| 摘要 |
PURPOSE:To obtain a desired amplitude frequency characteristic accurately by applying inverse Fourier transformation by a 2nd kind sampling frequency when the amplitude frequency characteristic is set by a 1st kind sampling frequency to an input section to obtain impulse response thereby using a real part of the impulse response as a filter coefficient, and setting the result to an external transversal filter. CONSTITUTION:The relation of the Hilbert transformation is used from the inputted amplitude frequency characteristic to combine the 1st kind sampling frequency and the 2nd kind sampling frequency to obtain a transfer function. When setting the amplitude frequency characteristic by the 1st kind sampling frequency, the obtained transfer function is subject to inverse Fourier transformation by the 2nd kind sampling frequency to obtain an impulse response, and when the amplitude characteristic is set by the 2nd kind sampling frequency, inverse Fourier transformation is applied by the 1st kind sampling frequency to obtain the impulse response. Then the real part of the impulse response obtained by the inverse Fourier transformation is used as the filter coefficient, and set to the external transversal filter. Thus, the desired amplitude frequency characteristic is obtained accurately without ripple without using the window function.
|
