Patent attributes
A frequency stability measuring apparatus for measuring a frequency fluctuation of a signal outputted from a given signal source includes: a reference signal output unit that outputs a reference frequency signal; a mixer that mixes a signal outputted from the signal source with the reference frequency signal outputted from the reference signal output unit and outputs a resultant signal; a filter that allows a low-frequency component of the signal outputted from the mixer to pass therethrough; a waveform-shaping circuit that shapes a waveform of a signal outputted from the filter; a counter that counts a number of pulses of a signal shaped by the waveform-shaping circuit; and a control unit that calculates average frequencies of the signal outputted from the filter within respective measurement periods of a predetermined length, and calculates and outputs a standard deviation of the average frequencies calculated
