After you initialize your GPS receiver for the first time, you need to change a few of the receiver’s default system settings. You only need to do this once, and a few GPS receivers will prompt you to make some of these changes as part of the initialization process. These changes are mostly to customize settings based on your location and needs. Check your user manual for specific information on how to change the system settings described below. An example of a GPS receiver system settings page is shown in Figure 5-2.
Figure 5-2:
A GPS receiver system settings page showing time options.
Although GPS receivers have a number of system settings that you can change, here are some of the important settings you’ll want to initially adjust:
Time: Your GPS receiver gets very precise time data from atomic clocks aboard the satellites, but it’s up to you how the time will be displayed. You need to specify
• Whether to use 24-hour (military time) or 12-hour (AM and PM) time
• Whether Daylight Savings Time is automatically turned on and off
• What your time zone is (or your offset from UTC)
Your GPS receiver gets time data from the satellites in the UTC format. UTC stands for Coordinated Universal Time (no, the acronym doesn’t match the meaning), an international time standard. UTC is a time scale kept by laboratories around the world, using highly precise atomic clocks. The International Bureau of Weights and Measures uses time data collected from the labs to establish UTC, which is accurate to approximately one nanosecond (about a billionth of a second) per day. In 1986, UTC replaced Greenwich Mean Time (GMT) as the world time standard. The Greenwich meridian (prime meridian, or zero degrees longitude) is the starting point of every time zone in the world. GMT is the mean time that the earth takes to rotate from noon to the following noon. These observations have been kept since 1884 at the Royal Observatory in Greenwich, England. In hours, minutes, and seconds, UTC and GMT always have the same values.
Units of measure: Your GPS receiver can display distance information in statute (such as feet and miles), nautical (knots), or metric (meters and kilometers) formats. The default setting for GPS units sold in the United States is statute, so unless you’re boating or want to use the more logical metric system, leave the setting as-is.
Coordinate system: By default, your GPS receiver displays positions in latitude and longitude. If you want to use location coordinates in a different format, now’s the time to change the setting.
Datum: The default datum for all GPS receivers is WGS 84. Unless you’re planning on using your receiver with maps that have a different datum, leave the default setting.
Battery type: The default battery setting on most GPS receivers is alkaline. If you’re using another type of battery, select the correct type. The battery type setting doesn’t affect the GPS receiver’s operation; it only ensures that the battery life is correctly displayed on the screen because different types of batteries have different power characteristics.
Language: Most GPS receivers are multilingual, so if you’d rather view the user interface in a language other than English, it’s as simple as selecting a different language from a menu.
