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发表于 2017-6-14 20:50:29
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The NMEA protocol on u-blox receivers can be configured to the need of customer applications using
CFG-NMEA.
There are two NMEA standards supported. The default NMEA version is 2.3. Alternatively version 2.1 can be
enabled (for details on how this affects the output refer to section Position Fix Flags in NMEA Mode).
The NMEA standard differentiates between GPS, GLONASS, and combined GNSS receivers using a two-letter
message identifier, the 'Talker ID'. Depending upon device model and system configuration, the u-blox receiver
could output messages using any one of these Talker IDs.
By default, receivers configured to support GPS, SBAS and QZSS use the 'GP' Talker ID, receivers configured to
support GLONASS use the 'GL' Talker Id, and receivers configured for any other GNSS or any other
combinations of GNSS use the 'GN' Talker ID
NMEA defines a satellite numbering system for GPS, SBAS, and GLONASS. Satellite numbers for other GNSS
can be configured using CFG-NMEA. Unknown satellite numbers are always reported as a null NMEA field (i.e.
GPS.G7-SW-12001-B Public Release Page 48 of 196
an empty string)
The NMEA specification indicates that the GGA message is GPS specific. However, u-blox recievers support the
output of a GGA message for each of the Talker IDs. |
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