User manual

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moving data onto the flash card. The duration of the data transfer is 10% - 15% of the elapsed
profile time.
ACM Measurements
The ACM logs a 2-axis tilt measurement, a 3-axis compass measurement, and a 4-axis
velocity measurement in each record. Each datum is stored as a scaled integer in two bytes with
eighteen bytes in a record. ACM records are also acquired at a nominal rate of 1.85 Hz and can
be logged internally for approximately 8.75 hours before filling the ACM's 1 Mbyte data
memory. The measured current drain of the ACM is 25 mA while logging internally and 40 mA
while moving data onto the flash card.
NOTE
The sensors do not log time tags with their measurements; all time tags are recorded in the
engineering files.
The overall data acquisition rate for the primary instrument suite is approximately
50 bytes/second. At a profiling rate of 25 cm/s the acquisition rate is 200 bytes/meter or
200 Mbytes per million meters of travel. The acquisition of engineering data is an incremental
increase on this that brings the total to roughly 220 Mbytes per million meters.
During a profile the system queries the CTD for real-time depth (pressure)
measurements. The information is used to determine when the end of a profile has been reached
or an obstruction has been encountered. These algorithms are described in more detail in Chapter
7, “User Interface”. The MMP can continue to conduct a deployment if one or both of the
primary sensors is damaged or otherwise fails to communicate.
Standard settings for deployment on the MMP exist for both the CTD and the ACM. The
logged quantities described above are the most important aspect of the standard settings, which
are described in detail in Chapter 7, “User Interface”.
NOTE
The MMP can support non-standard sensor settings, however, McLane strongly recommends
that you use the standard settings for all MMP deployments.
Appendix B-10