• Title/Summary/Keyword: Feedback Signal

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Interference Cancellation System to Prevent the Oscillation of the Wireless Communication System using the Same Frequency (동일 주파수 무선통신 시스템의 발진방지를 위한 간섭잡음제거기)

  • 김선진;김남영
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.3
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    • pp.253-262
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    • 2003
  • In this paper, the interference cancellation system, which is used to cancel the feedback signal in the wireless communication system with the same frequency, is studied. The time varying feedback signal generated from transmitter antenna to receiver antenna reduces the performance of the receiver system. the interference cancellation system using adaptive feedback method(AF-ICS) is suggested to prevent the oscillation of the receiver system and maintain the maximum output power of the power amplifier by the reduction of time-varying feedback signal and also this paper conforms that the oscillation disappears from the output signal by cancellation of the feedback signal and the total output power is satisfied the system specification.

Feedback Interference Cancellation System of RF Relay Utilizing the LMS Algorithm (LMS 알고리즘을 이용한 RF 중계기의 궤환 간섭신호 제거 시스템(Interference Cancellation System))

  • Kim, Min-Soo;Ahn, Sung-Soo
    • 전자공학회논문지 IE
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    • v.45 no.1
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    • pp.38-43
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    • 2008
  • This paper presents a new interference cancellation method to remove the oscillation due to feedback signal of RF relay. In this paper, we estimate the feedback signal using to LMS(Least Mean Square) algorithm and remove the interference through attenuation signal arbitrary corresponding to feedback signal. From the various performance analysis for various doppler effects, a proposed method prevents from oscillation using -30dB attenuation signal as a cancellation value of feedback signal.

Implementation of Auto-tuning Positive Position Feedback Controller Using DSP Chip and Microcontroller (디지털신호처리 칩과 마이크로 컨트롤러를 이용한 자동 조정 양변위 되먹임 제어기의 구현)

  • Kwak, Moon K.;Kim, Ki-Young;Bang, Se-Yoon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.8 s.101
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    • pp.954-961
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    • 2005
  • This paper is concerned with the implementation of auto-tuning positive position feedback controller using a digital signal processor and microcontroller. The main advantage of the positive position feedback controller is that it can control a natural mode of interest by tuning the filter frequency of the positive position feedback controller to the natural frequency of the target mode. However, the positive position feedback controller loses its advantage when mistuned. In this paper, the fast fourier transform algorithm is implemented on the microcontroller whereas the positive position feedback controller is implemented on the digital signal processor. After calculating the frequency which affects the vibrations of structure most, the result is transferred to the digital signal processor. The digital signal processor updates the information on the frequency to be controlled so that it can cope with both internal and external changes. The proposed scheme was installed and tested using a beam equipped with piezoceramic sensor and actuator. The experimental results show that the auto-tuning positive position feedback controller proposed in this paper can suppress vibrations even when the target structure undergoes structural change thus validating the approach.

Implementation of Adaptive Positive Popsition Feedback Controller Using DSP chip and Microcontroller (디지털신호처리 칩과 마이크로 컨트롤러를 이용한 적응 양변위 되먹임 제어기의 구현)

  • Kwak, Moon-K.;Kim, Ki-Young;Bang, Se-Yoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.498-503
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    • 2005
  • This paper is concerned with the implementation of adaptive positive position feedback controller using a digital signal processor and microcontroller The main advantage of the positive position feedback controller is that it can control a natural mode of interest by tuning the filter frequency of the positive position feedback controller to the natural frequency of the target mode. However, the positive position feedback controller loses its advantage when mistuned. In this paper, the fast fourier transform algorithm is implemented on the microcontroller whereas the positive position feedback controller is implemented on the digital signal processor. After calculating the frequency which affects the vibrations of structure most the result is transferred to the digital signal processor. The digital signal processor updates the information on the frequency to be controlled so that it can cope with both internal and external changes. The proposed scheme was installed and tested using a beam equipped with piezoceramic sensor and actuator. The experimental results show that the adaptive positive position feedback controller proposed in this paper can suppress vibrations even when the target structure undergoes structural change thus validating the approach.

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A Study On the Feedforward Linear Power Amplifier Using Imperfect Signal Cancellation And Feedback (Imperfect Signal Cancellation과 Feedback을 이용한 Feedforward 선형전력증폭기에 관한 연구)

  • Park, Jung-Min;Yang, Seung-In
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2003.11a
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    • pp.87-90
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    • 2003
  • In this paper, A feedforward linear power amplifier is analyzed for imperfect signal cancellation and negative feedback for basestaion of IMT2000 band. the distortion generatied by the error amplifier is reduced using an imperfect signal cancellation for a 1-carrier WCDMA source by 4.3dB at 2.5MHz offset and 6dB at 5MHz offset of IMSR(intermodulation signal power ratio) compared to a perfect signal cancellation system. additionally, An imperfect signal cancellation using negative feedback improved 1.3dB and 8.2dB at 2.5MHz and 5MHz offset of IMSR compared to an imperfect signal cancellation.

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A Feedback and Noise Cancellation Algorithm of Hearing Aids Using Dual Microphones (이중 마이크를 사용한 보청기의 궤환 및 잡음제거 알고리즘)

  • Lee, Haeng-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.7C
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    • pp.413-420
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    • 2011
  • This paper proposes a new adaptive algorithm to cancel the acoustic feedback and noise signals in the binaural hearing aids. The convergence performances of the proposed algorithm are improved by updating coefficients of the feedback canceller after the speech signal is cancelled from the residual signal with dual microphones. The feedback canceller firstly cancels the feedback signal from the microphone signal, and then the noise canceller reduces the noise by the beamforming method. To assure that binaural hearing aids converge stably, the left-sided hearing aid only is converged firstly, next the right-sided hearing aid only is converged. To verify performances of the proposed algorithm, simulations were carried out for a speech. As the results of simulations, it was proved that we can advance 14.43dB SFR(Signal to Feedback Ratio) on the average for the feedback canceller, 10.19dB SNR(Signal to Noise Ratio) improvement on the average for the noise canceller, in case that this algorithm is used.

Interference Cancellation System using Adaptive Feedback Method (적응성 궤환방식을 이용한 간섭잡음제거기)

  • 김선진;이제영;이종철;김종헌;이병제;김남영
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.2
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    • pp.183-191
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    • 2003
  • In this paper, the interference cancellation system, which is used to cancel the feedback signal In the wireless communication system with the same frequency, is studied. The time-varying feedback signal generated from transmitter antenna to receiver antenna reduces the performance of the receiver system. The interference cancellation system using adaptive feedback method(AF-ICS) is suggested to prevent the oscillation of the receiver system and maintain the maximum output power of the power amplifier by the reduction of time-varying feedback signal.

Acoustic Feedback and Noise Cancellation of Hearing Aids by Deep Learning Algorithm (심층학습 알고리즘을 이용한 보청기의 음향궤환 및 잡음 제거)

  • Lee, Haeng-Woo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.14 no.6
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    • pp.1249-1256
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    • 2019
  • In this paper, we propose a new algorithm to remove acoustic feedback and noise in hearing aids. Instead of using the conventional FIR structure, this algorithm is a deep learning algorithm using neural network adaptive prediction filter to improve the feedback and noise reduction performance. The feedback canceller first removes the feedback signal from the microphone signal and then removes the noise using the Wiener filter technique. Noise elimination is to estimate the speech from the speech signal containing noise using the linear prediction model according to the periodicity of the speech signal. In order to ensure stable convergence of two adaptive systems in a loop, coefficient updates of the feedback canceller and noise canceller are separated and converged using the residual error signal generated after the cancellation. In order to verify the performance of the feedback and noise canceller proposed in this study, a simulation program was written and simulated. Experimental results show that the proposed deep learning algorithm improves the signal to feedback ratio(: SFR) of about 10 dB in the feedback canceller and the signal to noise ratio enhancement(: SNRE) of about 3 dB in the noise canceller than the conventional FIR structure.

A Study on Digital RF Repeaters with Interference Cancellation System

  • Han, Yong-Sik;Yang, Woon-Geun
    • Journal of information and communication convergence engineering
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    • v.8 no.2
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    • pp.150-154
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    • 2010
  • In this paper, the adaptive interference cancellation system (ICS) in order to cancel the feedback signal in the wireless communication system is proposed. We cancel the interference with the attenuation signal corresponding to the feedback signal and estimate the feedback signal by using Normalized Least Mean Square (NLMS) algorithm. The proposed scheme showed a better performance of interference cancellation in the measurement results.

A Study on 800 MHz 1W Cartesian Feedback Linearized Power Amplifier for TETRA Signals (TETRA 신호를 위한 800 MHz 대역 1W 급 Cartesian feedback 선형 전력 증폭기에 관한 연구)

  • Oh, Duk-Soo;Kim, Ji-Yeon;Chun, Sang-Hyun;Kim, Jong-Heon
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.7 no.4
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    • pp.76-85
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    • 2008
  • In this paper, a 800 MHz 1 W cartesian feedback linearized power amplifier is designed and fabricated for TETRA handset application. For amplification of TETRA signal with 200 kHz narrow bandwidth, amplifier linearization performance of more than 30 dBc is improved through the cartesian feedback linearizer at the offset Sequency of ${\pm}25$ kHz. It is clear that the linearization performance is affected by imbalance of gain and phase between I/Q signals and also DC offset. The linearization performance can be maximized by the compensation of those influences. Cartesian feedback is suitable for a liearization technique of narrow band signal with QAM and another modulation signals, as well.

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