Abstract
Multiple wireless maintenance monitors can be affixed to an industrial machine and its subcomponents. Each monitor can collect samples from the industrial machine. For some applications, including failure analysis of parts with rotating elements, measuring or estimating the rotation speeds of the rotating elements can be helpful. In many industrial machines having rotating elements that are mechanically interactive with one another, the rotating elements can have proportional rotation speeds, governed by relationship functions. Rotating elements also generate magnetic fields, which can be used to determine the rotation speeds of the elements. Embodiments include wireless monitors, equipped with magnetometers to sense the magnetic fields generated by the rotating elements and estimate rotation speeds of those components. Additional embodiments include synchronizing sample outputs from the monitors and using inner-machine relationship functions to determine unknown rotation speeds of machine subcomponents.