摘要:
A first tunable wavelength pulse light source (22) is driven by a reference signal to emit a first optical pulse. An optical demultiplexer (24) demultiplexes a first optical pulse emitted from the first pulse light source (22) into a reference optical pulse and an incident optical pulse to be sent into an object to be measured. An optical multiplexer (26) multiplexes the reference optical pulse and an outgoing optical pulse passing through the object to output multiplexed light. A second pulse light source (23) generates a second optical pulse which is synchronous with the first optical pulse and delays a predetermined time for each period of the first optical pulse. A sampling unit (27, 27a, 27b) receives the multiplexed light and the second optical pulse to obtain an optical pulse train signal proportional to the intensity of the multiplexed light obtained in synchronism with the second optical pulse. From the optical pulse train signal from the sampling unit (27, 27a, 27b), a signal processor (37) obtains an envelope formed by peaks of individual optical pulses forming the optical pulse train. The wavelength dispersion of the object is obtained by measuring the delay time of the outgoing optical pulse passing through the object on the basis of intervals between the peaks of the envelope.
摘要:
A first tunable wavelength pulse light source (22) is driven by a reference signal to emit a first optical pulse. An optical demultiplexer (24) demultiplexes a first optical pulse emitted from the first pulse light source (22) into a reference optical pulse and an incident optical pulse to be sent into an object to be measured. An optical multiplexer (26) multiplexes the reference optical pulse and an outgoing optical pulse passing through the object to output multiplexed light. A second pulse light source (23) generates a second optical pulse which is synchronous with the first optical pulse and delays a predetermined time for each period of the first optical pulse. A sampling unit (27, 27a, 27b) receives the multiplexed light and the second optical pulse to obtain an optical pulse train signal proportional to the intensity of the multiplexed light obtained in synchronism with the second optical pulse. From the optical pulse train signal from the sampling unit (27, 27a, 27b), a signal processor (37) obtains an envelope formed by peaks of individual optical pulses forming the optical pulse train. The wavelength dispersion of the object is obtained by measuring the delay time of the outgoing optical pulse passing through the object on the basis of intervals between the peaks of the envelope.
摘要:
A hitless path switching method without a bit loss. A bit error in the same digital line signals is continuously monitored independently of a predetermined data blocks of a working path (51) and a protection path (61). If a bit error occurs in the working path and no bit error occurs in the protection path, a switching trigger is produced and the switching from the working path to the protection path is performed on the data block basis. Only correct data are transferred to downstream apparatuses. A reliable hitless switching is achieved not only in response to a failure in its own path, but also in response to a bit error. Using data blocks of one frame length with an indicator for bit error check placed at its top makes an effective switching possible.
摘要:
A hitless path switching method without a bit loss. A bit error in the same digital line signals is continuously monitored independently of a predetermined data blocks of a working path (51) and a protection path (61). If a bit error occurs in the working path and no bit error occurs in the protection path, a switching trigger is produced and the switching from the working path to the protection path is performed on the data block basis. Only correct data are transferred to downstream apparatuses. A reliable hitless switching is achieved not only in response to a failure in its own path, but also in response to a bit error. Using data blocks of one frame length with an indicator for bit error check placed at its top makes an effective switching possible.
摘要:
In an optical transmission system applicable to a SDH network, communication between two line terminating equipments is performed in a form of a STM frame composed of a SOH field and a payload, which is determined by CCITT recommendations. The line terminating equipment provides a FEC circuit which is preferably arranged at a location between MSP and MST function blocks. The FEC circuit is designed to perform coding/decoding operations, using a cyclic Hamming code, directly on each AU-4 message derived from the STM frame. Otherwise, the FEC circuit performs operations on each k-bit interleaved AU-4 message (where 'k' is an integer larger than 1). Check bits generated by a FEC coding circuit are written into undefined byte areas in a MSOH field, and error correcting is performed at a decoder circuit on the basis of embedded check bits, therefore FEC operations are performed within a multiplex-section layer. A FEC processing circuit is constituted by shift registers each of which is connected by exclusive-or logic so as to execute FEC processing calculation generating a remainder by a generator polynomial. For a FEC code on direct AU-4 message, the FEC processing circuit in parallel configuration for lowering an operational clock rate is determined by a matrix form calculation, which creates an output vector indicating a set of shift registers' data in a future clock timing from an input vector consisting of data stream in message and initial shift registers' values.