| 摘要 |
PURPOSE: To generate the background noise having an arbitrary gain value by generating the exclusive OR signal between a code signal for gain setting and a random number bit or its inverted signal in each period of a frame clock and supplying this generated signal to a signal processing part as background noise data in the background noise period. CONSTITUTION: A random number generation circuit 21 artificially generates random numbers independently taking '0' or '1' in each frame period synchronously with a frame clock FCK and successively outputs it. A gain adjustment signal S5 outputs a binary code indicating the value of a prescribed gain in series synchronously with a data clock DCK. Since exclusive OR between this signal S5 and a random number data signal S21 is operated by a logic part 22, background noise data as the output signal coincides with the signal S5 in the frames of random number data '0' but coincides with the code obtained by inverting bits or the signal S5 in the frames of random number data '1'. The noise reproduced based on this background noise has a wide frequency band and is sufficiently used.
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