초록 ▼

The transmitter in a power line communications system applies to the power line encoded logical-one and logical-zero bit signals consisting of signals formed respectively of predetermined different sequences of frequencies. The receiver, coupled to the power line, includes a first homodyne, non-cohe

The transmitter in a power line communications system applies to the power line encoded logical-one and logical-zero bit signals consisting of signals formed respectively of predetermined different sequences of frequencies. The receiver, coupled to the power line, includes a first homodyne, non-coherent, quadratic demodulator for demodulating the logical-one bits and a second for demodulating the logical-zero bits. The first demodulator produces, locally, and in first and second channels, respectively, a first reference signal that is a replica of the logical-one bit sequence of frequencies and a second reference signal that is the replica in quadrature. The second demodulator produces, locally, and in third and fourth channels, respectively, cooresponding third and fourth reference signals for the logical-zero bit sequence. Each of the four reference signals is applied to a corresponding analog multiplier for multiplication by the input signal in each channel. The output of each multiplier is applied to a low pass filter that passes only the dc component of the product signal which in turn is squared. The resultant signals in the first and second channels are summed to provide a first output signal, and the resultant signals in the third and fourth channels are summed to provide a second output signal. Compensation circuitry cancels error voltages developed in the demodulatin channels as a result of component offset, and the two output signals are integrated over a bit period and then compared to each other to detect a logical-one or logical-zero bit.

대표청구항 ▼

A system for wideband transmission of data on an electricity distribution network, comprising: at least one transmitter including means for generating encoded signals corresponding respectively to logical-one bits and logical-zero bits, each encoded signal corresponding to a logical-one bit consisti

A system for wideband transmission of data on an electricity distribution network, comprising: at least one transmitter including means for generating encoded signals corresponding respectively to logical-one bits and logical-zero bits, each encoded signal corresponding to a logical-one bit consisting of a first predetermined, unrelated sequence of frequencies and each encoded signal corresponding to a logical-zero bit consisting of a second, different predetermined, unrelated sequence of frequencies; means for coupling said encoded signals on said electricity distribution network; at least one receiver having means for receiving from said at least one transmitter, input encoded signals on said electricity distribution network, and a homodyne demodulator including first demodulator means in a first frequency channel means for converting said logical-one bit signals into corresponding first dc signals, second demodulator means in a second frequency channel means for converting said logical-zero signals into corresponding second dc signals; offset compensation means coupled to said receiver for compensating any error voltage developed by said receiver as a result of offset voltage produced by components of said receiver; and comparator means for comparing output signals from said first and second channel means for indicating a logical-one or logical-zero bit.