A carrier state modulator system is described in which a stream of digital data bits is encoded by modulating the amplitude or phase of a carrier wave. A transmitter modulates the amplitude of a selected number cycles of the carrier in accordance with the state of each digital data bit. A receiver decodes the carrier state modulated signal by determining a phase score for the specified number of cycles of the modulated signal, the phase score based on a number of samples of the amplitude on a positive side of each cycle of the modulated signal that is above a selected amplitude and a second number of samples of an amplitude on a negative side of each cycle of the modulated signal that is below the selected amplitude. The value of the encoded digital data bit of the modulated signal is determined from the phase score.