Angle of arrival
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The angle of arrival (AoA) of a signal is the direction from which the signal (e.g. radio, optical or acoustic) is received.
Measurement
Measurement of AoA can be done by determining the direction of propagation of a radio-frequency wave incident on an antenna array or determined from maximum signal strength during antenna rotation.
The AoA can be calculated by measuring the
Generally this TDOA measurement is made by measuring the difference in received phase at each element in the antenna array. This can be thought of as beamforming in reverse. In beamforming, the signal from each element is weighed to "steer" the gain of the antenna array. In AoA, the delay of arrival at each element is measured directly and converted to an AoA measurement.
Consider, for example, a two element array spaced apart by one-half the wavelength of an incoming RF wave. If a wave is incident upon the array at boresight, it will arrive at each antenna simultaneously. This will yield 0° phase-difference measured between the two antenna elements, equivalent to a 0° AoA. 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 optics, AoA can be calculated using interferometry.
Applications
An application of AoA is in the
AoA is generally used to discover the location of pirate radio stations or of any military radio transmitter.
In
Limitation
Limitations on the accuracy of estimation of angle of arrival signals in digital antenna arrays are associated with jitter ADC and DAC.[1]
See also
- Geolocation
- GNSS
- GSM localization
- Multilateration
- Radiolocation
- Time of arrival
- Triangulation
- Trilateration
- Wideband Space Division Multiple Access
- Direction finding