Nmea Sentence Type; Introduction Of Gpsonextra - Quectel UC20 GNSS At Command Manual

WCDMA Module
UC20 GNSS AT Commands Manual

1.2. NMEA Sentence Type

The NMEA sentences are compatible with NMEA-0183 protocol, and all of the standard NMEA sentences
have two kinds of prefix.
For GPS sentences, the prefix is "GP", as below:
 GPGGA - Global Positioning System Fix Data, Time, Position and related fix data.
 GPRMC - Recommended minimum data.
 GPGSV - Detailed satellite data.
 GPGSA - Overall satellite data.
 GPVTG - Vector track and speed over the ground.
And for GLONASS sentences, the prefixes are "GL" and "GN", as below:
 GLGSV - Detailed satellite data.
 GNGSA - Overall satellite data.
 GNGNS -

1.3. Introduction of gpsOneXTRA

gpsOneXTRA assistance enhances standalone performance, and simplifies GNSS assistance delivery to
GNSS engine, including ephemeris, almanac, ionosphere, UTC, health and coarse time assistance.
Booting with gpsOneXTRA, TTFF (Time to First Fix) can be reduced by 18 to 30 sec (or more in harsh
signal environments). And the gpsOneXTRA data needs to be updated once per day (or every a couple of
days) from an XTRA server on the network.
In order to apply gpsOneXTRA feature in GNSS engine, valid gpsOneXTRA assistance data is necessary.
Firstly download a new gpsOneXTRA binary file from one of the gpsOneXTRA assistance web servers via
HTTP. The files are named xtra.bin for GPS only and xtra2.bin for GPS+GLONASS. The exact file size is
less than 50kB:
http://xtra1.gpsonextra.net/xtra.bin
http://xtra2.gpsonextra.net/xtra.bin
http://xtra3.gpsonextra.net/xtra.bin
http://xtra1.gpsonextra.net/xtra2.bin
http://xtra2.gpsonextra.net/xtra2.bin
http://xtra3.gpsonextra.net/xtra2.bin
gpsOneXTRA data needs to be updated regularly. Actually, you can query the gpsOneXTRA data status
by AT+QGPSXTRADATA?, then you can update gpsOneXTRA data properly.
UC20_GNSS_AT_Commands_Manual Confidential / Released 5 / 25