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Design and development of a high-and-low-altitude air observation system for rainmaking process in Thailand
(2019-06-01)
Chodkaveekityada, P.
;
Wardkein, P.
Thailand has been known as a top agricultural exporter in the world. But in every year, we miss a lot of opportunities to export some agricultural products due to drought condition. In the years 2017 and 2018, the areas in risk of a drought crisis were 47 areas throughout the whole country amounting to around 1.5 million acres. There was not enough water to grow plants in these areas. As a matter of fact, Thailand is located near the equator which has more cumulative rainfall volume than any other areas in the world. Still, drought crisis happens every year. One of the reasons behind this may be lack of valid predictive information. Weather information is very important for an agricultural country. Thailand has not invested sufficiently in building an effective weather sensor network. A compromise has been made by employing high technology to produce rain in specific areas instead to alleviate drought crisis. This work was a design and development of a high-and-low-altitude air observation system suitable for rainmaking process in Thailand that aimed to reduce the import of advanced and expensive technology.
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Enhanced mathematical model for studying fundamental behaviors of injection locked relaxation oscillator
(2015-01-01)
Kitipongwatana, A.
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Koseeyaporn, P.
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Koseeyaporn, J.
;
Wardkein, P.
This article proposes the analytical model for studying behaviors of injection locked relaxation oscillator (ILRO). The proposed model enhanced from N. Soltani's model can be used to demonstrate behaviors of the ILRO in case the input frequency is higher than the natural frequency, namely, necessarily physical conditions for locking, locked ranges, detuning behaviors and frequency division. The proposed model is verified by simulation results of the ILRO based on 0.35um-CMOS technology of TSMC.
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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.
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Punchalard, R.
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Wardkein, P.
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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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Heart detection and diagnosis based on ECG and EPCG relationships
(2011-08-26)
Phanphaisarn, W.
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Roeksabutr, A.
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Wardkein, P.
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Koseeyaporn, J.
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Yupapin, PP
A new design of a system for preliminary detection of defective hearts is proposed which is composed of two subsystems, in which one is based on the relationship between the electrocardiogram (ECG) and phonocardiogram (PCG) signals. The relationship between both signals is determined as an impulse response (h(n)) of a system, where the decision is made based on the linear predictive coding coefficients of a heart's impulse response. The other subsystem uses a phase space approach, in which the mean squared error between the distance vectors of the phase space of the normal heart and abnormal heart is judged by the likelihood ratio test (Λ) value, on which the decision is made. The advantage of the proposed system is that a heart's diagnosis system based on the ECG and EPCG signals can lead to high performance heart diagnostics. © 2011 Phanphaisarn et al, publisher and licensee Dove Medical Press Ltd.
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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.
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Punchalard, R.
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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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A four-quadrant multiplier based on CCII+s
(2010-07-30)
Narksarp, W.
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Pawarangkoon, P.
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Buakaew, S.
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Kiranon, W.
;
Wardkein, P.
This paper presents an analog multiplier based on non-inverting (positive type) second generation current conveyor (CCII+). The proposed circuit can perform as a four-quadrant multiplier. The circuit employs only two positive type second generation current conveyors and two n-channel JFET transistors. The circuit does not require any external passive circuit elements. Simulation results are included to confirm the capability of the circuit with the theory. Moreover, applications of the squarer, frequency doubler and amplitude modulator are demonstrated.
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First order complex adaptive FIR notch filter
(2010-07-30)
Punchalard, R.
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Silaphan, V.
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Koseeyaporn, J.
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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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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.
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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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Statistical performance of the direct frequency estimation algorithm for the adaptive FIR notch filter
(2010-07-30)
Silaphan, V.
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Punchalard, R.
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Loetwassana, W.
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Koseeyaporn, J.
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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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