Patent ID: 7522835
Filing Date: 2009-04-21
Classification: H04B,H04J

Abstract:
1. A system for testing optical communication channels for wavelength division multiplexed optical communication, comprising: a first set of optical transmitters and optical receivers at a first site: a second set of optical transmitters and optical receivers at a second site: optical fibers between the first site and the second site, wherein the first set of optical transmitters are connected to the second set of optical receivers over a first optical fiber, and wherein the second set of optical transmitters are connected to the first set of optical receivers over a second optical fiber; wherein each of the first set and the second set is configured in a cascaded configuration to define a single continuous communication path from an input of a first optical transmitter to an output of a last optical receiver through all the optical transmitters and all the optical receivers in the first set at the first site and in the second set at the second site and through the optical fibers; a bit error rate tester to generate a bit error rate test signal, wherein the bit error rate test signal is transmitted over the single continuous communication path; a performance monitor in each of the optical transmitters and each of the optical receivers, wherein each performance monitor comprises an optical-to-electrical converter converting an input optical signal into an electrical signal, a signal conditioning unit conditioning the electrical signal, an analog-to-digital converter, a microprocessor calculating and saving Bit Interleave Parity for each flame, a clock and data recovery unit performing clock and data recovery, a decision circuit receiving Bit Interleave Parity for each frame from the clock and data recovery unit and a saved Bit Interleave Parity for each previous frame from the microprocessor, and an error monitoring unit incrementing a counter responsive to a difference from the decision circuit between the saved Bit Interleave Parity and the received Bit Interleave Parity, and wherein each performance monitor actively monitors bit errors by calculating Bit Interleave Parity for each frame and comparing it to a calculated Bit Interleave Parity for a next frame to detect if there are one or more bits errors in a particular communication channel and Q by adjusting a decision level threshold provided by the microprocessor; and a diagnostic analyzer to analyze diagnostic output signals from the error monitoring unit of each performance monitor to identify at least one faulty communication channel in the single continuous communication path, and wherein each of the diagnostic output signals from a respective error monitoring unit indicates a number of bit errors which were produced from a first optical transmitter up to and including a the output of the corresponding optical transmitter or receiver associated with the the respective error monitoring unit; and wherein the diagnostic output signals enable the diagnostics analyzer to isolate bit errors in a particular communication channel of the single continuous communication path while simultaneously testing all of said optical communication channels.