distance tool box - IQ data and hopping sequence

RE: distance tool box - IQ data and hopping sequence

RachelK — Tue, 18 Mar 2025 14:42:57 GMT

Thank you for your response! This makes it much more clear.

RE: distance tool box - IQ data and hopping sequence

Elfving — Tue, 18 Mar 2025 14:33:45 GMT

That would make sense to me. I just checked with our NDT team, and yes - the NDT does use more than 40, 80 might be correct. NDT is a proprietary solution after all, and the HW does allow access to more than what BT SIG specifies, so there is no reason to avoid using more channels.

Regards,

Elfving

RE: distance tool box - IQ data and hopping sequence

RachelK — Tue, 18 Mar 2025 14:09:30 GMT

Hello Elfving,

I did an inverse Fast Fourier Transformation both over all channels ranging from 2404 to 2478 MHz as well as over all even channels in this range (which should be the BLE channels). Strangely enough I get a significant better results if I perform an IFFT over all 80 channels. Do you have any idea why?

Regards,

Rachel

RE: distance tool box - IQ data and hopping sequence

Elfving — Tue, 18 Mar 2025 11:22:55 GMT

Hi Rachel,

[quote user="RachelK"] I have been able to extract the hopping sequence with nrf_dm_get_hopping_sequence() when building the application on the network core. [/quote]

Glad to hear it! 🙂

[quote user="RachelK"]

I have one more question, that might seem obvious but unclear to me, but why is the size of the IQ data 80 instead of 40, given that BLE only uses 40 frequency channels?

[/quote]

I think this is for the same reason mentioned in this previous case.

Regards,

Elfving

RE: distance tool box - IQ data and hopping sequence

RachelK — Tue, 18 Mar 2025 10:37:11 GMT

Hello Elfving,

Thank you for your response. I have been able to extract the hopping sequence with nrf_dm_get_hopping_sequence() when building the application on the network core.

I have one more question, that might seem obvious but unclear to me, but why is the size of the IQ data 80 instead of 40, given that BLE only uses 40 frequency channels?

Kind regards,

Rachel

RE: distance tool box - IQ data and hopping sequence

Elfving — Tue, 04 Feb 2025 15:08:34 GMT

Hi Rachel,

I am not sure if we have an example of it in use, but you can atleast have a look here. Are you getting any errors?

Regards,

Elfving

RE: distance tool box - IQ data and hopping sequence

RachelK — Tue, 28 Jan 2025 15:21:44 GMT

Hello,

How did you retrieve the hopping sequence? I am able to get the IQ data, but I cannot figure out how to run the function nrf_dm_get_hopping_sequence to get the hopping sequence.

Regards,
Rachel

RE: distance tool box - IQ data and hopping sequence

Elfving — Thu, 05 Jan 2023 09:10:05 GMT

Hello again, and thank you for your patience over the Holidays.

[quote user=""]

1. The IQ data array size is 80 and the hopping sequence array size is 75 then how can I match them?

[/quote]

As you've correctly deduced, channels 0-3 and 79 are not used and reported as 0. The IQ data is reported ordered, meaning the each entry in the array is reporting the corresponding frequency (2400 + index MHz). The first measurement that is reported at index 4 corresponds to 2404 MHz and the last one that is reported at index 78 corresponds to 2478 MHz. We used to use all of the 80 frequencies 2400, 2401, ..., 2479 MHz and is the reason for why the size of the IQ data array is 80. The data is not reported in the order of the hopping sequence but in order of ascending frequency.

[quote user=""] This is one example of the hopping sequence index and it seems that each device keeps using always same sequence even after reboot.[/quote]

The hopping sequence changes when the seed changes which should be the case for every ranging. We used to have a bug in the sample where the hopping sequence was always the same, which might be what you are experiencing. This is fixed on the main branch or the latest release.

Regards,

Elfving

RE: distance tool box - IQ data and hopping sequence

eleven-x_devteam — Thu, 22 Dec 2022 14:26:03 GMT

Happy holidays! :-)

RE: distance tool box - IQ data and hopping sequence

Elfving — Thu, 22 Dec 2022 14:23:37 GMT

Hello,

Unfortunately I will have to get back to you on this after the Holidays.

Regards,

Elfving