What happens when you turn on the fast time constant (differentiator) control of a radar?

When the fast time constant (differentiator) control of a radar is activated, it primarily focuses on providing a clearer and more defined presentation of the radar display by shortening the echoes of objects detected. This function allows for the suppression of persistent clutter, especially in the presence of sea waves and other background noise. By reducing the duration of echoes, it helps to minimize the display of non-moving targets, resulting in cleaner images and making it easier to distinguish between the actual targets of interest and surrounding clutter.

This functionality is critical for increasing the radar's effectiveness in navigating and monitoring environments where background noise might otherwise obscure vital information. The ability to reduce clutter over the entire Plan Position Indicator (PPI) screen ensures that the radar operators can interpret the data more accurately, enabling better decision-making while navigating or operating in busy maritime environments.