Step 1 - Click the Magnetometers Button
In the Settings window in SAACR_raw2data, click the Magnetometers button. To get to this button, you will need to go up to step 5 in the SAACR_raw2data How-To Guide. The Magnetometers button is only to be used for the first run through SAACR_raw2data!
Figure 1: The Settings window in SAACR_raw2data
Step 2 - Backup Your Data
The Magnetometer Function dialog appears on the first run through SAACR_raw2data when a magnetometer is present. It is important to note that re-initializing magnetometer settings will change all converted data! It is very important that you backup your existing files if you are changing magnetometer settings. You will be reminded to save all files before re-initializing. Once your files are backed up, click the Continue button in the Magnetometer Function dialog to proceed with magnetometer configuration.
Figure 2: Last chance to backup files before configuring magnetometers
Step 3 - Select a Quiet Time
In the SAACR_magtool window, each ShapeArray's magnetometer data will be displayed in a separate tab.
Figure 3: The SAACR_magtool window
Select a quiet time by clicking in the Change in Azimuth per mag graph in the top half of the window. This will highlight a sample with a vertical line and indicate the data and time of the sample. The objective is to select headings that are not influenced by some disturbance, such as a large vehicle parked near the ShapeArray. You can right-click on the vertical line and select the Cancel option to deselect the selected time.
Repeat this step for each ShapeArray in the tabs at the top of window. For more information, go to Magnetometers section of the SAACR_raw2data manual.
Step 4 - Review Local Magnitude Strength (LMS)
The Local Magnitude Strength (LMS) is represented in the lower graph, as shown in Figure 3 above. The LMS can be near unity in some locations but can be quite different from 1 in others. Check the LMS value for your site (can be found on the Internet) and verify that the values are within about 15% of expected. If not, there may be ferrous materials present.
Step 5 - Optional, Enable / Disable Magnetometers
You can optionally enable or disable individual magnetometers within each ShapeArray. The magnetometers in the array are displayed with checkboxes near the top of the window in the Enabled Mags section. A magnetometer can be disabled by deselecting its checkbox. Turn off a magnetometer if you think its data is questionable due to nearby iron or something else that affects the LMS.
Step 6 - Complete Magnetometer Configuration
Once you have selected quiet times for the magnetometers in each ShapeArray, click the Done button,as shown in Figure 3 above, to save the magnetometer configuration.
At this point, SAACR_raw2data will need to reconvert the raw data to correct for the new roll offset. Click the Yes button to rerun the conversion or the No button to prevent the roll offset from being applied.
Figure 4: Reprocess data with new roll offsets
Step 7 - Optional, Manually Rerun SAACR_raw2data
If the No button was selected in the previous step, then SAACR_raw2data will need to be run again. When you rerun SAACR_raw2data, click Reset at startup. Ensure all settings are correct and click the OK button. All subsequent conversions can be performed using the Auto button to convert new data.