• Journal of the Optical Society of Korea
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• v.13 no.2
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• pp.227-233
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• 2009

We investigated the polarization-mode dispersion (PMD) tolerance for 40Gb/s non-return to zero (NRZ), duobinary NRZ, return to zero (RZ), carrier-suppressed RZ (CS-RZ), and duobinary-carrier-suppressed RZ (DCS-RZ) modulation formats with a forward error correction (FEC) coding. The power penalty has been calculated as a measure of the system performance due to PMD. After comparison of the PMD tolerance of various modulation formats, our results suggest that RZ signals have the best tolerance against the effect of first-order PMD only. The duobinary NRZ modulation format is most resilient to PMD when both first- and second-order PMD are considered. However, the duobinary NRZ modulation format is the most sensitive to the incident angle of the input signal to a fiber axis in the presence of first- and second-order PMD, leading to incident angle-dependent power penalty. The coding gain by FEC can cope with the power penalties induced by first- and second-order PMD up to a DGD value of 16ps.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.826-833
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• 2002

Generally, it is announced that RZ pattern gives a better transmission performance than NRZ pattern in ultra-high speed transmission above 10Gbps. In this paper, we propose a wavelength converter for RZ data which can controls XPM in SOA by locating polarization controllers within optical fiber loop mirror and demonstrate its performance through simulation and 10Gbps data experiment. The proposed structure needs only one polarization dependent SOA for implementation compared to previous XPM ones to make the cost down. And it provides non-inverted pattern outputs at two output ports respectively.

• Journal of Advanced Navigation Technology
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• v.2 no.1
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• pp.53-60
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• 1998

This paper describes some design concepts and design parameters of RZ-SSB which allows full carrier insertion into the single side band to overcome the severe fading in aeronautical telecommunication, and it is described in ARINC Spec. in the name of AME(AM Equivalent), and the necessary transmission bandwidth of RZ-SSB is similar to that of a aeronautical telecommunication. As an amplitude limiter manage to remove the amplitude fading without degrading the quality of output signal, the receiver acts like the FM demodulators. Using the digital Signal Processing(DSP) techniques in the design of transceiver systems has become a performance enhancement of the signal quality and reliability, and making use of DSP, it's able to design low cost, compact transceiver and reduce its weight. For avionics systems is able to eliminate the inherent disadvantages in RZ-SSB, the results of experimental tests suggest that the adoption of RZ concepts is suitable for aeronautical telecommunication transceiver systems use in HF band.

• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.109-120
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• 2005

In this paper, bit error rate (BER) characteristics, sensitivity and minimum allowable launching power are numerically investigated as a function of amplifier spacing that consisted of 1,200 km WDM systems with MSSI method. It is conformed that the sensitivity and minimum allowable launching power are gradually degraded as amplifier spacings are gradually expanded, but those are not largely affected by modulation format. The sensitivity of RZ transmission system is smaller than that of NRZ transmission system, but minimum allowable launching power of NRZ transmission system is smaller than that of RZ transmission system. And, it is confirmed that the best amplifier spacing in NRZ and RZ transmission system is less than 50 km, because the sensitivity and minimum allowable launching power are less affected by fiber dispersion, channel wavelength and pump light power.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.233-241
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• 1997

New UBV Photometric observations for a close binary RZ Cas were obtained at the Chungbuk National University Observatory for 42 nights from October 1991 to March 1993, and standardized UBV light curves were constructed. From the primary light curves, the eight minimum times were determined by using a new light element. We confirmed the primary minimum was totality and derived the average duration was 18.1 minutes corresponding to $0.^{p}01$. The photometric and spectroscopic solutions were calculated with the obtained light curves and the radial velocity curves of Duerbeck & Hanel(1979) by using Wilson-Devinney method. From these values, the absolute dimensions of this binary system were estimated.

• Journal of the Optical Society of Korea
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• v.12 no.4
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• pp.232-239
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• 2008

We investigated how the polarization-mode dispersion (PMD) tolerance was degraded by semiconductor optical amplifier (SOA)-induced chirp for the 10 Gb/s nonreturn-to-zero (NRZ), duobinary NRZ, return-to-zero (RZ), and carrier-suppressed RZ (CS-RZ) modulation formats. The power penalty was calculated as a measure of the system performance due to PMD for a given SOA-induced chirp. Considering only first-order PMD, all modulation formats have a similar PMD tolerance regardless of SOA-induced chirp. On the other hand, when both first- and second-order PMD are considered, the PMD tolerance of all modulation formats with the exception of the CS-RZ modulation format are degraded by SOA-induced chirp. Among all modulation formats considered here, the NRZ modulation format has the PMD tolerance with the highest sensitivity to SOA-induced chirp. When the peak-to-peak chirp induced by SOAs is $0.28{\AA}$, its PMD tolerance is degraded up to 4 dB for a differential group delay (DGD) of 50 ps. However, the PMD tolerance of the CS-RZ modulation format is largely unaffected by SOA-induced chirp.

• Korean Journal of Optics and Photonics
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• v.11 no.6
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• pp.400-404
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• 2000

All-optical clock recovery from a 10 Gb/s RZ signal has been demonstrated using an actively mode-locked figure-eight laser incorporating a semiconductor optical amplifier in the loop-mirror scheme. Optical pulses with 10 ps pulse width were modulated by a LiNb03 external modulator at $2^{23}-1$ PRES and injected into the clock recovery circuit to extract optical pulses with 12 ps width. Regeneration of the original bit pattern has been accomplished by modulating the recovered clock with the same modulator, and no power penalty was observed at $10^{11}$..

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.75-81
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• 2020

We introduce a new visible light communication (VLC) method in which three-level return-to-zero (RZ) modulation is used for flicker-free transmission. In the VLC transmitter, the three-level RZ modulation ensures that the average optical power is constant; thus, a flicker-free light-emitting diode (LED) light is achieved. In the VLC receiver, a resistor-capacitor high-pass filter is used for generating spike signals, which are used for data recovery while eliminating the 120 Hz optical noise from adjacent lighting lamps. In transmission experiments, we applied this method for wireless transmission of an air quality sensor message using the visible light of an LED array. This configuration is useful for the construction of indoor wireless sensor networks for air pollution monitoring using LED lights.

• Bulletin of the Korean Mathematical Society
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• v.47 no.5
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• pp.987-996
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• 2010

In this paper, we investigate the Cauchy-Rassias stability in Banach spaces and also the Cauchy-Rassias stability using the alternative fixed point for the functional equation: $$f(\frac{sx+ty}{2}+rz)+f(\frac{sx+ty}{2}-rz)+f(\frac{sx-ty}{2}+rz)+f(\frac{sx-ty}{2}-rz)=s^2f(x)+t^2f(y)+4r^2f(z)$$ for any fixed nonzero integers s, t, r with $r\;{\neq}\;{\pm}1$.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.198-199
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• 2005