June 18-28th:
A small conglomerate of folks from the University of Delaware, Washington College, United States Naval Academy, University of New Hampshire, and EdgeTech are combining forces for a 10-day mapping blitz of Assateague Island National Seashore (AINS). This National State Parks project will utilize sidescan and multibeam sonar to create a variety of bathymetric data products, along with other auxiliary data collected from AUV and ROV operations.
As a new graduate student in the CSHEL lab, part of my tasking is to configure our Real Time Kinematic (RTK) GPS system for use in this project. RTK GPS differs from other GPS systems in that it keeps position uncertainty down to only one or two centimeters, in contrast to errors of several meters as you might find with your iPhone or handheld GPS. RTK GPS relies on a fixed base station to provide corrections in real-time, which then sends those corrections to any number of rover units. A correction-broadcasting network can be used in place of a base station, as long as the survey area has a moderate cell signal.
We are launching two research vessels in operation for this project, the R/V Joanne Daiber (University of Delaware) and R/V Lookdown (Washington College), at the Curtis Merrit Harbor in Chincoteague, Virginia. This is the first field employment of the R/V Daiber since its recent acquisition by the University of Delaware. Its primary use will be for ROV and AUV operations, while the R/V Lookdown will focus its efforts on mapping. Before the R/V Lookdown began mapping, we set up the RTK GPS base station close to their slip at the harbor and took a few data points next to their boat with a rover. The crew aboard the Lookdown cross-referenced the elevations we provided from the GPS with their boat's positioning system, and were able to match it within a few millimeters.
The RTK GPS has several implications for this project and for future endeavors. One of our goals is to eventually configure the RTK GPS with an external radio modem to push its corrections to the AUV, allowing for more precise measurement. In the meantime, we are processing sonar data from the first few days as we wait for the sea state to lay down enough for us to get back out on the boat. Our ultimate project objective is to map the entirety of AINS and compare it to previously collected NOAA data to isolate effects from Hurricane Sandy. This information may be integral in understanding how to better manage coastlines as well as prepare and protect from future storm events.
-Danielle Ferraro
