Rotation speed determination

A system comprising:

• a plurality of monitors, each monitor comprising:
• a wireless communication module, a microcontroller, an accelerometer, and a battery module, each monitor configured to collect machine samples from a machine or a subcomponent of the machine in a plant, the monitor in wireless communication with a gateway, the gateway configured to transmit the samples to one or more servers in a maintenance and monitoring infrastructure;
• in a machine, having two or more subcomponents, monitors affixed to the machine and/or the subcomponents, wherein the subcomponents comprise rotating elements, each rotating element of a subcomponent, having a corresponding rotation speed;
• the system comprising one or more processors, wherein the one or more processors are configured to perform or cause to perform operations comprising:
• a first monitor, collecting samples from a first subcomponent of the machine, generating a first monitor output sample waveform;
• wherein the first monitor comprises a magnetometer;
• the first monitor, sensing a magnetic field, generated by a rotating element of the first subcomponent, the magnetic field proportional to the rotating speed of the first subcomponent;
• translating the sensed magnetic field to a rotation speed of the first subcomponent;
• with a rotation speed estimator, receiving the translated rotation speed of the first subcomponent;
• with the rotation speed estimator, generating an estimated rotation speed of the first subcomponent;
• wherein the rotation speeds of the subcomponents are related with a relationship function;
• determining rotation speeds of the remaining subcomponents, based on the relationship function and the estimated rotation speed;
• providing the determined rotation speeds as input to one or more maintenance models;
• the one or more maintenance models, generating a diagnosis or detection of a maintenance issue in the machine, based at least in part on the determined rotation speeds.