Re-Tweeted GPS Messages

If the DVL is set to re-tweet (forward, relay, pass thru) GPS messages, any message (sentence) coming in the GPS hardware port is forwarded to the main communication link to the host. Differing GPS units may output various kinds of NMEA sentences. Messages are forwarded line-by-line (sentence-by-sentence). Each message is appended to the string “GPS:” to differentiate it from the DVL’s $GPRMC output message. Messages may be delayed by up to 0.25 seconds.

The re-tweeted GPS sentences from the Cerulean Sonar GPS may include:

Message	Description
$GPGSA and/or $GNGSA	GPS dilution of position and active satellites
$GPGSV	Number of SVs in view, PRN, elevation, azimuth, and SNR
$GPVTG and/or $GNVTG	Actual track made good and speed over ground
$GPGGA and/or $GNGGA	Time, position, and fix related data
$GPGLL and/or $GNGLL	Position data: position fix, time of position fix, and status
$GPTXT	Free text, manufacturer defined
$GPRMC and/or $GNRMC	Minimum recommended Position, Velocity, and Time