Tiếng ViệtOfficial website of Navitel Vietnam: http://navitelvietnam.com
You can see frequently asked questions of Navitel Navigator from here
You can see frequently asked questions of Navitel Navigator from here
POI (Points of Interest) are objects on the map connected with the infrastructure of the society, such as shops, pharmacies, fuel stations, hospitals, theatres, sightseeing attractions etc. As a rule they are divided into groups. POI may be used to find a relevant place when travelling. The information about such object may include address, telephone number, opening hours etc.
The A-GPS uses the space segment of the GPS, cellular networks and mobile phones or smartphones which do not necessarily have their own real GPS module for position finding. The A-GPS is a paid service. In the online mode, which is the basic one, the coordinates are determined outside the terminal device, thus it is not necessary to have a real GPS module. However, thick cellular network coverage is needed. In the offline mode the A-GPS system is used to transmit an almanac and ephemerides through the cellular network, which decreases the time of the cold and warm start for a real GPS-receiver.
The most widely used are the polar coordinate system and the Cartesian (rectangular) coordinate system.
In the polar system a coordinate (latitude and longitude) is measured in degrees, minutes and seconds.
1 degree=60 minutes, 1 minute=60 seconds. The minutes and seconds are often substituted with the decimals of a degree, a minute or a second. So, the basic formats are as follows:
ggg/mm/ss,ssss
ggg/mm,mmm
gg,gggggg
This should be taken into account when using the coordinates for marking or searching a certain point in your navigation device.
The Cartesian coordinate system is connected with using the Universal Transverse Mercator projection and implies the evolution of 6-degree segments of the Earth surface (zones) on a flat surface. The coordinates are defined by the zone number, the distance (in km) from the central meridian of the zone (the X coordinate) and from the equator (the Y coordinate). To avoid negative numbers, Eastern displacement and Northern displacement are introduced for the Southern Hemisphere.
In the polar system a coordinate (latitude and longitude) is measured in degrees, minutes and seconds.
1 degree=60 minutes, 1 minute=60 seconds. The minutes and seconds are often substituted with the decimals of a degree, a minute or a second. So, the basic formats are as follows:
ggg/mm/ss,ssss
ggg/mm,mmm
gg,gggggg
This should be taken into account when using the coordinates for marking or searching a certain point in your navigation device.
The Cartesian coordinate system is connected with using the Universal Transverse Mercator projection and implies the evolution of 6-degree segments of the Earth surface (zones) on a flat surface. The coordinates are defined by the zone number, the distance (in km) from the central meridian of the zone (the X coordinate) and from the equator (the Y coordinate). To avoid negative numbers, Eastern displacement and Northern displacement are introduced for the Southern Hemisphere.
In fact, the Earth has the form of a geometric body which is not a sphere nor even a spheroid. Its form is more complicated, however, in geodesy the form of the Earth is represented with a spheroid. This allows to determine the coordinates of each point of the Earth without using overcomplicated mathematical methods. The parameters of the spheroid are chosen so that the mean-square deviations of the model from the reality are minimal for the Earth as a whole or for any particular country or region. That is why there are more than a hundred reference spheroids. The chosen spheroid model and the coordinate system based on this spheroid compose the datum.
The GPS system uses the WGS84 coordinate system based on the GRS80 spheroid model.
The established coordinate system, the latitude, the longitude and the height unambiguously determine the coordinates of any point on the Earth.
The GPS system uses the WGS84 coordinate system based on the GRS80 spheroid model.
The established coordinate system, the latitude, the longitude and the height unambiguously determine the coordinates of any point on the Earth.
The satellite signal, which is transferred on a frequency of L1=1575,42 MHz, is aimed for civil use and is transmitted without any limitation, free of charge, with no usage fee.
GPS (Global Positioning System) is a radio-navigational satellite system aimed at precise position, speed and time determination.
GPRS (General Packet Radio Service) is a secondary structure over the GSM cellular communication technology, which provides packet data transmission. GPRS allows a user of the cellular communication network to exchange data with other devices connected to the GSM network and having access to an external network, including the Internet. Therefore, these are two completely different systems, which are not directly interconnected, even though the abbreviations sound similar.
GPRS (General Packet Radio Service) is a secondary structure over the GSM cellular communication technology, which provides packet data transmission. GPRS allows a user of the cellular communication network to exchange data with other devices connected to the GSM network and having access to an external network, including the Internet. Therefore, these are two completely different systems, which are not directly interconnected, even though the abbreviations sound similar.