| 摘要 |
<p>PURPOSE:To improve a noise level at silent time by judging a silent state when the output of a logic circuit, which outputs a signal when detecting a continuous data value is fixed and fine, is continued for prescribed time. CONSTITUTION:Serial digital audio data to be supplied to a terminal 1 are respectively supplied to a silence detection circuit 2 of an L channel, silence detection circuit 3 of an R channel and timing controller 4. The silence detection circuit 2 detects that the continuous data value is fixed, namely, that a direct current at an arbitrary level is existent in the input data. The silence detection circuit 3 detects that the input data are set to a fine level from the high-order and middle-order bits of the continuous data value. When it is detected that there is the direct current in the input data and that this direct current is the fine level, a prescribed signal is supplied from the logic circuit to a timer means and the timer means is activated. When there is no change in the output of the logic circuit and such a state is continued for the prescribed time, the silent state is judged. Thus, the noise level in the silent state can be widely improved.</p> |
