Control loop apparatus and method therefor
AssigneeAgilent Technologies, Inc.
InventorGordon Old
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Abstract
In the field of optical communications, the need to remove jitter from a Synchronous Digital Hierarchy (SDH) or Synchronous Optical NETwork (SONET) datastream is recognized. Consequently, the present invention provides a First-In-First-Out (FIFO) buffer having a read-out clock frequency that is controlled in response to a depth error of the FIFO buffer. The control of the read-out clock frequency is achieved by a hardware control loop coupled to the FIFO buffer. The period of the control loop is a product of the frequency at which the depth error of the FIFO buffer is acquired and another factor. The another factor is the number of states of logic employed by the control loop raised to an integer power.
Claims26
A control loop apparatus having a control loop period associated therewith and employing n-state logic, the apparatus comprising:
- a first processing element capable of acquiring data at a rate determined by a predetermined clock signal, the data corresponding to a parameter to be controlled;
- further processing elements arranged to generate, when in use, a control signal in response to the acquired data;
- wherein the control loop period is a mathematical product of a period of the clock signal and a constant, the constant being the number of logic states of the n-state logic raised to a first integer power.
In a control loop apparatus having a control loop period associated therewith and employing n-state logic, a method of operating the control loop apparatus, the method comprising the steps of:
- acquiring data at a rate determined by a predetermined clock signal, the data corresponding to a parameter to be controlled;
- generating a control signal in response to the acquired data;
- and
- setting the control loop period to be a mathematical product of a period of the clock signal and a constant, the constant being the number of logic states raised of the n-state logic to a first integer power.
Dependencies are inferred from the claim text.