Raystar 120 SDGPS Receiver Compact and accurate the Raystar 120 WAAS compatible Satellite Differential Receiver provides pinpoint accuracy to Raymarine's family of Raycharts and Raychart compatible Radars and Sounders. A self contained waterproof GPS receiver and antenna combined, the Raystar 120 delivers accuracy better then 3 meters by decoding GPS correction signals from the WAAS (Wide Area Augmentation System)