What Functions Do the GPS Navigation System Have ?
Map query:
You can search you want to go in the end position on the operating terminal.
The position information of records you often have to go, and preserved, andcan share the position information.
Near the fuzzy query attachment or a location such as a gas station, hotel, ATMinformation.
Route planning:
The GPS navigation system based on the starting point and destination of yourset, a route planning automatically.
The planning of line can be set whether to go through some way point.
The planning of line can set whether to avoid high speed etc..
Automatic pilot.
◎ speech navigation: speech in advance to the driver with the intersection turning, navigation system and other traffic information, like a understand roadguide tells you how to drive to the destination. One of the most important functions in navigation, make you without watching the operation terminal, canreach the destination safely through the voice prompt.
◎ picture navigation: on the operating terminal, will display the map, and the position, the car is now running speed, the distance to the destination, the routeplanning tips, intersection turning traffic information prompt.
The re planning line: when you don't run according to the planning of the line, orthe wrong road, GPS navigation system will be based on your location, you re planning a new destination of the line.
Satellite tracking and receiving
A total of 24 GPS satellites orbiting along six tracks (each four group), generally not more than 12 satellites in the same side of the earth, most of the GPS receiver can track 8 ~ 12 satellites. Calculation of LAT/LONG (2 dimensional)coordinate needs at least 3 satellites. Plus a 3 dimensional coordinates can becalculated. For a given location, the GPS receiver to know at this time what the satellite in the vicinity, because it constantly receives updates from the signalssent by satellite.
Satellite channel
Some consumer GPS devices have 2 ~ 5 parallel channel receiver of satellite signals. Because there may be up to 12 satellites are visible (the average value is 8), this means that the GPS receiver must visit each of the satellites in order to obtain information about each satellite.
Most GPS receivers available in the market are 12 parallel channel type (vision,car navigation products are 20 parallel channel type), which allows them to continuously track the information of each satellite, 12 channel receiver advantages include rapid cold start and initialization of satellite information, but also can have better reception results in the forest area. General 12 channel receiver does not need an external antenna, unless you are in a closed space,such as the cabin, the carriage.
Positioning time
This is when you reboot your GPS receiver, it determines the position of the time required for now. For the 12 channel receiver, if you are in the last location near the location, location of the cold start time is generally 3 to 5 minutes, hot start 15 to 30 seconds, and for 2 channel receiver, more than most of the cold start15 minutes, hot start 2 to 5 minutes.
Positioning accuracy
Most of the GPS receiver in the horizontal position accuracy of 5m ~ 10m, but it is only in the case of SA is not open.
The DGPS function
In order to the effect of SA and atmosphere refraction caused by reduced to a minimum, a device called a DGPS transmitter. It is a fixed GPS receiver (in anexploration site 100km ~ 200km radius settings) receive the signal from the satellite, it knows exactly what is the precise transmission theory to the satellite signal, and then compare it with the actual transfer time, and then calculate the"difference", this is very close to in SA and atmospheric refraction, it will send outthe difference, other GPS receiver can use it to get a more accurate position reading (error 5m to 10m or less).
Many GPS equipment provider settings in some areas of the DGPS transmitter,for its customers free of charge, as long as customers are buying GPS receiverswith DGPS function.
Signal interference
To give you a good location, the GPS receiver needs at least 3 to 5 satellites are visible. If you are in the valley or tall buildings on both sides of the street, or in the dense jungle, you may not be with enough satellite link, which can not be located or can only get the two-dimensional coordinates. Similarly, if you're in a building inside, you may not be able to update your location, some GPS receivers have a separate antenna can be attached to the windshield, or an external antenna can be placed on the roof, the receiver which helps you get more satellite signals.