Most bats use echolocation for orientation and prey catching. They emit species- and situation-specific ultrasonic sounds and receive from the echoes information about the location, the shape, and the velocity of located targets. It is necessary to study the animals in their habitats under natural conditions in order to understand the foraging and echolocation behavior of bats. The Technical University of Darmstadt, Germany developed a signal-processing system, which makes it possible to analyze bat signals and track a bat's flight paths in the field. The propagation time differences of bat sounds between several microphones are measured with a new correlation technique. A correlation receiver forms the bats sounds in narrow pulses and allows a time resolution of 2 (mu)s. The signals can be detected and analyzed with a high reliability down to a signal-to-noise ratio of -2 dB. The microphone configuration is optimized for the tracking problem and keeps Doppler ambiguity low. The distance related location error of a flight path tracking is between 0.2% and 2%. The range of the tracking method is between 15 and 50 m.