| 摘要 |
An electricity meter includes an input circuit operable to generate signals representative of a line voltage waveform and a line current waveform. A processing circuit is connected to the input circuit and is operable to generate energy consumption data based on the input signals. A communications circuit is also connected to the processing circuit. The communications circuit includes an optical receiver having a single photo-transistor, a single capacitor and two resistors. The photo-transistor is operable to act as a switching device that allows varying amounts of current to pass in association with received light pulses. This action allows light signals received by the photo-transistor to be converted into electrical signals. The electrical signals are passed across the first resistor. These electrical signals are differentiated by the capacitor and the second resistor to filter out low frequency signals created by ambient light.
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