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Simple and accurate frequency to voltage converter
(2010-07-30)
Lorsawatsiri, A.
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Kiranon, W.
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Silaruam, V.
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Sangpisit, W.
;
Wardkein, P.
A new technique has been developed for frequency to voltage converter. This technique, based on a very simple operating principle, comprises a differentiator, two RMS-DC converters, and a divider. The proposed converter provides an accurate output and a linear transfer characteristic. Moreover, its output response has input-amplitude independent characteristic. The performance of this converter is evaluated by computer simulation. The simulation results are in good accordance with the theoretical analyses.
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Adaptive IIR notch filters based on new error criteria
(2008-03-01)
Punchalard, R.
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Lorsawatsiri, A.
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Koseeyaporn, J.
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Wardkein, P.
;
Roeksabutr, A.
Modified indirect and direct plain gradient (MIPG and MDPG) algorithms using new error criteria for second-order adaptive IIR (infinite-impulse response) notch filters (ANFs) with constrained poles and zeros are proposed in this paper. The proposed techniques are based on modifying error functions of the standard indirect and direct ANFs. In this work, the proposed error criteria are modified as the mean value of the product of the two signals which are, respectively, produced by the FIR (finite-impulse response) and IIR sections of the ANFs. Due to a non-zero slope straight line-like characteristic of the new cost functions, the gradient based adaptive algorithm rapidly converges to an optimum solution resulting in faster convergence speed than that of the conventional method. The closed form expressions for steady-state estimation bias and mean square error (MSE) of the proposed algorithms are also carried out. In addition, extensive simulations of the proposed algorithms compared to other methods are provided to support the theoretical analyses. Although, there are some limitations in the proposed algorithms, however, the demonstrated results obtained from tested algorithms at the same condition confirm that the proposed MIPG and MDPG algorithms are superior to others in convergent speed. © 2007 Elsevier B.V. All rights reserved.
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Direct frequency estimation based adaptive algorithm for a second-order adaptive FIR notch filter
(2008-02-01)
Punchalard, R.
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Lorsawatsiri, A.
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Loetwassana, W.
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Koseeyaporn, J.
;
Wardkein, P.
This work deals with the problem of the frequency estimation of a sinusoidal signal corrupted by broad-band noise. The direct frequency estimation based adaptive algorithm for a second-order adaptive finite impulse response (FIR) notch filter (AFNF) is thus proposed. The proposed algorithm employs the bias removal technique to remove the bias existing in the estimated parameter. The performances including the rate of convergence and the mean square error (MSE) can be easily controlled by using only one parameter, i.e., step size parameter. Moreover, the proposed filter is simple to implement and suitable for real-time applications. In addition, the difference equations for the convergence in the mean and mean square, and the closed form expressions for the steady-state estimation bias and MSE are also carried out. Finally, the simulation results are provided to confirm the theoretical analysis. © 2007 Elsevier B.V. All rights reserved.
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Unbiased equation error adaptive IIR notch filter
(2007-12-01)
Punchalard, R.
;
Lorsawatsiri, A.
;
Loetwassana, W.
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Koseeyaporn, J.
;
Wardkein, P.
This paper presents the unbiased gradient algorithm for the equation error adaptive IIR notch filter (UEANF). The proposed algorithm employs the bias removal technique to remove the bias existing in the estimated parameter, resulting in obtaining good estimate of the parameter. Moreover, the convergence property is improved as compared with the conventional adaptive IIR notch filter (ANF). The computer simulations are provided to confirm the performances of the proposed technique. ©2007 IEEE.
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Unbiased plain gradient algorithm for adaptive IIR notch filter with constrained poles and zeros
(2007-12-01)
Punchalard, R.
;
Lorsawatsiri, A.
;
Loetwassana, W.
;
Koseeyaporn, J.
;
Wardkein, P.
An unbiased plain gradient (UPG) algorithm for a constrained adaptive IIR notch filter (ANF) is presented in this paper. The proposed algorithm employs the bias removal technique to remove the bias existing in the estimate of the filter parameter, resulting in good estimation. The computer simulation results have shown that the proposed technique is unbiased. ©2007 IEEE.
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Steady-state analysis of an unbiased equation error adaptive IIR notch filter
(2007-12-01)
Punchalard, R.
;
Lorsawatsiri, A.
;
Loetwassana, W.
;
Koseeyaporn, J.
;
Wardkein, P.
This paper presents the steady-state analysis of the unbiased equation error adaptive IIR notch filter (UEANF). The difference equation for the convergence in the mean and the steady-state estimation bias is derived in closed forms. In addition, the simulation results are provided to confirm the theoretical analysis. Finally, the comparisons among the UEANF, the equation error adaptive IIR notch filter (EANF) and the output error adaptive IIR notch filter (ANF) based on theory as well as simulations have shown that the UEANF outperforms the ANF in its convergence rate and it provides unbiased estimate of the desired parameter as compared with the EANF and the ANF as well. ©2007 IEEE.
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Adaptive howling suppressor in an audio amplifier system
(2007-12-01)
Loetwassana, W.
;
Punchalard, R.
;
Lorsawatsiri, A.
;
Koseeyaporn, J.
;
Wardkein, P.
The acoustic feedback causes a howling phenomenon in an audio amplifier system. This problem does not only annoy hearing but also can damage an amplifier system. The IIR adaptive howling suppressor (AHS) in an audio amplifier system is thus proposed in this paper. The algorithm of adaptive process is achieved by using the variable momentum least mean square (VMLMS). With this algorithm, the performance improvement and higher convergence rate can be success. The proposed AHS, which is placed between a preamplifier section and a power amplifier section, acts as a narrow bandwidth notch filter whose frequency characteristic can reduce a howling spectrum. The simulation results show good improvement in the howling suppression of the proposed AHS system. Moreover, the performance comparisons show that the proposed system is performed over the AHS conventional FIR and FALE structures at the same environment condition. ©2007 IEEE.
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Unbiased constrained adaptive IIR notch filter using direct frequency estimation algorithm
(2007-12-01)
Punchalard, R.
;
Lorsawatsiri, A.
;
Loetwassana, W.
;
Koseeyaporn, J.
;
Wardkein, P.
An unbiased constrained direct adaptive IIR notch filter is presented in this paper. The proposed algorithm employs the bias removal technique to remove the bias existing in the estimate of the filter parameter, resulting in good estimate of filter parameter. The theoretical analysis for the difference equation for the convergence in the mean is derived in closed form and confirmed by the computer simulations. ©2007 IEEE.

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