| 摘要 |
PURPOSE:To determine the size of an input signal with high accuracy by changing the sampling frequency according to the input signal frequency, and changing the input signal so that it may be the center frequency at all times the filter characteristic. CONSTITUTION:When an external cyclic signal Sp is applied to the clear terminals CLRs of a counter 1 and a counter 2, both the counter 1 and the counter 2 get in initial conditions, and the output signals are all cleared, and the output of a decoder 2d also gets in initial condition. Accordingly, by the external signal Sp, the cycle of the output signal (S/H, DSP interrupt signal) of the decoder 2d can be made variable. That is, the center frequency changes in proportion to the frequency of the external synchronous signal Sp. Accordingly, if one changes the external synchronous signal Sp according to the system frequency of the power system, from the characteristic of a filter, the system frequency can always be made the center frequency of the band pass filter. |
