A system for three-dimensional animal tracking in laboratory conditions is proposed. A mobile device that has one infrared and one ultrasonic sensor, equipped with memory and/or radio transmitter, is attached to a moving creature. One compact stationary box is placed in the vicinity； it emits a pre-determined sequence of short infrared pulses, short ultrasonic signals and two planar, radially emitted light beams that move through the area of interest with constant angular speed in two orthogonal directions. The mobile device receives two angular coordinates in the form of two time intervals between an infrared pulse and the next two orthogonal planar beam receptions, and it receives one linear coordinate in the form of the time interval between an infrared pulse and the next ultrasonic signal reception, taking into account the speed of sound in the air. The ultrasonic emitter is driven by a pulse-width modulated signal to make it undetectable by animals.
