Angle of Arrival measurement

I hope everyone is staying safe and healthy.

I am trying to implement the PDOA measurement described in “Angle of Arrival Estimation Using Decawave
DW1000 Integrated Circuits” by Dotlic, et. al.

Looking at the complex values in Figure 4, and using phase = atan2(im,re) like the code in the
PDOA development kit does, I get a negative phase difference Phase(a) - Phase(b)
for the first (direct) pulse, which has an AOA (theta) of +45 degrees in Figure 3.

For the second (reflected) pulse I get a zero phase difference for an AOA of 0 degrees.

From this it seems like the slope of phase PDOA vs. theta should be negative.
PDOA(theta = 0) = 0; PDOA(theta = +45) = negative.

This negative slope also agrees with my test of the code; if I assume Antenna A is the “master”,
Phase(a) - Phase(b) decreases as theta increases and Antenna A moves further away from the
transmitter than Antenna B.

However, the equations as well as Figure 5 and Figure 10 show a positive slope of PDOA vs AOA.

Can anyone clarify why we see this seeming inconsistency in the sign of the slope of PDOA vs AOA?

  • Robert Berger
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