Patent ID: 7995299

Claim:
An apparatus for evaluation of a magnetic recording medium, the apparatus comprising: a spin stand which rotates the magnetic recording medium; a magnetic recording/reproduction head; a mechanism to position the magnetic recording/reproduction head above the magnetic recording medium; a signal generator for generating square-wave signals at an arbitrary frequency f s ; a recording circuit which processes the square-wave signals at frequency f s for recording on the magnetic recording medium using the magnetic recording/reproduction head; a spectrum analyzer which performs frequency analysis of reproduced signals y k reproduced by the magnetic recording/reproduction head, and generates a power spectrum of the waveform of the reproduced signals y k ; storage means for storing a function E f relating to frequency, which is calculated in advance; and calculating means for calculating, for the power spectrum generated by the spectrum analyzer, a signal-to-noise ratio by taking as the denominator a value obtained by adding values obtained by multiplying each frequency component of the power spectrum by the square of the function E f , excluding the vicinities of the frequency f s and harmonics thereof, and as the numerator a value of the power spectrum at the frequency f s multiplied by the square of the value of the function E f at the frequency f s .