US Patent 10228444 Method and system for determining whether a portable key device is located in an active area in relation to a barrier

It is presented a method for determining whether a portable key device is located in an active area in relation to a barrier. The method is performed in an access control device and comprising the steps of: detecting a first angle of arrival of a wireless signal from the portable key device using a first pair of separated antennas; detecting a second angle of arrival of a wireless signal from the portable key device using a second pair of separated antennas; determining a first pair of directions based on the first angle of arrival; determining a second pair of directions based on the second angle of arrival; determining a position of the portable key device to be where one of the first pair of directions intersects one of the second pair of directions; and determining whether the portable key device is located in the active area based on the position.