| 摘要 |
PURPOSE:To prevent misjudgement due to level difference fluctuation in a short time by taking out the level difference of each input audio signal and performing the stereo/monoral decision by means of a signal obtained after deciding levels while equipped with the prescribed hysterisis with the signal with this level difference. CONSTITUTION:The level difference signal of two-channel input audio signals (L and R), that is, for example, the output signal from a peak hold circuit 17 is sent to a hysterisis decision circuit part 20 performing the level decision with the hysterisis. This level difference signal (a) is sent to respective comparison devices 21 and 22 of the hysterisis decision circuit part 20. The switching operation where the output changes from 'L' to 'H' according to the rising of a comparison output signal (c) from the comparison device 21 and the output changes from 'H' to 'L' according to the rising of the output signal (d) from the comparison device 22. It is decided as stereo when the output from this hysterisis circuit 23 is 'H', and decided as monoral when 'L'. |
