The multibeam lines of the two surveys were planned to achieve the full coverage, with an average overlap of 15-20%. During the acquisition in 1999 the lines collected in the 1996 survey were input on the MERLIN logging workstation in order to have the proper guidelines for the routes.
figure
Fig. 25 shows the lines that were collected during the two surveys.
The logging procedure was designed in order to minimize the risks of data loss and to have an easier handling of the files during the post-processing phase. For these reasons, we decided to close and open new raw multibeam files every two hours on straight routes and at every turn larger than 10 degrees.
Once the file was closed, it was pushed on the network by NFS or FTP
as soon as possible and logged by another UNIX workstation.
The raw data file integrity was then checked by importing it on the Neptune
package and, finally, backed up on CD-ROMs, DATs and Magneto-optical
cartridges. A double check with the files on the MERLIN workstation
allowed the deletion to make space for the incoming multibeam data. For additional
safety the data were also backed up on line on a DAT during the acquisition
by the MERMAID tape logging facility.
