| 摘要 |
A method for improving signal quality while simultaneously enhancing the data rate in a communications system in which individual signaling events are, at least in principle, capable of representing a bit of digital intelligence. When the method is applied to power-line communication systems, the pattern of signaling events extends over some integer multiple of four cycles of the power-line wave. Signaling events of each particular type are found in exactly half of the cycles contained in any pattern. Patterns containing but one type of signaling event are arranged into orthogonal patterns-the term orthogonal implying that each pattern can be sensed only by a detection mode that maximizes the signal therefrom, and the application of any detection mode to a pattern for which it is not optimum will result in no net accumulation of signal. When two types of independent signaling events which yield signals of comparable magnitude are achieved they are arranged into pseudo-orthogonal patterns to further expand the data rate without impairing signal quality. Under these conditions quaternary coding proves to be the preferred technique. Examples are given wherein a multiplicity of simultaneous noninterfering messages are transmitted under circumstances where it is possible to transmit them in synchronism. Where multiple messages cannot be synchronized the method can be used to increase the data rate through the use of encoding schemes based on numerical bases greater than binary.
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