There is disclosed a method and apparatus for detecting motion by a video encoder. The method starts with dividing a target block whose motion is to be detected into blocks at different pixel positions. A reference image block is extracted from a reference image. The degrees of similarity of the blocks to the reference image block are simultaneously calculated by a calculating unit. A block having the highest degree of similarity is determined, based on their degrees of similarity. A vector corresponding to the determined block is taken as a motion vector representing the block.

A system and method for ensuring that a monitored individual is located within a designated area is provided. Generally, the system contains a portable transmitter capable of being removably secured to the individual. A proximity sensor is provided, which is capable of detecting the portable transmitter if the portable transmitter is located within a predefined range of the proximity sensor. The system also contains a sensor that is capable of determining if an object is located within a predefined area. A monitoring station is provided for performing an event if the portable transmitter is detected by the proximity sensor and the object is within the predefined area.