DETECTING SYSTEM FOR POSITION OF AIRCRAFT

摘要

PROBLEM TO BE SOLVED: To restore a system quickly in the case of a state that a specific secondary monitoring radar apparatus cannot transmit a query signal and that the position of an aircraft cannot be detected. SOLUTION: In a system, secondary monitoring radar apparatus 71, 72 whose effective range is overlapped transmit query signals I1, I2 whose repetitive cycle is different from each other, a plurality of target detection circuits B1 to Bn which are installed in remote places extract, from response signals R, only pulses having the cycle of the previously selected signal when the same response signals R are returned from an aircraft transponder 52 so as to be synchronized with cycles of the respective query signals I1, I2, and a position computing circuit 2 detects the position of an aircraft on the basis of a time difference which is found from pieces of receiving-time information M1 to Mn on the pulses. In the system, a cycle change part 1 in which, when the pieces of receiving-time information M1 to Mn cannot be obtained, the cycles which are selected by the respective target detection circuits B1 to Bn are changed over to the cycle of the query signal of the other secondary monitoring radar apparatus is installed.