The AoA can be calculated by measuring the time difference of arrival (TDOA) between individual elements of the array.
In beamforming, the signal from each element is weighed to "steer" the gain of the antenna array.
If a wave is incident upon the array at broadside, then a 180° phase difference will be measured between the elements, corresponding to a 90° AoA.
In submarine acoustics, AoA is used to localize objects with active or passive ranging.
Limitations on the accuracy of estimation of angle of arrival signals in digital antenna arrays are associated with jitter ADC and DAC.