User manual

transfers the sensor data to the flash card. The time limit applies only to the period of profiler
motion during a single profile. It does not include the sensor logging intervals that occur before
and after profile motion or the time required to move data from the sensors to the flash card.
Changes to shallow or deep pressure settings trigger the firmware to calculate the time
that will be required to cover that distance: profile time limit = 1.25 × (deep pressure - shallow
pressure) / nominal profiling speed.
The additional time (25%) is added to account for slower profiling near the battery life
limit. The operator can accept or manually change the suggested time limit. Note that any
subsequent changes to the shallow or deep pressures will automatically update the profile time
limit, overwriting the manual change.
The profile time limit has an absolute maximum value of 8 hours. The memory capacity
and the data rate of the CTD and the ACM limit internal logging to approximately 8.5 hours (the
FSI CTD produces 9 byte records at ~1.85 Hz and has ~0.5 Mbyte of available internal storage
and the FSI ACM produces 18 byte records at ~1.85 Hz and has ~1.0 Mbyte of available internal
storage).
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.
In general, the profile time limit will not be reached. Setting the time limit to 8 hours
maximizes 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. Range is 10 seconds to 8 hours in 1 second increments.
Stop Check Interval <C>
Stop check interval sets the frequency of checks during profile motion to determine 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 electronics enters low power sleep
(LPS) between checks.
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