Methods and systems for indirectly profiling a secondary surveillance radar (ssr) and determining a position of an aircraft using thereof

A method for indirect profiling a Secondary Surveillance Radar (SSR), comprising:

• at a Passive Secondary Surveillance Radar (PSSR), the PSSR not being able to receive interrogation signals from the SSR:
• (a) collecting transponder response signals from an opportunistic aircraft, the opportunistic aircraft being:
• (i) equipped with a transponder and has an Automatic Dependent Surveillance-Broadcast (ADS-B) Out functionality;
• (ii) in the Line-of-Sight with both the SSR and the PSSR;
• and
• (iii) interrogated, during one or more rotations of the SSR, with interrogation signals from the SSR when the opportunistic aircraft is within a beam of the SSR;
• (b) receiving an ADS-B Out response from the opportunistic aircraft and decoding a spatial position of the opportunistic aircraft from the ADS-B Out response;
• (c) determining a staggered Pulse Repetition Frequency (PRF) pattern of the SSR using the collected transponder response signals, the decoded spatial position of the opportunistic aircraft, a position of the ownship and a position of the SSR, and a predetermined transponder response time at the opportunistic aircraft.

A Passive Secondary Surveillance Radar (PSSR), not being able to receive interrogation signals from a Secondary Surveillance Radar (SSR), the PSSR comprising:

• (a) means for collecting transponder response signals from an opportunistic aircraft to interrogation signals from the SSR during one or more rotations of the SSR;
• the opportunistic aircraft is:
• (i) equipped with a transponder and has an Automatic Dependent Surveillance-Broadcast (ADS-B) Out functionality;
• (ii) in the Line-of-Sight with both the SSR and the PSSR;
• (iii) interrogated with the interrogation signals from the SSR, when the opportunistic aircraft is within a beam of the SSR during said one or more rotations of the SSR;
• (b) means for receiving an ADS-B Out response from the opportunistic aircraft and decoding a spatial position of the opportunistic aircraft from the ADS-B Out response;
• (c) means for determining a staggered Pulse Repetition Frequency (PRF) pattern of the SSR using the collected transponder response signals, the decoded spatial position of the opportunistic aircraft, a position of the ownship and a position of the SSR, and a predetermined transponder response time at the opportunistic aircraft.