| 摘要 |
DIGITIZATION OF VIDEO SIGNALS A band limited composite video television signal has summed with it, at a reduced amplitude, a frequency modulated audio carrier signal at a higher frequency. The sum signal is sampled and digitized at a sampling frequency which is at least twice the audio carrier frequency and is more than three times the frequency of a color subcarrier in the composite video signal, and is not related thereto. The sampling frequency is derived from a transmission network, whereby stuffing of the digitized signal for transmission is eliminated, and multiplexing of several digitized signals is facilitated. At a decoder, the digital signal is converted back into an analog signal and the audio carrier signal amplitude boosted using filtering. Picture quality of a reproduced television signal is enhanced in that quantizing noise in the video signal becomes uncorrelated from line to line and frame to frame, due to dithering effects by the audio carrier signal. |
