Abstract: In a wavelength division multiplexed (WDM) optical communication system having optical transmitters and receivers communicating via a optical channels, the bit error rate (BER) for the optical channels is tested simultaneously by performing a BER measurement for the cascaded chain. A BER test signal is supplied from a BER tester to a first optical transmitter. The BER test signal passes through the optical channels. The last optical receiver in the cascaded chain supplies the test signal to the BER tester measure the BER. The measured BER is compared to a predetermined system BER threshold to determine if the optical channels meet their specified BER values. Each optical transmitter and receiver includes a performance monitoring circuit that monitors the quality of the BER signal supplied to the optical transmitter/receiver for identifying one or more optical channels that the measured BER exceeds a predetermined system BER threshold.

Abstract: A method and apparatus for performing parallel asynchronous testing of a plurality of optical modules utilizes state machines that may be implemented in a common controller. Desired optical tests are selected by an operator. The invention determines if a testing process or instrument required for the selected optical tests is available. A COM port may also be locked for each of the selected optical tests from among a plurality of COM ports to prevent interference between different tests. By reserving resources such as COM ports and testing instruments in this fashion the invention may asynchronously initiate execution of the selected optical tests. If a resource such as a COM port, testing process or instrument is not currently available, the test is place in COM port and testing queues to await availability of that resource. Once a test is completed, the resource is unlocked so that one of the state machines may asynchronously initiate another test.

Abstract: A system for conducting optical tests on a plurality of optical modules includes a plurality of optical signal sources and optical signal degradation elements optically communicating with input switches. The input switches sources supply optical test signals to optical modules (units under test) plugged into a common shelf. Output optical switches supply the output signals to a range of optical test equipment. A controller utilizes a database of test recipes to supervise and control the optical signal sources, optical signal degradation elements, units under test, input switches, output switches, and test equipment to conduct a variety of optical tests on the modules. With this architecture it is possible to subject a variety of different optical modules to a variety of different optical tests.

Abstract: A system for calibrating a plurality of optical modules includes a plurality of optical signal sources and optical signal degradation elements optically communicating with input switches. The input switches supply optical test signals to optical modules (units under test) plugged into a common shelf. Calibration switches including variable optical attenuators may be used to adjust the input signal levels and alternately supply adjusted signals to an optical power meter and the units under test. A controller is used to control the adjustment and thereby provide defined, measured signal levels to the units under test. By reading data from the units under test and using these defined signal levels, the optical modules may be calibrated or diagnosed. Output optical switches are used in a similar fashion to calibrate or diagnose the outputs of the units under test. In addition to input/output power calibration, the invention may also perform wavelength calibrations.

Abstract: An apparatus and method are provided for monitoring the Q-factor of a plurality of main signals that are simultaneously transmitted across a fiber optic line using wave division multiplexing. In particular, the includes an optical tap, a tunable optical bandpass filter, and a Q-detection circuit. The optical tap operates to tap the fiber optic line to provide a plurality of tapped signals corresponding to the plurality of main signals. The tunable optical bandpass filter acts to select one of the plurality of tapped signals, by only passing a selected signal in a chosen channel frequency band. The Q-detection circuit then determines the Q-factor of the selected signal. This operation can be performed sequentially for each of the plurality of tapped signals to provide a measure of the Q-factor for each of the plurality of main signals. This operation can also be continually repeated to provide a constant measurement of the Q-factor of each of the plurality of main signals.

Abstract: A testing circuit is provided for determining the Q-factor of an optical communication system. In the testing circuit, a variable attenuator attenuates a received optical signal in response to an attenuator control signal. A first optical-to-electrical converter converts a first portion of the attenuated optical signal into an electrical data signal. A second optical-to-electrical converter converts a second portion of the attenuated optical signal into a first power indication signal. A decision circuit detects high and low data bits in the electrical data signal based on a plurality of threshold voltage signals, and provides decision signals indicative of the results of these determinations. An error monitoring circuit receives the decision signals, determines the bit error rate of the incoming optical signal for the plurality of threshold voltages, and provides bit error rate signals.

Abstract: A defruiter for filtering fruit replies from a reply data signal in a radar system. The defruiter includes a window memory, a main memory, a counter and a main defruiter. Another version of the defruiter includes the items listed above and, additonally, a data memory and a buffer. The window memory stores reply data for a number of range intervals and a number of pulse repetition times. The main memory provides and receives reply data to and from, respectively, the window memory. The counter determines the number of replies occurring in a number of range intervals and a number of pulse repetition times. The main defruiter allows reply data to be provided to a data processor of the radar system when a reply occurs in the center part of the window memory and when the number of replies determined by the counter is greater than or equal to a window parameter. The number of fruit replies occuring within the reply data supplied to the data processor of the radar system is therefore reduced.