[Problem] To quickly and accurately estimate the distance or relative positional relationship between a plurality of wireless devices. [Solution] A wireless device is provided with an RF-signal transmission means, an RF-signal reception means, a loopback path, and a control means. The control means comprises a timing-pulse-signal transmission means, a timing-pulse-signal reception means, a delay-length reception means, and a distance estimation means. The loopback path loops RF signals transmitted by the RF-signal transmission means back to the RF-signal reception means. When the wireless device transmits a first timing-pulse signal and a second wireless device receives same, said second wireless device transmits a second timing-pulse signal. The second wireless device also transmits a delay length indicating the length of time between the reception of the first timing-pulse signal and the transmission of the second timing-pulse signal. The abovementioned distance estimation means estimates the distance between the wireless devices on the basis of the received first and second timing-pulse signals and the aforementioned delay length.
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