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NMEADataFormat / 3GPGSA


GPS DOP and active satellites. This sentence provides details on the nature of the fix. It includes the numbers of the satellites being used in the current solution and the DOP. DOP (dilution of precision) is an indication of the effect of satellite geometry on the accuracy of the fix. It is a unitless number where smaller is better. For 3D fixes using 4 satellites a 1.0 would be considered to be a perfect number, however for over determined solutions it is possible to see numbers below 1.0.


Where: GSA Satellite status A Auto selection of 2D or 3D fix (M = manual)

     	3        	3D fix - values include: 		1 = no fix
                                       			2 = 2D fix
                                       			3 = 3D fix
     	04,05...	PRNs of satellites used for fix (space for 12) 
     	2.5      	PDOP (dilution of precision) 
     	1.3      	Horizontal dilution of precision (HDOP) 
     	2.1      	Vertical dilution of precision (VDOP)
     	*39      	the checksum data, always begins with *
Page last modified on April 28, 2009, at 09:40 AM