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广泛使用于现代数据测量和处理系统中的模拟磁带记录仪是较理想的数据记录、貯存、重放用装置。然而,直接记录(DR)方式中有限的磁带磁化特性线性范围,及脉冲频率调制(RFM)方式中磁带速度变动导致的录放噪声电平等,使模拟磁带记录仪的记录动态范围有限。若需进一步提高模拟磁记录的信噪比,技术上有许多困难。例如DR方式的磁带记录仪欲取得50分贝的信噪比,其磁道宽度须为现行磁道宽度的100倍,显然不能付诸于实用。随着计算技术的发展,磁记录就在数字编码和模拟磁记录技术的基础上,发展了原始数据信号不受调制波幅度限制及带速变动影响的脉冲调制(PCM)记录方式。
An analog tape recorder widely used in modern data measurement and processing systems is an ideal device for data recording, storage and playback. However, the limited linear dynamic range of tape magnetization in the direct recording (DR) mode and the recording noise level due to tape speed fluctuations in the pulse frequency modulation (RFM) mode make the recording dynamic range of the analog tape recorder limited. There are many technical difficulties to further improve the S / N ratio of analog magnetic recording. For example, DR tape recorders want to achieve 50 dB SNR, the track width to be 100 times the current track width, obviously can not be put into practical use. With the development of computing technology, magnetic recording has been developed on the basis of digital coding and analog magnetic recording technology to develop a pulse-recording (PCM) recording system in which the original data signal is not affected by the amplitude of modulation wave and the change of belt speed.