Abstract: A system protocol for the composite shift key communication of binary signals in which a transmitting transceiver transmits a first summed signal having a first qualifying signal at a qualifying signal frequency Wqt as one of the summed signal components only when a binary signal is desired to be transmitted. The transmitting transceiver ceases transmission of the first qualifying signal Wqt as a transmitted signal or as a component of a composite summed signal when neither a binary zero nor a binary one is desired to be transmitted. The receiving transceiver signals to the transmitting transceiver when the binary signal transmission is being successfully received by transmitting thereto a second qualifying signal Wqr. The receiving transceiver drops the transmission of the second qualifying signal Wqr when the binary signal transmission is not being successfully received, or is being received with perceived errors therein.

Abstract: A Composite Shift Keying (CSK) modulation technique is described which provides enhanced error detection capability in a noisy transmission medium, such as an AC power line. A modulating binary signal causes the generation of two of three possible transmitted signals, and when the modulating binary signal is idle, no signal is transmitted. When the modulating signal is active, a single frequency qualifying signal (of radian frequency Wqt) is transmitted. If the active binary signal is a logical 0, an additional single frequency (of radian frequency W0) is transmitted along with Wqt. If the active binary signal is a logical 1, a different single frequency (of radian frequency W1) is transmitted with Wqt.