• Journal of Institute of Control, Robotics and Systems
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• v.20 no.8
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• pp.890-894
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• 2014

In this paper, we derive the CRLB (Cramer-Rao Lower Bound) of effective carrier-to-noise power ratio ($C/N_0$) estimation for a GPS (Global Positioning System) L1 C/A (Coarse/Acquisition) signal under band-limited white noise jamming environments. The quality of a received GPS signal is commonly described in terms of its $C/N_0$, implying that the noise is white and thus can be described by scalar noise density. However, if some intentional interference is received to a victim GPS receiver, then the $C/N_0$ is no longer the efficacious performance indicator. The correct and straightforward measurement to analyze the receiving situation is the effective $C/N_0$. In this paper, we consider a band-limited white noise jamming whose bandwidth is 2MHz and is the same as one of the first null-to-null bandwidth of the GPS L1 C/A signal.

• Journal of the Korea Society of Computer and Information
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• v.25 no.7
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• pp.1-8
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• 2020

In this paper, we present an implementation of high speed image data transfer using XDMA for a video signal generation / acquisition device developed as a military test equipment. The technology proposed in this study obtains efficiency by replacing the method of copying data using the system buffer in the kernel area with the transmission and reception through the DMA engine in the FPGA. For this study, the device was developed as a PXIe platform in consideration of life cycle, and performance was maximized by using a low-cost FPGA considering mass productivity. The video I/O board implemented in this paper was tested by changing the AXI interface clock frequency and link speed through the existing memory copy method. In addition, the board was constructed using the DMA engine of the FPGA, and as a result, it was confirmed that the transfer speed was increased from 5~8Hz to 140Hz. The proposed method will contribute to strengthening defense capability by reducing the cost of device development using the PXIe platform and increasing the technology level.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.121-131
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• 2015

Passive emitter localization is preferred to use a small number of receivers as possible for the efficiency of strategic management in the field of modern electronic warfare support. Accurate emitter localization can be expected when utilizing continuous measurable parameters and a appropriate combination of theirs. For this reason, we compare CRLB (Cramer-Rao lower bound) of two moving platform with various measurable parameters to choose a appropriate combination of parameters for a better localization performance. And we propose the passive emitter localization method based on Levenberg-Marquardt algorithm with combined TDOA/FDOA and DOA to achieve better accuracy of emitter localization which is located on the ground and stationary. In addition, we present a method for determining the initial emitter position for LM algorithm's input to avoid the divergence of estimation and local minimum.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.50-54
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• 2015

In this paper, we report on a high performance 94 GHz MMIC mixer module using 0.1-um metamorphic high electron mobility transistors (MHEMTs). A modified resistive mixer with a RF amplifier was proposed in this work for low conversion loss and high LO-RF isolation. The MMIC mixer module was fabricated using a MMIC chip and CPW-waveguide transitions. The fabricated mixer chip and module showed a low conversion loss of 6.3 dB and 9.5 dB, and LO-RF isolations of 24.8 and 30.4 dB at 94 GHz, respectively. This results are superior to those of previously W-band (75-110 GHz) MMIC mixers.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.48-53
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• 2008

In this paper, we developed the MMIC low noise amplifier using 100 nm metamorphic HEMTs technology in combination with coplanar circuit topology for 94 GHz applications. The $100nm\times60{\mu}m$ MHEMT devices for the MMIC LNA exhibited DC characteristics with a drain current density of 655 mA/mm, an extrinsic transconductance of 720 mS/mm. The current gain cutoff frequency $(f_T)$ and maximum oscillation frequency $(f_{max})$ were 195 GHz and 305 GHz, respectively. The realized MMIC LNA represented $S_{21}$ gain of 14.8 dB and noise figure of 4.6 dB at 94 GHz with an over-all chip size of $1.8mm\times1.48mm$.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.189-197
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• 2014

This work proposes a 12b 100 MS/s $0.11{\mu}m$ CMOS three-step hybrid pipeline ADC for high-speed communication and mobile display systems requiring high resolution, low power, and small size. The first stage based on time-interleaved dual-channel SAR ADCs properly handles the Nyquist-rate input without a dedicated SHA. An input sampling clock for each SAR ADC is synchronized to a reference clock to minimize a sampling-time mismatch between the channels. Only one residue amplifier is employed and shared in the proposed ADC for the first-stage SAR ADCs as well as the MDAC of back-end pipeline stages. The shared amplifier, in particular, reduces performance degradation caused by offset and gain mismatches between two channels of the SAR ADCs. Two separate reference voltages relieve a reference disturbance due to the different operating frequencies of the front-end SAR ADCs and the back-end pipeline stages. The prototype ADC in a $0.11{\mu}m$ CMOS shows the measured DNL and INL within 0.38 LSB and 1.21 LSB, respectively. The ADC occupies an active die area of $1.34mm^2$ and consumes 25.3 mW with a maximum SNDR and SFDR of 60.2 dB and 69.5 dB, respectively, at 1.1 V and 100 MS/s.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.64-72
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• 2013

Recently, stream cipher Rabbit was selected for the final eSTREAM portfolio organized by EU ECRYPT and as one of algorithm in part of ISO/IEC 18033-4 Stream Ciphers on ISO Security Standardization. However, a feasibility of practical power analysis attack to algorithm in experiment was introduced. Therefore, we propose appropriate methods such as random masking and hiding schemes to secure against power analysis attack on stream cipher Rabbit. We implement the proposed method with increment of 24% operating time and 12.3% memory requirements due to maintaining a high-speed performance. We use a 8-bit RISC AVR microprocessor (ATmegal128L chip) to implement our method for practical experiments, and verify that stream cipher Rabbit with our method is secure against power analysis attack.

• Journal of Korea Game Society
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• v.9 no.5
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• pp.117-125
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• 2009

In real-time strategy simulation (RTS) game each team is composed of agents and executes strategies to win other team. Strategy needs agents' cooperation in each team. This needs multi-agent system (MAS). Centralized decision making, one of decision making in MAS, selects actions not to agents but to team by a coordinated agent. Decentralized decision making costs high because each agent communicates with each other. In this paper we propose a system which controls agents by grouping and allocates roles through negotiation by a coordinated agent. Then, when one of allocated actions is not executed or failed, a coordinated agent allocates its role to another agent. We make experiments in starcraft, famous RTS game. When a proposed method is applied, the performance of attack and defense is increased. The improved agents' team wins eight times per ten games.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.5
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• pp.62-68
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• 2010

This study is to identify target locations with low false alarms on thermal infrared images obtained from natural environment. The proposed method is different from the previous researches because it uses morphology filters for Gabor response images instead of an intensity image in initial detection stage. This method does not need precise extracting a target silhouette to distinguish true targets or clutters. It comprises three distinct stages. First, morphological operations and adaptive thresholding are applied to the summation image of four Gabor responses of an input image to find out salient regions. The locations of extracted regions can be classified into targets or clutters. Second, local texture features are computed from salient regions of an input image. Finally, the local texture features are compared with the training data to distinguish between true targets and clutters. The multi-layer perceptron having three layers is used as a classifier. The performance of the proposed method is proved by using natural infrared images. Therefore it can be applied to real automatic target detection systems.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.7
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• pp.767-773
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• 2014

The carrier-to-noise power ratio is a key parameter for determining the reliability of PVT (Position, Velocity, and Time) solutions which are obtained by a GNSS (Global Navigation Satellite System) receiver. It is also used for locking a tracking loop, deciding the re-acquisition process, and processing advanced navigation in the receiver subsystem. The representative carrier-to-noise power ratio estimation schemes are the narrowband-wideband power ratio method (NW), the MM (Moment Method), and Beaulieu's method (BL). The NW scheme is the most classical one for commercial GNSS receivers. It is often used as an authoritative benchmark for assessing carrier-to-noise power estimation schemes. The MM scheme is the least biased solution among them, and the BL scheme is a simpler scheme than the MM scheme. This paper focuses on the less biased estimation with low complexity when the residual phase noise remains, then proposes a novel carrier-to-noise power ratio estimation scheme with low complexity for GNSS receivers. The asymptotic bias of the proposed scheme is derived and compared with others, and the simulation results demonstrate that the complexity of the proposed scheme is lowest among them, while the estimation performance of the proposed scheme is similar to those of the BL and MM schemes in normal and high gained reception environments.