• Title/Summary/Keyword: 수중 전자기 신호

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New Sidelobe Canceller for 3-D Phased Array Radar in Strong Interference (강한 간섭 신호를 제거하기 위한 3차원 위상배열 레이다용 새로운 부엽제거기)

  • Cho, Myeong-Je;Han, Dogn-Seog;Jung, Jin-Won;Kim, Soo-Joong
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.10
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    • pp.144-155
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    • 1998
  • The array weights that will maximize the SNR for any type of noise environment are determined by the function of the antenna design configuration and the directions of receiving target and interference signals. The conventional SLCs(sidelobe cancellers) using the SNR maximization perform worst from the saturation of the receiving system of main channel when the main antenna has pattern with high gain at the arrival angle of strong interference. In this paper, the new SLC is accomplished by using two independent antenna architecture. Main antenna is implemented with adaptive nulling, which is used for rejecting high-power interference primarily. Auxiliary antenna is realized with adaptive array for receiving interference signal to be suppressed completely, which has a characteristics of sufficient gain for every direction. The new SLC is implemented with above both antennas. We show that the new SLC, which consists of the adaptive nulling main antenna and the adaptive array auxiliary antenna, is useful in reducing the effect of strong interference like jammer, because the adaptive nulling at main antenna prevents its receiver and signal processor for saturation by strong interference. The proposed SLC has improved SNR over the conventional SLCs. The improved SNR at sidelobe region is typically more than 7 dB for a given test signal. Moreover, it improves the SNR of about 20 dB under strong interference at mainlobe.

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Performance Analysis of Spread Spectrum Underwater Communication Method Based on Multiband (다중 밴드 기반 대역 확산 수중통신 기법 성능분석)

  • Shin, Ji-Eun;Jeong, Hyun-Woo;Jung, Ji-Won
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.13 no.5
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    • pp.344-352
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    • 2020
  • Covertness and performance are very important design goals in the underwater communications. To satisfy both of them, we proposed efficient underwater communication model which combined multiband and direct sequence spread spectrum method in order to improve performance and covertness simultaneously. Turbo coding method with 1/3 coding rates is used for channel coding algorithm, and turbo equalization method which iterately exchange probabilistic information between equalizer and decoder is used for receiver side. After optimal threshold value was set in Rake processing, this paper analyzed the performance by varying the number of chips were 8, 16, 32 and the number of bands were from 1 to 4. Through the simulation results, we confirmed that the performance improvement was obtained by increasing the number of bands and chips. 2~3 dB of performance gain was obtained when the number of chips were increased in same number of bands.

A Study on Underwater Electro-magnetic Signature Prediction Due to Hull Corrosion of a Naval Ship (함정의 선체 부식에 의한 수중 전자기 신호 예측에 관한 연구)

  • Chung, Hyun-Ju;Yang, Chang-Seob;Ju, Hae-Sun;Jeon, Jae-Jin
    • Journal of the Korea Institute of Military Science and Technology
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    • v.15 no.2
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    • pp.177-185
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    • 2012
  • Corrosion currents flow through the seawater due to the different electrochemical potential between a hull and a propeller under the draft line of ship. Additionally, in order to protect the hull and other sensitive anodic parts of the ship from corrosion, the corrosion protection system, called impressed current cathodic protection(ICCP) equipment has been installed in most naval ships. Those currents could be harmful to the electromagnetic silencing of the naval ship because sea mines are triggered by even a feeble field value. In this paper, we described electric and corrosion related magnetic fields by ship's galvanic corrosion and a corrosion protection system, and prediction results of electric and corrosion related magnetic fields at any depth for the model ship.

A Study on the Applicability of High Manganese Steel to Naval Ship Hulls (고망간강의 함정 선체 적용 가능성에 관한 연구)

  • Kwangho Shin
    • Journal of the Society of Naval Architects of Korea
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    • v.61 no.1
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    • pp.61-67
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    • 2024
  • A naval mine is an effective weapon system implemented for defending defends ports and seas. A mine is an underwater weapon that poses a great threat to ships sailing over the sea from shallow areas. Most of the influence-type naval mines detect magnetic field signals from ships and determine the final time of fire. Therefore, the level of underwater electro-magnetic signatures of ships is a key requirement for determining the survival of ships in wartime situations where mines are emplaced. The main reason why the high manganese steel is attracting attention for naval ship hulls is its nature as a non-magnetic steel. The non-magnetic hull does not generate electro-magnetic signatures; thus, it has the advantage improving the stealth of the ship. In this paper, I examine whether this material can be applied in the hulls material of naval ships that must be ableto reduce underwater electro-magnetic signatures by considering the non-magnetic characteristics of the first developed high manganese steel in the world.

New Frequency-domain GSC using the Modified-CFAR Algorithm (변형된 CFAR 알고리즘을 이용한 새로운 주파수영역 GSC)

  • Cho, Myeong-Je;Moon, Sung-Hoon;Han, Dong-Seog;Jung, Jin-Won;Kim, Soo-Joong
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.36S no.2
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    • pp.96-107
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    • 1999
  • The generalized sidelobe cancellers(GSC's) ar used for suppressing an interference in array radar. The frequency-domain GSC's have a faster convergence rate than the time-domain GSC's because they remove the correlation between the interferences using a frequency-domain least mean square(LMS) algorithm. However, we have not fully used the advantage of the frequency-domain GSC's since we have always updated the weights of all frequency bins, even the interferer free frequency bin. In this paper, we propose a new frequency-domain GSC based on constant false-alarm rate(CFAR) detector, of which GSC adaptively determine the bin whose weight is updated according to the power of each frequency bin. This canceller updates the weight of only updated according to the power of each frequency bin. This canceller updates the weight of only the bin of which the power is high because of the interference signal. The computer simulation shows that the new GSC reduces the iteration number for convergence over the conventional GSC's by more than 100 iterations. The signal-to-noise ration(SNR) improvement is more than 5 dB. Moreover, the number of renewal weights required for the adaptation is much fewer than that of the conventional one.

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