Marine Geoscience Data System will be updating services related to the Academic Seismic Portal on Thursday July 2nd - Monday July 6th. This may cause temporary interruptions in service. We apologize for any inconvenience this may cause.

MGDS Vocabulary: Nav Type

DVL/USBLReal-time DVL dead-reckoning navigation supplemented with USBL.
LBL:RenavCleaned Long BaseLine (LBL) navigation data.
GPS/WireOutShip navigated with GPS, but instrument launched on a wire. Typically, a layback calculation is done to determine the precise instrument location.
DGPSDifferential GPS
LAYBACK:RenavLAYBACK navigation was used, but repositioning was done during post-processing, typically based on feature-matching.
DVL:Renav:ConfirmedIndicates that the DVL:Renav positions have been confirmed by human inspection.
DVL/LBL:Renav:ConfirmedIndicates that the DVL/LBL:Renav positions have been confirmed by human inspection.
GPSGlobal Positioning System
DVLDoppler Velocity Log
DVL/LBL:RenavPost-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.**
LORANLOng RAnge Navigation
RTK GPSReal-Time Kinematic GPS
ACOUSTIC_RANGING/GPSAcoustic ranging from a GPS-navigated ship to identify the location of instrumentation on the seafloor.
INS/DVL:RenavPost-processed INS Inertial Navigation System (INS) navigation aided by Doppler Velocity Log (DVL) data.
DVL/USBL:RenavPost-processed to merge Doppler Velocity Log (DVL) with Ultra-Short BaseLine (USBL) navigation.
DVL/LBL/INSReal-time DVL dead-reckoning navigation supplemented with LBL navigation and INS (Inertial Navigation System) navigation.
LAYBACK/LBLLayback navigation supplemented with LBL
GPS:AssumedGPS was available and has been assumed to be the source of navigational information.
USBLUltra-Short Baseline
LocalePosition substituted from neighboring physiographic feature or deployed instrument.
LBLReal-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.
GLONASSGlobal Navigation Satellite System
DVL/LBLReal-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.
LAYBACKLayback 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).
DVL:RenavDVL 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.