Title: Dual density 800 bpi NRZI and 1600 bpi PE read circuit for a digital magnetic tape transport

Abstract: A dual density read circuit for a digital magnetic tape transport selectively responds to information recorded on magnetic tape in either an 800 bpi NRZI format or a 1,600 bpi phase encoded format. The read circuit includes a differentiating circuit coupled to differentiate and square the read head signal, a latch circuit coupled to latch an NRZI output data signal only when the differentiated read head signal has a change of polarity after being at a given polarity for a predetermined minimum period of time, and first and second gating circuits coupled to selectively pass the NRZI output data signal and the differentiated read head signal when enabled by NRZI and phase encoded read signals respectively. The read circuit advantageously uses common circuit components while providing excellent noise immunity for either the NRZI or phase encoded data formats.

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Inventors: Gray, Martin D. (Sierra Madre, CA, US)

Application Number: 538532
Filing Date: 1975-01-06
Publication_date: 1976-03-30
Assignee: C. J. Kennedy Company (Altadena, CA)
Primary Class(es): 360/40 360/41, 360/42
Other Classes:
US Patent Ref:

3581297

May, 1971

Behr et al.

360/40.

Other Refs:
Primary Examiner: Canney, Vincent P.
Assistant Examiner:
Attorney: Fraser and Bogucki