NMEA $GPGSA messages

Hello everyone!,

A quick example on what $GPGSA messages are. Keep in mind that the sentence Identifier can also be displayed as $GNGSA. The message is the same but some GNSS receivers use this format.

GPS DOP and active satellites
eg1. $GPGSA,A,3,16,18,22,24,3.6,2.1,2.23C
eg2. $GPGSA,A,3,19,28,14,18,27,22,31,39,1.7,1.0,1.3

1 = Mode:
M=Manual, forced to operate in 2D or 3D
A=Automatic, 3D/2D
2 = Mode:
1=Fix not available
3-14 = IDs of SVs used in position fix (null for unused fields)
15 = PDOP
16 = HDOP
17 = VDOP