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Author: search.filters.author.Punchalard, R.

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    An Application of an Adaptive Signal Processing Scheme for a QPSK Signal Demodulation
    (2022-01-01)
    Inban, P.
    ;
    Punchalard, R.
    ;
    Loedwassana, W.
    ;
    Benjangkaprasert, C.
    An adaptive digital signal processing scheme applied for a digital communication has been presented in the press. The model of an ANC is utilized to demodulate in a coherent detection scheme for a received QPSK signal. The coefficients of the system will be updated by the least mean square (LMS) algorithm that is controlled in the adaptation sequence according to the symbol duration of the received signal. Since such a manner is performed, the system is similar to integrate and dump (I&D) correlator in behavior. The analysis and simulation results have implied that the desired information signal can be recovered from the received signal by the proposed scheme with the same performance as the conventional optimum demodulation.
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    An Improved RLS-based Interference Cancellation
    (2022-01-01)
    Inban, P.
    ;
    Punchalard, R.
    ;
    Benjangkaprasert, C.
    An improved algorithm for mitigating the effect of power line interference in electrocardiogram (ECG) recording systems is presented. The proposed algorithm includes an interference detector (ID), an interference fundamental frequency estimator (IFFE), and an interference estimator (IE). The ID is used to evaluate the existence of the interference before recording. If it is present, the IFFE and IE are employed in the next steps. In the absence of interference, the observed signal is directly sent to the recorder and monitor. The presence of the ID can improve the performance of the system in terms of computational efficiency and system speed. The IFFE can track the variation of the interference frequency. Extensive computer simulations were run to demonstrate the performance of the proposed system.
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    Direct-Lattice Adaptive Notch Filter for Frequency Estimation and Tracking
    (2022-01-01)
    Inban, P.
    ;
    Punchalard, R.
    ;
    Benjangkaprasert, C.
    This paper presents a direct-lattice adaptive notch filter (DLANF) for frequency estimation and tracking. The proposed filter is the cascade of an all-pole direct form structure filter with an all-zero lattice predictor. The normalized gradient algorithm is used to adjust the filter parameter. This technique outperforms some conventional adaptive filters in terms of convergence time and provides a small mean square error (MSE). Computer simulations are conducted to show the superiority of the proposed filter.
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    Linear prediction based adaptive algorithm for a complex sinusoidal frequency estimation
    (2013-06-01)
    Punchalard, R.
    ;
    Wardkein, P.
    The complex direct frequency estimation (CDFE) adaptive algorithm is developed and proposed in this paper. The motivation of this work is obtained from the previous real DFE (RDFE) adaptive algorithm. The methodology of the CDFE is based on the linear prediction property of complex sinusoidal signals. The proposed algorithm is unbiased and computationally efficient. Moreover, it is easy to implement and appropriate for real-time applications. In addition, the convergence behavior is analyzed and the steady-state mean square error (MSE) of the frequency estimate is derived in closed form. Computer simulations are treated to corroborate the theoretical analysis. © 2013 Published by Elsevier GmbH.
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    Novel algorithm for sinusoidal interference cancellation
    (2011-12-01)
    Nosan, A.
    ;
    Punchalard, R.
    ;
    Wardkein, P.
    ;
    Koseeyaporn, J.
    A simple and efficient method for canceling sinusoidal interference is presented in this paper. The interference of known frequency is modeled as a sum of unknown amplitude and zeros phase sine and cosine components. The amplitude of those components are sequentially estimated interms of Wiener-Hopf solutions using cumulative average system. Additionally, in order to avoid any look-up tables for generating the sine and cosine signals, the coupled-digital oscillator is employed instead. It has been demonstrated that the proposed method can efficiently and rapidly cancel sinusoidal interference as compared with the previous method. © 2011 IEEE.
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    Unbiased plain gradient algorithm for a second-order adaptive IIR notch filter with constrained poles and zeros
    (2010-08-01)
    Loetwassana, W.
    ;
    Punchalard, R.
    ;
    Koseeyaporn, J.
    ;
    Wardkein, P.
    This article proposes an unbiased plain gradient algorithm for a second-order adaptive IIR notch filter with constrained poles and zeros. The proposed algorithm employs removing a dominant parameter that produces inherent bias. By using this technique, the performances are improved with slight expense in computational complexity. In this paper, theoretical analysis for deriving the estimations of bias and mean square error (MSE) at steady state are presented in closed form. Moreover, the stability bound of the algorithm is also derived. To confirm the analytical results, the computer simulations are provided to corroborate the effectiveness of the proposed algorithm. Furthermore, the performances of the algorithm are also compared with the plain gradient (PG) and modified plain gradient (MPG) algorithms. © 2010 Elsevier B.V. All rights reserved.
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    First order complex adaptive FIR notch filter
    (2010-07-30)
    Punchalard, R.
    ;
    Silaphan, V.
    ;
    Koseeyaporn, J.
    ;
    Wardkein, P.
    This paper presents a first order complex adaptive finite impulse response (FIR) notch filter (FIR-ANF) to track and estimate the frequency of complex sinusoidal signal corrupted by Gaussian noise. This research also presents gradient based adaptive algorithm for adjusting the filter coefficient. Computer simulation results have shown that, as compared with the conventional first-order complex adaptive infinite impulse response (IIR) notch filter (IIR-ANF), the proposed technique has faster convergence time, especially, when the initial value of algorithm is far from the true solution.
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    Statistical performance of the direct frequency estimation algorithm for the adaptive FIR notch filter
    (2010-07-30)
    Silaphan, V.
    ;
    Punchalard, R.
    ;
    Loetwassana, W.
    ;
    Koseeyaporn, J.
    ;
    Wardkein, P.
    The Mean square error (MSE) of direct frequency estimation algorithm (DFE) for the adaptive FIR notch filter is presented in this paper. The developed analysis technique is capable of tracking the simulations very well in the steady state. The proposed method is based on the merging between the analysis technique for linear predictor and the second-order adaptive FIR notch filter. Computer simulations have been treated to corroborate with the theoretical analysis.
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    Novel digital FM demodulation
    (2009-12-01)
    Punchalard, R.
    ;
    Koseeyaporn, J.
    ;
    Wardkein, P.
    A very simple method to demodulate the digital frequency modulated (FM) signal is presented in this paper. A unit delay operator, multiplier, lowpass filter, arccosine function, and adder are employed. The proposed method is easily adjusted and controlled. The computer simulations are conducted to demonstrate the performance of the proposed technique. ©2009 IEEE.
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    Indirect frequency estimation based on second-order adaptive FIR notch filter
    (2009-07-01)
    Punchalard, R.
    ;
    Koseeyaporn, J.
    ;
    Wardkein, P.
    This paper deals with estimating the frequency of sinusoidal signal buried in broad band noise. The simple unbiased indirect frequency estimation (IFE) algorithm is proposed for a second-order adaptive finite impulse response (FIR) notch filter with constrained zeros. The technique of estimating input noise variance is employed to remove the bias existing in the estimated filter parameter. Also, the difference equation for the convergence of the expectation of the estimated parameter and the closed-form of steady state estimation mean square error (MSE) are derived. In addition, extensive simulations are conducted to corroborate the efficiency of the proposed estimator with the theoretical analysis. © 2009 Elsevier B.V. All rights reserved.