Error compensation for a wireless sensor using a rotating microstrip coupler to stimulate and interrogate a saw device

Many mechanical systems contain rotating parts used to transfer power from one part of the system to another. The system's efficiency and longevity can be increased by measuring the speed and loading of the rotating parts. Passive wireless sensors are ideal for instrumenting rotating parts because they require no connecting wires and no stored energy. The sensor measurements contain read errors when the stationary interrogation circuit and the rotating sensor are not ideally aligned. The read errors are a function of the angular offset between the stationary interrogation circuit and the passive sensor. As such, the read errors are deterministic. A measurement of the angular offset between the stationary interrogation circuit and the passive sensor is used to determine a correction factor that cancels out the read error to produce a compensated sensor signal.