Low Pass Filtering of Data Recorded on Magnetic Tape in Frequency Modulated Form.

摘要

Demodulators typically include low pass filters to recover signals from wideband frequency modulated carriers. Multispeed analogue tape machines normally require the carrier frequency to be set to a value proportional to tape speed. Reproducing hardware usually includes sets of filters, with bandwidth proportional to tape speed, for use with the demodulators. By dividing the frequency of the reproduced signal, a filter corresponding to a lower tape speed can be used and low pass filtering of recorded data signals can be readily achieved. However some unwanted noise components can be generated. These noise components are examined critically and a method of reducing them is demonstrated. (Author)