Nmea Sentences Type; Introduction Of Gpsonextra - Quectel EC20 GNSS At Command Manual

LTE Module Series
EC20 GNSS AT Commands Manual

1.2. NMEA Sentences 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 - Positioning System

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. After
booting 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)
which is obtained from an XTRA server on the network.
In order to use gpsOneXTRA feature, you should ensure that valid gpsOneXTRA assistance data is
available. Firstly download a new gpsOneXTRA binary file from one of the gpsOneXTRA assistance web
servers via HTTP. The files are named as xtra.bin for GPS only and xtra2.bin for GPS+GLONASS. The
exact file size should be 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. You can query the gpsOneXTRA data status by
AT+QGPSXTRADATA? to update gpsOneXTRA data properly.
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