When clicking on the Motion Detector Channel Box in the Sensor Setup window, you will notice a few additional options, some of which are particular to that sensor.
When the Reverse Direction this option 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. The reverse direction option is also available on the force sensor and the force plate.
The Set Offset option will call up a box where you can 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 .4 m being read as 0 m.
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 (room temp). 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.