An analogy is made between a machine component (or system) and a communications channel. During operation, information is sent as a signal over a communications channel from transmitter to receiver. The signal over the channel is altered by limited dynamic bandwidth, nonlinearities and noise. The goal is for the receiver to extract and reproduce the message, despite distortions and noise. Design of communications systems is aided by powerful theorems of Shannon (1949), which establish minimum signal to noise ratios for error free transmission.

A machine component (or system) accepts a “signal” from an upstream component, by its function alters that signal, and then passes the “signal” on to the next downstream component. In the analogy of this article, a machine is a communications channel. When operating properly, the “signal” from an upstream component is “received” by a downstream component. Faults in the machine which disrupt functionality alter the “signal”. Faults will be viewed as agents that alter system parameters or contaminate the signal with “noise”. Unless the signal to noise ratio is kept sufficiently high, downstream components cannot “resolve” the “signal message” error free, and the machine malfunctions.

In this article, Shannon’s theorem’s will be applied to machinery to establish performance limits, and develop a failure criteria to assess functionality of new or degraded machinery. With these, operational condition of machinery and maintenance needs can be predicted.

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