41
Chapter 7 Available NMEA and UBX Messages
7.1 NMEA Protocol
The NMEA protocol expresses the data in the format of ASCII. This is a standard
format for GPS applications. The module (FV-25) outputs two types of NMEA
messages. One is the standard NMEA messages, that are widely accepted by plotters
and GPS related devices, and the other is u-blox proprietary NMEA messages.
7.1.1 Standard NMEA Messages
The module can output 10 standard NMEA messages, which are
GGA – Global Positioning System Fix Data;
GLL – Geographic Position – Latitude/Longitude;
GRS – GNSS Range Residuals;
GSA – GNSS DOP and Active Satellites;
GST – GNSS Pseudorange Error Statistics;
GSV – GNSS Satellites in View;
RMC – Recommended Minimum Specific GNSS Data;
TXT – Test Transmission;
VTG – Course Over Ground and Ground Speed;
ZDA – Time & Date.
The default output messages include all messages except the TXT message. Those
messages are output at comm. port 1 at the rate of 19200 bps (default setting). The
request for outputting user-selected standard NMEA messages is the “$xxGPQ,..”
message (referred to the following interpretation for GPQ). The port settings can be
performed by sending the “$PUBX,41,..” message (ASCII format) or UBX-CFG-PRT
message (Binary format).
The following will summarize the available NMEA messages. More information
about the NMEA messages refers to “NMEA 0183, Standard For Interfacing Marine
Electronic Devices, Version 2.30, March 1, 1998”.
NOTE: In the NMEA messages, the position fix is valid only if the following
conditions are satisfied: 1) at least three satellites observable (i.e. 2D or 3D); 2) for
the 3D case, the position accuracy should be less than the setting value of the
“Position Accuracy Mask”; 3) The PDOP value is constrained by the setting value of
