Patent ID: 9026403
Filing Date: 2015-05-05
Classification: G01R

Abstract:
1. A frequency measurement device that measures a frequency of a measurement signal continuously, comprising: a reference signal source that generates a reference signal; a frequency divider/multiplier section that generates a frequency division/multiplication reference signal obtained by dividing or multiplying the reference signal by a frequency division ratio or a frequency multiplication ratio; a first counter section that outputs a first count value obtained by measuring a number of the rising and/or falling edge of the measurement signal within a prescribed period determined based on the frequency division/multiplication reference signal; a first low pass filter that removes a high frequency component included in the first count value; a coefficient deriving section that derives a conversion coefficient based on the frequency division/multiplication reference signal, the coefficient deriving section including: a conversion section that multiplies an output value of the first low pass filter by the conversion coefficient or a reciprocal of the conversion coefficient, the conversion section multiplying the output value of the first low pass filter by the reciprocal of the conversion coefficient; and the frequency divider/multiplier section changing the frequency division ratio or the frequency multiplication ratio dynamically so that a value of an operating point parameter defined by a fractional portion of a ratio x/y of a frequency x of the measurement signal to a frequency y of the frequency division/multiplication reference signal is changed to be within a predefined range.