A ROM-based high-accuracy line frequency and line frequency deviation meter

The meter is based entirely on basic digital circuits and does not include a microprocessor. A large-capacity ROM is used to convert the data, which are proportional to the line period, into line frequency and line frequency deviation. The meter provides 0.001-Hz resolution and an updating speed of 4 times per second. A computer algorithm for developing the ROM memory map is also presented. A prototype of the meter has been constructed and found to work well.<
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