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US 6,549,572 B1Granted
Method and apparatus for automated time domain monitoring in optical networks
AssigneeTelcordia Technologies, Inc.
InventorsWilliam T. Anderson, Thomas C. Banwell, Nim K. Cheung, James E. Hodge
Life of this patent
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Abstract
Methods and apparatuses are provided for determining characteristics of an input optical signal in an optical network. An optical signal monitoring apparatus estimates a minimum time interval between transitions in the input signal, determines a clock signal based on the estimated minimum time interval, and performs a time domain measurement on the input signal based on the determined clock signal. The optical signal monitoring apparatus samples the input signal based on the determined clock signal and determines the characteristics of the input signal.
Claims41
A method for determining time domain characteristics of a monitored input signal from an optical network comprising the steps of:
- estimating a minimum time interval between consecutive transitions in the input signal;
- determining a variable bit rate of the input signal based on the estimated minimum time interval;
- recovering the input signal's clock signal based on the determined bit rate;
- and
- performing a time domain measurement on the input signal based on the determined bit rate and the recovered clock signal.
2 more elements
A method for determining time domain characteristics of a monitored input signal from an optical network comprising the steps of:
- estimating a minimum time interval between transitions in the input signal;
- determining a variable bit rate of the input signal based on the estimated minimum time interval;
- recovering the input signal's clock signal based on the determined bit rate;
- and
- performing a time domain measurement on the input signal based on the recovered clock signal, said performing step including the step of reconstructing a digital signal from the monitored input signal by sampling the input signal based on the recovered clock signal.
2 more elements
A method for determining time domain characteristics of a monitored input signal from an optical network comprising the steps of:
- estimating a minimum time interval between transitions in the input signal;
- determining a variable bit rate of the input signal based on the estimated minimum time interval;
- recovering the input signal's clock signal based on the determined bit rate;
- and
- performing a time domain measurement on the input signal based on the recovered clock signal, the performing step including the steps of:
- sampling the recovered clock signal and the input signal at a plurality of times to generate a clock signal histogram and an input signal histogram;
- and
- using the clock signal histogram to calibrate the timing sequence of the sampled input signal histogram.
5 more elements
A method for determining time domain characteristics of a monitored input signal from an optical network comprising the steps of:
- estimating a minimum time interval between transitions in the input signal;
- determining a variable bit rate of the input signal based on the estimated minimum time interval;
- recovering the input signal's clock signal based on the determined bit rate;
- and
- performing a time domain measurement on the input signal based on the recovered clock signal, the performing step including the steps of:
- sampling the recovered clock signal and the input signal at a plurality of times to generate a clock signal histogram and an input signal histogram;
- and
- using the clock signal histogram to calibrate the amplitude of the sampled input signal histogram.
5 more elements
A method for determining time domain characteristics of a monitored input signal from an optical network comprising the steps of:
- estimating a minimum time interval between transitions in the input signal;
- determining a variable bit rate of the input signal based on the estimated time interval;
- recovering the input signal's clock signal based on the determined bit rate;
- and
- performing a time domain measurement on the input signal based on the recovered clock signal, and wherein the estimating step includes the steps of:
- generating a plurality of test pulses that correlate to the transitions in the input signal;
- and
- adjusting the duration of each of the plurality of test pulses such that the minimum time intervals between the transitions in the input signal match the durations of the corresponding plurality of pulses.
5 more elements
A method for determining characteristics of an input signal comprising the steps of:
- estimating a minimum time interval between transitions in the input signal;
- determining a clock signal based on the estimated minimum time interval;
- and
- performing a time domain measurement on the input signal based on the determined clock signal;
- wherein the estimating step includes the steps of:
- generating a set of delayed input signals using a set of programmable delay times, respectively;
- comparing the transitions in the input signal with the set of delayed input signals;
- and
- identifying the nearest predetermined delay times that are before and after the minimum transition time interval between the transitions in the input signal.
6 more elements
A method for determining characteristics of an input signal comprising the steps of:
- estimating a minimum time interval between transitions in the input signal;
- determining a clock signal based on the estimated minimum time interval;
- and
- performing a time domain measurement on the input signal based on the determined clock signal;
- wherein the estimating step includes the steps of:
- generating a set of delayed input signals using a set of programmable delay elements delaying the input signal based on a set of predetermined delay times, respectively;
- comparing the transitions in the input signal with the set of delayed input signals;
- and
- adjusting one or more of the programmable delay elements, such that minimum time intervals between the transitions in the input signal match one or more of the set of predetermined delay times.
6 more elements
An apparatus for determining time domain characteristics of a monitored input signal from an optical network comprising:
- a forward rate detector that determines the input signal's bit rate by measuring the minimum time interval between consecutive transitions in the input signal, said forward rate detector including a transition detector and line rate estimation circuitry;
- a clock recovery circuit that recovers the input signal's clock signal based on the determined bit rate;
- and
- a measurement circuit that performs a time domain measurement on the input signal based on the recovered clock signal.
1 more element
An apparatus for determining the time domain characteristics of a monitored input signal from an optical network comprising:
- a forward rate detector that determines the input signal's bit rate by estimating a minimum time interval between transitions in the input signal;
- a clock recovery circuit that recovers the input signal's clock signal based on the determined bit rate;
- and
- a measurement circuit that performs a time domain measurement on the input signal based on the recovered clock signal, the measuring circuit comprising:
- a delay generator that generates a first pulse synchronized to the recovered clock signal;
- a sampler driver that generates a second pulse in response to the first pulse;
- and
- a first sampler that measures a plurality of instantaneous values of the input signal gated by the second pulse in order to generate a histogram of the input signal.
5 more elements
An apparatus for determining time domain characteristics of a monitored input signal from an optical network comprising:
- a forward rate detector that determines the input signal's bit rate by estimating a minimum time interval between transitions in the input signal;
- a clock recovery circuit that recovers the input signal's clock signal based on the determined bit rate;
- and
- a measurement circuit that performs a time domain measurement on the input signal based on the recovered clock signal, the measurement circuit comprising:
- a decision circuit that reconstructs a digital signal from the monitored input signal by sampling the input signal based on the recovered clock signal.
2 more elements
An apparatus for determining the time domain characteristics of a monitored input signal from an optical network comprising:
- a forward rate detector that determines the input signal's bit rate by estimating a minimum time interval between transitions in the input signal;
- a clock recovery circuit that recovers the input signal's clock signal based on the determined bit rate;
- and
- a measurement circuit that performs a time domain measurement on the input signal based on the recovered clock signal, the measurement circuit comprising a storage device storing a location of data associated with the input signal wherein the storage device is referenced based on the determined bit rate.
1 more element
An apparatus for determining time domain characteristics of a monitored input signal from an optical network comprising:
- a forward rate detector that determines the input signal's clock signal based on the determined bit rate;
- and
- a measurement circuit that performs a time domain measurement on the input signal based on the recovered clock signal, the measurement circuit comprising:
- a delay generator that generates a first pulse synchronized to the recovered clock signal;
- a sampler drive that generates a second pulse in response to the first pulse;
- a first sampler that measures a plurality of instantaneous values of the input signal gated by the second pulse to generate an input signal histogram;
- and
- a second sampler that measures a plurality of instantaneous values of the recovered clock signal gated by the second pulse to generate a clock signal histogram used to calibrate the input signal histogram.
5 more elements
An apparatus comprising:
- a forward rate detector that estimates a minimum time interval between transitions in an input signal;
- a clock recovery circuit that determines a clock signal based on the estimated minimum time intervals;
- and
- a measurement circuit that performs a time domain measurement on the input signal based on the determined clock signal;
- wherein the forward rate detector comprises a minimum transition interval detection circuit that compares time intervals between consecutive transitions in the input signal with one or more reference intervals, the minimum transition interval detection circuit comprising:
- a delay element that delays a first transition in the input signal by a first predetermined delay time and delays a second transition in the input signal by a second predetermined delay time;
- and
- a comparator that compares the delayed first transition with the second transition.
5 more elements
An apparatus comprising:
- a forward rate detector that estimates a minimum time interval between transitions in an input signal;
- clock recovery circuit that determines a clock signal based on the estimated minimum time interval;
- and
- a measurement circuit that performs a time domain measurement on the input signal based on the determined clock signal;
- wherein the forward rate detector comprises
- a minimum transition interval detection circuit that compares time intervals between consecutive transitions in the input signal with one or more reference intervals, the minimum transition interval detection circuit comprising
- a set of delay elements that generate a set of delayed input signals based on a set of predetermined delay times;
- and
- a comparator that compares transitions in the set of delayed input signals with the transitions in the input signal.
6 more elements
An apparatus comprising:
- a forward rate detector that estimates a minimum time interval between transitions in an input signal;
- a clock recovery circuit that determines a clock signal based on the estimated minimum time interval;
- and
- a measurement circuit that performs a time domain measurement on the input signal based on the determined clock signal;
- wherein the forward rate detector comprises:
- a minimum transition interval detection circuit that compares time intervals between consecutive transitions in the input signal with one or more programmable reference intervals;
- and
- a register that adjusts the programmable reference intervals such that one or more of the adjusted reference intervals match the minimum time interval between the transitions in the input signal.
5 more elements
Dependencies are inferred from the claim text.