Apparatus and associated methods relate to health-monitoring of a magnetic speed probe (14). An inductive coil (18) of the magnetic speed probe (14) is used for two purposes: i) to sense a changing magnetic field caused by rotation of a rotating member; and ii) to radiatively transmit radio-frequency signals for determining the health of the magnetic speed probe (14). A signal generator (20) coupled to the inductive coil (18) of the magnetic speed probe (14) generates the radio-frequency signals that, when conducted by the inductive coil (18), cause the inductive coil (18) of the speed probe to act as a radio transmitter by radiatively transmitting the radio-frequency signals. The radio-frequency signals transmitted by the inductive coil (18) are detected by a radio receiver (24). The radio-frequency signals received are indicative of health of the magnetic speed probe (14).
The analysis of the received radio signals can involve emitting of a signal having a fixed frequency and determining of the amplitude of the received signal. It can also involve a frequency sweep of the radio signals applied to the coil, evaluating the amplitudes of the received signal and determining the maximum amplitude, which may indicate the resonant frequency of the coil. The received signals may be compared with reference values indicating normal operation.