Angle calculation using phase difference

[SRINATH]

Hi, I am working on the angle of arrival calculation for direction finding. I am trying to calculate the AOA using below formula:

theta = arcsin (phase_difference *  wavelength) / (2 * pi * d)

with reference to https://github.com/MSBeni/AoA_IQsamples/issues/1 AoA_v3.pdf.

But In bluetooth core specification (Core_v5.1.pdf) I have attached below, they are calculating theta using below formula(page 282):

theta = arccos (phase_difference *  wavelength) / (2 * pi * d)

Core_v5.1.pdf: https://www.scribd.com/document/416017215/Core-v5-1-pdf# 

I am confused with this, which formula should I use to calculate the theta. Whether it depends on any other features?

[Elfving]

Hello,

Note the difference between fig1 in the paper and the illustration from the BLE spec. I think they just define θ a bit differently in the paper you've linked to, and changed the math to compensate.

Btw, I would recommend you to check out our whitepaper on direction finding if you haven't already.

Regards,

Elfving