| 摘要 |
PURPOSE:To reduce the transient effect at coefficient switching, by initially setting a digital filter device in switching the coefficients of prestored transfer function. CONSTITUTION:A digital filter consists of adders 1, 2, multipliers 4, 5, 8, 9, 10, ROM6 storing the coefficients of a transfer function, a coincidence detection circuit 11, a latch 16 and a comparison circuit 17. The ROM6 is addressed with a cut-off frequency data from the latch 16, and coefficients a1, a2, b1, b2, (k) are applied to each multiplier. In changing the coefficients, a new cut-off frequency data is stored in the latch 16 with a read-in control signal R from the coincidence circuit 11, the ROM6 is addressed with the output and the coefficients are switched. At the same time, an output CL of the comparison circuit 17 clears delay circuits 3, 7 and initially sets this digital filter. Thus, the transient effect at coefficient switching can be decreased. |
