Appendix: Software Specification; General Nmea Format - ProGin T-368 User Manual

Appendix: Software Specifications
NMEA Protocol
The T-368 interface protocol is based on the National Marine Electronics Association (NMEA)
interface specification, namely, the NMEA 0183 standard. The T-368 is capable of supporting the
following NMEA message formats specifically developed and defined by SiRF.
NMEA Message Prefix
$GPGGA
$GPGLL
$GPGSA
$GPGSV
$GPMSS
$GPRMC
$GPVTG
$GPZDA

General NMEA Format

The general NMEA format consists of an ASCII string commencing with a '$' character and
terminating with a <CR><LF> sequence. NMEA standard messages commence with 'GP' then a
3-letter message identifier. The message header is followed by a comma delimited list of fields
optionally terminated with a checksum consisting of an asterix '*' and a 2 digit hex value representing
the checksum. There is no comma preceding the checksum field.
calculated as a bitwise exclusive of the characters between the '$' and '*'.
representation, the number of digits in each number will vary depending on the number and precision,
hence the record length will vary. Certain fields may be omitted if they are not used, in which case
the field position is reserved using commas to ensure correct interpretation of subsequent fields.
Format
Time, position and fix type data.
Latitude, longitude, time of position fix and status.
GNSS DOP and active satellites
Satellites in view.
Radio beacon signal-to-noise ratio, signal strength,
frequency, etc.
Recommended minimum specific GNSS data.
Speed and course over ground.
Date and time.
13
Direction
Out
Out
Out
Out
Out
Out
Out
Out
When present, the checksum is
As an ASCII
T-368 User's Guide v1.0