Provided are a method and apparatus for performing medical catheterization using electrical power circuitry disposed outside a medical catheter and remote internal circuitry disposed within the medical catheter. At least one of the power circuitry and the internal circuitry is isolated from electrical ground. Exactly two wires connect the power circuitry to the internal circuitry and a signal generator is provided for generating an alternating carrier that is communicated from the power circuitry to the internal circuitry via the wires. Decoders are disposed in the power circuitry and the internal circuitry, and a transceiver performs half-duplex data communication between the power circuitry and the internal circuitry by alternately modulating the carrier voltage amplitude in one of the power circuitry and the internal circuitry and decoding the modulated carrier voltage amplitude in another of the power circuitry and the internal circuitry.
