Animal Location Tracker (ALT)

The Animal Location Tracker (ALT) is a coil array telemetry receiver. It takes the form of a rectangular platform upon which we can place an animal cage. The coil array is beneath the platform. The ALT uses these coils to decode telemetry signals and also to measure the strength of the radio-frequency signal at each coil. Because the strength of the received signal increases as the transmitter moves closer to the coil, we can use these power measurements to provide a crude estimate of animal location. The Neurotracker uses the weighted centroid of received power as its measurment of transmitter location. The absolute accuracy of this measurement is no better than ±10 cm. As an animal moves in a straight line across the platform, for example, its measured position veers from side to side. Nevertheless, the ALT provides a robust measurement of activity, by which we mean an distance the animal moves in a given time. It provides a robust measurement of proximity, by which we mean the average distance between two animals. Its measurement of movement direction and rotation are also robust, so that we can tell if the animal is moving north, south, east, or west, and we can tell if it is rotating clockwise or anticlockwise. If we have video of several similar animals in a cage, we can use the ALT's direction and rotation measurements to determine which animal the video contains which transmitter, a process we call video disambiguation.