Abstract: A small continuous loop tape recorder is connected to receive audio signals from a broadcast receiver, and a timer is provided to activate the recorder at intervals to record selected broadcast events. A mechanism is provided to manually activate the playback portion of the recorder whereby a previously recorded event is played back at a desired time. The receiver may be an integral part of a self-contained broadcast recorder unit, the receiver may be a conventional AM or FM broadcast receiver to which the recorder unit is connected, or there may be a combination of a self-contained receiver-recorder unit with a conventional broadcast receiver.

Abstract: A data evaluator employing an endless loop which has the capability of eliminating a standard signal from a test signal so as to result in the depiction of an accurate defect signal. The data evaluator of the instant invention generally comprises two record and play back heads, an endless loop which travels an endless path across the opposed record and play back heads, and a synchronizing device employed to synchronize the signals which simultaneously are played across two opposed record and play back heads.

Abstract: The broadband auditory thresholds of marine mammals are determined by an apparatus which compensates for the animals' movement artifact. A number of evoked responses to audio stimuli are average during discrete time intervals. This approach reduces the effects of potentials attributed to movements of the animal, for example, the opening and closing of the blow hole. A threshold detector circuit, a tape delay and related circuitry electronically cooperate to block potentials attributed to the movement artifact when the potentials exceed the likely magnitude of the evoked response. Optionally, an oscilloscope is used to provide a visual representation of the evoked response and the potentials are manually inhibited when the movement artifact masks or otherwise overrides the evoked response.

Abstract: A method and means for filtering and intensifying signal components of a desired predetermined period of repetition wherein a plurality of recording heads in tandem arrangement are provided, adjacent recording heads being equally spaced from each other. A magnetic tape is drawn past the recording heads at a constant velocity. The recurring signal component of desired period of repetition is delivered to the recording heads simultaneously and in such a way that the portion of the magnetic tape upon which each individual recording of the desired signal component is made by each recording head reaches the next recording head simultaneously with the next such signal component. As a result the amplitude of the desired signal component is increased on the magnetic tape and the amplitude of all other periods of repetition is relatively reduced. The summated signal can be reproduced by means of a playback head and an appropriate readout means.