| 摘要 |
PCT No. PCT/FR93/00373 Sec. 371 Date Dec. 5, 1994 Sec. 102(e) Date Dec. 5, 1994 PCT Filed Apr. 14, 1993 PCT Pub. No. WO93/21727 PCT Pub. Date Oct. 28, 1993A television (TV) signal alignment method and device are disclosed which provide a clear TV picture. The alignment method provides reduced noise. Despite transmission noise, the alignment method reduces noise at frequencies lower than 15 kHz which is generated by the alignment device, to below the visual perception threshold. This improves signal-to-noise ratio. The alignment method and device reduce this noise while rejecting 50 Hz and 25 Hz frequencies of greater than 30 dB. At each line of an image, the alignment method and device use a feedback loop to successively align a plateau at a first start of the current line of a television signal, which has transmission noise superimposed thereon, on the plateau of the preceding line. This is performed to restore the DC component of the television signal. The low-frequency noise generated in the loop and superimposed on the plateau of the television is reduced by distributing a sampled television signal into two branches of a noise-reduction device at the input of the loop. The sampled television signal is preserved in the first branch, while it is filtered in the second branch. The filtered and preserved signals are subtracted. The level of the plateau of the current line are estimated from the level of the plateau of the preceding line by integrating and storing the level of the plateau corresponding to the current line and adding, successively, the level of the plateau of the preceding line and of the current line. The estimate of the level of the plateau is subtracted from the television signal.
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