Interpolation to Reduce Difficulty in D/A Conversion
It is difficult to design an analogue low-pass filter for D/A conversion if the sampling frequency is very near to Nyquist’s frequency; even if the sampling frequency is not near the Nyquist frequency, it is still difficult to avoid the distortion which arises from low-pass filtering in D/A conversion. This difficulty must be overcome in the design of PCM transmission systems for colour television. This problem is especially serious in the systems like television where we cannot avoid the repeated use of A/D and D/A conversions 8 or 9 times over, for example. The difficulty can be overcome by interpolation of the samples. This technique was proposed by the authors (Taki et al., 1978) and independently by Ninomiya (1978). Real-time digital interpolation for D/A conversion of the PCM’d NTSC video signal was also demonstrated in Taki et al. (1978).
KeywordsSampling Frequency Digital Filter Interpolation Technique Full Adder Nyquist Frequency
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- Taki, Y., Hatori, M., Hatakeyama, Y., and Sano, J., “Demodulation of PCM Signal by Interpolation Technique,” Inst. Electronics Coram. Engrs. Japan, Proc. Ann. Conf. Coram. (1978), p. 526 (in Japanese).Google Scholar
- Ninomiya, Y., “Digital Interpolation in D/A Conversion,” Inst. Television Engrs. Japan, Proc. Ann. Conf., Vol. 10 (1978), p. 8 (in Japanese).Google Scholar