NAVIGATION FIELD DATA

The file nav.dat located in directory nav contains the raw navigation that was collected during the sidescan component of the field program with the USGS differential GPS system. The shorebased station for the GPS was the Coast Guard beacon at Cape Henlopen, DE. The navigation is an ASCII file with six fields separated by tabs.
Field 1: date and time (julian day:hour (GMT):minute:second)
Field 2: Latitude (ie. 39d26.4093)
Field 3: Longitude (ie. -74d17.5293)
Field 4: Speed (computed from the navigation)
Field 5: Heading (computed from the navigation)
Field 6: Water Depth (derived from an Odem digital echo sounder). Depths are in meters, but have not been corrected for the depth of the transducer, which was about 2 m below the sea surface, nor for the tide.
Navigaton fixes are at 10 second intervals, and the file is separated by a # -b into three parts each representing one night of sidescan surveying.
During the first night (146:22:29:05 through 147:09:59:20) only the port channel of the sidescan was functional. During the second night (147:22:32:22 through 148:09:04:20) and third night (149:01:48:07 through 149:11:01:00) both channels of the sidescan were working. Comments are preceeded with a ## in the data records. Though the navigation for the first day of the survey can be found on this disk, the collected sidescan is not considered useful and, therefore, has not been archived here.

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