Both radar systems provide precise automatic adjustment of gain, sea state and rain rejection plus full range manual adjustment for all parameters. The performance of the processing circuits used to optimize the radar image has been significantly improved. For example, sea clutter interference is reduced by automatically adjusting the received signal processing circuits for each successive search bearing rather than relying upon a global adjustment that treats the entire screen equally. Raymarine's system simplifies operator adjustment of the radar with an additional choice of four preset operating modes: Buoy, Harbor, Coastal and Offshore, each optimized for the average conditions implied by their names, ranging from a flat water surface viewed at short range to moderate open sea conditions. The signal-shape-based data processing employed in digital radar improves the ability of the system to differentiate between closely adjacent targets and reduces interference that results from the side lobes of the antenna. The result is a cleaner, more precise radar image of both close-in and distant targets.