A system includes first unit, a processor and a transmitter. The processor is located in the first unit to generate data to be communicated to a second unit that is physically separated from the first unit. The transmitter includes an antenna, a first circuit and a push-pull amplifier. The first circuit generates signals that are indicative of the data, and the push-pull amplifier drives the antenna with a signal that is indicative of the data in response to the signals generated by the first circuit. The amplifier also establishes an output power from the amplifier to the antenna to less than about one hundred milliwatts.