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US5058140A Expired / Lapsed US ⏱️ 0.0 years remaining

Self-correcting serial baud/bit alignment

Assignee: International Business Machines Corp
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Filing: 1990-03-12
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Granted: 1991-10-15
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Expires: 2010-03-12
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Abstract

Abstract Described is a circuit arrangement that aligns the receiver of a communications device with the bit boundaries of a serially received data stream. The circuit arrangement delays a bit in a synchronized data stream and correlates it with a next bit in the data stream. If the bits are equal, a signal is generated to reset a synchronization latch. Thereafter, the receiver is synchronized to the incoming data.

Inventors

  • 👤 Mark A. Johnson

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-04 08:49
CPC Classifications
H; H04; H04L; H04L7/00; H04L7/0079; H04L7/0054; H04L7/0066; H04L7/0083

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 216 words
In a serial data communications system wherein a data record is transmitted as a serial data stream from a transmitting device through a communications medium to a receiving device which includes a universal asynchronous/synchronous receiver/transmitter (USART) unit that receives said serial data stream and change it into a parallel data stream and change it into a parallel data stream and forward said data to a subsystem of said receiving device, a circuit arrangement positioned in said USART for synchronizing said receiver to the bit cell boundaries of received data streams comprising: a first circuit means for generating clock pulses with a predetermined frequency; a second circuit means responsive to the clock pulses for aligning said clock pulses with the serial data record and outputting pulses D R ; delay means for delaying D R and generating pulses B R ; a third circuit means for correlating D R and B R and outputting a control signal; a synchronizing latch means having an input signal terminal, a clocked terminal coupled to the first circuit means, a positive and a negative output; and a fourth circuit means having an output coupled to the signal terminal, a first input coupled to the third circuit means and a second input coupled to the negative output of the synchronizing latch means.
Claim 2
Dependent Claim 216 words
In a serial data communications system wherein a data record is transmitted as a serial data stream from a transmitting device through a communications medium to a receiving device which includes a universal asynchronous/synchronous receiver/transmitter (USART) unit that receives said serial data stream and change it into a parallel data stream and change it into a parallel data stream and forward said data to a subsystem of said receiving device, a circuit arrangement positioned in said USART for synchronizing said receiver to the bit cell boundaries of received data streams comprising: a first circuit means for generating clock pulses with a predetermined frequency; a second circuit means responsive to the clock pulses for aligning said clock pulses with the serial data record and outputting pulses D R ; delay means for delaying D R and generating pulses B R ; a third circuit means for correlating D R and B R and outputting a control signal; a synchronizing latch means having an input signal terminal, a clocked terminal coupled to the first circuit means, a positive and a negative output; and a fourth circuit means having an output coupled to the signal terminal, a first input coupled to the third circuit means and a second input coupled to the negative output of the synchronizing latch means.
Claim 3
Dependent Claim 35 words
The circuit arrangement of claim 1 further including a fifth circuit means for gating signals generated on the positive output of the synchronizing latch means with the clock pulses to generate a decoded clock signal.
Claim 4
Dependent Claim 15 words
The circuit arrangement of claim 2 wherein the fifth circuit means includes an "AND" gate.
Claim 5
Dependent Claim 19 words
The circuit arrangement of claim 3 wherein the decoded clock signal is one-half the frequency of said clock pulses.
Claim 6
Dependent Claim 51 words
The circuit arrangement of claim 2 further including: a logic circuit means for generating status signals whose state is dependent on the coding of the received serial data stream; a sixth circuit means coupled to the third circuit means and being responsive to the status signals for generating decoded data signal.
Claim 7
Dependent Claim 27 words
The circuit arrangement of claim 5 further including data latch means responsive to the decoded data signal and the decoded clock signal to output latched data signals.
Claim 8
Dependent Claim 17 words
The circuit arrangement of claim 1 wherein the second circuit means and the delay means include latches.
Claim 9
Dependent Claim 16 words
The circuit arrangement of claim 1 wherein the third circuit means include a logical OR circuit.
Claim 10
Dependent Claim 131 words
In a serial data communications system wherein a data record is transmitted as a serial data stream from a transmitting device through a communications medium to a receiving device which includes a serial communications controller (SCC) that receives said serial data stream, processes it and forwards said data to a subsystem of said receiving device a circuit arrangement comprising: a latch means for quickly and continuously synchronizing said receiver to the bit cell boundaries of the serial data stream; and a circuit means for monitoring the bit stream to determine changes in bit pattern and generating control signals that reset the latch means to a logical zero state only when the changes in the bit pattern do not occur within a predetermined number of bits or within a selected time interval.
Claim 11
Dependent Claim 131 words
In a serial data communications system wherein a data record is transmitted as a serial data stream from a transmitting device through a communications medium to a receiving device which includes a serial communications controller (SCC) that receives said serial data stream, processes it and forwards said data to a subsystem of said receiving device a circuit arrangement comprising: a latch means for quickly and continuously synchronizing said receiver to the bit cell boundaries of the serial data stream; and a circuit means for monitoring the bit stream to determine changes in bit pattern and generating control signals that reset the latch means to a logical zero state only when the changes in the bit pattern do not occur within a predetermined number of bits or within a selected time interval.

References Cited (Backward Citations)

US4740962A Cited
US4754457A Cited
US4847877A Cited
US4763341A Cited
US4868853A Cited
US4744081A Cited
US4879731A Cited
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USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1994-10-14 1995-04-15 1995-10-15 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1998-10-14 1999-04-15 1999-10-15 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2002-10-14 2003-04-15 2003-10-15 $7700.00 Window Closed / Lapsed

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