Importance

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Abstract

The present facsimile transmission system is a combination of the prior Skipping White Space (SWS) system which is a digital system capable of rapid transmission, and the prior AM-PM-VSB (Amplitude Modulation, Phase Modulation, Vestigial Side Band Modulation), which is a simple analog system. Each scanning line of a picture is divided into a plurality of blocks each of which has a plurality of picture cells, and only those blocks having a black cell are transmitted as a picture signal. On the other hand the block having no black cell is not transmitted, and instead, the flag information indicating that the block is omitted is transmitted. Also a line synchronization signal is transmitted for each scanning line. When said signals (picture signals, flag information and a line synchronization signal) are modulated into an AM-PM-VSB signal, a picture signal is modulated as an ordinary analog signal, and a flag information and a line synchronization signal has the twice level as high as the highest level of the picture information, and have the duration longer than that of each picture cell. Thus, although a simple analog AM-PM-VSB system is utilized, the important information like a line synchronization signal and a flag information which affect much to the received picture quality are transmitted with a small error rate and a high reliability.

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First Claim