Abstract: The development of transmission technologies have resulted in a several tens Gbps optical transmission system. In the present invention, a low-speed FPGA receives a plurality of several Gbps signals according to a very high-speed parallel converting unit and the SFI-5, divides each of the plurality of several Gbps signals into a plurality of several hundreds (Mbps) parallel signals, and processes the plurality of several hundreds (Mbps) parallel signals in order to constitute an SFI-5 receiving end.

Abstract: Provided is an apparatus for and method of automatically controlling skew between transmitted data, which is caused when a common low-speed field-programmable gate array (FPGA) transmits signals having a transmission rate in the range of tens of Gbps to an optical transponder. The apparatus and method can transmit data with a transmission rate of several Gbps irrespective of the type of the FPGA.

Abstract: Provided is an apparatus for an optical clock extraction, which is capable of providing high optical amplification rate and more efficient noise cancellation by using a Fabry-Perot (FP) filter and an optical amplifier. In the apparatus, an optical circulator changes a direction of an inputted optical signal. The FP filter extracts different frequency components existing on a spectrum of the inputted optical signal and being spaced apart by a clock frequency, removes noise from a reflected and amplified optical signal, and transmits the resulting signal to the optical circulator. An optical amplifier performs a primary amplification to equalize two different frequency components outputted from the filter, and performs a secondary amplification on an optical signal reflected and fed back thereto. A reflector reflects the primarily-amplified optical signal to the optical amplifier.

Abstract: Provided are an integrated dielectric resonator filter and a clock extraction device using the integrated dielectric resonator filter. The integrated dielectric resonator filter includes: a microwave substrate; a disc type dielectric resonator installed on the microwave substrate and having predetermined diameter and height; an input and output transmission line installed on both sides of the disc type dielectric resonator to transmit input and output signals; and a metal cover enclosing the disc type dielectric resonator to form a predetermined volume, opened toward the input and output transmission line, and closed in an orthogonal direction to the input and output transmission line.

Abstract: A multi-channel data verifying apparatus and method are provided. The apparatus includes a receiver receiving N data channels and a deskew channel generated by sequentially extracting a predetermined data bit from the each of N data channels, and a deskew channel error detector detecting whether the deskew channel received by the receiver corresponds to an expected deskew channel generated and stored based on the test signal or generated based on the previously received deskew channel. Accordingly, data channels, a deskew channel and the entire data capacity can be verified and thus the cause of a problem in the transmission and reception of multi-channel data can be identified in advance.

Abstract: There is provided an apparatus for transmitting and receiving data with various data capacity at high speed. The apparatus for transmitting and receiving data includes a client signal interface block converting client signals being received through media into a high-capacity electrical signal and selectively interfacing the converted high-capacity electrical signal through high-speed multi-channel; a framer receiving the selectively interfaced electrical signal from the client signal interface block and multiplexing and mapping the received electrical signal into 40 G multi-channel frame signals; and a SERDES & transceiver receiving the 40 G multi-channel frame signals from the framer, multiplexing the received multi-channel frame signals with the 40 G serial signals and transmitting the multiplexed 40 G serial signals.

Abstract: There are provided a wideband electric signal mixer capable of mixing two inputted electric signals having a wideband frequency spectrum. The wideband electric signal mixer includes an input terminal controlling an input interface and a phase of a differential signal of a first electric signal and a second electric signal, having a wideband spectrum; a signal mixing terminal comprising a transmission gate switch receiving and outputting the second electric signal and mixing the first electric signal with the second electric signal by turning the transmission gate switch on and off using the differential signal of the first electric signal passing through the input terminal; and an output terminal providing an output interface between a mixing signal outputted from the signal mixing terminal and an external circuit unit and amplification function of the mixing signal.

Abstract: Disclosed is a device and method for optical supervisory channel framing in an optical transport network system including at least one of an optical transmission section, an optical multiplex section, and an optical channel section. A maintenance signal is generated according to a first LOS (Loss OF Signal) signal generated from at least one of the optical transmission section, the optical multiplex section, and the optical channel section. The maintenance signal and a frame-related channel such as a message communication channel are multiplexed to generate an optical supervisory channel frame. The optical supervisory channel frame is output to another device including a repeater and a terminal system through a single supervisory channel.

Abstract: Provided are an operation circuit for a modified Euclidean algorithm in a high-speed Reed-Solomon (RS) decoder and a method of implementing the modified Euclidean algorithm. Since a finite state machine (FSM) for generating a stop signal and an FSM for generating a control signal that controls a swap operation, a shift operation, and a polynomial operation for each basic cell of the modified Euclidean algorithm are used, an area-efficient RS decoder can be realized without using a conventional degree computation unit for comparing and calculating degrees.

Abstract: An apparatus for generating a Carrier-Suppressed Return-to-Zero (CS-RZ) signal is disclosed. The apparatus includes a mixer, a Low Pass Filter (LPF), a driver amplifier and a single external modulator. The mixer generates a modulator input by mixing data with a half clock signal. The LPF band-limits the modulator input data into low frequency band data. The driver amplifier amplifies the modulator input data generated by the mixing of the mixer and the band-limiting of the LPF. The external modulator generates CS-RZ signal, in which the phases of adjacent pulses have been inverted, by applying bias voltage to the modulator input data to be placed at the null point of the transfer function of the external modulator.

Abstract: Provided are an apparatus and method for generating an optical return-to-zero (RZ) signal using an electronic integrated circuit that generates an electric RZ signal. The apparatus for generating an optical RZ signal includes an electronic integrated circuit generating an electric return-to-zero (RZ) signal based on an input data signal and a clock signal, a driving amplifier amplifying the electric RZ signal, a light source outputting a carrier having a predetermined wavelength, and a modulator modulating the carrier according to the amplified RZ signal. The electronic integrated circuit can be constructed in a single electronic circuit chip, and thus the size of the optical transmission system can be reduced.

Abstract: Provided are a method and an apparatus for optically extracting a clock signal, that can be realized at low costs while minimizing an influence by input patterns and noises. In the method, optical signals having predetermined wavelength components are extracted using two FBG filters in order to extract a clock component from an input optical signal. After that, an influence by input filters is minimized by passing the extracted optical signals having the predetermined wavelengths through a Fabry-Perot filter.

Abstract: Provided are a method and apparatus for increasing transmission capacity for large-capacity high-speed signal transmission in an optical transport network (OTN). A method and apparatus for increasing transmission capacity are needed, which can transmit a large-capacity high-speed signal in order to transmit a signal through a united OTN by adapting signals from various tributary signal networks which have been independently operated for voice, image, or data transmission. Although various types of techniques such as Time Division Multiplexing (TDM), Wavelength Division Multiplexing (WDM), and an optical Printed Circuit Board (PCB) method have been performed, the techniques have various limitations. Therefore, a method and apparatus is provided for embodying a large-capacity optical transmission network, which overcome the limitations by using a Virtual Concatenation (VC) method.

Abstract: Provided are a method and an apparatus for converting an interface between high speed data having various capacities. The apparatus includes a data transmitting part and a data receiving part. The data transmitting part generates a deskew channel having respective timing data of a plurality of data transmitted from a first communicating device, and outputs the generated deskew channel together with the plurality of data to a second communicating device. The data receiving part compares the deskew channel transmitted from the second communicating device with the plurality of data to measure skew values of the data, aligns bits and bytes of the plurality of data using the skew values, and transmits the plurality of data to the first communicating device.

Abstract: Provided is an apparatus and method for all-optically controlling both a gain and a gain flattening. The apparatus includes: a first amplifier automatically controlling a gain of the apparatus through a feedback loop while amplifying a received optical signal; a fixed gain flattening unit receiving the amplified optical signal from the first amplifier and compensating for the gain according to a wavelength of the received optical signal; and a second amplifier automatically controlling the gain through a feedback loop while amplifying the optical signal input from the fixed gain flattening unit. Accordingly, even if the number of channels of an input WDM optical signal varies, both of a gain and a gain flattening can be all-optically controlled.

Abstract: The present invention relates to none return to zero (NRZ) modulation method. The NRZ optical modulation is performed by combining a clock signal and NRZ data at a sending end and signal distortion capable of being generated when the clock signal and the NRZ data are combined is optimized by controlling the magnitude and phase of the clock signal. At the receiving end, the clock signal is extracted by performing narrow band band-pass filtering of the detected optical signal transmitted from a transmitter and data is recovered using the clock signal. Therefore, a receiver structure for clock extraction is simpler, an error rate of data recovery is lower by clearly extracting the clock signal, and transmission distance of the optical signal is longer.

Abstract: A synchronous transfer mode (STM)-256 adder/dropper which provides a communication path between STM-64 optical channels in an apparatus of multiplexing STM-64 optical channels into STM-256 electrical signals, is provided. The STM-256 adder/dropper transmits STM signals by multiplexing the STM signals at a low speed and simultaneously provides a communication path between lower channels.

Abstract: A switching apparatus for switching an optical channel overhead in an optical supervisory channel is disclosed. The switching apparatus can suppress a terminated optical channel defect occurred by a defect of upper layers of the optical channel or a defect of the optical channel transmitter and also can maintain the corresponding optical channel at the wavelength converted optical transport network system. Furthermore, an apparatus for forwarding an optical channel maintenance signal is disclosed too. The apparatus includes the switching apparatus and transmits only an add and drop optical channel maintenance signal information to the CPU and generate the LOS suppression signal with respect to the optical channel according to the occurrence of malfunction, thus directly transmitting the suppression signal to the corresponding optical channel unit.

Abstract: Provided is a multi-mode open-loop type clock extraction apparatus. In the apparatus, a power divider block divides an input data signal into two data signals. A first band-pass filter block and a second band-pass filter block extract a first clock frequency component or a second clock frequency component contained in the data signal output from the power divider. A first amplifier block and a second amplifier block amplify the first clock frequency component and the second clock frequency component respectively. Accordingly, it is possible to extract the respective clock signals corresponding to N data rates from the N data signals with various data rates using a single clock extraction apparatus.

Abstract: An optical receiver in an optical communication system, and more particularly, to a method and an apparatus for optimizing a decision level of a signal output from an optical receiver to obtain a minimum bit error rate (BER) by measuring output characteristics of the optical receiver and adjusting a reference voltage of the optical receiver based on a measurement result. The provided method includes measuring the strength of an electric signal at a modulated frequency out of the frequency elements of the output electric signal in the optical receiver, generating a reference voltage based on the strength data of the electric signal, inputting the reference voltage to the optical receiver and re-measuring the strength of the electric signal output from the optical receiver to determine whether the strength of the signal is minimum, and maintaining the reference voltage when the strength of the signal is minimum and adjusting the reference voltage in other cases.