Inclinometers

There are many differences between the two systems that make comparisions difficult, but there is a specific instance where a valid comparison can be made.

Readings cannot be compared directly, even if they are in the same units. Readings from both types of sensor contain an unavoidable offset. The offset is removed from traversing probe data by combining readings from two passes with opposite orientation of the sensor. The two-pass survey is not possible with IPIs, so the embedded offset value remains.

Profile plots cannot be compared directly. Pofile plots (cumulative-deviation plots) are made by accumulating the tilt readings from each interval or sensor. The tilt of the probe or sensor is controlled by its contact with the casing. The contact points are 0.5m apart for the traversing probe, but 1m, 2m, or 3m apart for the IPI sensor. Thus the two instruments will share at most just one contact point and always report different tilt angles.

Profile-Change Plots offer the only opportunity for comparison. These “cumulative displacement” plots are made by comparing current profile with the initial profile. The comparision removes the embedded offsets from the IPI values, but the different points of contact withing the casing are still a factor. That said, if the bottom wheels of the probe and bottom wheels of the IPI are positioned at exactly the bottom depth and the top wheels of the probe and top wheels of the IPI are positioned at exactly the same top depth, the value at the top depth should be comparable. In addition, the overall appearance od the plot should be roughly comparable.

Allow the backfill around the inclinometer to stablize and wait for installation stresses to dissipate. Start recording readings right away, but choose baselines readings after readings have been stable for several days.

Probably not. If sensors are pulled from the casing and then reinstalled, the previous baseline readings are unlikely to compare well. Output will stabilize after some time passes, but even slight differences in the positioning of the sensors will appear as changes (movement) in plots. It is better to establish a new baseline.

Vibration adds noise to the output of any accelerometer-based sensor. The noise degrades the precision of the data, but the mean value of the data can still be used to show trends. Filtering and averaging could possibly improve the data.

Strong vibrations can cause sensors to shift within the casing. The movement may be small, but the result is a change in tilt. The direction and magnitude of the shifts are random, so the resulting data values look erratic. One possible way to prevent shifting of the chain is to fill the casing with sand or soft grout.

There are some notes in the manual, but here are some additional points:

1. Check that the casing is deep enough to contain the chain of sensors. Note that a 60 meter chain will not fit properly in a 60 meter casing. The bottom sensor must not touch the bottom of the casing and the top of the chain should end well below the top of the casing. Also allow some room for the suspension kit at the top. If the casing is not deep enough, shorten one of the gauge tubes. Be sure to note the final length.
2. Fit gauge tubes to each sensor. Test the connection for rigidity.
3. Use cable ties to hold signal cables neatly against the gauge tubes. Signal cables must not touch the walls of the casing.
4. Use cable ties to hold connectors neatly against the gauge tubes. Put one cable tie above and one below the connector to ensure that it is not pulled apart.
5. When the entire chain is in the casing, try lowering it below the intended depth and then pull it back up to the depth. This should put the chain into tension and theoretically shorten the time needed before a baseline reading can be acquired.

DMM for Windows has been replaced by DigiPro2.
The basic version of DigiPro2 is free to use, just as DMM was.

DMM was written in Microsoft VB6. Microsoft discontinued support for VB6 development tools some time ago, making bug fixes and further development nearly impossible. In addition, Microsoft warned that Windows 7 would not support for the VB6 runtime. In fact, they relented and included some minimal VB6 runtime support in Win7, but it is certain that DMM will stop running in some future update of Windows.

For that reason, we developed DigiPro2 to replace both DMM and the original DigiPro. Development took over a year, but it is written in C# and is guaranteed to run on future updates of Windows. We encourage everyone to migrate to DigiPro2 sooner rather than later.

Please take a look at the DataMate Communications FAQ.

DMM for Windows makes this easy. Here’s how:

1. Select the misplaced survey.
2. Click Edit Add to pop up the edit window.
3. Choose the correct installation from the drop down list at the top of the edit window, and click OK. This makes a copy of the survey and places it under the correct installation.
4. Finally, clean up the database. The original survey – the one you copied – is still there. Select it and click the delete button to remove it from the database.

After you do this, check the installation information stored in your Digitilt DataMate. Is it correct?

Make a composite setup database. Here’s how:

To send installations and datasets (surveys) to the DataMate, you make a “setup” database. To make a setup database, simply save your project database as a setup database. DMM makes a copy of the database and then strips out any data, so all that remains is installation information. To add a previous survey to the setup database, view your project database and setup database side by side (Use the Ctrl-T Tile command) and click-drag-and-drop the needed surveys from the project database to the setup database. Just drop the survey anywhere in the white window. It will find its own way home. Now you can close the project database, but keep your setup database open.

Now, open another project database and tile it side by side with your setup database. You’ll be doing click-drag-and-drop operations again. Click-drag-and-drop surveys that you want in the DataMate. The surveys will bring installation information automatically. (Watch out: if you drag an installation, the installation will bring along all of its surveys. So drag a survey, not an installation).

Repeat this for any other installations that you need. Keep in mind that the DataMate has a 40 installation limit and limited space for datasets (surveys).

When the setup database holds the installations and surveys that you need, send the setup to the DataMate. This will cause the DataMate to delete everything that is in its memory and replace it with the contents of the setup database. So be sure that you have retrieved anything that you want from the DataMate before you send the setup.

You can’t do exactly that, but here is a workaround that provides the same result.

1. Choose “DataMate -> Retrieval All.”
2. DMM retrieves data and displays a temporary database (“Data retrieved from DataMate”).
3. Delete any unwanted data from the temporary database.
4. Choose “DataMate ->Send Setup” to transfer the edited database to the DataMate.
5. You’ll see a warning. Click OK to continue.
6. Now the DataMate contains the edited database.

Do it this way: CLICK, then drag and drop. First click on the survey to select it. You’ll see the color change. After the survey is selected, you can drag and drop it. Give it a try: CLICK, drag, and drop. It works.