U.S. patents available from 1976 to present.
U.S. patent applications available from 2005 to present.

Method and apparatus for adaptive clock recovery

Patent 5396492 Issued on March 7, 1995. Estimated Expiration Date: Icon_subject April 28, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Patent References

3754098

Local area network control system synchronization with phase-lock loop
Patent #: 4759041
Issued on: 07/19/1988
Inventor: Anderson ,   et al.

Method and means for transferring a data payload from a first SONET signal to a SONET signal of different frequency Patent #: 5142529
Issued on: 08/25/1992
Inventor: Parruck, et al.

Inventor

Assignee

Application

No. 054332 filed on 04/28/1993

US Classes:

370/412, Queuing arrangement370/466, Converting between protocols370/517, Including delay device375/371Phase displacement, slip or jitter correction

Examiners

Primary: Safourek, Benedict V.
Assistant: Jung, Min

Attorney, Agent or Firm

International Class

H04J 003/06

Abstract

An adaptive clock recovery arrangement for deriving a synchronous clock from an asynchronous, packet stream such as an asynchronous transfer mode (ATM) cell stream. The deviation in the magnitude of information stored in a first-in-first-out memory is continually monitored, and the synchronous clock frequency, referred to as the adaptive line clock frequency, is adjusted in a plurality of modes, under the control of a processor. The adjustment is made in response to a detected increasing condition of the monitored deviation. The adjustments are open-loop adjustments made without continually adjusting the adaptive line clock frequency based on the monitored deviation. Damping is substantially reduced compared with "conventional" PLL arrangements because the open-loop adjustments result in a rapid frequency correction with perfect or nearly perfect deadbeat damping, i.e. without the frequency oscillations that continue after the correct frequency is reached in closed-loop arrangements.

Other References

  • R. C. Lau, "A Clock Recovery Scheme for ATM Circuit Emulsion", Bellcore, Oct. 10, 1988
  • K. Yamazaki, "Introduction to AAL type 1", Document AVC-214, Mar. 9, 199
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