Monitoring unit for optical burst mode signals
View Patent ↗The invention has for its object to provide a monitoring unit, particularly for optical burst mode signals in asynchronous optical networks based on, e.g., Internet or ATM (ATM=asynchronous transfer mode). The monitoring unit for burst mode signals comprises a detector for performing a Q-factor measurement in dependence on at least one variable and at least one fixed amplitude threshold value and on at lest one variable and at least one fixed phase value. This detector contains a burst mode amplitude detector for generating a fixed amplitude threshold value for each burst, a burst mode clock recovery circuit for generating a fixed phase value for each burst, a burst detector for detecting the beginning of each burst, and a control logic for generating a variable amplitude threshold value and a variable phase value for each burst.
1. A monitoring unit for monitoring optical burst mode signals, the monitoring unit comprising:
a detector for performing a Q-factor measurement with regard to the optical burst mode signals based on at least one variable amplitude threshold value, at least one fixed amplitude threshold values, at least one variable phase value and at least one fixed phase value, said detector comprising:
a burst mode amplitude detector for generating a fixed amplitude threshold value for each optical burst mode signal to be included in the measurement,
a burst mode clock recovery circuit for generating a fixed phase value for each optical burst mode signal to be included in the measurement,
a burst detector for detecting respective beginnings of the burst mode signals, and
a control logic for generating the variable amplitude threshold value and the variable phase value for each optical burst mode signal to be included in the measurement.
2. The monitoring unit as set forth in claim 1 , wherein the detector further comprises:
a first comparator for comparing the optical burst mode signals with associated variable amplitude threshold values generated by the control logic,
a second comparator for comparing the optical burst mode signals with associated fixed amplitude threshold values generated by the burst mode amplitude detector,
a first decision circuit, for passing on output signals of the first comparator based on variable phase values generated by the control logic,
a second decision circuit, for passing on output signals of the second comparator based on fixed phase values generated by the burst mode clock recovery circuit, and
an EXOR gate for combining output signals of the first and second decision circuits.
3. The monitoring unit as set forth in claim 2 , wherein the detector further comprises:
a burst synchronization logic for receiving an output of the burst detector and determining respective beginnings of payloads of the optical burst mode signals, and
a gate for receiving an output of the EXOR gate and controlled by the burst synchronization logic for passing error signals to a processing unit which estimates a Q factor.
4. The monitoring unit as set forth in claim 3 , wherein the detector further comprises:
an extraction unit for receiving an output of the burst synchronization logic and extracting header or control information for selective measurement of specific burst mode control signals, and
a switch which is connected between the extraction unit, the burst synchronization logic, and the gate, and is controlled by the control logic.
5. The monitoring unit as set forth in claim 1 , further comprising an optical-to-electrical converter for converting the optical burst mode signals to electric input signals for the burst mode amplitude detector, the burst mode clock recovery circuit, and the burst detector.