Leica GR10 - B2: Used Symbols for Describing the NMEA Formats

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B2: Used symbols for describing the NMEA formats
Background information
NMEA messages consist of various fields. The fields are:
• Header
• Special format fields
• Numeric value fields
• Information fields
• Null fields
Certain symbols are used as identifier for the field types. These symbols are described in this section.
Header
Symbol
Field
Description
Example
$
-
Start of sentence
$
--ccc
Address
•
-- = alphanumeric characters identifying
the talker
Options:
GP = GPS only
GL = GLONASS only
GN = Global Navigation Satellite System
• ccc = alphanumeric characters
identifying the data type and string
format of the successive fields. This is
usually the name of the message.
GPGGA
Special format fields
Symbol
Field
Description
Example
A
Status
•
A = Yes, Data Valid, Warning Flag Clear
• V = No, Data Invalid, Warning Flag Set
V
llll.ll
Latitude
•
Degreesminutes.decimal
• Two fixed digits of degrees, two fixed
digits of minutes and a variable number
of digits for decimal fraction of minutes.
• Leading zeros are always included for
degrees and minutes to maintain fixed
length.
4724.538950
yyyyy.yy
Longitude
•
Degreesminutes.decimal
• Three fixed digits of degrees, two fixed
digits of minutes and a variable number
of digits for decimal fraction of minutes.
• Leading zeros are always included for
degrees and minutes to maintain fixed
00937.046785