Specifications

106
Table 5.12.1. Logger memory size and data capacity.
Flash card size
(MB)
Spectra capacity
(months)
Displacements
capacity (months)
128 36 4.7
256 36 11*
512 36 24*
1024 36 49*
2048 36 100*
*displacement files may contain multiple days per file
5.12.5 Raw displacements file
These files are identified by the RDT suffix. Initially, one file contains 48 displacement data
messages of half an hour each, covering one single day. However, if the number of
displacement files exceeds 256 (> 256 days or approximately > 8 months), one file can contain
more consecutive days of raw data. The filename is made up of the maximum significant wave
height H
s
during that day coded in 3 characters and the exact date. The max{H
s
} label is coded
as 3 characters A-Z corresponding to 0-25. The first character has a power of 676 cm, the
second has a power of 26 cm and the third has a power of 1 cm. The date is coded as MMDDY
and applies to the last sample in the file. To give an example: 05123AAC.RDT, means 5
December 2003, max{H
s
} label = 2 cm
In case buoy measurements continue while all reserved displacement data memory has
been filled, previous displacement data is selectively overwritten. The selection algorithm works
as follows. Displacements (vertical, north and west data) are logged per day. The half-hourly H
s
is also logged and the file is labelled by the maximum H
s
that occurred during that day. All
displacements are logged until the reserved space is filled. When the reserved space has been
filled, the files with the smallest H
s
(usually the least interesting files) are replaced by files with
greater H
s
. As a result, the reserved space on the flash card is completely filled with
displacement data of days with a rough sea and consequently high maximum H
s
.
The
W@ves21 software package supports reading and analyzing the RDT-files generated
by the logger.
5.12.6 Spectrum/system files
The SDT suffix identifies the spectrum/system file. Note that these files are not the 'spectrum
file' and system file' described under data formats, section 5.7. The filename itself carries the
month and year. To give an example: S11-2002.SDT, for November 2002. Each file contains a
month of half-hourly spectrum/system-file messages, hence 31*24*2 = 1488 messages at the
maximum. Furthermore, the name of the file contains the month and the year. The
W@ves21
software package supports reading and analyzing SDT-files generated by the logger.