| 摘要 |
An HDTV signal is converted to an NTSC bandwidth by analog encoding changing its conventional serial element format to a parallel element format. The picture elements of several HDTV scan lines are combined by fractal scanning and all simultaneously expressed over the time period of one NTSC scan line as individual frequency components within a given spectrum every component maintaining a constant amplitude corresponding to its original modulation level. The procedure is repeated at the NTSC scan line rate. The encoder controls the number of individual frequency components to achieve an HDTV level of information transmission and the frequency spacing between the individual frequency components to effect a bandwidth compression to NTSC levels. A decoder changes the received parallel element format to a serial element format and uses fractal scanning to separate the combined lines for conventional presentation. The parallel element format of the signal is not detectable by the serial element decoding of a conventional NTSC receiver and the fractal scanning is not definable through conventional scanning methods. The HDTV signal encoded by this method is therefore transmitted in the same channel as an existing NTSC transmission and the existing NTSC transmission uses fractal scanning to increase its own informational content to independent HDTV levels while maintaining an NTSC bandwidth.
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