| 摘要 |
PURPOSE:To obtain a desired band emphasis and attenuation characteristic at a high speed with less number of coefficient data by using a special FIR digital filter. CONSTITUTION:A digital audio signal fed to an input terminal 1 via an optical fiber is converted electrically by an optical interface 2, subjected to serial/ parallel conversion, for example, fed to a latch circuit 3, where the result is latched. The equalizing characteristic of the output of the latch circuit 3 is varied by a DSP 4 according to the designation of a characteristic input section 13, the result is fed to a latch circuit 5, parallel/series-converted by an optical interface 6 and converted into an optical signal, extracted from a terminal 15 and fed to an optical fiber. A controller 9 and the DSP 4 revise the filter coefficient in response to the designation from the characteristic input section 13, the coefficient of the band is added to obtain a new coefficient. Since the FIR digital filter is used, the constitution is simplified, various characteristics are combined by less number of coefficient data, the degree of freedom of the characteristics is large and the operation is attained in a short time. |
