FREQUENCY MEASURING METHOD AND APPARATUS FOR BIPOLAR SIGNALS

摘要

PROBLEM TO BE SOLVED: To accurately measure the frequencies of bipolar signals without being affected by any phase deviation between positive and negative pulses.

SOLUTION: The leading edge of a pulse string of a clock to be measured resulting from B/U conversion of bipolar signals by a B/U converter 110 is counted with a first counter 120; a measuring period is so set in advance on the basis of the count as to make the polarities of the pulses determining the timing of start and that of ending the measuring period coincide with each other; and a second counter 130 that counts in accordance with a reference clock is validated in the measuring period; and the frequency of the clock to be measured is calculated by using the count of the second counter.

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