Lowrance electronic iFINDER GO - Manual (Page 10)

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This pocket-sized computer also contains an antenna and specialized
scanning receiver, something like your car radio. But instead of your
favorite dance tunes, this receiver tunes in to a couple of dozen GPS
satellites circling the earth. (It will also listen in to the WAAS satellites
in orbit, but more about that in the upcoming segment introducing you
to GPS and WAAS.)
iFINDER listens to signals from as many satellites as it can "see" above
the horizon, eliminates the weakest signals, then computes its location
in relation to those satellites. Once iFINDER figures its latitude and
longitude, it plots that position on the moving map shown on the
screen. While the screen is updated once a second, your iFINDER is
making these internal calculations and determining its position several
times a second!
The performance doesn't stop there. Stored in the permanent memory of
each iFINDER is a basic background map of the entire world. We lock it in
here at the factory — you can't change or erase this map.
Another portion of iFINDER's onboard memory is devoted to recording
GPS navigation information, which includes waypoints, event marker
icons, trails and routes. This lets you look back the way you came.
Think of this data storage like the hard drive memory in a computer or
a tape in a cassette tape recorder. You can save several different GPS
data files, erase 'em and record new ones, over and over and over again.
Introduction to GPS and WAAS
Well, now you know the basics of how iFINDER does its work. You
might be ready to jump ahead to Section 2, Installation & Accessories,
on page 9, so you can install the batteries. 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 6. 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 avail-
able at first, but it was less accurate because the military scrambled
the signal somewhat, using a process called Selective Availability (SA).
GPS proved so useful for civilian navigation that the federal govern-
ment discontinued SA on May 2, 2000, after the military developed