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UNDERSTANDING GPS NMEA SENTENCES

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  GPS Receivers and NMEA Standards The data given by the  GPS receiver  includes many information like position (latitude and longitude), altitude, speed, time etc. In its standards, NMEA has specified to send  a series of data in a sentence . A particular sentence is totally self-reliant and is independent from other sentences. There are standard sentences for particular type of data and for various categories of devices. NMEA has also provided the functionality for individual companies to write their own sentences ** NMEA sentence ** GPS devices transmit location information in NMEA standard. The ascii-formatted data are called sentences. There are many sentence types, each convey specific information about the GPS data. Example of NMEA Sentences :  GSV – Satellite Data $GPGSV,3,3,12,27,21,097,29,30,16,264,31,46,,,36,06,,,*7E GGA – Fix Data $GPGGA,054851.0,3300.684396,N,11706.839925,W,1,08,0.7,180.5,M,-25.0,M,,*61 GSV – Satellite Data $GPGSV,3,3,12,27,21,...
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GPS

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  how a GPS works :  The 24 GPS satellites are in orbit. They move permanently around the Earth, with 6 different trajectories. On the ground, a small box called a GPS receiver communicates with at least 3 satellites. This device measures the distance separating it from the satellites (trilateration). This information allows it to calculate its coordinates, in other words its position. The communication between the satellites and the receivers is done through signals emitted by the satellites. The receiver is able to calculate the speed of propagation of the waves emitted to deduce the distance between them. It contains a chip or a chipset, a key component to perform these calculations. the three elements of GPS GPS is made up of three different components, called segments, that work together to provide location information.   The three segments of GPS are: Space (Satellites) —  The satellites circling the Earth, transmitting signals to users on geographical position...
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