Patent ID: 7391359

Claim:
A Mode S transponder transmission signal decoder for decoding a Mode S transponder transmission signal transmitted by a transponder mounted on an aircraft, comprising: a differential processing unit which performs differential processing for the Mode S transponder transmission signal; an auto correlation arithmetic operation unit which performs an arithmetic operation of a degree of auto correlation between an increasing change rate and decreasing change rate of a power level in the signal which has been subjected to the differential processing; a pulse regeneration unit which specifies a position of a pulse in the signal which has been subjected to the auto correlation arithmetic operation processing and regenerates the pulse based on the degree of auto correlation and a standard of a Mode S signal, the degree having been obtained by the auto correlation arithmetic operation processing; a phase locked loop unit which performs gate processing and phase locked processing for the regenerated pulse based on the standard of the Mode S signal; and a decoding unit which decodes the Mode S transponder transmission signal based on the pulse which has been subjected to the gate processing and the phase locked processing.