A radio navigation aid operated and maintained by the U.S. Coast Guard. It is used as a supplemental system for harbor approach navigation and inland navigation. Magnetic North Represents the direction of the north magnetic pole from the observer's position. The direction a compass points. Magnetic Variation Errors in magnetic compass readings caused by changes in the earth's magnetic field at different locations on the planet.
Navigational charts list the variation and a yearly level of increase.
A graphic representation of a geographic area and the features in it. Multiplexing Receiver A GPS receiver that switches at a very rapid rate between satellites being tracked. Typically, multiplexing receivers require more time for satellite acquisition, and are not as accurate as parallel channel receivers. Multiplexing receivers are also more prone to lose a satellite fix in dense woods than parallel channel GPS receivers. Multipath An error caused when a satellite signal reaches the GPS receiver antenna by more than one path.