| 摘要 |
PROBLEM TO BE SOLVED: To make a circuit single in configuration and small in scale by limiting the band of high definition television(HDTV) signals, performing conversion to the scanning line number of a present television system, executing a required signal processing and reducing a processing rate. SOLUTION: The HDTV signals are band-limited in a band limiting circuit 2 and a sampling rate for performing the signal processing thereafter is reduced. At the time, the band is limited by the power of two. For instance, when the HDTV signals of 74.25MHz are limited to a half band, the rate of output signals from the band limiting circuit 2 becomes 37.125MHz. Further, when the scanning line number is converted from 1125 lines to 525 lines (a conversion ratio is 15:7) in a scanning line number conversion circuit 3, the sampling rate of the output signals of the scanning line number conversion circuit becomes 37.125×7/15=17.325(MHz) and the sampling rate for performing the signal processing for obtaining NTSC signals thereafter is lowered.
|
