[0]: samples count 45, cte type AOA, slot durations: 2 [us], packet status CRC OK, RSSI -670

IQ sample content :

sample[0] = I:-2 Q:1

sample[1] = I:3 Q:-3

sample[2] = I:-4 Q:1

sample[3] = I:2 Q:-3

sample[4] = I:-4 Q:2

sample[5] = I:3 Q:-1

sample[6] = I:-4 Q:1

sample[7] = I:2 Q:-5

sample[8] = I:4 Q:3

sample[9] = I:-4 Q:-5

sample[10] = I:0 Q:-6

sample[11] = I:2 Q:-4

sample[12] = I:2 Q:3

sample[13] = I:1 Q:0

sample[14] = I:0 Q:-1

sample[15] = I:0 Q:0

sample[16] = I:0 Q:1

sample[17] = I:3 Q:4

sample[18] = I:3 Q:0

sample[19] = I:0 Q:-4

sample[20] = I:-4 Q:5

sample[21] = I:-6 Q:2

sample[22] = I:-3 Q:-3

sample[23] = I:1 Q:-5

sample[24] = I:-1 Q:-2

sample[25] = I:2 Q:0

sample[26] = I:0 Q:-1

sample[27] = I:1 Q:-1

sample[28] = I:6 Q:-6

sample[29] = I:0 Q:-2

sample[30] = I:-6 Q:0

sample[31] = I:5 Q:1

sample[32] = I:4 Q:5

sample[33] = I:-1 Q:4

sample[34] = I:-5 Q:-1

sample[35] = I:-2 Q:0

sample[36] = I:0 Q:0

sample[37] = I:-1 Q:-1

sample[38] = I:-1 Q:-1

sample[39] = I:-5 Q:-5

sample[40] = I:-3 Q:1

sample[41] = I:0 Q:5

sample[42] = I:0 Q:-6

sample[43] = I:3 Q:-5

sample[44] = I:3 Q:0

can you help me?

[Simonr]

Hi, can you explain what you mean by "distinguish which IQ samples are from the antenna array"? The antenna array receives IQ samples from the beacon. The received IQ samples you get you'll need to convert into vector form to review properly, using an AOA algorithim, which we don't provide. You can check out this page for information on the various formulas used to translate IQ data between polar and rectangular form.

Best regards,

SImon

[swz_nordic]

Thank for your reply.i know your mening.i said that the sample 8 is from the secend antenna,the sample 9 is from the third antenna and so on.

The AOA algorithmn  have to use phase diffrence to get the direction.For example,so you have to the nubers 2 or 3 receive the sample iq numbers.do you think so?

[Simonr]

Yes, the direction finding is based on the phase difference between the antennas. But what exactly is the issue/question here?

Best regards,

Simon

[swz_nordic]

ok,i use the phase diffence to calculate the angle.the formula is below.

but when i  use Matlab from my iq sample to get the phase diffrence.then i use it to get the angle of DF. 

I find the angles are not corect.the below are my calculating result.