Browse Prior Art Database

Position Decode Unit

IP.com Disclosure Number: IPCOM000092545D
Original Publication Date: 1966-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Chesarek, DJ: AUTHOR

Abstract

This circuit locates a series of missing bits in a clocked data stream. Clock pulses are counted until the first missing data bit occurs. Then every other clock pulse is counted until the data bits again appear. The circuit computes the center of the sequence of missing bits.

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Position Decode Unit

This circuit locates a series of missing bits in a clocked data stream. Clock pulses are counted until the first missing data bit occurs. Then every other clock pulse is counted until the data bits again appear. The circuit computes the center of the sequence of missing bits.

In the drawing, M and G are R-S flip-flops, F is a T flip-flop and A and B are single-shots. For each pulse C of clock generator 10, single-shots A and B emit a short pulse A and B, respectively, in sequence, which are used to strobe. Pulse A strobes the data D and its complement D' via And's 12 and 14. Flip-flop M is set and trigger F changes state at the first missing data bit. Flip-flop G is set at the first data bit present after a series of missing bits.

During the time of missing bits, trigger F emits one gate pulse for each pair of strobe A pulses. Or 16 provides an input to And 18 for each data bit or, through signal F, for each 2 pair of strobe A pulses. Coincidence of signal G', no data, and the output of Or 16 causes counter 20 to increment for each strobe 13 pulse. In the example, counter 20 settles at a count of six, thus indicating that the center of the sequence of five missing data bits is six bit periods from the first present data bit.

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