Disclosed is an apparatus and method for detecting presence of persons or objects within an environment. The apparatus and method may determine a difference in relative position between transmitters having an unknown room position. A transmitter may emit coded signals that may be detected by other transmitters within the room and properties of the coded signal can form a baseline for comparison to new signals after the baseline is established. Through the use of coded signals and relative distance location between transmitters, movement and position of persons or objects within the room may be determined.