• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.674-681
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• 2006

In this paper, a new receiver with low complexity for a DS-UWB system which can eliminate efficiently the multiple access interference and the detrimental effects caused by multi-paths is proposed. The performance of conventional DS-UWB receivers depends greatly on the types and lengths of spreading codes. Generally, as the length of spreading codes increases, the receiver performance improves. But, the receiver performance does not improve satisfactorily in a multi-paths fading environment. Through computer simulations, it can be shown that the proposed DS-UWB receiver eliminate the multi-paths effects efficiently in a multi-user, multi-paths fading environment, and the user capacity can be increased dramatically using the proposed receiver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1501-1509
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• 2001

Recently, the use of wireless communication systems has been rapidly increasing, which results in a difficult problem in efficient control of limited frequency resources. As a way of solving this problem, the ultra wideband time hopping impulse radio system attracts much attention. The impulse radio system communicates pulse position modulated data using Gaussian monocycle pulses of very short duration less than 1 nsec. Thus the transmitted signal has very low power spectral density and ultra wide bandwidth from near D.C. to a few GHz. It is blown that it hardly interferes with the existing communication systems because of its very low power spectral density. The purpose of this paper is to characterize multipath propagation of the impulse radio signal and to evaluate the performance of the correlator-based receiver for the multipath environments. In this paper, we consider the deterministic two-path model and the statistical indoor multipath model of Saleh and Valenzuela. For the two-path model the output of the correlator with the ideal reference waveform varies according to the relative difference between the indirect path delay and the time interval of PPM, and to the indirect path gains. In addition, the characteristics of bit error rates is measured for the two models through computer simulation. The simulation results indicate that the performance of the impulse radio system depends both on the relative difference between the indirect path delay and the time interval of PPM, and on the indirect path gains. Furthermore, it is observed that the reference signal designed for the AWGN channel can not be applied to the multipath channels.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.78-84
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• 2012

In this paper, we introduced the design technique about a Ka band receive module for millimeter wave seekers. The receiver module consists of a waveguide, circulator and transition for antenna connection, and a limiter and gain control amplifier for receiver protection. This module is comprised of a sum, azimuth and elevation channel for receiving monopules signal, and a SLB channel for the acquisition of jamming signal. In this paper, receiver gain and range of gain control dependent on ADC nonlinear characteristic was analyzed and designed for wide dynamic range receive. In the test result of the fabricated Ka-band receive, the frequency band is 1 GHz, the noise figure is as low as 8.2 dB, the gain is $56{\pm}2dB$, the dynamic range is 135 dB, the gain congtrol is more than 86 dB, the channel isolation is more than 35 dB.