MGDS Vocabulary Terms: nav_type

ACOUSTIC_RANGING/GPS, Acoustic ranging from a GPS-navigated ship to identify the location of instrumentation on the seafloor.
DGPS, Differential GPS
DVL, Doppler Velocity Log
DVL/LBL, Real-time DVL dead-reckoning navigation supplemented with LBL navigation to help constrain fixes to a geographic coordinate system.  Errors on the order of 10s (sometimes 100s) of meters are likely in these data.
DVL/LBL/INS, Real-time DVL dead-reckoning navigation supplemented with LBL navigation and INS (Inertial Navigation System) navigation.
DVL/LBL:Renav, Post-processed to merge DVL with LBL navigation.  When combined with LBL navigation, precision depth measurements, and gyrocompass attitude
data, DVL navigation can result in vehicle
positioning accuracy ranging from <1 meter to 10s of meters depending on deployment geometry and
conditions, and the nature of the post-processing [Kinsey and Whitcomb, 2004, 2006; Ferrini et al., 2005; Kinsey et al., 2006; Ferrini et al., 2007].  **Note that sample position information derived from this navigation product MUST be manually verified (e.g. with bottom photos) to ensure the success of navigational post-processing.**
DVL/LBL:Renav:Confirmed, Indicates that the DVL/LBL:Renav positions have been confirmed by human inspection.
DVL:Renav, DVL data post-processed to remove obvious errors in Doppler position data. Errors on the order of 10s of meters are likely to exist in these data and are due to the limitations of dead-reckoning navigation with DVL sonars.  Users should refer to bottom photos to verify positioning information.
DVL:Renav:Confirmed, Indicates that the DVL:Renav positions have been confirmed by human inspection.
DVL/USBL, Real-time DVL dead-reckoning navigation supplemented with USBL.
DVL/USBL/INS, Real-time DVL dead-reckoning navigation supplemented with USBL and INS
DVL/USBL:Renav, Post-processed to merge Doppler Velocity Log (DVL) with Ultra-Short BaseLine (USBL) navigation.
DVL/USBL/TRN, Real-time DVL dead-reckoning navigation supplemented with USBL and TRN
GLONASS, Global Navigation Satellite System
GPS, Global Positioning System
GPS:Assumed, GPS was available and has been assumed to be the source of navigational information.
GPS/WireOut, Ship navigated with GPS, but instrument launched on a wire. Typically, a layback calculation is done to determine the precise instrument location.
INS/DVL:Renav, Post-processed INS Inertial Navigation System (INS) navigation aided by Doppler Velocity Log (DVL) data. 

LAYBACK, Layback navigation is typically calculated based on (1) the ship's GPS coordinates, (2) the amount of wire out to the towed platform, (3) the water depth of the platform (if available).
LAYBACK/LBL, Layback navigation supplemented with LBL
LAYBACK:Renav, LAYBACK navigation was used, but repositioning was done during post-processing, typically based on feature-matching.
LBL, Real-time Long BaseLine navigation [Hunt et al., 1974; Milne, 1983].  Utilizes travel times from acoustic transponders deployed near the seafloor to calculate positional information.  Motion of the transponders, which are typically deployed on long tethers (up to 600 m in high relief terrain), result in motion of the reference frame, introducting positioning uncertainties on the order of meters.  
LBL:Renav, Cleaned Long BaseLine (LBL)  navigation data.
Locale, Position substituted from neighboring physiographic feature or deployed instrument.
LORAN, LOng RAnge Navigation
NotApplicable, Navigational information is not available.
NotProvided, Navigational information was not provided.
RTK GPS, Real-Time Kinematic GPS
TRN, Terrain Relative Navigation
USBL, Ultra-Short Baseline