| 摘要 |
Digital information is transmitted via a power supply network in accordance with a simulated digital waveform carrying digital information injected into the power supply network by a high voltage injector 4b, the simulated digital waveform having been generated by a generator 4a that builds the waveform out of predetermined harmonic frequencies of a signal frequency that is not a harmonic of power frequency. The high voltage injector includes drive stage transistors coupled to the power supply network and a chopping unit that rapidly turns the drive stage transistors on and off in conformance with the shape of a low frequency waveform. This permits an increase of the life expectancy of the transmitting equipment and control of heating of the transistors by altering the duty cycle, whilst maintaining broadcast of the digital signal to the receivers for much of the time assuring reliability of transmission to the receivers. The invention is especially suitable for the broadcast of standard time signals to many receivers across the power supply network as well as other types of control signals.
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