Abstract: A digital television receiving system includes a first known data detector, a second known data detector, and a selector. The first known data detector detects a location of a first known data sequence in a broadcast signal by calculating a first correlation value between the broadcast signal and a first reference known data sequence. Similarly, the second known data detector detects a location of a second known data sequence in the broadcast signal by calculating a second correlation value between the broadcast signal and a second reference known data sequence. The selector selects the location information detected by one of the first and second known data detectors with a greater correlation value.

Abstract: A digital television receiving system includes a frame encoder, a data randomizing and expanding unit, a group formatter, a block processor, a deinterleaver, and a multiplexer. The frame encoder encodes an enhanced data frame for error correction. The data randomizing and expanding unit randomizes the encoded enhanced data and expands the randomized enhanced data. The group formatter forms a group of enhanced data having head, body, and tail regions and inserts the expanded data and transmission parameters into the body region. The block processor codes the group of enhanced data, and the deinterleaver deinterleaves the coded enhanced data. The packet formatter formats the deinterleaved enhanced data into enhanced data packets.

Abstract: A television transmitting system includes an encoder, a data randomizing and expanding unit, a group formatter, a deinterleaver, and a packet formatter. The encoder codes enhanced data for error correction, permutes the coded data, and further codes the permuted data for error detection. The randomizing and expanding unit randomizes the error-detection-coded data and expands the randomized data. The group formatter forms a group of enhanced data having one or more data regions and inserts the expanded enhanced data into at least one of the regions. The deinterleaver deinterleaves the group of enhanced data, and the packet formatter generates enhanced data packets.

Abstract: A DTV transmitting system includes a frame encoder, a randomizer, a block processor, a group formatter, a deinterleaver, and a packet formatter. The frame encoder builds an enhanced data frame and adds parity data into the data frame. The frame encoder further divides the data frame into first and second sub-frames including first and second portions of the parity data, respectively, and permutes a plurality of the first sub-frames and a plurality of the second sub-frames, respectively. The randomizer randomizes enhanced data in the permuted sub-frames, and the block processor codes the randomized data at a rate of 1/N1. The group formatter forms a group of enhanced data having one or more data regions and inserts the 1/N1 coded data into at least one of the data regions. The deinterleaver deiniterleaves the group of enhanced data, and the packet formatter formats the deinterleaved data into enhanced data packets.

Abstract: A channel equalizer includes a first transformer, an estimator, an average calculator, a second transformer, a coefficient calculator, a compensator, and a third transformer. The first transformer converts normal data into frequency domain data, where a known data sequence is periodically repeated in the normal data. The estimator estimates channel impulse responses (CIR) during known data intervals adjacent to each normal data block. The average calculator calculates an average value of the CIRs. The second transformer converts the average value into frequency domain data. The coefficient calculator calculates equalization coefficients using the average value, and the compensator compensates channel distortion of each normal data block using the coefficients. The third transformer converts the compensated data block into time domain data.

Abstract: A channel equalizer includes an overlap unit, an estimator, a calculator, a compensator, and a save unit. The overlap unit overlaps a group of data packets in a broadcast signal. The group data packets include a head, a body, and a tail, and a known data sequence is periodically included in the body. The estimator estimates a CIR of each data region the body using the known data sequence, and it further estimates CIRs of data regions in the head or tail using the CIRs obtained for the data regions in the body. The calculator calculates equalization coefficients based on the CIRs estimated by the estimator, and the compensator compensates channel distortion of the overlapped data using the equalization coefficients. The save unit saves the compensated data.

Abstract: A DTV receiver includes a tuner tuning to a channel to receive a broadcast signal, and a demodulator demodulating the broadcast signal. The receiver further includes a first decoder which decodes main and enhanced data included in the demodulated signal by calculating soft decision values for the enhanced data and hard decision values for the main data. The receiver further includes a second decoder for decoding the main and enhanced data for first forward error correction, and a third decoder for decoding the FEC-decoded enhanced data for second forward error correction.

Abstract: A reflective semiconductor optical amplifier (RSOA) and an operating system based on a downstream optical signal reuse method with feed-forward current injection are provided. The RSOA has two active regions and includes a reflecting plane that reflects an input optical signal; and an optical amplifying semiconductor including a rear portion, which is positioned at a side of the reflecting plane and to which a signal having polarity opposite to that of the input optical signal is injected, and a front portion, which is positioned at a side opposite to the side of the rear portion facing the reflecting plane and which the input optical signal is passed though and a signal used to modulate a reflected input optical signal from the reflecting plane to an output optical signal is injected into.

Abstract: A DTV transmitter includes a pre-processor pre-processing enhanced data, a data formatter generating enhanced data packets including the pre-processed data and inserting known data place holders to the data packets, and a multiplexer multiplexing the enhanced data packets with main data packets. It further includes an RS encoder which RS-codes the multiplexed data packets, and a data interleaver which interleaves the RS-coded data packets. The RS encoder adds systematic RS parity data to each main data packet and adds non-systematic RS parity place holders to each enhanced data packet. The RS encoder adds the RS parity place holders such that the RS parity place holders are placed after the enhanced data within each interleaved enhanced data packet.

Abstract: A DTV transmitter includes a pre-processor expanding original enhanced data, a data formatter generating enhanced data packets including the expanded enhanced data and inserting known data place holders into the data packets, a multiplexer multiplexing the enhanced data packets with main data packets including main data, and an RS encoder adding systematic RS parity data to each main data packet and adding non-systematic RS parity data holders to each enhanced data packet. It further includes a data interleaver interleaving the RS-coded data packets, a known data generator generating know data symbols, a converter converting the interleaved data packet into symbols, and a symbol processor processing the converted symbols. The symbol processor removes symbols representing the null data, encodes symbols representing the original enhanced data at a rate of N/M, and replaces symbols representing the know data place holders with known data symbols.

Abstract: Provided are an apparatus and method for tracking a wavelength in a passive optical subscriber network in which a central base station and at least one subscriber terminal are connected via a remote node. The apparatus includes a first wavelength aligning unit multiplexing and aligning wavelengths of optical signals from a plurality of single-mode optical sources of the central base station; a second wavelength aligning unit multiplexing and aligning wavelengths of optical signals transmitted to the remote node from a plurality of single-mode optical sources of the subscriber terminal; and a third wavelength aligning unit demultiplexing and aligning wavelengths of optical signals from the second wavelength aligning unit, the third wavelength aligning unit being included in the central base station.

Abstract: Provided are extendable loop-back passive optical network (PON) and scheduling method and apparatus for the same. The loop-back type PON includes an OLT (optical line terminal) including a wavelength-tunable optical transmitter and a wavelength-locked optical receiver, and an RN (remote node) including an optical coupler/splitter, the optical coupler/splitter receiving optical signals from the wavelength-tunable optical transmitter and splitting the optical signals by wavelength so as to transmit the optical signals to corresponding ONTs (optical network terminals). Each of the ONTs transmits upstream data to the OLT using the same wavelength as the wavelength of the optical signal received from the OLT through the RN. Since the optical network makes use of the TDM and WDM communication schemes, the optical network can be maintained and upgraded at lower cost.

Abstract: A DTV receiver includes a tuner, a demodulator, a known sequence detector, and a frequency domain equalizer. The tuner initially receives a broadcast signal including valid data in which a known data sequence is periodically repeated. The demodulator demodulates the broadcast signal, and the known sequence detector detects the known data sequence from the demodulated signal. The frequency domain equalizer compensates channel distortion of the demodulated broadcast signal in a frequency domain using the detected known data sequence. In addition, the DTV receiver may further include a time domain equalizer which compensates channel distortion of the time domain signal, or a noise canceller which removes a predicted noise from the time domain signal.

Abstract: Provided is a method of increasing the number of subscribers using a time division duplexing (TDD) technology in a wavelength division multiplexing (WDM)/Ethernet passive optical network (WE-PON) system, and more particularly, a method of increasing the number of subscribers admissible per wavelength using a TDD technology. In an existing WE-PON, due to an amplitude squeezing effect (ASE) in an optical network terminal (ONT) and an optical output power restriction in an optical line terminal (OLT), there is a disadvantage in that 4 or more subscribers cannot be simultaneously accommodated per wavelength. However, the present invention enables accommodation of a maximum of 16 subscribers per wavelength by applying a TDD technology to a medium access control (MAC) protocol.

Abstract: A method of storing a pattern matching policy and a method of controlling an alert message are provided.

Abstract: Provided are an optical transmission apparatus and an optical access network for a wavelength-division multiplexing optical network with sub-carrier multiplex and sub-carrier multiple access schemes. The optical transmission apparatus includes: a multiplexer and/or demultiplexer demultiplexing M forward A band optical signals having wavelengths each comprising a plurality of sub-carriers and multiplexing M backward B band optical signals having wavelengths each comprising a plurality of sub-carriers; a plurality of optical power splitters splitting each of the M forward A band optical signals into N optical signals; a plurality of optical receivers receiving backward optical signals belonging to a C band; and M optical transmitters converting the backward optical signals in the C band into the M backward B band optical signals.

Abstract: A DTV transmitter includes a pre-processor expanding original enhanced data, a data formatter generating enhanced data packets and inserting known data into the data packets, a multiplexer multiplexing the enhanced data packets with main data packets, a data randomizer randomizing the multiplexed data packets, an RS encoder RS-coding the randomized data packets, and a data interleaver interleaving the RS-coded data packets. The DTV transmitter further includes a byte-symbol converter converting the interleaved data packets into corresponding symbols, and a symbol processor encoding symbols representing the original enhanced data.

Abstract: A Reflective Semiconductor Optical Amplifier (RSOA) for compensating for light loss in an optical link, an RSOA module for improving polarization dependency using the RSOA, and a Passive Optical Network (PON) for increasing economical efficiency and practical use of a bandwidth using the RSOA are provided. The PON includes a central office comprising a plurality of optic sources transmitting a downstream signal and a plurality of first receivers receiving an upstream signal; at least one optical network terminal (ONT) including a second receiver receiving the downstream signal and an RSOA which receives the downstream signal, remodulates the downstream signal into the upstream signal, and transmits the upstream signal in loopback mode; and a remote node interfacing the central office with the ONT. The upstream signal and the downstream signal are transmitted between the remote node and the ONT via a single optical fiber. The remote node includes an optical power splitter at its port connected to the ONT.

Abstract: Provided are a physical coding sublayer (PCS) apparatus and an Ethernet layer architecture for a network-based tunable-wavelength passive optical network (T-PON) system employing an Ethernet communications technology, and more particularly, to a PCS apparatus and an Ethernet layer architecture for supporting a series of initialization function of allocating wavelengths between an optical line terminal (OLT) and an optical network terminal (ONT) and arranging the allocated wavelengths. A PCS layer transmits and allocates wavelength information such that wavelengths for setting a link between an OLT and an ONT are allocated, optical wavelengths within the ONT are observed while a system operates to allow continuous control so that operating of the system can be stably maintained.

Abstract: Provided are an apparatus and method for processing analog monitoring signals by using a serial bus. The apparatus includes a multiplexer receiving at least one analog signal and outputting only one of the at least one analog signal in response to a predetermined control signal; an analog-to-digital converter converting the output analog signal into a digital signal; a first controller generating the control signal, outputting the control signal to the multiplexer, and controlling the operation of the analog-to-digital converter; and a bus controller outputting the digital signal via an external serial bus. Accordingly, analog monitoring signals are received, converted into digital data, and output via serial bus even when a large number of analog monitoring signals are present, only if the address input to the apparatus is identical to unique address of the apparatus.