• Title/Summary/Keyword: 다중 밴드

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A Study on Performance Prediction Methods for Multi-Band Underwater Communication (수중 통신에서 다중 밴드 성능 예측 기법 연구 )

  • Ji-Won Jung
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.16 no.2
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    • pp.61-68
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    • 2023
  • Multi-band method which allocate the same data to different frequency bands, improves performance by compensating Doppler spreading and selective fading in underwater communications. The drawback of multi-band configuration may have worse performance because performance degradation in a particular band affects the output from the entire bands. It is very important to find which band is superior or inferior band in order to improve performance. Therefore this paper analyzes performance prediction algorithms of each band. This paper proposes three kinds of prediction methods. Through the ocean tests, this paper confirms utilizing the preamble error rates is most efficient algorithm among of them.

Features Extraction of Remote Sensed Multispectral Image Data Using Rough Sets Theory (Rough 집합 이론을 이용한 원격 탐사 다중 분광 이미지 데이터의 특징 추출)

  • 원성현;정환묵
    • Journal of the Korean Institute of Intelligent Systems
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    • v.8 no.3
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    • pp.16-25
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    • 1998
  • In this paper, we propose features extraction method using Rough sets theory for efficient data classifications in hyperspectral environment. First, analyze the properties of multispectral image data, then select the most efficient bands using discemibility of Rough sets theory based on analysis results. The proposed method is applied Landsat TM image data, from this, we verify the equivalence of traditional bands selection method by band features and bands selection method using Rough sets theory that pmposed in this paper. Finally, we present theoretical basis to features extraction in hyperspectral environment.

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Performance analysis and experiment results of multiband FSK signal based on direct sequence spread spectrum method (직접 수열 확산 방식 기반 다중 밴드 FSK 신호의 성능 분석 및 실험 결과)

  • Jeong, Hyun-Woo;Shin, Ji-Eun;Jung, Ji-Won
    • The Journal of the Acoustical Society of Korea
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    • v.40 no.4
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    • pp.370-381
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    • 2021
  • This paper presented an efficient transceiver structure of multiband Frequency Shift Keying (FSK) signals with direct sequence spread spectrum for maintaining covertness and performance. In aspect to covertness, direct sequence spread spectrum method, which multiplying by Pseudo Noise (PN) codes whose rate is much higher than that of data sequence, is employed. In aspect to performance, in order to overcome performance degradation caused by multipath and Doppler spreading, we applied multiband, turbo equalization, and weighting algorithm are applied. Based on the simulation results, by applying 4 number of multiband and number of chips are 8 and 32, experiments were conducted in a lake with a distance of moving from 300 m to 500 m between the transceivers. we confirmed that the performance was improved as the number of bands and chips are increased. Furthermore, the performance of multiband was improved when the proposed weighting algorithm was applied.

Vegetation Change Detection using Change Vector Analysis (CVA 변화탐지 기법을 이용한 식생 변화 탐지)

  • 김혜진;김선수;김용일
    • Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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    • 2004.03a
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    • pp.295-300
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    • 2004
  • 변화탐지를 위하여 기존에 사용하던 화소차 혹은 화소비 변화탐지 기법은 단밴드의 영상을 사용하므로 다중분광 자료를 활용하기 어렵고 변화지역의 유형을 추출하는데 적절하지 못하다는 단점이 있다. 후분류 변화탐지 기법은 다중분팡 영상의 활용이 가능하고 변화지역의 변화 유형을 파악할 수 있지만 변화탐지 성과가 분류 결과의 정확도에 의해 크게 영향을 받는다. 이에 반해 CVA(Change Vector Analysis) 변화탐지는 여러 밴드의 다중분광 영상을 이용하여 변화지역을 탐지할 뿐 아니라 피복 변화의 경향을 파악할 수 있어 보다 효율적인 기법으로 평가받고 있다. 기본적인 CVA 변화탐지는 일반적으로 다중분광 영상의 red 밴드와 infrared 밴드의 영상을 조합하여 변화탐지를 수행하여 식생 및 인공물의 변화를 탐지한다. 본 연구에서는 단순한 red/NIR 밴드간의 조합 외에 식생의 특성을 계수로 변환하는 PDA(Pattern Decomposition Analysis) 변환 및 Tasseled Cap 변환 결과를 이용한 CVA 변화탐지를 수행하고 각 결과의 정확도를 비교하여 보다 효율적인 식생 변화탐지 기법을 제안하고자 하였다.

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A study on weighting algorithm of multi-band transmission method using an estimated BER (추정 BER을 이용한 다중 밴드 전송 기법의 가중치 알고리즘 연구)

  • Shin, Ji-Eun;Jeong, Hyun-Woo;Jung, Ji-Won
    • The Journal of the Acoustical Society of Korea
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    • v.40 no.4
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    • pp.359-369
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    • 2021
  • In underwater communications, to compensate performance degradation induced from rapidly changing channel transfer characteristic, multi-band communication method which allocate the same data to different frequency bands is used. However, the multi-band configuration may have worse performance than the single-band one because performance degradation in a particular band affects the output from the entire bands. This problem can be solved through a receiving end that analyzes error rates of each band, sets threshold values and allocates lower weights to inferior bands. Therefore, this paper proposed a weighting algorithm based on estimated Bit Error Rate (BER) which analyzes reliability of received data based on the performance difference between demodulated and decoded data. Employing turbo codes with coding rate of 1/3, we evaluate the performance of the proposed weighted multi-band transmission model in real underwater environments based on optimal simulation parameters. Through the sea trial experiment, we confirmed error performance was improved by applying the proposed weighting algorithm.

Feature Selection for Image Classification of Hyperion Data (Hyperion 영상의 분류를 위한 밴드 추출)

  • 한동엽;김혜진;김대성;조영욱;김용일
    • Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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    • 2003.04a
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    • pp.94-99
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    • 2003
  • 다중분광 영상의 정확한 지형지물 분류를 수행하기 위하여 분류 클래스의 훈련지역 선정과 선정된 클래스의 분리도 분포가 중요하다. 최근에 이용되고 있는 위성탑재 초다중분광 영상은 많은 밴드를 포함하고 있기 때문에 데이터 처리가 어렵고, 노이즈로 인하여 다중분광 영상보다 분류 결과가 나쁜 경우도 나타난다. 특히 대상지역의 클래스에 따른 훈련지역의 선정시 밴드수에 비해 상대적으로 제한된 훈련화소 크기로 인하여 공분산 행렬의 계산에 어려움이 따른다. 따라서 본 연구에서는 Hyperion 데이터를 이용한 분류를 수행하기 위하여 필요한 유효 밴드 추출 방식을 알아보고, 분류영상의 정확도 평가를 통하여 추출된 밴드와 분류 클래스의 적합성 관계를 확인하고자 한다 이 과정에서 클래스 분리도를 이용하여 정확도 평가 이전에 밴드와 클래스 선정의 타당성을 확인할 수 있다.

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A Study on Multiband FTN Method for Improving Throughput Efficiency (전송 효율 향상을 위한 다중 밴드 FTN 기법 연구)

  • Seo, Jung-Hyun;Baek, Chang-Uk;Jung, Ji-Won
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.11 no.3
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    • pp.235-240
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    • 2018
  • FTN method which transmits signals faster the Nyquist rate is representative method for improving throughput efficiency sacrificed performance due to inter-symbol interference. To compensate performance loss, in this paper, we propose a multiband FTN method which split the coded bits into several bands and transmits signals applying FTN method. As coded bits are being assigned different bands, number of samples per bit of each band is increased, it induced performance improvement by noise averaging effect. In the simulations, compared the performance of single band FTN method and multiband FTN method when the interference rate is 25%. The results of simulation show the performance of proposed method is better than that of single band FTN one by 0.3dB~0.5dB.

Performance Analysis of Multiband Transmission Technique in Underwater Acoustic Communication (수중 음향 통신에서 다중 밴드 전송 기법의 성능 분석)

  • Lee, Hui-Su;Baek, Chang-Uk;Do, Dae-Won;Jung, Ji-Won
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.11 no.3
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    • pp.253-258
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    • 2018
  • The multiband communication technique is effective in terms of performance and throughput efficiency because it can overcome selective frequency fading by allocating the same data to different frequency bands in the environment of rapidly changing channel transfer characteristic. In addition, the transmission distance can be further extended while overcoming various underwater channel environments. In this paper, we analyzed the performance of multiband transmission technique in underwater communication by increasing number of band using Turbo pi code with a coding rate of 1/3. Simulation results shows that the performance is improved when the number of bands is increased based on the received SNR.

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.

Spatio-spectral Fusion of Multi-sensor Satellite Images Based on Area-to-point Regression Kriging: An Experiment on the Generation of High Spatial Resolution Red-edge and Short-wave Infrared Bands (영역-점 회귀 크리깅 기반 다중센서 위성영상의 공간-분광 융합: 고해상도 적색 경계 및 단파 적외선 밴드 생성 실험)

  • Park, Soyeon;Kang, Sol A;Park, No-Wook
    • Korean Journal of Remote Sensing
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    • v.38 no.5_1
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    • pp.523-533
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    • 2022
  • This paper presents a two-stage spatio-spectral fusion method (2SSFM) based on area-to-point regression kriging (ATPRK) to enhance spatial and spectral resolutions using multi-sensor satellite images with complementary spatial and spectral resolutions. 2SSFM combines ATPRK and random forest regression to predict spectral bands at high spatial resolution from multi-sensor satellite images. In the first stage, ATPRK-based spatial down scaling is performed to reduce the differences in spatial resolution between multi-sensor satellite images. In the second stage, regression modeling using random forest is then applied to quantify the relationship of spectral bands between multi-sensor satellite images. The prediction performance of 2SSFM was evaluated through a case study of the generation of red-edge and short-wave infrared bands. The red-edge and short-wave infrared bands of PlanetScope images were predicted from Sentinel-2 images using 2SSFM. From the case study, 2SSFM could generate red-edge and short-wave infrared bands with improved spatial resolution and similar spectral patterns to the actual spectral bands, which confirms the feasibility of 2SSFM for the generation of spectral bands not provided in high spatial resolution satellite images. Thus, 2SSFM can be applied to generate various spectral indices using the predicted spectral bands that are actually unavailable but effective for environmental monitoring.