Indicates the type of signal or technique being used by the GPS receiver to determine its location. For example it indicates the quality of the signal, or the accuracy and reliability of the location being reported. The fix type is determined by the receiver based on number of satellites visible, the type of GPS receiver and the GPS technology being used.
The NmeaFixType can be one of:
(0) An invalid GPS fix type. Indicates that there is no satellite signal being received or there are not enough satellites available for proper location determination.
(1) A standard GPS fix type. Indicates a standard GPS signal, or Standard Positioning Service (SPS) is being used. SPS is the standard specified level of positioning and timing accuracy that is available, without qualification or restrictions, to any user on a continuous worldwide basis.
(2) A differential GPS fix type. Indicates that Differential GPS is being used to provide increased accuracy over SPS. This technique uses a network of fixed ground based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions.
(3) A PPS GPS fix type. Indicates that Precise Positioning System, encrypted for government use is being used by the receiver. PPS is the most accurate positioning, velocity, and timing information continuously available, worldwide, from the basic GPS.
(4) A real time kinematic GPS fix type. A technique used in land survey based on the use of carrier phase measurements of the GPS signals where a single reference station provides the real-time corrections of even to a centimeter level of accuracy.
(5) A float real time kinematic GPS fix type. The type is very similar to the fixed RTK (Enums.NmeaFixTypeRTK) method of calculating location, but is not as precise, typically around
20 cm to
1 meter accuracy range.
(6) An estimated GPS fix type. The type is the determination of a location based on computations of position given an accurately known point of origin and measurements of speed, heading and elapsed time.
(7) A manual input mode GPS fix type. Indicates that the location has been manually entered into the GPS receiver, and is not based on the satellite system.
(8) A simulation mode GPS fix type.