Signal processing device and search method

A search method of searching for a direction in which a search target device is present,

• the search target device including a power reception circuit,
• the search method comprising:
• transmitting, while changing a direction of a directional antenna configured to wirelessly transmit electric power to the search target device, a search signal in the direction in which the directional antenna is directed;
• and
• searching for the direction of the search target device based on a magnitude of electric power of a response signal transmitted from the search target device which has received the search signal.

A sensor system comprising:

• a search target device including a power reception circuit;
• and
• a signal processing device configured to supply a search signal so as to search for a direction in which the search target device is present, the signal processing device comprising:
• a directional antenna which has a variable direction, and is configured to wirelessly transmit electric power to the search target device;
• a transmission circuit configured to wirelessly transmit the search signal for searching for the search target device;
• and a detection circuit configured to receive a response signal transmitted from the search target device which has received the search signal, and to supply a detection signal corresponding to electric power of the response signal,
• wherein the search signal is transmitted in a direction in which the directional antenna having the variable direction is directed.