CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

RE: CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

batuhanates — Wed, 14 Jul 2021 14:48:37 GMT

I've already examined and used the direction finding samples for the standard ble way which sends CTE in AUX_SYNC_IND. But I'm trying to find a non-standard way for sending CTE in AUX_ADV_IND instead.

Could you explain what do you mean by using direct radio? Is it possible for you to share the code for transmitter if it's not a private project?

RE: CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

Hardik.Harpal — Wed, 14 Jul 2021 14:38:22 GMT

Now there are samples on NCS

https://github.com/nrfconnect/sdk-nrf/tree/master/samples/bluetooth/direction_finding_connectionless_rx

https://github.com/nrfconnect/sdk-nrf/tree/master/samples/bluetooth/direction_finding_connectionless_tx

I have done non standard ble way using direct radio

RE: CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

batuhanates — Wed, 14 Jul 2021 14:32:03 GMT

Hi, I was wondering if you've find a solution for this problem. I am trying something similar, but instead of AUX_EXT_IND I am trying to send CTE in AUX_ADV_IND.

The solutions could be similar so, I would appreciate any help or suggested starting points if you've managed to make it work in a stable way.

RE: CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

Simonr — Thu, 18 Feb 2021 07:45:25 GMT

[quote user="Hardik.Harpal"]Is there any starting point available from nordic regarding it?[/quote]

I'm sorry, but we don't have anything but the previously mentioned whitepaper publicly available as of yet. You're correct that the SoftDevice will not be used in any direction finding projects by us, as we will focus on getting it to the NCS SDK.

Please see section 2.2 in the whitepaper for information on how you determine the correct angle of arrival by sampling phase and switching antennas. Angle calculation can be do9ne using the following equation:

Best regards,

Simon

RE: CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

Hardik.Harpal — Wed, 17 Feb 2021 12:32:51 GMT

Thank you for clarification.

I was able to get IQ data (at the moment only two antenna is used for switching) but it is with ADV_EXT_IND PDU only. Using ADV_EXT_IND and not using inline CTE info sending using NRF RADIO with DFE settings, but as that is not as per BLE specs.

As per my understanding Periodic Advertisement implementation with sync based on raw NRF Radio peripheral as per BLE specs without Soft device for both Tx(broadcaster) and Rx(Scanner) will be a complex and time consuming task. Am I right? Is there any starting point available from nordic regarding it?

Can you comment on IQ data, Is my understanding correct on how sample taken with respects to antenna with my configuration for DFE?

Reading from switching slot should be discarded for phase difference calculation?

Can you guide me in right direction for phase difference calculation? What are the different methods?

r_df_params.mode = RADIO_DFEMODE_DFEOPMODE_AoA,
r_df_params.cteinlinectrlen = RADIO_CTEINLINECONF_CTEINLINECTRLEN_Disabled,
r_df_params.cteinfoins1 = RADIO_CTEINLINECONF_CTEINFOINS1_NotInS1,
r_df_params.cteerrorhandling = RADIO_CTEINLINECONF_CTEERRORHANDLING_Yes,
r_df_params.ctetimevalidrange = RADIO_CTEINLINECONF_CTETIMEVALIDRANGE_20,
r_df_params.dfeinextension = RADIO_DFECTRL1_DFEINEXTENSION_CRC,
r_df_params.tswitchspacing = RADIO_DFECTRL1_TSWITCHSPACING_2us,
r_df_params.tsamplespacingref = RADIO_DFECTRL1_TSAMPLESPACINGREF_250ns,
r_df_params.tsamplespacing = RADIO_DFECTRL1_TSAMPLESPACINGREF_250ns,
r_df_params.repeatpattern = RADIO_DFECTRL1_REPEATPATTERN_NoRepeat,
r_df_params.agcbackoffgain = 0,
r_df_params.tswitchoffset = 0,
r_df_params.tsampleoffset = RADIO_DFECTRL2_TSAMPLEOFFSET_1us,
r_df_params.sampletype = 0,
r_df_params.s0conf = 0,
r_df_params.s0mask = 0,
r_df_params.numof8us = 0x3,

Antenna #	Slot Type	I	Q
1	Sampling	123	-110
		154	-44
		164	24
		147	84
		104	130
		46	159
		-18	165
		-80	146
		-129	104
		-152	39
		-149	-40
		-126	-111
		-84	-153
		-25	-164
		44	-153
		106	-122
		149	-75
		164	-16
		151	51
		113	111
		58	152
		-5	165
		-68	149
		-121	109
		-152	53
		-156	-14
		-135	-83
		-94	-135
		-36	-159
		30	-154
		90	-125
		137	-79
1	Switching	40	159
		-27	161
		-93	147
		-138	151
	Sampling	-153	179
		-153	203
		-162	187
		-187	115
2	Switching	-215	9
		-212	-90
		-165	-147
		-87	-134
	Sampling	-1	-55
		58	49
		71	134
		36	171
1	Switching	-26	162
		-94	133
		-148	111
		-183	119
	Sampling	-197	147
		-204	164
		-211	140
		-221	65
2	Switching	-222	-40
		-200	-134
		-147	-181
		-75	-152
	Sampling	-2	-60
		46	52
		51	138
		10	171
1	Switching	-57	153
		-121	112
		-165	82
		-193	79
	Sampling	-213	100
		-229	113
		-236	91
		-226	19
2	Switching	-195	-82
		-141	-169
		-75	-202
		-15	-157
	Sampling	31	-51
		50	66
		37	150
		-6	176

Regards,

Hardik Harpal

RE: CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

Simonr — Tue, 16 Feb 2021 06:16:08 GMT

Glad to hear that you've already read our whitepaper.

It seems you have understood this correctly, and Connection-less CTE transmission will only be possible with AUX_SYNC_IND PDU type advertisement, which means CTE will be sent on secondary advertisement channels according to the BLE spec.

As for your application, I haven't seen how exactly you're doing IQ transmission on primary channels, but it should be possible to get usable results by advertising and scanning on the primary channels as well, although it will be out of spec, so you're definitely on the right track.

Best regards,

Simon

RE: CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

Hardik.Harpal — Tue, 16 Feb 2021 03:59:09 GMT

[quote userid="75734" url="~/f/nordic-q-a/71632/cte-can-be-only-appended-in-aux_sync_ind-so-it-will-be-on-secondary-advertisement-channel/294418#294418"]To get started with Direction finding with our products, I would recommend reading our DIrection Finding Whitepaper which describes how to configure and enable the Bluetooth Direction Finding features of nRF52 and 53 series.[/quote]

Following that from day one.

[quote userid="75734" url="~/f/nordic-q-a/71632/cte-can-be-only-appended-in-aux_sync_ind-so-it-will-be-on-secondary-advertisement-channel/294418#294418"]Let me check with our experts on the matter whether your assumptions on secondary advertisements are correct. I'll get back to you when I hear from them.[/quote]

Ok.

RE: CTE can be only appended in AUX_SYNC_IND, So it will be on secondary advertisement channel?

Simonr — Mon, 15 Feb 2021 14:22:23 GMT

To get started with Direction finding with our products, I would recommend reading our DIrection Finding Whitepaper which describes how to configure and enable the Bluetooth Direction Finding features of nRF52 and 53 series.

Let me check with our experts on the matter whether your assumptions on secondary advertisements are correct. I'll get back to you when I hear from them.

Best regards,

Simon