Positioning sensor and direction estimation method

A method for estimating an incoming direction of a signal in a positioning sensor, the positioning sensor including

• a transmission antenna that transmits a transmission signal to a predetermined area in search of a moving body,
• a plurality of reception antennae, each of which receives a reception signal, one or more a plurality of the reception signals received includes a reflection signal generated by the moving body reflecting the transmission signal,
• a receiver that observes each of the plurality of reception signals in a predetermined sampling cycle in a predetermined period,
• a processor, and
• a memory,
• the method comprising:
• calculating, by the processor, a plurality of complex transfer functions, each of the plurality of complex transfer functions representing a propagation characteristics between the transmission antenna and each of the plurality of reception antennae based on each of the plurality of reception signals;
• recording, by the processor, each of the plurality of complex transfer functions in the memory as being associated with each time point at which each of the plurality of reception signals is observed, each of the plurality of reception signals corresponding to each of the plurality of complex transfer functions;
• extracting, by the processor and among the plurality of complex transfer functions, a plurality of pairs of two complex transfer functions respectively corresponding to two time points in a predetermined interval;
• calculating, by the processor, a plurality of pieces of differential information representing a difference between a pair of two complex transfer functions included in each of the plurality of pairs of two complex transfer functions, each of the plurality of pieces of differential information being expressed by a vector of N dimensions;
• and
• estimating, by the processor, a direction to a location of the moving body, with respect to the positioning sensor based on each of the plurality of pieces of differential information.