Lowrance 3500c 操作指南

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页码 136
Non aviators can use WAAS signals to make their GPS navigation even 
more accurate. Your unit receives both GPS and WAAS signals. How-
ever, WAAS has some limits you should know about. 
First, the U.S. government has not completed construction of the WAAS 
system, so it is not yet fully operational. The ground stations are in 
place, but only a few of the needed WAAS satellites have been launched. 
WAAS can boost the accuracy of land GPS navigation, but the system is 
designed for aircraft. The satellites are in a fixed orbit around the 
Equator, so they appear very low in the sky to someone on the ground 
in North America. Aircraft and vessels on open water can get consis-
tently good WAAS reception, but terrain, foliage or even large man-made 
structures frequently block the WAAS signal from ground receivers. 
You'll find that using your GPS receiver is both easy and amazingly 
accurate. It’s easily the most accurate method of electronic navigation 
available to the general public today. Remember, however, that this 
receiver is only a tool. Always have another method of navigation avail-
able, such as a map or chart and a compass. 
Also remember that this unit will always show navigation information 
in the shortest line from your present position to a waypoint, regardless 
of terrain! It only calculates position, it can’t know what’s between you 
and your destination, for example. It’s up to you to safely navigate 
around obstacles, no matter how you’re using this product. 
How to use this manual: typographical conventions 
Many instructions are listed as numbered steps. The keypad and arrow 
"keystrokes" appear as boldface type. So, if you're in a real hurry (or 
just need a reminder), you can skim the instructions and pick out what 
menu command to use by finding the boldface command text. The fol-
lowing paragraphs explain how to interpret the text formatting for 
those commands and other instructions: 
Arrow Keys 
The arrow keys control the movement of dotted cross-hair lines on your 
mapping screen called the cursor. The arrow keys help you move 
around the menus so you can execute different commands. They are 
represented by symbols like these, which denote the down arrow key, 
the up arrow, the left arrow and the right arrow: 
↓ ↑  →. 
Keyboard 
The other keys perform a variety of functions. When the text refers to a 
key to press, the key is shown  in bold, sans serif type. For example, the 
"Enter/Icons" key is shown as 
ENT 
and the "Menu" key is shown as 
MENU