International Business Machines Corporation

Mayo Foundation for Medical Education and Research

David C Casler

Joan LaVerne Mitchell

Piet C De Groen

Computation of variance or variance of the autocorrelation over a moving window of various sizes of a signal containing noise and possibly a small digital signal provides a sensitive, frequency independent indication of the likelihood of the presence of a small pulse, chirp or even spread spectrum digital signal possibly obscured by noise or larger signals in the signal to much lower signal-to-noise ratios than previously possible. Large signals in the signal which may also obscure any small signal are removed to a different signal path from the noise and small signals by subtraction after compression and reconstruction of the large signal. The compression noise thus added to the signal may also increase sensitivity of the variance of the autocorrelation to small signals obscured by the large signals. Controlling storage in response to the computed variance or variance of the autocorrelation allows substantial avoidance or limitation of storage of signals which contain only noise.

Using statistics to locate signals in noise

Embodiments of the present invention provide devices and techniques for detecting anomalies in monitored environments. In one embodiment of the invention, data may be acquired by monitoring an environmental variable. Based on the acquired data, statistics may be calculated which model the behavior of the environmental variable. Based on the calculated statistics, a long-term behavior and a short-term behavior of the statistics may also be calculated. A difference between the long-term statistics and the short-term statistics may then be calculated. If the difference between the long-term statistical behavior and short-term statistical behavior exceeds a dynamic or predefined threshold, an action may be taken.

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Montrose, CO, United States of America

David C Casler