System for detecting position of object having data carrier

摘要

A plurality of data carriers are prepared and possessed by, for example, persons who enter a building. The data carrier spread spectrum modulates a carrier signal of a predetermined frequency by an assigned Gold series corresponding to an ID code and transmits the modulated signal. Leaky cables each having a predetermined length are two-dimensionally distributed and arranged in the building. A frequency converter is connected to one end of each of the leaky cables and frequency converts the spread spectrum signal from the data carrier which has propagated the leaky cable into a frequency unique to the cable and sends the converted frequency signal to a central receiving unit through a transmission cable. The receiving unit individually demodulates the signal series from the reception signals and sequentially executes correlation calculations between the signal series and the Gold series assigned to the data carriers. The position of the leaky cable where the data carrier exists is obtained on the basis of a time difference between the time when a correlation peak value of the reception signal series demodulated by the frequency unique to the data carrier has been obtained by the correlation calculations and the time when a correlation peak value of the reception signal series demodulated by the frequency unique to the leaky cable has been obtained. The data carrier is discriminated from reference Gold series used in the correlation calculations of the correlation peak values.