Lowrance electronic GlobalMap 3300C - Manual (Page 10)

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NOTICE!
The storage and operation temperature range for your unit is from -4
degrees to +167 degrees Fahrenheit (-20 degrees to +75 degrees Cel-
sius). Extended storage or operation in temperatures higher or lower
than specified will damage the liquid crystal display in your unit. This
type of damage is not covered by the warranty. For more information,
contact the factory's Customer Service Department; phone numbers are
listed on the last page.
How Lowrance GPS Works
You'll navigate faster and easier if you understand how the unit scans
the sky to tell you where you are on the earth — and, where you're go-
ing. (But if you already have a working understanding of GPS receivers
and the GPS navigation system, skip on ahead to Section 2, Installation
& Accessories on page 11. If you're new to GPS, read on, and you can
later impress your friends with your new-found knowledge.)
First, think of your unit as a small but powerful computer. (But don't
worry — we made the units in this series easy to use, so you don't need
to be a computer expert to find your way!) The unit includes a keypad
and a screen with menus so you can tell it what to do. The screen also
lets the unit show your location on a moving map, as well as point the
way to your destination.
This gimbal-mounted unit uses an external antenna/receiver module,
which makes the whole system work 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.)
Your unit 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 it figures its latitude and longitude,
it plots that position on the moving map shown on the screen. The
whole process takes place several times a second!
The performance doesn't stop there. Stored in the permanent memory
of each GPS unit 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.
The background map is suitable for many navigation chores, but for
maximum accuracy and much more detail, you need our optional map-
making software, MapCreate
 6. Some unit features — such as
searching for businesses and addresses — won't work without a custom