方法4采用选通视频测量法,这种方法近来在一些自动测量仪器上可以利用。它是通过在场消隐期间的空行上测量复合二阶失真分量而不必使节目中断。这是一种典型的自动测量,需要在非加密频道上进行,不过硬件配置是一样的。 这种方法的优点是在所有非加密频道上都可自动监测复合二阶失真而不必使节目中断。对于标准频道划分中的第五和第六频道来讲,复合三重差拍(CTB)分量就不 Method 4 uses gated video measurements, a method that has recently become available on some automatic measurement instruments. It measures the complex second-order distortion components on blank lines during a blanking interval without having to interrupt the program. This is a typical automatic measurement that needs to be done on unencrypted channels, but the hardware configuration is the same. The advantage of this approach is that it automatically detects composite second-order distortion on all non-encrypted channels without having to interrupt the program. For the fifth and sixth channels in the standard channel division, the composite triple beat (CTB) component is not