In this paper a system for proximity detection of small sized animals like bats is presented. The system is based on a time slotted communication between compact low weight mobile nodes. For precise time synchronization of the nodes a scalable grid of base stations is proposed that distributes a time reference signal using a time division multiple access (TDMA) scheme.

The system parameters are chosen considering the timing constraints caused by the severe requirements to the mobile nodes. In a power consumption analysis the system operation time limited by the 1.8 g nodes is calculated to be 7.4 days. First field test results are shown which proof the functional capability of the system’s principle.