The X-Band Motion Detector operates in the X-band frequency of 10.525GHz and indicates detected movements with oscillations in its high/low output.
The X-Band Motion Detector's sensor is a common ingredient in security systems and automatic door openers, and can detect movements in a room, yard, or even on the other side of a wall. Sensitivity is manually adjustable with a potentiometer, offering direct line of sight detection from roughly 2.4 to 9m.

Operating frequency: 10.525GHz
Less prone to false triggers than passive infrared (PIR) motion sensors
Active-high enable pin with internal pull-up resistor
Trim potentiometer for manually adjustable sensitivity
4-Pin SIP header for breadboard or through-hole prototyping
Built-in series resistor for compatibility with the Propeller microcontroller and other 3.3V devices
Plated test point hole for monitoring pre-comparator signal
Power supply requirement: regulated 5Vdc @ 8mA
Communication: High (3.9V) / low (0V) signal oscillates with motion
Dimensions: 46 x 45 x 19mm
Operating temperature range: 0 to +55°C

Parallax offer an extensive range of sensor, communication and interface modules for the experimenter working on robotic systems. Most are supplied with extensive documentation making them ideal for use in education. Further information and tutorials are available from the Parallax website: http://learn.parallax.com/