7OperationNOISE REJECTIONNOISE REJECTION is to reject noise interference from nearby fishing vessels.Each press of the 【 】or【 】key changes the ability for rejecting theinterference as follow:ZOOMBottom-lock zoom ModeIf Bottom lock zoom is on, the zoom section moves so the bottom is alwaysdisplayed in the zoom section, regardless of changes in depth.Bottom lock zoom is not available in dual-frequency mode or range relay