| 摘要 |
PROBLEM TO BE SOLVED: To reduce time required for polling by sending inquiry data to inquire about requests of data transmission sequentially and allowing a terminal equipment to send data in response to the inquiry data. SOLUTION: An identification number 0 is given to a terminal equipment replying the inquiry data at first and an identification number (k) being a natural number incremented from 1 sequentially is assigned to other terminal equipments, and a transmission reference timeβis expressed asβ=d+2α(0), whereα(k) is a transmission delay time between the center equipment and the terminal equipment whose identification number is (k), d is a time length of the inquiry data, r is a time length of the reply data,δis a prescribed time and s is a prescribed time satisfying a relation of 0<=s<=δ. The transmission delay time between the center equipment and the terminal equipmentα(k) is measured by conducting loopback transmission between each terminal equipment and the center equipment. The terminal equipment whose identification number is k sends reply data after a time expressed in equation after the end of reception of the inquiry data. Then a terminal equipment is located depending on at which time the reply data are received.
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