In order to use the dGPS, it is imperative that we understand the basics of GPS navigation.

The two components of a GPS coordinate are latitude and longitude. Together, these two numbers allow a GPS receiver to pinpoint its exact position on Earth. Mapping systems such as Google Maps use a decimal-degree format to represent latitude and longitude, meaning these values are in the form dd.mmmmmm. The dGPS provides latitude and longitude information in an integer decimal-degree format, which means it always expresses position figures as an integer, or whole number, in the form ddmmmmmm. You can think of it as a decimal-degree format where the decimal point has been removed. For example, a hypothetical latitude value in decimal-degree format could be 40.948162  degrees; the dGPS would report this latitude as 40948162 .

The sign of the latitude and longitude values indicate which hemisphere the GPS receiver is located in. A positive latitude indicates that the GPS is in the northern hemisphere, and a negative latitude indicates a location in the southern hemisphere; the greater the magnitude of the latitude value, the farther the GPS is from the equator. A positive longitude value indicates that the GPS is in the eastern hemisphere, and a negative longitude indicates a location in the western hemisphere; the magnitude of the longitude value indicates the distance from the prime meridian.

In an open field, a GPS receiver can pinpoint its location to within 1–3 meters. Environmental obstructions such as trees or buildings block the GPS receiver's line of sight to the sky and cause the signal sent by the satellite to bounce before it reaches the GPS receiver. This causes the GPS's accuracy to decrease. To obtain the best accuracy, use the dGPS in an environment with few obstructions. Because there is always some amount of error inherent in determining GPS position, the coordinates provided by a GPS receiver are considered estimates.