1991 Fiscal Year Final Research Report Summary
Research on Spread-Spectrum Modulation and Demodulation System Using Real-Valued Orthogonal Pseudonoise Sequences
| Project/Area Number |
02650249
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
電子通信系統工学
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| Research Institution | Kagoshima University |
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Principal Investigator |
TANADA Yoshihiro Kagoshima Univ., Fac. of Eng., Professor, 工学部, 教授 (70033248)
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| Co-Investigator(Kenkyū-buntansha) |
YUNOKUCHI Kazutomo Kagoshima Univ., Fac. of Eng., Assistant, 工学部, 助手 (10094187)
NAGASAWA Yoji Kagoshima Univ., Fac. of Eng., Professor, 工学部, 教授 (80005313)
YOSHIDA Hiroshi Kagoshima Univ., Fac. of Eng., Professor, 工学部, 教授 (20037849)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Real-valued orthogonal pseudonoise sequence / Amplitude-modulated code / Pulse-width-modulated code / Spread-spectrum communication / Quasi-synchronous SSMA / Digital correlation processing / Process gain / Desired to undesired signal ratio |
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| Research Abstract |
This research has been performed from 1990 to 1991, for the purpose of developing spread-spectrum modulation and demodulation system using real-valued orthogonal pseudonoise sequences with the better crosscorrelation properties than those of M-sequences and of urging the practical application of this system to high-quality spread-spectrum communication system. The process from design to experiment has been investigated to be understandable for the engineers in this field.
It is shown that the synchronous or quasi-synchronous spread-spectrum transmission of the amplitude-modulated code and the pulse-width-modulated code enables multichannel interference suppressed to the low level according to theory. The experimental system adopts digital signal processing at a low frequency range, but a high-speed special processor will realize a practical system of high bit rate. The achievements of this project are the followings.
(1)Design of modulation and demodulation system
An amplitude-modulated c
… More
ode and a pulse-width-modulated code as well as correlation processing are designed so that multichannel interference does not occur in a synchronous or quasi-synchronous spread-spectrum multiple access. Effects of quantization error, additive noise and frequency band on correlator output are made clear through analysis and simulation.
(2)Construction of modulation and demodulation system
In the constructed system, the amplitude-modulated code or the pulse-width-modulated code due to the real-valued pseudonoise sequences of 256 length, passes through a band-pass transmission channel and is demodulated by a front- or back-end digital correlator based on the fast Fourier transform.
(3)Experiment for estimating modulation and demodulation system
When two different codes are multiplexed and demodulated along with additive noise, correlator output waveform, process gain, improvement ratio of desired to undesired signal ratio and bit error rate show the high performance of the values close to theory. Less
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