| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a position immediately below a beacon, taking into consideration the receiving state and phase decision in many frames. SOLUTION: A beacon emits AM signals with mutually different phases in both directions to the forward side and to the backward side of a beacon passing, while emitting the same traffic information signal in both the directions. An electric field strength detecting part 16 detects received electric field strength E and a phase detecting part 15 detects a phase of an AM signal SAM for every frame. A processing part 18 increments or decrements a phase count valueθ, corresponding to whether the AM signal phases are the same phases or opposite phases and monitors a peak valueθp of the phase output value (1), when the received electric field strength E is larger than a set strength Es1; it decides that a moving terminal exists at the position immediately below the beacon; and when (2) the peak valueθp is larger than a set peak value and the difference between the peak valueθp and the phase count valueθis a set value or more. |
