| 摘要 |
The present invention relates to a method and an apparatus for generating an electronic test signal, and particularly to the use of such a method and apparatus for calibrating meters used to measure electrical characteristics such as voltage, current, phase angle and power. A user may select via a user input control the frequency domain characteristics of a desired electronic test signal including a user-defined set of amplitudes and phases of a fundamental frequency and one or more harmonic frequencies. A processor generates from the user-defined set of amplitudes and phases a frequency domain output set of amplitudes and phases for the fundamental frequency and one or more harmonic frequencies, which is then converted into a first time domain set of amplitudes extending over at least one cycle of the fundamental frequency. The first time domain set of amplitudes is communicated to a digital-to-analog output stage which generates an electronic test signal corresponding to the time domain set of amplitudes. The test signal is fed back to an analog-to-digital feedback input stage which generates a feedback time domain set of amplitudes extending over at least one cycle of the fundamental frequency. The feedback time domain set of amplitudes is converted by the processor into a feedback frequency domain set of amplitudes and phases for the fundamental frequency and one or more harmonic frequencies The processor then compares the feedback frequency domain set of amplitudes and phases with the user-defined set of amplitudes and phases, and when necessary modifies the output set of amplitudes and phases to reduce any differences between the feedback time domain set of amplitudes and phases and the user-defined set of amplitudes and phases.
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