This report describes the solution planed to a determined problem consisting in detecting radio- controlled slope soaring airplanes through a gate in races (FAI, F3F discipline). The current method is a judge with a flag, which implies a subjective and slow reaction capability that induces irregular and, hence, unfair mistakes. Therefore, the need of improving the system brings us to design a solution to this problem based on an angle of arrival detection system whose evolution will be exposed in detail going from the development of the frst idea to the building of a prototype and projection of further improvement to finally make a commercial product. 2015/2016