摘要:
An active radio frequency identification (RFID) apparatus having an additional transmitter in addition to a single transmitter is provided. The active RFID apparatus includes a first transmitter including a first pseudo noise (PN) code generator to generate a direct sequence spread spectrum (DSSS) introduced by ISO/IEC (International Organization for Standardization/International Electrotechnical Commission) 24730-2 or ISO/IEC 18185-5 type B; and a second transmitter including a second PN code generator to perform an AND operation on an initial value and a fed back value and shift the resultant value of the AND operation, to perform an XOR operation on particular bits from among the shifted bits and to perform an XOR operation again on the shifted bits and the resulting value of the XOR operation to finally generate a PN code. Accordingly, where an additional PN code is added besides an existing PN code, a PN code having excellent auto correlation characteristics allowing discrimination of the PN code itself and cross-correlation characteristics providing a code discrimination ability with respect to another code can be generated.
摘要:
Provided are an apparatus and a method for generating a return-to-zero (RZ) signal, including: a first modulator receiving a first signal having a predetermined frequency to modulate, compensate for and output a first laser beam; a second modulator receiving a second signal complementary to the first signal to modulate, compensate for, and output a second laser beam; a mixer mixing signals output from the first and second modulators to output a third signal; and a third modulator modulating the third signal into an RZ signal and outputting the RZ signal.
摘要:
The method for operating an optical transponder, which performs maintenance of a signal in the optical transponder having a digital wrapper in an optical transmission system including multiple layers, includes (a) calling a processor for processing an interrupt when the interrupt is generated from the digital wrapper according to monitoring of a received signal; (b) the called processor detecting what defect is generated in the received signal and detecting whether or not the received signal requires maintenance; (c) performing defect processing in the case that a defect is detected at (b) or is cancelled; and (d) controlling the digital wrapper according to the defect and maintenance processing result.
摘要:
Disclosed herein is an apparatus for controlling a decision threshold voltage to an optical receiver, which is capable of automatically controlling the decision threshold voltage to the optical receiver appropriately to signal level decision on the basis of a low-frequency band signal component of an output signal from the optical receiver. The apparatus is adapted to control the level of the decision threshold voltage to the optical receiver, which converts an input optical signal into an electrical signal. To this end, the apparatus comprises a voltage detector for branching off part of the output signal from the optical receiver and detecting a corresponding voltage, a differential comparator for comparing the voltage detected by the voltage detector with a reference voltage inputted thereto and outputting the resulting differential voltage, a low pass filter for filtering the differential voltage from the differential comparator at a predetermined low frequency band and supplying the resulting voltage as the threshold voltage to the optical receiver, and a voltage controller for controlling the reference voltage to the differential comparator on the basis of a differential voltage between the threshold voltage from the low pass filter and a predetermined voltage corresponding to a predetermined minimum bit error rate.
摘要:
Provided are an optical fiber amplification method and apparatus for controlling a gain. Initial values including target gains of first and second amplifications for an optical amplifier amplifying the input light signal are set. Power of the input light signal is measured and the power of first and second backward pump lights proceeding in the opposite direction to the input light signal is controlled based on the measured power. The input light signal is firstly amplified and a first amplification gain of the amplified light signal is calculated. Power of a first forward pump light proceeding in the same direction as the input light signal is controlled so that the first amplification gain can be substantially equal to the target gain of the first amplification. The firstly amplified light signal is secondly amplified and a second amplification gain with respect to the input light signal is calculated. The power of a second forward pump light proceeding in the same direction as the input light signal is controlled so that the second amplification gain can be substantially equal to the target gain of the second amplification.
摘要:
To track the location of a terminal in an indoor space by using a pseudo GPS signal transmitter, a GPS signal sent from an artificial satellite is received, and a clock signal of the artificial satellite is extracted from the received GPS signal to perform synchronization with the artificial satellite. Once synchronization with the artificial satellite is performed, a pseudo GPS signal is generated, and the transmission time of the pseudo GPS signal is controlled. The GPS signal is sent to the terminal located in the indoor space by a plurality of transmitting antennas based on the controlled transmission time, thereby enabling the terminal located in the indoor space to track its location.
摘要:
An apparatus and method of generating a pseudo noise (PN) code is provided. The apparatus for generating the PN code includes: a memory device unit including a plurality of memory devices; an exclusive-OR (XOR) operation unit receiving output values of at least two memory devices among output values of the plurality of memory devices to output an XOR operation value with respect to the received output values; and a PN code generation unit generating the PN code based on an output value of the XOR operation unit.
摘要:
Optical signals transmitted through an optical cable are converted into digital data of bits “1” and “0” on the basis of a reference voltage, and errors generated during transmission of the optical signals are corrected using Forward Error Correction (FEC). A method includes extracting numbers of occurrence of errors for bits “1” and “0” recovered through the FEC. Thereafter, the extracted numbers of occurrence of errors for bits “1” and “0” are compared with each other. A reference voltage used to judge levels of the signals to be level “1” or “0” is controlled if the numbers of occurrence of errors for bits “1” and “0” are not equal to each other. The current reference voltage is maintained if the numbers of occurrence of errors for bits “1” and “0” are rendered equal to each other.
摘要:
A low-noise optical fiber amplifier for performing a long-distance optical transmission in a wavelength division multiplexing optical transmission apparatus is provided. This amplifier includes a first optical fiber amplifier having a pre-stage optical fiber, and a first coupler for supplying pump light to the pre-stage optical fiber; a dispersion compensating Raman amplifier (DCRA) connected to the first optical fiber amplifier and having a dispersion compensating optical fiber (DCF) that compensates for the dispersion accumulated in an optical line and generates a Raman gain, and a second coupler for supplying Raman pump light onto the DCF; and a second optical fiber amplifier connected to the DCRA, and including a post-stage optical fiber and a third coupler for supplying pump light onto the post-stage optical fiber. Accordingly, this optical fiber amplifier is used for terrestrial WDM optical transmission, and thus has remarkably low noise figure compared to the existing optical amplifiers. For this reason, the optical fiber amplifier is available in long-distance transmission, and can be used in optical networks.
摘要:
Provided are a Radio Frequency Identification (RFID) tag and apparatus and method for locating a RFID tag without comparing arrival times of blink signals transmitted from the RFID tag in order to quickly trace a location of the RFID tag. The RFID tag includes a tag ID generator configured to generate a tag ID of the RFID tag, a blink generator configured to generate a plurality of sub-blink signals that form the blink signal, a sub-blink ID generator configured to generate sub-blink IDs for the generated sub-blink signals, a sub-blink ID inserter configured to insert the generated sub-blink IDs into the sub-blink signals, and a transmitter configured to transmit the blink signal having the tag ID and the sub-blink IDs.