| 摘要 |
PURPOSE:To improve the quality of an output analog signal, by converting the sampling frequency of a digital signal to high, and passing it through a D/A converter. CONSTITUTION:A PCM digital signal sampled at the sampling frequency f1 and quantized and coded is inputted to an interpolating device 6, and after the signal is converted into a digital signal having the sampling frequency converted substantially N-times, and applied to a digital low pass filter 7 having the pass band extremity frequency fp' being <=1/2-time the f1 and the block end frequency fs' being f1/2. A band limit digital signal extracted from the digital low pass filter 7 is applied to a D/A converter 9. The D/A converter 9 consists of a D/A converting section 9a and a sample-and-hold circuit section 9b and is constituted so as to convert the digital signal having Nf1 of the sampling frequency into an analog signal. An analog low pass filter 10 eliminates the frequency component of >=3f1/2 included in the analog signal extracted from the D/A converter 9. |
