Orion NMEA User Manual
GPS Receiver Module
Micro Modular Technologies Pte. Ltd.
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No. 3, Ubi Avenue 3, #03-02 Crocodile House 408857 Singapore
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www.micro-modular.com
3
Standard NMEA Output Sentences
The following format conventions have been used in accordance with the NMEA standard with
implementation specifics noted:
•
When a data field is null, the unit of measure field will also be null.
•
Three digits are used for decimal fraction of seconds in UTC time.
•
Four digits are used for decimal fraction of minutes in latitude and longitude.
•
Two digits are used for Satellite IDs, with a leading zero if necessary.
•
DTM: Six digits are used for decimal fraction of latitude and longitude offsets. Two digits are
used for decimal fraction of altitude offset. Datum Subdivision Code is null.
•
GGA: UTC starts from zero time and changes to measured time when the fix becomes valid.
Altitude is reported referenced to the ellipsoid, and the Geoidal Separation is null.
•
GLL: UTC time field as in GGA.
•
GSA: Satellite ID numbers are in the range 00 to 99.
•
GSV: No implementation-specific notes.
•
RMC: UTC time field as in GGA. Course and Speed over ground as in VTG. Magnetic
Variation is null.
•
VTG: Course over ground is reported with 0.1 degree precision, Speed over ground is
reported with 0.1 unit precision for both knots and km/h fields. Magnetic Course is null.
•
ZDA: Local zone hours are presented as user has configured. Default is null. The hour zone
is reported with two digits (with leading zero when necessary), and with leading minus sign
when necessary. Local zone minutes are presented as two digits (with leading zero when
necessary) and is always zero or positive. UTC time field as in GGA.
Message ID
Description
Default
DTM
Datum reference
N
GGA
GPS fix data
Y
GLL
GPS latitude & longitude
N
GSA
DOP and active satellites
Y
GSV
Satellites in view
Y
RMC
Recommended Minimum GNSS Data
Y
VTG
Course over ground and ground speed
N
ZDA
Time, date, & local time zone
N
Table 1 – Standard NMEA Output Sentences