Patent ID: 7778785

Claim:
A measuring apparatus for measuring a signal-to-noise ratio of a discrete waveform which is output from an AD converter in response to an input signal, the signal-to-noise ratio indicating a ratio of a signal component of the input signal to noise generated by the AD converter, the measuring apparatus comprising: a spectrum compensating section that receives a spectrum of the discrete waveform output from the AD converter, and compensates the received spectrum in accordance with a non-symmetric sideband between an upper sideband and a lower sideband of the received spectrum, the upper and lower sidebands being defined with respect to a fundamental frequency of the input signal, the non-symmetric sideband being a portion of one of the upper and lower sidebands in the positive frequency range of the spectrum that does not overlap the other one of the upper and lower sidebands when the spectrum is centered around the fundamental frequency of the input signal so that the upper and lower sidebands overlap each other; and a phase noise waveform calculating section that calculates a phase noise waveform of the discrete waveform based on the spectrum which has been compensated by the spectrum compensating section.