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在MS(磁聚焦、电偏转) 型摄象管中,由于出现了其它聚焦、偏转方式所没有的特有噪声(频谱的频率一般在数兆赫,通常简称为“固有噪声”),故应搞清其产生的原因,并探索可否消除噪声的方法。首先通过实验测量,可推断出产生固有噪声的两个原因:返回电子束和偏转脉冲的噪声;其次,根据推断的原因,对固有噪声产生的机理和性质进行理论分析,并由模拟试验得到证实。其结果是:根据推断的原因,可以充分地说明实测现象。作为防止的措施,试用了将返回电子束散焦或将其吸收或产生无噪声的积分偏转脉冲等方法,其结果比较两者的影响,固有噪声产生的主要原因是偏转脉冲的噪声;另外,在实际应用中,欲获得足够的信噪比图象,必须将偏转脉冲的信噪比确保在85dB(pp值比)左右。
In the MS (Magnetic Focusing, Electrical Deflecting) type of picture tube, due to the appearance of other noises inherent in other focusing and deflecting modes (the frequency of the spectrum is generally several megahertz, often referred to as “inherent noise”), Its causes, and to explore ways to eliminate noise. First of all, through experimental measurements, we can deduce the two causes of inherent noise: the return of the electron beam and the deflection pulse of the noise; secondly, based on the reasoning of the inherent noise generation mechanism and the nature of a theoretical analysis confirmed by the simulation test . The result is: Based on inferred reasons, it is possible to fully explain the observed phenomena. As a preventive measure, a method of defocusing the electron beam or returning it to an absorbed or generated noise-free integral deflection pulse has been tried. As a result, the influence of both of them is compared. The main reason for the generation of the natural noise is the noise of the deflection pulse. In practice, to obtain a sufficient signal-to-noise ratio, the signal-to-noise ratio of the deflection pulse must be guaranteed to be around 85 dB (pp ratio).