Mode S radar

A Mode S radar which specifies an aircraft by transmitting interrogations to a Mode S transponder installed in an aircraft, by receiving replies to the interrogations, and by then decoding the contents of the received replies, the Mode S radar comprising:

• acquisition means, which transmits a Mode S only all-call interrogation, and which thereby accomplishes an initial acquisition of an aircraft equipped with a Mode S transponder;
• first obtainment means, which transmits UF=4 and UF=5 as Mode S selective interrogations to the Mode-S-transponder-equipped aircraft with the initial acquisition having been accomplished by the acquisition means, and which thereby obtains a Mode A code as a DF=5 reply from the Mode-S-transponder-equipped aircraft;
• scan counting means, which counts the number of scans performed on the Mode-S-transponder-equipped aircraft after the initial acquisition;
• second obtainment means, which transmits UF=4 and UF=5, as Mode S selective interrogations, to the Mode-S-transponder-equipped aircraft every time the number of scans counted by the scan counting means reaches a preset optimal number of scans after a Mode A code is obtained by the first obtainment means, and which thereby re-obtains a Mode A code as a new DF=5 reply from the Mode-S-transponder-equipped aircraft;
• and
• generation means, which generates a detection report on the aircraft.