Precision Measurement Engineering, Inc.
Precision Measurement Engineering, Inc.
Downward direction profiling is used when measurement of the bottom
boundary layer is desired. The host computer and SCAMP control dialog must be properly
installed as described in the Installing the SCAMP Software , Checking the Batteries, and the Assembling the
SCAMP stand sections.
Assembly of SCAMP
SCAMP is most conveniently shipped and stored dis-assembled. It must be assembled prior to profiling. Assembly is accomplished by the following steps:
| Place the retrieval line loop over the
sensor cover and onto the SCAMP. Place the float assembly over the sensor cover and onto the SCAMP. Place the 5151 float retainer ring over the sensor cover and onto the SCAMP. |
|
| Carefully remove the sensor cover. Do this in a sitting position with the SCAMP rotated so that the Accurate CT sensor is either on the right or left side. Do this so that the relative slant of the sensor cover as it comes off the retaining threads is visible relative to the Accurate CT sensor. Since the Accurate CT sensor is the farthest sensor from SCAMP's center it is the most likely sensor to be damaged when removing the sensor cover. |
|
| Screw the sensor guard into place. Use a small cable tie or bit of dental floss to tie one of the guard's legs to one of the sensor seal nuts bases. This will prevent the unscrewing of the guard during a SCAMP deployment. Should the guard come unscrewed the retrieval cable can slip loose and the SCAMP will be lost. The sensor guards screw on tightly, but this extra precaution is low-cost insurance. The picture displays an older version of this guard. |   |
| Install the drag assembly and tighten the thumbscrews. Be sure that the thumbscrews find the groove in the end sleeve on the SCAMP. If the SCAMP slips from the drag assembly it can be lost. |
|
| Wire the drag assembly in
the 90 degree from SCAMP axis position using the holes in the arms provided and bits of
weight wire. Move the retrieval line loop and float assembly against the drag plate. |
|
| Move the 5151 float retainer ring against the float. Tighten the thumbscrew on the float retainer ring. |
|
| Place a sufficiently large ballast weight (sheet lead supplied with the SCAMP) around the sensor end on the SCAMP tube just aft of the sensor guard. Tape this in place. The SCAMP must be nose heavy. You may have to add floats and weight. |
|
| Place the SCAMP on the SCAMP stand with the sensors in the water contained by the bucket. |
|
| Insert the drag plate wing retainer pin located on the retrieval line into the drag plate arms. Insure that the I/O connector cover is securely in place over the I/O connector. Water must not enter this connector!! |
|
Mission Definition
You must program SCAMP to implement the desired profile. Once programmed, the SCAMP will implement the profile over and over with data from each profile stored separately in SCAMP’s memory. Missions are defined by the following steps:
Establish communication with the SCAMP
Select the Mission tab, shown below
Define Starting Conditions for Data Recording. The conditions you define are ‘OR’d by SCAMP for the purposes of determining when to begin a profile. SCAMP will begin a profile when it determines that any one of the conditions you define are true. You must carefully consider the definitions you make here.
In a downwards profile SCAMP must usually begin sampling as near to the surface as possible. The Begin Depth should be defined to be 1 meter although it can be defined deeper should a deeper start be desired. You must provide sufficient Begin Delay time for SCAMP to be deployed and reach the desired depth. You can supply substantially more Begin Delay time and thereby depend upon a depth start, but normally a Begin Time start is used and scanning begun with SCAMP above the surface.
Define Ending Conditions for Data Recording. At the time the profile
begins scanning and operates its release motor for two seconds. Thereafter SCAMP descends
while collecting data. You should define Acquire Scans with sufficient scans to collect
data over the length of the water column. SCAMP scans at 100 scans per second and
nominally travels at 10 cm/second giving a nominal 1000 scans per meter. Allow extra scans
to cover uncertainties in depth and SCAMP travel rate. Disconnect SCAMP from the host computer and place the I/O cover onto the
I/O connector prior to profiling.
Profiling
SCAMP will acquire multiple profiles without uploading of data or re-definition of missions. Between profiles SCAMP enters a low power ‘sleep’ state to conserve batteries. Prior to each profile SCAMP must be ‘awakened’. After SCAMP is awake it can be placed into the water and perform its mission.
(Note that SCAMP will not acquire a profile if connected to the host computer!)Profiles are implemented with the following steps:
Place a finger against the release screw. Hold the Start Magnet near the SCAMP, about half way between the ends. Magnet should be alligned with the Accurate CT sensor. When SCAMP senses the magnet it will immediately rotate the release screw for a brief period. The magnet should be removed at this time. SCAMP reviews its internal state to determine if sufficient battery and memory resources exist to acquire the impending profile. If insufficient resources are available SCAMP will return to sleep mode. if sufficient resources are available and after about 2 seconds, SCAMP will operate its release motor twice briefly. At this time SCAMP will define the current pressure as zero depth and begin evaluating starting conditions for data recording as described in the section above. (Note that since SCAMP's pressure transducer is located at end opposite SCAMP's sensors, sensor zero depth will be different and must be adjusted by the customer's software.) Once it begins evaluating start conditions, SCAMP must complete a profile before it will return to the sleep state. (See the Aborting a Profile section if a profile must be aborted.)
| Lift the SCAMP from the stand and place it in the water with the sensors downward. Release it and pay out the retrieval line as it sinks. |
|
The SCAMP must be free of retrieval line tension as it travels the water column. You must pay out sufficient retrieval line to prevent cable tension as the SCAMP travels away from the boat. Also, in windy conditions the boat will be blown away from the SCAMP and then the retrieval line must be paid out to compensate.
After more than (10 seconds/meter * depth) seconds have passed, then recover the SCAMP by hauling it back with the retrieval line.
| When the SCAMP is alongside the boat, lift it by the retrieval line or the sensor guard (don't touch the sensors) until you can grasp it by the SCAMP tube. Lift it into the boat. Once retrieved, place the SCAMP again in the stand with the sensors in the bucket. |
|
A final note: SCAMP profile files are named with the time that SCAMP determined a starting condition became true and began the profile.
