10 Technical appendix GPS180PEX
10.2.12 Format of the NMEA 0183 String (GGA)
The NMEA (GGA) String is a sequence of characters starting with the ‘$GPRMC’ character and ending with
the characters CR (carriage return) and LF (line-feed). The format is:
$GPGGA,
hhmmss.ss,bbbb.bbbbb,n,lllll.ll,e,A,vv,hhh.h,aaa.a,M,ggg.g,M„0*cs
<CR><LF>
The letters printed in italics are replaced by ASCII numbers or letters where as the
other characters are part of the time string. The groups of characters as defined below:
$
Start character, ASCII Code 24h
sending with one bit accuracy at change of second
hhmmss.ss the current time:
hh
hours
(00..23)
mm
minutes
(00..59)
ss
seconds
(00..59, or 60 while leap second)
ss
fractions
of seconds
(1/10 ; 1/100)
A
Status (A = time data valid)
(V = time data not valid)
bbbb.bbbbb latitude of receiver position in degrees
leading signs are replaced by a space character (20h)
n
latitude, the following characters are possible:
‘N’
north of equator
‘S’
south d. equator
lllll.lllll
longitude of receiver position in degrees
leading signs are replaced by a space character (20h)
e
longitude, the following characters are possible:
‘E’
east of Greenwich
‘W’
west of Greenwich
A
Position fix (1 = yes, 0 = no)
vv
Satellites used (0..12)
hhh.h
HDOP (Horizontal Dilution of Precision)
aaa.h
Mean Sea Level altitude (MSL = altitude of WGS84 - Geoid Separation)
M
Units, meters (fixed value)
ggg.g
Geoid Separation (altitude of WGS84 - MSL)
M
Units, meters (fixed value)
cs
checksum (EXOR over all characters except ‘$’ and ‘*’)
<CR>
Carriage Return, ASCII Code 0Dh
<LF>
Line Feed, ASCII Code 0Ah
GPS180PEX
Date: 28th March 2018
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