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Automated Animal Tracking Using Phase Interferometry

When tracking small animals, researchers often rely upon low-powered beacon collars with limited functionality, usually emitting a simple pulse-CW VHF signal. These animal collars typically are tracked by the researchers using handheld directional antennas, and require the researcher to manually locate and record the position of the animals. In this paper, we will outline an automated tracking tower that can be deployed in the wilderness to constantly monitor the location of the desired tracking collars.

This paper details a student design of an expandable animal tracking system integrated into a field-deployable 20ft. tower. The receiver employs several phase-synchronized Software Defined Radios (SDRs) to implement a phase interferometric measurement of the signal’s direction of arrival. Calibration and time synchronization between the individual channels of the receiver is achieved by synchronizing a white noise calibration signal. The system measures and store the bearing, animal identification, and time of animal contacts. The system has been measured to be able to accurately determine the angle of arrival within 5 degrees of accuracy at a range of at least 0.75 miles. This automated tracking system can provide a much less labor-intensive method for researchers to monitor wildlife patterns and can be deployed in fairly remote locations for several weeks without requiring any human input.