抄録
A noise reducer is an essential part of a MUSE decoder to reduce transmission noise caused by FM analogue transmission. Although the present MUSE system uses a noise reducer depending on the receiving signal to noise ratio, the decoded video signal to noise ratio in moving areas is still worse than in stationary areas. Furthermore our new proposal for improving picture quality of moving areas in a MUSE decoder is accomplished by extending the band width of moving areas. This improvement increases a decoded noise in moving areas, so the noise reduction in moving areas appears to be more important then ever before.
We have developed a new video noise reducer, based on shifting the d. c. level of a noisy video signal, and a median type filter for a noise detector. We have tested this new type of noise reducer using a MUSE decoder. It showed experimentally better noise reduction ratio than a conventional noise coring reducer.
To operate this noise reducer efficiently it is necessary to detect the noise level correctly, but this is impossible from a video signal. In MUSE, however, the noise level of the transmission channel can be easily detected by calculating an integral of a noise level in a prepared level of TV lines. Thus in a MUSE decoder, the new noise reducer works efficiently to reduce transmission channel noise.
