Browse Prior Art Database

Interblock Gap Generation

IP.com Disclosure Number: IPCOM000075416D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Martin, H: AUTHOR

Abstract

In generating IBG's (interblock gaps) using tachometer pulses during a start/stop mode of a reel-to-reel transport, consideration should be given to the distribution of the tape between the two reels 10 and 11. This is particularly true in systems using low-cost motor control circuits for operating tape-driving capstan 12 and the reels. Tachometer 14 generates tape-transporting information for use by control circuits 15. The tachometer signals indicate tape displacement past transducer 13 in the absence of tape slip. A preset number of tachometer signal cycles are used to meter the length of an IBG being generated.

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Interblock Gap Generation

In generating IBG's (interblock gaps) using tachometer pulses during a start/stop mode of a reel-to-reel transport, consideration should be given to the distribution of the tape between the two reels 10 and 11. This is particularly true in systems using low-cost motor control circuits for operating tape-driving capstan 12 and the reels. Tachometer 14 generates tape-transporting information for use by control circuits 15. The tachometer signals indicate tape displacement past transducer 13 in the absence of tape slip. A preset number of tachometer signal cycles are used to meter the length of an IBG being generated.

During rapid deceleration mode of the reel-to-reel transport, a tape reel having a large amount of tape may cause the tape to backlash, a short bidirectional tape movement. Whenever tachometer 14 is nondirectional, i.e., it cannot distinguish between forward and backward direction of tape movement, such backlash causes tachometer 14 to indicate erroneous tape movement equal to twice the backlash. This description teaches a method of minimizing such false indications.

An ideal IBG between blocks of data signals 16 and 17 may have a length of 400 tachometer signal cycles. The tachometer count is made during deceleration and acceleration modes; for example, block 16 may be first written and the tape stopped such that transducer 13 is in contact with the tape within the IBG; then, to write block 17, the tape is accelerated. The ta...