iGPS-M USER’S MANUAL
9
Software Interface
NMEA Protocol
iGPS-M receiver currently supported 21NMEA commands and 7 NMEA messages. The NMEA
commands include NMEA, START, STOP, STORE, RESTORE, AUTOSTART, FIXRATE, DATUM, PWRDOWN,
PPSMODE, SURVEYLEN, CABLEDEL,PPSPOS, PULSEPOS, PULSELEN, INITAID, ALTAID, SETLIMIT,
SYNCMODE, SW, and HW. The respond messages include GPGLL, GPGGA, GPVTG, GPRMC, GPGSA,
GPGSV, and “PFST,FOM”.
NMEA Messages
The NMEA-0813 message consists of fields as following:
$GP<message id>,<data field>,<data field>,,, ..*<checksum><CR><LF>
Message starts with ‘$GP’ followed by message id field. Message data fields are separated
by commas ( , ) and the message ends after checksum field and carriage return <CR>
and line feed <LF> control characters. Delimiter ‘*’ precedes the checksum field.
Note that data fields may be NULL (missing). Null data fields contain no characters
but are still separated by commas, for example:
$GPGGA,134158.48,6016.3072,N,02458.3788,E,1,08,1.2,,,,,,0000*1E
GLL –Geographic Position –Latitude/Longitude
Latitude and Longitude, UTC time of fix and status.
Format: $GPGLL,xxmm.dddd,<N|S>, yyymm.dddd,<E|W>,hhmmss.dd,S,M*hh<CR><LF>
Example: $GPGLL,6016.3073,N,02458.3791,E,134157.48,A,A*26
Parameter Description Example
xxmm.dddd Latitude, xx = degrees, mm = minutes, dddd = de
part of minutes 60 deg.
16.3073 min.
<N|S> Either character N or character S,
N = North, S = South North
yyymm.dddd Longitude, yyy = degrees, mm = minutes
dddd = decimal part of minutes 24 deg.
58.3791 min
<E|W> Either character E or character W,
E = East, W = West East
hhmmss.dd UTC time, hh = hours, mm = minutes, ss = seconds
dd = decimal part of seconds 13:41:51.48
SStatus indicator, A = valid, V = invalid Valid
MMode indicator, A =autonomous, N =data not valid
