OPTICAL BEACON AND IDENTIFICATION METHOD OF UPLINK RECEPTION POSITION USING THE SAME

PROBLEM TO BE SOLVED: To improve a position orientation accuracy of an uplink reception position in a final division area UA1 in a PD division type optical beacon 4.SOLUTION: The optical beacon 4 comprises: a position identification part 50 for identifying either representative point of Aas an uplink reception position in the Abased on a light reception level generated in each PD; and a storage part 48 for, in advance, storing a downstream end position of Aat which a PD1's light reception level is equal to a value obtained by multiplying a total value of the light reception level of all PDin an UA's boundary location by a prescribed factor. The position identification part 50 updates a threshold value for Ato a value obtained by multiplying a total value of the light reception level of all PDin a previous uplink information reception by the specific factor when a previously identified uplink reception position is in a range from the UA's boundary location to Aand the uplink reception position is included in A. The stored downstream end position is regarded as an A's representative point when the PD1's light reception level in the current uplink information reception is more than or equal to the updated threshold level.