ALS - Interval Measurements
This page describes how to capture multiple measurements from the light sensor.
Last updated
This page describes how to capture multiple measurements from the light sensor.
Last updated
Multiple measurements from the DAQ-M are usually performed when measuring the ambient light spectrum (ALS), to assist with calibrating multispectral Survey3 images for percent reflectance.
To measure the ambient light spectrum use the Lighting Mode (Recorder) in the SCANNER application
The time for each measurement scan is based on the Frame Average setting in the SCANNER application. The default Frame Average value of 20 provides a good balance of averaging measurements and a fast response between scans. Adjusting the Frame Average value to a larger number may improve your measurement average.
If the SCANNER application is warning you about saturation, then the light is too bright, and you need to use the frame secondary diffuser.
Start capturing the measurement in the SCANNER application by tapping the play/start button.
The next screen will ask you to set the duration. If you want to start recording now, the chose the recording interval to capture the measurements at, as well as the duration of the recording time.
Pressing the Ok button will start the recording. The Recording status bar will iterate as the measurements are captured. The fraction to the right of the status bar shows: "the number of measurements captured" / "the total number to capture".
If you want to set a recording for a future date, then choose Custom in the first Duration screen and you will be presented with the Duration (1/2) screen. Tap the blank line below the From to set the starting date and time. Do the same for the To, the end of the recording date and time.
The final Duration (2/2) screen confirms the future start and end recording times. It will also pre-fill the Total records field with the maximum number of recordings possible. The length of time between the start and end times, divided by the number of records, produces the Period value. You can then edit the Period value to a value higher than the default, and the Total records number will update accordingly.
Once you press Ok on the Duration (2/2) screen, the application goes into standby mode, waiting for the future recording start time.
If you press the Stop button at the bottom during recording a warning will appear:
When the recording finishes, the recording status bar shows you the number of measurements that are saved on the DAQ-M.
Once the recording is finished you can click the save icon at the bottom right:
Type a unique name in the Save Records screen. Choose to show each result as it saves it on the main screen by checking the box. Click Ok to save it:
If you checked the "Render Record Result" box then the graph updates as the status bar shows the saving progression:
Place the DAQ-M into a Frame that has the white diffuser disk on it. Examples include the and . The diffuser allows the DAQ-M to be used in bright lighting environments, such as in direct sunlight.
If there are recordings on the device then they will be overwritten if you try to start a new recording. If you need to save the recordings on the DAQ-M internal memory then you need to . You will be shown the below warning to delete the memory prior to each new recording. Click continue to erase the internal memory and start a new recording:
You can safely stop the recording at any time and the already saved data will exist on the device. Just remember that you cannot stop and then start it again. You first must in order to start a new recording again
Once recordings are saved you can or the saved data.
