User manual

estimate to the nearest hour or quarter hour. Note that any subsequent changes to the shallow or
deep pressures will automatically update the profile time limit, overwriting the manual change.
The time limit has an absolute maximum value of 8 hours. The internal memory capacity
and the data rate of the CTD and the ACM limit logging to approximately 8.5 hours (the CTD
produces 9 byte records at ~1.85 Hz and has ~0.5 Mbyte of available internal storage. The ACM
produces 18 byte records at ~1.85 Hz and has ~1.0 Mbyte of available internal storage).
At a nominal speed of 25 cm/s, the MMP can profile the maximum excursion of
6000 meters in ~6.7 hours. The time limit is dynamically incremented during a profile whenever
the mid-water obstacle ramming behavior is triggered. The increment includes the duration of the
two additional velocity ramps, the zero pressure rate interval, and the stop check interval. The
time limit is reset to 8 hours whenever an increment raises the time limit above the absolute
maximum.
When everything goes as expected during a deployment the profile time limit is not
reached. Setting the time limit to 8 hours allows the system to maximize the amount of time to
reach the stop on each profile and each profile will likely terminate on pressure or pressure rate.
However, if there are problems acquiring pressure measurements, this approach will also result in
the maximum amount of time pushing against the physical stop and wasting battery energy.
McLane recommends accepting the time limit calculated by the system, or manually rounding to
the next quarter hour.
Allowed range: 10 seconds to 8 hours in 1 second increments.
Stop Check Interval <C>
Stop check interval determines the frequency of system checks during profile motion to
see if the MMP has reached a stop. The checks include examination of the ambient pressure, the
pressure rate, the elapsed time, battery voltage and motor current. The TT8v2 enters low power
sleep between checks.
G-51