The possible fix quality indications for GPGGA sentences.

Class Variable INVALID_FIX The fix is invalid.
Class Variable GPS_FIX There is a fix, acquired using GPS.
Class Variable DGPS_FIX There is a fix, acquired using differential GPS (DGPS).
Class Variable PPS_FIX There is a fix, acquired using the precise positioning service (PPS).
Class Variable RTK_FIX There is a fix, acquired using fixed real-time kinematics. This means that there was a sufficient number of shared satellites with the base station, usually yielding a resolution in the centimeter range. This was added in NMEA 0183 version 3.0. This is also called Carrier-Phase Enhancement or CPGPS, particularly when used in combination with GPS.
Class Variable FLOAT_RTK_FIX There is a fix, acquired using floating real-time kinematics. The same comments apply as for a fixed real-time kinematics fix, except that there were insufficient shared satellites to acquire it, so instead you got a slightly less good floating fix. Typical resolution in the decimeter range.
Class Variable DEAD_RECKONING There is currently no more fix, but this data was computed using a previous fix and some information about motion (either from that fix or from other sources) using simple dead reckoning. Not particularly reliable, but better-than-nonsense data.
Class Variable MANUAL There is no real fix from this device, but the location has been manually entered, presumably with data obtained from some other positioning method.
Class Variable SIMULATED There is no real fix, but instead it is being simulated.
INVALID_FIX =
The fix is invalid.
GPS_FIX =
There is a fix, acquired using GPS.
DGPS_FIX =
There is a fix, acquired using differential GPS (DGPS).
PPS_FIX =
There is a fix, acquired using the precise positioning service (PPS).
RTK_FIX =
There is a fix, acquired using fixed real-time kinematics. This means that there was a sufficient number of shared satellites with the base station, usually yielding a resolution in the centimeter range. This was added in NMEA 0183 version 3.0. This is also called Carrier-Phase Enhancement or CPGPS, particularly when used in combination with GPS.
FLOAT_RTK_FIX =
There is a fix, acquired using floating real-time kinematics. The same comments apply as for a fixed real-time kinematics fix, except that there were insufficient shared satellites to acquire it, so instead you got a slightly less good floating fix. Typical resolution in the decimeter range.
DEAD_RECKONING =
There is currently no more fix, but this data was computed using a previous fix and some information about motion (either from that fix or from other sources) using simple dead reckoning. Not particularly reliable, but better-than-nonsense data.
MANUAL =
There is no real fix from this device, but the location has been manually entered, presumably with data obtained from some other positioning method.
SIMULATED =
There is no real fix, but instead it is being simulated.
API Documentation for Twisted, generated by pydoctor at 2018-07-14 04:53:34.