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Frequency Synchronization of Deadtracked VFC's

IP.com Disclosure Number: IPCOM000075137D
Original Publication Date: 1971-Aug-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Somermeyer, HF: AUTHOR

Abstract

In self-clocking magnetic recording systems, the read variable-frequency clock (VFC) of each read-back channel is synchronized based upon the read-back data signal. Occasionally, for one reason or another, the phase synchronization necessary for data detection is lost. In a multitrack environment, that read-back channel associated with a record track on the media is deadtracked until the V/FC associated with such record track can be again phase-synchronized, such as by preamble or post-amble bursts of synchronization signals found at the beginning and end of phase-encoded data blocks. Additionally, marker signals having unique phase-indicating characteristics can be interspersed among the data signals for resynchronizing the deadtracked V/FC for subsequent data detection.

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Frequency Synchronization of Deadtracked VFC's

In self-clocking magnetic recording systems, the read variable-frequency clock (VFC) of each read-back channel is synchronized based upon the read- back data signal. Occasionally, for one reason or another, the phase synchronization necessary for data detection is lost. In a multitrack environment, that read-back channel associated with a record track on the media is deadtracked until the V/FC associated with such record track can be again phase-synchronized, such as by preamble or post-amble bursts of synchronization signals found at the beginning and end of phase-encoded data blocks. Additionally, marker signals having unique phase-indicating characteristics can be interspersed among the data signals for resynchronizing the deadtracked V/FC for subsequent data detection. To minimize rephasing time, it is desirable to frequency synchronize the deadtracked V/FC in accordance with the relative velocity between the media and the transducer. The frequency of the read-back signal has a direct relationship to the relative velocity between the record media and the transducer.

In the multitrack environment, the deadtracked V/FC may be frequency synchronized with VFC's of other channels. However, in a single-track magnetic recording system, there are no additional VFC's available to frequency synchronize the deadtracked VFC. However, in most media transports, a tachometer is operatively associated with a tape-driving capstan in a capstan system or in a reel in a pure reel-to-reel transp...