• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.3C
• /
• pp.69-76
• /
• 2005

In this paper, we propose a biorthogonal modulation employing a constant-amplitude transmission of multi-code signals by introducing a simple constant-amplitude coding scheme with redundant bits. The proposed constant-amplitude biorthogonal multi-code (CABM) modulation can provide high spectral efficiency compared with a conventional direct sequence/spread spectrum (DS/SS) modulation. Nevertheless the proposed CABM modulation can keep up a constant-amplitude signal. Additionally, we propose various types of demodulation structures for the CABM modulation. Simulation results show that bit error rate (BER) performance and hardware complexity of the proposed CABM modulation are highly improved in comparison with those of a constant-amplitude orthogonal multi-code (CAOM) modulation.

• Proceedings of the KIEE Conference
• /
• 2003.11b
• /
• pp.71-74
• /
• 2003

The signal processing algorithm for a PSD(Position Sensitive Detector) using amplitude modulation/demodulation is addressed in this paper. Dark currents and external noises such as daylight and fluorescent lights are eliminated by using amplitude modulation/demodulation and a low pass filter. The proposed amplitude modulation/demodulation method for a PSD sensor is compared with pulse amplitude modulation method. The proposed amplitude modulation is proved to be more accurate and robust than PAM method by analysis and experiments. Multiple measurements using one PSD sensor by amplitude modulation/demodulation is also addressed. The Power variation of light source is compensated by normalization process using a divider.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.491-491
• /
• 2009

Wind turbines produce aerodynamic noise which fluctuate periodically at a blade passing frequency. This sound characteristic is called amplitude modulation, or swishing sound. Several previous studies claimed that this amplitude modulation has a possibility to increase noise annoyance. Thus, this study performed a listening test to find the relationship between the amplitude modulation in wind turbine noise on noise annoyance. The stimuli for the listening test was recorded from a 1.5MW wind turbine in Jeju island. The result of the listening test shows that the amplitude modulation in wind turbine noise significantly increase noise annoyance. Moreover, this study analytically examined the effect of amplitude modulation on noise perception. The result indicates that amplitude modulated sound can be easily perceived even though the background noise level is higher than the sound level of the signal.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.1
• /
• pp.493-499
• /
• 2011

To improve the bandwidth efficiency of conventional orthogonal modulation, the MCTO(Multi-Code Trans-Orthogonal) modulation, which is modified orthogonal modulation, was proposed. However, the RF(Radio Frequency) power amplifier for the MCTO modulation is too complex to reject the amplitude distortion due to the non-constant amplitude property of the MCTO. Therefore, in this paper, CAMCTO(constant-amplitude multi-code trans-orthogonal) modulation is proposed by using the constant-amplitude encoding algorithm for multi-code signal. Additionally, the performance of the proposed CAMCTO modulation is compared with those of the orthogonal modulation and the MCTO modulation by using the computer simulation. The computer simulations show that the bandwidth efficiency of the proposed CAMCTO modulation is better than that of the conventional orthogonal modulation.

• Journal of Internet Computing and Services
• /
• v.9 no.1
• /
• pp.21-32
• /
• 2008

In this paper, we propose new modulation schemes using the conventional CACB (Constant Amplitude Coded Multicode Biorthogonal) modulation with constant amplitude property. Also the proposed modulation schemes supports high transmission data rate by increasing the spectral efficiency, In order to obtain the high spectral efficiency, the $Q^2$AM (Quadrature-Quadrature Amplitude Modulation) and CA-$Q^2$AM (Constant Amplitude-$Q^2$AM) are used. We explain the simplest combining modulation scheme of CACB and $Q^2$AM (i.e., CACB-$Q^2$AM). However, this modulation scheme cannot support the constant amplitude property. Hence the first CACB-CA-$Q^2$AM (or CACB-CA-$Q^2$AM I) modulation scheme is proposed for the constant amplitude property. In the modulation scheme, the redundant constant amplitude encoding (spectral efficiency decrease) is required. Therefore, the second CACB-CA-$Q^2$AM (or CACB-CA-$Q^2$AM II) modulation scheme is proposed retaining the constant amplitude and the spectral efficiency. Computer simulations show that the proposed CACB-CA-$Q^2$AM II is the efficient modulation scheme.

• Journal of Institute of Control, Robotics and Systems
• /
• v.6 no.11
• /
• pp.981-986
• /
• 2000

A pulse amplitude modulation(PAM) controller is designed for the 3 axis attitude control of a sounding rocket. a certain number of fixed level of thrust are used for the pulse amplitude modulation and the nonlinearity of the controller is considered to examine the existence of the limit cycles and the stability analysis is carried out with the aid of Nyquist plot.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.180.1-180.1
• /
• 2010

Wind turbine noise is generally lower than that from other environmental noise sources such as road and railway noise. Nevertheless, some residents living more than 1km away from wind turbines have claimed that they suffer sleep disturbance due to wind turbine noise. Several researchers have maintained that residents near a wind farm may perceive large amplitude modulation of wind turbine noise at night, and this amplitude modulation is the main cause of the noise annoyance. However, to date only few studies exist on the prediction of the amplitude modulation of wind turbine noise. Thus, this study predicts amplitude modulated noise generated from a generic 2.5MW wind turbine. Semi-empirical noise models are employed to predict the modulation depth and the overall sound pressure level of the wind turbine noise. The result shows that the amplitude modulation is observed regardless of atmospheric stability, but the modulation depth in a stable atmosphere is 1~3dB higher than that in an unstable atmosphere near the plane of rotation where the blades move downward. Moreover, using the result of the noise prediction, this study estimates the maximum perceptible distance of the wind turbine noise cause by amplitude modulation. The result indicates that the wind turbine noise can be perceived at a distance of up to 1600m in the range of about 30~60 degree from the on axis in a extremely low background noise environment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.10a
• /
• pp.669-672
• /
• 2008

In this paper, we propose a constant-amplitude multi-rode trans-bi-orthogonal modulation scheme by introducing a simple constant-amplitude coding scheme with redundant bits and trans-code, which if a modified orthogonal modulation scheme. Generally speaking, the orthogonal modulation scheme is not appropriate for the high speed data transmission applications because of bad bandwidth efficiency. Therefore, we use the multi-rode trans-bi-orthogonal modulation with trans-code for high bandwidth efficiency. Moreover, redundant bits are used for constant-amplitude-coding. Finally, we compare the performance of the proposed scheme with the orthogonal modulation and constant-amplitude multi-code trans-orthogonal modulation by using the computer simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.1045-1046
• /
• 2013

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.3
• /
• pp.522-527
• /
• 2007

In this paper, we propose an error control coding scheme for constant-amplitude multicode-biorthogonal modulation. The product code is appropriate to the constant-amplitude multicode-biorthogonal modulation for the bit error rate performance improvement. In the constant-amplitude multicode-biorthogonal modulation, the vertical redundant bits are used for the constant amplitude coding. The proposed product code can be constructed by using the additional horizontal redundant bits. The hardware complexity of the encoder/decoder pair is very low. The simulation results show that the bit error rate performance of the proposed coding scheme is improve