The PN-40 comes equipped with a three-axis electronic compass that can provide compass direction while stationery. The electronic compass is disabled when moving and the GPS heading is used. The PN-40 makes it easy to calibrate the compass for use in the field; simply follow the ...The PN-40 comes equipped with a three-axis electronic compass that can provide compass direction while stationery.
The electronic compass is disabled when moving and the GPS heading is used. The PN-40 makes it easy to calibrate the compass for use in the field; simply follow the on-screen directions and you're set to go. DeLorme also includes an accelerometer, which in tandem with the compass provides the ability to figure the angle the GPS is tilted and determine an accurate compass reading regardless of how you are holding the PN-40 in your hand (tilted up, face down, etc.).
Accelerometers measure the amount of static acceleration due to gravity; by sensing the amount of dynamic acceleration, the PN-40 can analyze the way the device is moving and make adjustments. The PN-40 comes equipped with a barometric altimeter for providing accurate altitude readings. The barometric altimeter works in conjunction with the GPS to measure elevation when using auto calibration (if auto calibration is disabled, then the barometric altimeter is the only sensor providing elevation information).
GPS by itself can only factor an approximate altitude reading, but in conjunction with the altimeter the PN-40 can provide accurate elevation data.