Motion Detectors have a few additional features regarding their set up and data collection.
When clicking the Motion Detector channel box in the Sensor Setup dialog, you will notice a few additional options particular to the Motion Detector.
Reverse Direction
When Reverse Direction is checked, readings decrease when the target moves away from the Motion Detector. Frequently this option is used with the Zero option to create a coordinate system that is zero some set distance from the detector, and increasing and positive as the target is moved toward the detector.
Set Offset
Set Offset will allow you to set a value to offset every point collected with the sensor. The number you enter (either positive or negative) will offset the actual distance reading. For example, entering -0.4 meters will result in a distance of 0.4 m being read as 0 m.
Set Temperature
Sound moves at different speeds through air of different temperatures. The Set Temperature option lets you set the ambient temperature where you will be performing experiments. This number is used to calibrate the Motion Detector. The default is 20 degrees Celsius. The correction is small, so adjusting the temperature isn't always necessary. Only the Motion Detector allows this adjustment; the Go! Motion, when used by USB connection, corrects automatically for air temperature.
If you are using a Motion Detector and an analog sensor with a sample rate faster than the Motion Detector can support (over 50 samples/second), data collection will automatically enter Undersampling mode. In this mode, Logger Pro will collect data at a fast rate for the analog sensor but will set the rate for the Motion Detector to less that 50 samples/second. The Motion Detector columns will have many empty rows; this is normal. This mode is also called "Collision Mode."
A tutorial covering motion measurement is available. Choose Open from the File menu, then look in the Experiments folder to access it.