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本文介绍了彩电信号DPCM编码方案的设计和试验样机的组成。本方案不是把NTSC彩电信号分离为它的各成分,而是按复合信号原样进行直接DPCM编码,并以32Mb/s(PCM3次群)传送。其特点是:①取样频率比老的方案设计得低;②采用将亮度信号的预测值和载波色信号的预测值分别计算之后组成综合预测值的算法;③由于进行包括色同步信号在内的水平消隐信号的样值传送,因此可提高传送效率;④实行4比特/8比特准可变字长编码等等。试验样机大约被简化为分离编码时的1/2。另外,就其编码图象质量而言,所得性能足以满足图象传送业务中彩电信号的数字传送要求。
This article describes the DPCM color TV signal coding scheme design and test prototype. The program is not to separate the NTSC color TV signal into its various components, but according to the composite signal directly DPCM encoding, and 32Mb / s (PCM3 sub-group) to send. Its features are: (1) the sampling frequency is lower than that of the old scheme; (2) the algorithm which combines the predicted value of the luminance signal and the predicted value of the carrier color signal to form an integrated prediction value; (3) Horizontal blanking signal sample transfer, so can improve the transmission efficiency; ④ the implementation of 4 bit / 8 bit quasi-variable word length encoding and so on. The test prototype is roughly reduced to a factor of 1/2 when separating the code. In addition, for the quality of its coded pictures, the resulting performance is sufficient to meet the digital transmission requirements of color television signals in video transmission services.