| Summary: | Progress Code: completed Statement: The Ashtech GPS unit is not currently licensed to receive differential corrections and the AAD are not aware when they last paid for the annual subscription. A error value still exists for the Transducer/GPS offset, even after the script correction. A 5m error value has been applied in the horizontal accuracy calculation spreadsheet for this correction. The best assessment of the horizontal accuracy is therefore Order 2. Purpose Potential uses of the data include the updating of nautical charts and the creation of bathymetric datasets. The data processing was done by the Royal Australian Navy's (RAN) Deployable Geospatial Support Team (DGST) and was provided to the Australian Antarctic Data Centre by the Australian Hydrographic Office. The dataset is titled HI483A because the processing was done on a 2010/11 voyage to Mawson and HI 483 was going to be a RAN survey at Mawson. The RAN survey wasn't feasible because of sea ice. The data processed (12KHz EDO 323HP echo sounder data) was collected on the following voyages: 2006/07 V2, V4, V6 2007/08 SIP, V3, V6 2008/09 V0, V1, V2, V3, V5 2009/10 V0, V1, V2, V3, V4, V5, V7 2010/11 Trials, V1, V2, V3, VE2, VMS All voyage data sets were processed in the following manner. As the Aurora Australis sails from either Hobart, Tasmania or Fremantle, Western Australia all the shallow water data files containing depths less then 200m around these ports were not processed and deleted. If the sea floor image was too hard to determine during the voyage either parts of day lines were not processed or the whole line deleted depending on the quality of the data. This is evident with some day *.CSV files containing a second or third file, these files had the same file name and were given a end character of _2 or _3. Unfortunately the program Echoview is meant to allow the user to span gaps when processing a line but more often than not, this was not the case. So if there was a requirement to a have gap in the daily file then usually a second ...
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