ARU

Automatic Receiving Units (ARU) are portable, low-current receivers able to continuously collect data running from an automobile battery for about six weeks between charges or indefinitely with a 5 watt solar panel. An internal clock provides date-time stamps accurate to the nearest second over periods of many weeks. ARUs can record signal amplitude for continuous transmitters, in addition to pulse interval and pulse width from pulse transmitters, and coded data such as GPS locations from transmitters with built-in sensors.

A single ARU is sufficient to obtain temporal activity patterns. For direction finding, up to 8 antennas may be connected to an ARU. For instance, six directional antennas pointed every 60 degrees provide bearings over a full 360 degrees. Several ARUs deployed in this way provide bearing data for triangulation of animal locations. Data can be recorded in exchangeable memory modules and/or transmitted with third party equipment to a central location for display and storage.

Each ARU is capable of searching over 200 channels in the frequency range. However, time often constrains the list to much fewer.

The ARUs store data onto removable memory modules, each with about 4MB of raw data capacity. The time it takes to collect this data varies, but a module typically lasts at least two weeks.