Commonalities of Vehicle Data
The data package is delivered per cruise, with contained products grouped on a per-dive basis.
Navigation Data Sets
All NDSF vehicles are equipped with high precision Doppler Velocity Log (DVL) navigational systems (dead reckoning) that can be supplemented with acoustic Long-BaseLine (LBL) navigation. Bottom-lock DVL sonar is used to compute vehicle displacement, and LBL acoustic ranges are used to place the DVL displacement data in a geographical coordinate frame. Real-time positioning uncertainties of these systems used individually can be significant, as much as hundreds of meters, but the post-processing of LBL and DVL and high-precision gyro compass data results in a more precise navigational track [1,2,3,4].
First-order processing of LBL and DVL navigation data, which can be performed at sea, removes the most extreme positioning errors and also utilizes gyrocompass attitude to constrain vehicle position. This level of processing is provided as a standard data product for most NDSF vehicles. Second-order processing can be performed post-cruise by experienced specialists to further improve navigational data quality. Vehicle positioning accuracy can range from less than one meter to tens of meters depending on deployment geometry, operational conditions and the nature of the post-processing.
DVLNav is used to collect data from navigation, vehicle, and ship's systems and also provides a real-time display of estimated position and track history. DVLNav produces the following, which are included in the standard deliverables from each of the vehicles:
- Simple comma-delimited 1-second data file:
.csv suffix, logs time-stamped navigation and sensor data at 1 second intervals. One file per day. 1 MB/hour. Compresses 5:1.
- Comprehensive DSL Format Data file:
.dat suffix, logs ALL sensor and processed data, timestamped to 0.001 second. One file per hour, 60 MB/Hour. Compresses 10:1. Requires awk/grep and MATLAB to process.
- Screen Shot JPEG File:
.jpeg suffix. Timestamped (to the second) screen shot image of the DVLNAV screen. 500 KB/Image. Created by a DVLNav screenshot button.
- Hourly system configuration (INI file):
Logs the internal DVLNAV configuration once an hour. 6 KB.
See vehicle specifics for more information about the navigation data deliverables for that vehicle.
On Alvin, in which pilot and science observers have a limited field of view through portholes, video cameras and recorders augment visual observations. On Jason, video cameras are the only source of real-time visual information. Some of these are utility units while others are high quality units that provide images suitable for detailed observation and for recording. Video is recorded in two forms: a pristine version that is transferred to the WHOI Data Library, and a single working copy that is delivered to the Chief Scientist at the conclusion of the dive. In both forms, time and real-time vehicle position data (position, altitude, depth) data are recorded in audio tracks using the SMPTE standard. Information contained in the audio channels can be used to generate a customized video overlay. Working copies are overlain with user-defined parameters at the time of recording.
All NDSF vehicles are capable of carrying a bathymetric sonar, available by pre-cruise request. See vehicle specifics for more information about the sonar data deliverables for that vehicle.
Digital Still Photography
Each of the vehicles carries a digital camera for capturing still photography. Images are downloaded and archived in JPEG format, with date and time information denoted in the filename.
Autosnaps and Event Logging
Autosnaps are framegrabbed images that are extracted from video automatically at a customizable time interval and are coregistered with sensor data. On Alvin this is done with the Framegrabber system and on Jason this is done with the Virtual Van.
Additionally, an Eventlogger system gives Jason science users the ability to record dive event commentary that is coregistered with user-triggered autosnaps.
All vehicles carry sensors such as CTD, altimeter, compass, and gyroscope. AUVs ABE and Sentry each routinely carry a magnetometer. Alvin and Jason can be fitted with one if requested prior to your cruise. Note: Proper use of a magnetomoter requires mid-water column calibration of the sensor at each new location.
Alvin, Jason, and ABE each carry a forward-looking sonar unit for target detection and obstacle avoidance. We do not offer a standard product from these systems.
Science-provided equipment can be carried by each of the vehicles as long as the equipment doesn't exceed the vehicle's limits of size, weight, and power usage. Please allow significant lead time prior to your cruise to contact NDSF planning personnel and vehicle managers.
Contact the NDSF Data Manager
- Whitcomb, L., D. R. Yoerger, and H. Singh (1999a), Combined Doppler/LBL based navigation of underwater vehicles, paper presented at the 11th International Symposium on Unmanned Untethered Submersible Technology, Autonomous Undersea Syst. Inst., Durham, N. H.
- Whitcomb, L. L., D. R. Yoerger, and H. Singh (1999b), Advances in Doppler-based navigation of underwater robotic vehicles, paper presented at the IEEE International Conference on Robotics and Automation, Detroit, Mich.
- Ferrini, V.L., L. Whitcomb, J. Howland, D. Fornari, S.M. Carbotte, D. Kelley, T. Shank, M. Tivey, (2005). Navigation of UNOLS National Deep Submergence Facility (NDSF) Vehicles: Status Report and Guidelines for Data Acquisition. Ridge 2000 Community Progress and Planning Workshop, Vancouver, B.C., Canada.
- Kinsey, J.C., L.L. Whitcomb, D.R. Yoerger, J.C. Howland, V.L. Ferrini, O. Hegrenas, (2006). New Navigation Post-Processing Tools for Oceanographic Submersibles. Eos Trans. AGU, 87(52), Fall Meet. Suppl., Abstract OS33A-1678.