Introduction to GPS and Waas

files, this unit has a slot for an MMC (MultiMedia Card) or SDC (Secure Digital card) flash memory card. These solid-state memory devices are about the size of a postage stamp, but can hold data ranging from 8 MB to 1 GB in size. (Compare that to a floppy disk's 1.44 MB capacity!) The unit uses all that MMC space for two key GPS purposes. (The MMC is also used to record sonar logs. See page 5

First, you can backup your onboard GPS Data Files by copying them to the MMC. Since the MMC is removable (like a floppy disk or a cassette tape), you can store these GPS Data Files on a personal computer equipped with an MMC card reader. (Or store them on a pocketful of MMCs, if you don't have a computer.) Our MapCreate mapping software can save, edit or create its own GPS Data Files, which can be copied to the MMC and then loaded from the MMC into the unit's memory. (NOTE: No matter where they come from, GPS Data Files must be loaded from the MMC into memory before the unit can use them.)

The other key GPS use for MMCs is storage of special high-detail, custom maps, which you can produce on your computer with our MapCreate software. These MapCreate custom maps contain much greater detail than the basic background map. These Custom Map Files (file format *.lcm) can also be shared between other Eagle GPS or sonar/GPS units and personal computers. (For example, the exact same MMC, custom map files and GPS data files can be used interchangeably between your gimbal-mounted unit and the hand-held iFINDER GPS receiver.)

The unit automatically reads Custom Map Files directly from the MMC or SD card. To use a custom map, all you need to do is slide an MMC containing a map into the unit.

Well, now you know the basics of how the unit does its work. You might be ready to jump ahead to Section 2, Installation & Accessories, on page 11, so you can mount your unit and plug in the power. Or you might want to see how our text formatting makes the manual tutorials easy to skim. If that's the case, move on to "How to Use This Manual" on page

9.But, if you want to understand the current state of satellite navigation, look over this segment describing how GPS and its new companion WAAS work together to get you where you're going.

The Global Positioning System (GPS) was launched July 17, 1995 by the United States Department of Defense. It was designed as a 24- hour-a-day, 365-days-a-year, all weather global navigation system for the armed forces of the U.S. and its allies. Civilian use was also available, but it was less accurate because the military scrambled the signal somewhat, using a process called Selective Availability (SA.)