• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.293-296
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• 2004

This paper proposes an architecture of channel estimation for multi-band OFDM UWB systems presented to IEEE 802.15.3a by Multi-band OFDM alliance(MBOA). The multi-band OFDM (MB-OFDM) systems should have channel estimation for compensation of signal distortion by multi-band channel. The moving-averaging estimation algorithm and multi-band equalization architecture for MB-OFDM UWB systems proposed in this paper was verified by the simulation. Simulation results show that MB-OFDM system with the proposed architecture have the performance improved by about 3.4 dB compared to system with no channel estimation in 0.1$\pi$ phase-rotated channel.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.83-92
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• 2001

In this paper, the monopulse channel receiver which can be matched between channels through a wide bandwidth has been proposed. The effects of the gain and phase imbalance between channels on the slope of monopulse error signal were analyzed. Also, the matching method between channels in a wide bandwidth was proposed, by which monopulse slope could be stabilized. Using the implemented monopulse radar system the monopulse slope was measured in the anechoic chamber which include the moving horn antenna and the target signal generator. The results show that the wide band matching method is useful and applicable to various channel receivers

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.514-514
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• 2000

In this article, the realization of a precision full-wave rectifier circuit for analog signal processing, which operates throughout in the current domain, is presented. The circuit makes use of a MOS class B/AB configuration, and provides a wide dynamic range and wide-band capability. The rectifier has a simple circuit configuration and is suitable for implementing in CMOS integrated circuit form as versatile building block. The characteristic of the circuit exhibits a low distortion en the output signal at low level input signal. PSPICE simulation results demonstrating the characteristic of the proposed circuit are included.

• Journal of electromagnetic engineering and science
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• v.7 no.4
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• pp.154-160
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• 2007

A reconfigurable multi-band mixer for the SDR system is proposed. The proposed reconfigurable mixer is operated between $850\;MHz{\sim}2\;GHz$, which includes all commercial mobile communication service. Because the varactor diodes are used to select a specific frequency and to adjust the impedance characteristic of the selected frequency band, the proposed reconfigurable mixer can be achieved to similar performance across all of the tuning range. In addition, the designed reconfigurable mixer is applicable for the SDR system since it has a single signal path for the multi-band signals and wide band tuning range.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.256-258
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• 1999

In this article, an integrable circuit technique for implementing square root extractor for analog signal processing is described. The realization method makes use of the characteristic of MOS translinear principle. The proposed scheme achieves a wide dynamic range, wide-band capability and high accuracy. Simulation results demonstrating the performance of the proposed scheme are also presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5C
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• pp.540-547
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• 2009

In this paper, we propose a transceiver structure that can effectively improve BER(Bit Error Rate) performance for TR-UWB (Transmitted Reference Ultra Wide Band) systems based on impulse radio. Unlike coherent UWB systems that are too complex for practical implementation while having good BER performances, the complexity of the TR-UWB systems is quite low since they transmit data with the corresponding reference signals and demodulate the data through correlation using these received signals. However, the BER performance in the conventional TR-UWB systems is affected by SNR (Signal-to-Noise Ratio) of the reference templates used in the correlator. To this end, we propose a receiver structure that can effectively improve the BER performance by increasing the SNR of reference templates. Simulation results reveal that the proposed scheme achieves significant BER improvement as compared to the conventional TR-UWB systems.

• Journal of Astronomy and Space Sciences
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• v.19 no.4
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• pp.327-340
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• 2002

In this paper, we performed the design study of a wide-band digital autocorrelation spectrometer for the observation study of an extra-galaxy's spectral lines and the survey research of the special radio sources in field of the radio astronomy observational research. The autocorrelation spectrometer designed in this paper can be used to their spectrometer of any system because this spectrometer has a wide dynamic power and frequency range properties. In this system we use the aliasing sampling method to minimize the band loss. For the output signal of the correlator we can increase the signal processing speed using by a special DSP chip, the integration and the FFT using hardware, so this spectrometer can support the newest developed technique for the radio astronomy observation so called “On the fly” method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10C
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• pp.965-975
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• 2005

In this paper, we propose and evaluate joint carrier and sampling frequency offset estimation schemes based on the channel estimation sequences in PLCP (Physical Layer Convergence Procedure) preamble for the proper and effcient synchronization of the MB-OFDM WB (Multi-Band Orthogonal Frequency Division Multiplexing Ultra Wide Band) systems which have recently drawn explosive attention for future W-PAN (Wireless Personal Area Network) applications. In the joint estimation schemes, we first estimate the sampling frequency offset, and then estimate the carrier frequency offset using the estimated sampling frequency offset. Moreover, to improve the reliability of the estimated offset values, each process uses a combination scheme based on weighting factors. Simulation results using IEEE 802.15 Task Group 3a UWB channel models reveal that the estimation scheme using the simple weighting factors based on easily-measurable received signal power of each sub-channel shows favorably comparable performance to the ideal scheme using the weighting factors based on the perfectly-estimated frequency response of the channel.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.285-288
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• 2008

In ubiquitous computing environment the biological signal ECG (Electrocardiogram signal) is usually recorded with noise components. Adaptive interference (or noise) canceller do adaptive filtering of the noise reference input to maximally match and subtract out noise or interference from the primary (signal plus noise) input thereby adaptively eliminate unwanted interference from the ECG signal. Measured Stress ECG (or exercise ECG signal) signal have three major noisy component like baseline wander noise, motion artifact noise and EMG (Electro-mayo-cardiogram) noise. These noises are not only distorted signal but also root of incorrect diagnosis while ECG data are analyzed. Motion artifact and EMG noises behave like wide band spectrum signals, and they considerably do overlapping with the ECG spectrum. Here the multidimensional adaptive method used for filtering which is more effective to improve signal to noise ratio.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.553-563
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• 2010

This paper presents a tapered slot-antenna(TSA) for optimal impulse-signal transmission in ultra-wide band(UWB). The proposed TSA provides radiates in end-fire direction, which meets an impulse-radio UWB(IR-UWB) system demands(e.g., low loss, thus less error throughout the UWB band). In order to minimize the pulse distortion, we used an wideband impedance transformer and a microstrip slotline. The pulse fidelity characteristics was evaluated with finite-difference time-domain(FDTD) analysis technique and pulse fidelity correlation equation. Approximately 93.89 % pulse fidelity was obtained between the two antennas in 0.5 m range. Additionally, derived chirp Z-transform algorithm enables us to utilize the zoom-in option on the pulse signal in few nano-seconds below. Thus, it is possible to analyze the pulse signal distortion, delay or dispersion characteristics.