| 摘要 |
<p>PURPOSE:To takeout a regular index signal only so as to make controlling operation sure, by gating index signals remaining unerased which become lower than a fixed ratio against the maximum signal levels of reproduced RF signals by means of gate signals corresponding to areas higher than the dividing levels of the reproduced RF signals. CONSTITUTION:A gate signal forming circuit 120 is composed of a voltage control type variable gain amplifier (VCA) 121, peak detecting circuit 122 which detects the peak of the output of the VCA 121, envelope detecting circuit 123 which detects the envelope of the output of the VCA 121, and level comparator 125 which compares the output signal level of the envelope detecting circuit 123 with a reference signal level. By controlling the gain of the VCA 121, reproduced RF signals whose maximum signal is always constant are obtained and comparator outputs higher than the level of the reference signal which divides the maximum signal level of the reproduced RF signal at an optional ratio are supplied to an AND gate circuit 130. Then the AND output of a index signal and gate signal is outputted as a regular index signal.</p> |
