What data is used to calculate the AoA tag position

[Tom.Fu]

Dear Support Team

I read the <<Bluetooth: Direction finding connectionless locator>> document and saw the log in the picture below. But I don't know which data is the key data to calculate the elevation angle and azimuth angle and how to calculate the tag position. Many thanks.

Bluetooth: Direction finding connectionless locator — nRF Connect SDK 2.3.99 documentation (nordicsemi.com)

[Simonr]

Hi

The IQ samples that are used for sampling data come after this CTE[X]: samples count line at the bottom like below:

IQ sample content : 
sample[0] = I:5 Q:0
sample[X] = I:X Q:X

This is only raw IQ data though and it must be converted into vector form to be reviewed properly. We don't have have any specific sample code showing this, but you can check out this page for information on the various formulas used to translate IQ data between polar and rectangular form. Nordic will not provide a Direction Finding algorithm for you I'm afraid. 

Best regards,

Simon

[Tom.Fu]

Hi Simon

On the locator end, how many ways to filter the target tags? Many thanks.

[Simonr]

Hi

I'm not sure what you mean about "how many ways to filter". Do you mean how to convert the IQ data into vector form or what? This is heavily case by case dependent, and I don't know exactly how many different ways there is to do it, except a lot...

Best regards,

Simon

[Tom.Fu]

Hi Simon

Simon said: Do you mean how to convert the IQ data into vector form or what? 

Tom：Oh Sorry, Not that, I mean that how does one manufacturer 's locator only locate its own tag, that is to say, how a locator filter its own target tags. 

[Simonr]

Hi again Tom

Thank you for explaining! I see. The first (and probably easiest) thing that comes to mind is to use directed advertising and a filter to ensure that the transmitter only transmits to the locator, and that the locator only locate its own tag.

In the Scanning Module documentation you can see how to set up a filter for Directed advertising beacons. How to set it up on the transmitter side is explained in the CAF advertising module documentation here. If you don't care if other scanning devices can see the transmitter, just adding a filter/whitelist for the transmitter should be sufficient as well I believe, either a whitelist for the device names or a UUID that is advertised from the transmitter can be used.

Best regards,

Simon