Overview

Magnetic Variation data output enables the GPS module to output degree of magnetic variation & measured magnetic heading. This is particularly useful in aviation, marine and military GPS navigation devices where bearing is used to determine direction and navigation.

Background

Earth’s magnetic field is in constant motion and shifts in position with the passage of time. Consequently, the magnetic poles at both ends aren’t a precise indication of true geographical North and South.

Magnetic Variation, or magnetic declination, describe by signed degrees, is the angle between magnetic north (Nm ) and true north (geographic ,Ng). The variation is positive when the magnetic north is east of true north and negative when the magnetic north is west of true north.

A typical magnetic compass without any magnetic variation adjustment, can only points toward the “magnetic pole”, rather than true geographical pole. But true north is the direction in which the North Pole is located along the Earth's rotational axis.

The amount of magnetic variation may change by as few as couple degrees every hundred years, this may be insignificant to most travelers, but can be important for direction adjustment in professional aviation, marine, and military GPS navigation devices.

For example, as a ship cruises the east coast of the United States, the variation may range from 20 degrees west (in Maine), to zero (in Florida), to 10 degrees east (in Texas). Meaning a compass adjusted at the beginning of the journey would have a true north error of over 30 degrees if not adjusted for the changing variation.

Typically marine GPS units usually include this data in their RMC sentence, but most of embedded GPS modules, such as those used in transponders and other GPS receiver devices, do not provide the option for magnetic variation calculation.

GlobalTop Solution

GlobalTop supplies customized GPS firmware for magnetic variation information output used in the professional field, and is suitable for marine, aviation, or military GPS navigation devices and applications.

Requirement

Special firmware is required; please contact us for more details