Abstract: A pyrotechnic release mechanism is actuated by an electrical signal from a remote telemetry actuator such as a radio transmitter to cause two normally connected parts to separate. When used as shown with an animal collar mounted data acquisition system, the two parts can be separated to release the collar. If desired, a separate data storage device can be released to permit stored data to be recovered. The device comprises two parts with interfitting members normally held in position with a coupling pin. A pyrotechnic device is positioned behind the pin, and upon firing, the pin is moved sufficiently to clear one of the members at least, so that the two members will then separate. The device can be used to permit remotely controlled recovery of a part that is normally mounted together and which are to be separated.

Abstract: An activity sensor which provides an indication of motion caused by changes in acceleration of a person or animal, and wherein such changes of motion are sensed by a movable magnet which is biased to a rest position along a guide. The axis of the path of movement of the movable magnet is substantially parallel to the direction of accelerations of interest. A Hall effect sensor is provided for sensing motions of the movable magnet from its rest position, and it provides an output proportional to these movements.