| 摘要 |
PURPOSE:To decide factors of output variation of a reproducing signal accurately and easily by measuring the quantity of variation in the output spectrum of an equalizing circuit with time at least two frequencies as to the reproducing signal which is corrected by the equalizing circuit. CONSTITUTION:The reproducing signal from a recording medium where a signal is recorded with white noise is corrected by the equalizing circuit so that spectra S0 corresponding to >=2 optional frequencies f1 and f2 are uniform almost at the frequencies. Then, the quantity of variation in output spectrum with time at the frequencies f1 and f2 of the equalizing circuit is measured by, for example, a spectrum analyzer. Consequently, when the spectrum variation corresponding to the frequency f2 is larger than that corresponding to the frequency f1, it is decided that the output variation of the reproducing signal is caused by variation in spacing. When both quantity of spectrum variation are nearly equal, on the other hand, it is decided that the output variation of the reproducing signal is caused by tracking variation. Thus, the factors of the output variation of the reproducing signal are discriminated accurately and easily. |
