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本文介绍一种新颖的模拟磁带记录器,即脉冲宽度调制方式(PDM方式)磁带记录器.这种磁记录器信号噪声比高,在4.75厘米/秒的带速时,调频方式磁记录器的信号噪声比为38分贝左右,而PDM方式磁记录器的信号噪声比就可达到48分贝左右.原因在于PDM方式磁记录器受走带机构的颤动影响极小.因为走带机构的颤动会影响磁记录器的走带速度,走带速度的变化又对记录信号频率产生了调制.这种调制对调频方式磁记录器来说,会直接影响到机器的性能指标.走带机构颤动越大,其信号噪声比就下降得越多,信号的失真度也大.所以,调频方式的磁带记录器对走带机构的要求特别高,这样就给伺服系统带来复杂性.但对于PDM方式的磁带记录器来说,走带机构的颤动对性能指标的影响就小得多了.因影响机器性能指标的只是记录脉冲信号宽度的变化,而记录脉冲信号频率的变化几乎没有什么影响.所以PDM方式磁记录器,对走带机构的要求可低一些,走带精度
This article describes a novel analog tape recorder, the Pulse Width Modulation (PDM) tape recorder, which has a high signal-to-noise ratio of 4.75 cm / sec with a tape speed magnetic tape recorder Signal to noise ratio of about 38 decibels, and PDM magnetic recorder signal to noise ratio can be up to about 48 decibels, because the PDM magnetic recorder by the impact of the tape mechanism minimal impact.Because the tape drive mechanism will affect the flutter Magnetic tape recorder tape speed, tape speed changes and the modulation of the signal frequency modulation.This modulation on the FM magnetic recorder, will directly affect the performance of the machine.Facing the greater the vibration mechanism, Its signal-to-noise ratio to drop more, the signal distortion is also large.Therefore, the frequency of the tape recorder tape drive mechanism is particularly high, thus giving the servo system complexity.However, for the PDM tape Recorder, the tape mechanism flutter on the performance index is much smaller because of the impact of the machine performance indicators only changes in the width of the recording pulse signal, and recording pulse signal frequency changes almost no What effect. So PDM way magnetic recorder, the requirements of the tape drive mechanism can be lower, tape precision