Direct Conversion of FM Magnetic Tape Data into Digital Form

A system is described for decoding frequency-modulated magnetic tape data directly into digital form suitable for input to a digital computer. Included in the system is a very precise method used to compensate for flutter errors. The bypassing of standard demodulation, filtering, and analog-to-digital conversion permits a significant improvement in signal-to-noise ratio. This type of system is most advantageous when reproducing data from magnetic decks whose signal-to-noise ratios cannot be reliably expected to remain at a satisfactory level. Using electrocardiograms, it has been demonstrated that a real gain in the detection of low-amplitude waveforms can be achieved with this system as compared to conventional reproducing.