Method for Increasing the Time for Illumination of Targets by a Secondary Surveillance Radar

A secondary surveillance radar comprising:

• an antenna having a radiation diagram forming a Sum channel, Σ, a radiation diagram forming a Difference channel, Δ, and a diagram forming a Control channel, Ω,
• means for generating “Sum channel” interrogation messages and ISLS “Control channel” interrogation messages,
• means for transmitting these messages by the Sum and Control channels, respectively, of the antenna together with means for the reception and the processing of the radio signals received by the Sum, Control and Difference channels configured for detecting the aircraft responses on the signals received by the Sum channel of the antenna and for performing monopulse processing and SLS processing on these responses using the signals received by the Difference and Control channels of the antenna;
• wherein the means for generating interrogation messages are configured for also generating “Difference channel” interrogation messages;
• and
• wherein the transmission means are configured for the ability to transmit these messages by the Difference channel of the antenna, the means for generating interrogation messages comprising means for managing the transmission of each interrogation message to the corresponding transmission channel;
• and the means for the reception and the processing of the radio signals received by the Sum, Control and Difference channels are configured for detecting the responses from aircraft on the signals received by the Difference channel of the antenna, the means being configured and arranged in such a manner that, for a given moment, the transactions between the radar and a given aircraft can be carried out either by the Sum channel of the antenna lobe, or by the Difference channel, depending on the position of the target within the antenna lobe at the moment in question, or by both channels.