gfiadcp(5)

NAME
GFI ADCP - Quick Reference for ADCP CODAS Databases

DESCRIPTION
This manual page describes how to create CODAS databases from ADCP data files with emphasis on the instrumentation at GFI. If data have been acquired by DAS, refer to the CODAS User's Manual. This is file Manual.ps usually found in directory adcp/doc in the CODAS package installation directory. If processed data acquired with TRANSECT are to be loaded, use loadtnbp(1) or loadtbbp(1) for narrow band or broad band ADCP, respectively. Refer next to the CODAS User's Manual. If raw data from a narrow band ADCP acquired with TRANSECT are to be loaded, read the rest of this manual page and refer then to the CODAS User's Manual.

INTRODUCTION
In 1997, a SEAPATH 200 was installed M/S Ha/kon Mosby to get better attitude parameters and therefore improve current measurements over areas where bottom tracking was not available. At this time, there was no possibility to interface these data to the on board ADCP. Hence, a special interface to the synchro board has been developed for this purpose. It took however some time before this interface was built. During this period, GPS heading was logged separately, together by TRANSECT with the navigation data. Heading corrections could have been carried on five minutes averaged ensembles. However, because most of the data had been acquired in the Norwegian Sea, which is at least not famous for its calm conditions, it was first decided to write a utility to correct TRANSECT raw files and re-average them in playback mode by TRANSECT. However, it was found out very fast that this method was not reliable, because TRANSECT was not able to read always these corrected files (later it was also found that even some untouched files were rejected). Hence, a full averaging for these raw files was necessary. A simple utility was first written. It showed that data averaged with it were in many cases more reliable than those from TRANSECT processed files. Therefore, this utility has been further developed and this method of averaging ADCP data has been chosen. Its main disadvantage is that the acquired number of data is enormous compared to processed files (about 300 times). However, nowadays available hard disks and CDROM make it possible to apply this method and transport data without too many problems. Once averaged and loaded into a CODAS database, the file sizes do not differ. If averaging and loading of NBR ADCP is chosen, it is highly recommended to scan the raw ADCP and navigation files first. This step the same function as running scanping on DAS ping data files. It provides in addition the possibility to visualize these data within Matlab, and to output a synchronized navigation file for use during averaging. Once this step is carried out and data for averaging selected, the real process of averaging and loading data into a CODAS database can be performed. For further processing of ADCP data, refer to the CODAS User's Manual.

SCANNING RAW FILES
This step is carried out by scan_nbr(1). Its main purpose is to check the consistency of the data files. It also outputs information about configuration changes during acquisition, as well as malfunction of the transducer (the BIT status). Optionally, one can output some information about selected acquired variables and visualize them in Matlab with scan_bin(1m). This is useful if only parts of the acquired data are to be loaded into the database.

SCANNING NAVIGATION FILES
This step has the same purpose as the one for raw files, but it is of course designed for navigation files. It is carried out by scan_nav(1). As for raw files, selected variables can be selected for output and visualized within Matlab with scan_bin(1m).

LOADING ADCP DATA
The utility process(1) will merge and synchronize NBR ADCP and navigation data, average and load them into an ADCP CODAS database. For this purpose, producer definition file adcp_hm.def can be used. Some of the log information output during this process can be visualized within Matlab with process(1m).

SEE ALSO

gfiindex(5)
    Index of all GFI extensions.

AUTHOR
Pierre Jaccard, Geophysical Institute, University of Bergen, 1999.