Abstract: The present invention provides an apparatus for generating L-band light source and an optical signal amplifier, specifically, relates to an apparatus for generating L-band light source by increasing amplification gain against an L-band light to execute a stable resonating operation, and to an optical amplifier which amplifies L-band light signal efficiently. That is, it is possible to use the output light of the first optical fiber amplifier 10 as a pumping light of the second optical fiber amplifier 20 by connecting the first optical fiber amplifier 10 for supplying a maximum amplification gain against an input light having a wavelength of 1530 nm to 1560 nm with the second optical fiber amplifier 20 for supplying a maximum amplification gain against an input light having a wavelength of 1570 nm to 1610 nm in series, thus securing a satisfied amplification gain against a L-band light and to generate a desirable light source.

Abstract: An asynchronous transfer mode (ATM) switch system having a switch for exchanging an ATM cell between one of the inputs thereto and one of the outputs therefrom, comprises a plurality of linking blocks, an administrating block and a processor. Each of the linking blocks is coupled with the switch and applies the ATM cell to selected one of the inputs to the switch and checks whether or not the ATM cell is synchronized with a cell synchronization signal and activates a synchronization loss (SL) signal when the ATM cell is not synchronized with the cell synchronization signal.

Abstract: Disclosed relates to an L-band optical fiber amplifier which amplifies an L-band optical signal of 1570 nm to 1610 nm. In general, when a pumping light of 980 nm for example, output from a pumping light generating laser diode, is supplied to an erbium doped fiber EDF, an amplified spontaneous emission ASE having a bandwidth of 1530 nm to 1560 nm, namely, C-band is generated. The L-band optical fiber amplifier of the invention is configured in a manner that ASE transmitted in the backward direction, or a predetermined wavelength light selected from the bandwidth of 1530 nm to 1560 nm is reflected by a reflecting means and re-injected to EDF. A fiber bragg grating FBG or a reflecting mirror is applied as the reflecting means. The reflected light from the reflecting means is re-injected to EDF and acts as the pumping light, thus increasing the amplification gain for the L-band input light remarkably.

Abstract: A clock synchronization method, for use in generating a system clock of a predetermined frequency with reference to a reference clock, receives the reference clock, the system clock and a divided clock having a same frequency as that of the reference clock, wherein the divided clock is obtained by dividing the system clock by a predetermined integer. Phase deviations between the reference clock and the divided clock are obtained, wherein a phase deviation is the number of periods of the system clock in a section between a rising edge of the reference clock and a nearest rising edge of the divided clock. Consecutive phase deviations are averaged to thereby generate an average phase deviation of a 3rd order, wherein the number of averaged consecutive phase deviations varies according to phase jitter characteristics of the reference clock. And, the frequency of the system clock is controlled based on the average phase deviation of the 3rd order.

Abstract: An asynchronous transfer mode (ATM) switch system generates a divided clock pulse to be used in converting ATM cells into data of unit of a predetermined bit length. In the system, a clock pulse and a plurality of cell synchronization signals with different phases are obtained first. Based on the clock pulse and the cell synchronization signals, a selection control signal and a reset signal are issued. In response to the selection control signal, one of the cell synchronization signals is selected. An initialization control signal is derived in accordance with the selected one cell synchronization signal and the reset signal. In response to the initialization control signal, the divided clock pulse is obtained based on a previous divided clock pulse to generate the divided clock pulse.

Abstract: The present invention relates to a parallel combinatory CDMA (PC-CDMA) system that transmits and receives data by applying a predetermined pseudo number (PN) code corresponding to a plurality of bits, and more particularly relates to a multi-carrier PC-CDMA system, enhancing its efficiency by mixing the PN codes corresponding to the plurality of bits with respective orthogonal frequencies. The transmitting part includes a plurality of mixers 331 to 33n for mixing respective PN codes outputted from a plurality of mappers 321 to 32n with frequency signals having an orthogonal feature and a receiving part including a plurality of mixers 411 to 41n for mixing received signals with the same frequency signals mixed at the transmitting part. Accordingly, it is possible to decrease the number of PN codes needed in a PC-CDMA system by correlating the mappers 321 to 32n of the transmitting part and correlator 421 to 42n and data detectors 431 to 43n of the receiving part through the mixers 33 and 41 independently.

Abstract: An integrated services digital network (ISDN) switch capable of switching packets in each of access switching subsystems, includes a plurality of access switching subsystems including a time switch, for providing interfaces with subscriber equipments by using the ISDN standard interfaces; an interconnection network subsystem including a space switch, connected to the access switching subsystems, for performing functions such as space switching and network synchronization; and a central control subsystem, connected to the interconnection network subsystem, for supervising and controlling overall functions performed in each subsystem in the ISDN switch.