What is the biggest upgrade of Monopulse Secondary Surveillance Radars (MSSR) over older beacon radars?

Monopulse Secondary Surveillance Radars (MSSR) represent a significant advancement over older beacon radar systems primarily due to their ability to determine azimuth from a single return from a transponder. This capability allows MSSR to process the information more efficiently, producing precise angle measurements without the need for multiple scans. In older systems, determining the azimuth required multiple returns, which could lead to longer response times and potential inaccuracies due to the time delay between returns.

By using a technique that processes the received signal in such a way that the angle information can be extracted instantly from a single radar pulse, MSSR enhances the tracking capability of aircraft, ultimately improving overall air traffic management. This also translates into better performance in congested airspaces, where quick and accurate identification of aircraft locations is crucial.

The capabilities provided by MSSR align with modern needs for precision and efficiency in air traffic control, making this aspect of their technology the most notable upgrade.