Electronic chart system
12
7
：
Add marked points
20:
Showns the location
of this ship
8
：
Next point
21:
direction key (Up / down / Left
/right / upper left / upper right / Lower left / lower right)
9
：
MOB point storage
10
：
Brightness adjustment knob
22:
Narrow chart
11
：
Track color
23
：
Chart to enlarge
12
：
Track switch
13
：
prev /input method switch
Description:In the normal state of navigation,
，
〖
After
point
〗
Is to change the chart style
.
〖
prev
〗
key is to enter
the distance function
1-5 The background of GPS (Global
Positioning System)
1-5-1 GPS satellites:
GPS positioning system uses 24 satellites (21 plus 3 spare),satellite around the Earth
takes 11 hours 58 minutes. When all the satellites in their track,
We can
obtain
accurate positioning anywhere in the world all the day.
1-5-2. Positioning principle
:
Your position can be calculated according to the distance of the two satellite-to-ship.
We
Calculate
the time of ships satellite signal to get the distance(300000 miles or
186000 miles per second). However, The clock signal is not synchronous between
satellites and GPS receiver in the actual using, So it need third satellite signal to
calculate your position..
The vessel's position is the intersection of the three distance.
Note:
1.the actual GPS positioning accuracy is decided by The United States defense
departmentt ,precision: RMS<15m.
2.The GPS which measure the latitude, longitude and altitude is the WGS-84,
the
standard benchmark all the world.
