Abstract: The adaptive speed to changes in a primary source noise is increased through a noise detecting means feeding parallel multi-passband means and multi-transverse adaptive filter means, where each adaptive filter has its own individual adaptive step size means adjusted automatically according to the signal strength at each passband output. The output from each of the multi-adaptive filter means drives a secondary canceling source generating means where each multi-adaptive filter means is automatically adjusted to produce minimum sound in its passband at an error detecting means. Alternatively, the output from the noise detecting means is negated through a negation means, passed through a plant neutralization inverse means and an inverse delay means before driving the secondary source generating means.

Abstract: A method and apparatus for diagnosing the mechanical condition of a machine. The method of the invention includes the following steps: sensing a reference vibrational signal of the machine; creating a reference set of events from the reference vibrational signal of the machine; saving the reference set of events; sensing a test vibrational signal of the machine; creating a test set of events from the test vibrational signal of the machine; and, comparing the test set of events with the reference set of events to determine the mechanical condition of the machine. The invention further includes a method of extracting a set of events from a vibrational signal of a machine wherein a subset of the events corresponds to a physical action of the machine. The invention also includes a method of determining a set of clustered events for a machine from a plurality of sets of events, wherein each of the sets has a number of events therein.

Abstract: The invention provides a method and apparatus for diagnosing the mechanical condition of a machine. The method of the invention includes the following steps: sensing reference vibrational characteristics of a machine in the time domain; creating a reference signature from the reference vibrational characteristics; saving the reference signature; sensing test vibrational characteristics of the same machine in the time domain; creating a test signature from the test vibrational characteristics; automatically computing a measured distance between at least one point of the reference signature and at least one corresponding point on the test signature; automatically comparing the measured distance against a threshold value to determine if the machine is operating normally or abnormally; and providing a signal when the comparison indicates abnormal operation. An apparatus is also disclosed for implementing the method of the invention.