A system for sensing rotational frequency of a rotatable member and for monitoring health of the system, the system comprising: a radio-frequency signal generator configured to generate an electrical signal; a plurality of magnetic speed probes (20A - 20C) arranged in transmissive proximity with one another, wherein at least one of the plurality of magnetic speed probes is a transmitter-configured magnetic speed probe and wherein one or more of the plurality of magnetic speed probes are one or more receiver-configured speed probes, each of the plurality of magnetic speed probes includes: a magnet configured to generate a magnetic field proximate the rotatable member, wherein rotation of the rotatable member causes changes in the magnetic field generated by the magnet; an inductive coil positioned proximate the rotatable member; and an electrical-current sensor coupled to the inductive coil, the electrical-current sensor configured to sense coil current induced within the inductive coil, wherein the transmitter-configured magnetic speed probe(s) further include a signal coupler configured to couple the electrical signal generated by the radio-frequency signal generator into the inductive coil of the transmitter-configured magnetic speed probes, thereby radiatively transmitting an electromagnetic signal; and a speed-probe monitor electrically coupled to each of the electrical-current sensors of the one or more receiver-configured magnetic speed probes, the speed-probe monitor configured to determine, based on the coil current sensed by the electrical-current sensor of each of one or more receiver-configured magnetic speed probes in response to the electromagnetic signal radiatively transmitted by the transmitter-configured magnetic speed probe, health of the system. a radio-frequency signal generator configured to generate an electrical signal; a plurality of magnetic speed probes (20A - 20C) arranged in transmissive proximity with one another, wherein at least one of the plurality of magnetic speed probes is a transmitter-configured magnetic speed probe and wherein one or more of the plurality of magnetic speed probes are one or more receiver-configured speed probes, each of the plurality of magnetic speed probes includes: a magnet configured to generate a magnetic field proximate the rotatable member, wherein rotation of the rotatable member causes changes in the magnetic field generated by the magnet; an inductive coil positioned proximate the rotatable member; and an electrical-current sensor coupled to the inductive coil, the electrical-current sensor configured to sense coil current induced within the inductive coil, wherein the transmitter-configured magnetic speed probe(s) further include a signal coupler configured to couple the electrical signal generated by the radio-frequency signal generator into the inductive coil of the transmitter-configured magnetic speed probes, thereby radiatively transmitting an electromagnetic signal; and a magnet configured to generate a magnetic field proximate the rotatable member, wherein rotation of the rotatable member causes changes in the magnetic field generated by the magnet; an inductive coil positioned proximate the rotatable member; and an electrical-current sensor coupled to the inductive coil, the electrical-current sensor configured to sense coil current induced within the inductive coil, wherein the transmitter-configured magnetic speed probe(s) further include a signal coupler configured to couple the electrical signal generated by the radio-frequency signal generator into the inductive coil of the transmitter-configured magnetic speed probes, thereby radiatively transmitting an electromagnetic signal; and a speed-probe monitor electrically coupled to each of the electrical-current sensors of the one or more receiver-configured magnetic speed probes, the speed-probe monitor configured to determine, based on the coil current sensed by the electrical-current sensor of each of one or more receiver-configured magnetic speed probes in response to the electromagnetic signal radiatively transmitted by the transmitter-configured magnetic speed probe, health of the system.