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A Novel Multi-Slope Chirp Modulation and Demodulation with Instantaneous Chirp Rate Estimation
(2026-05-01)
Magkeethum, Apiwat
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Saechia, Sukkharak
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Wardkein, Paramote
The growth of Internet of Things (IoT) applications is driving demand for Low-Power Wide-Area Networks (LPWANs) to support higher data rates with the same energy efficiency. While Long Range (LoRa) provides excellent noise immunity and receiver sensitivity, its data rate might be insufficient for some applications, including those real-time applications in which LoRa is required to have infrequent transmissions to maintain low power consumption. In this paper, a novel modulation is introduced to address these limitations by utilizing narrowband chirp to represent a data symbol with chirp slopes, called a multi-slope chirp signal. At the receiver, a new blind non-coherent detection technique is also presented to recover the proposed signal. The simulation results confirm that the proposed scheme can successfully transmit information at 2 to 4 bits per symbol, and when compared to LoRa SF 6, it reduces the Time-on-Air (ToA) by half and also achieves an improvement in spectral efficiency in the frequency domain.
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Pwm and Differential Pwm Generation Circuits Based on Conventional Schmitt Trigger Cooperating with Integrator: Analysis and Implementation
(2025-01-01)
Saechia, Sukkharak
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Kaew-In, Chanapat
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Chatchaiphat, Nisukan
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Wardkein, Paramote
This paper presents systematic approaches to generate the Pulse Width Modulation (PWM) signal by leveraging a simple configuration based on an operational amplifier (op-amp) comprising the Schmitt Trigger circuit and the integrator circuit. Two PWM modulation techniques are proposed according to the input position of the information signal. First, utilizing inverting terminal of the Schmitt Trigger circuit as an input terminal can function as the PWM modulator. The resulting PWM output exhibits its duty cycle proportional to the derivative of the input signal. Second, when input signal is applied to the non-inverting terminal of the integrator circuit, the generated PWM signal whose duty cycle is proportional to both input and its integral. To ensure that the generated PWM signal conveys the message correctly, PWM demodulator is used to validate and confirm the results. Therefore, both proposed configurations effectively function as PWM modulators for both information signal and its integral. Finally, the results of in-depth mathematical analysis are validated and align well with all experimental results.
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Estimating an optimal setpoint to lessen errors in filling weighing system based on Kalman filtering
(2014-01-01)
Sinchai, Sakkarin
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Saechia, Sukkharak
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Limpiti, Tulaya
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Koseeyaporn, Jeerasuda
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Wardkein, Paramote
A weighing system in which a sensor is not mounted to a discharger especially in vertical filling gives rise to an excess of weight added to the given target of weight. In addition, the excess is not constant on account of some factors, such as vibration of the machine, flow of the substance, and cycle time of the system. These factors cause the surplus to oscillate. To overcome this problem, Kalman filtering is performed to predict the optimal setpoint to meet the defined target. To illustrate the performance of the proposed technique, the resulting outcome is compared with that of using the conventional statistical method. The results have shown that the proposed approach has significantly increased the speed and lowered the error. It is pointed out that the proposed algorithm may be preferable to the traditional statistical technique due to its effectiveness and its simple implementation. © 2014 IEEE.
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A simple synthesis technique of PWM signal
(2006-12-01)
Phanphaisarn, Wasu
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Saechia, Sukkharak
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Koseeyaporn, Jeerasuda
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Wardkein, Paramote
This article proposes a simple and accurate analytical technique for Pulse Width Modulation (PWM) harmonic spectrum whose carrier is asymmetrical ramp signal. The main concept is based on the fact that when a carrier pulse signal has much higher frequency than an information signal, period of the PWM signal is approximately constant. By considering PWM signal as a periodic signal, the one-dimensional exponential Fourier series is thus employed to be an analytical tool for mathematical analysis. The obtained analysis result in a closed form solution can therefore be utilized to easily synthesis the PWM signal. To illustrate the proposed concept, the synthesis results based on the proposed analysis are illustrated. The results show that the proposed analysis is not only a simple technique but also can provide accurate synthesis results. ©2006 IEEE.
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Human identification system based ECG signal
(2005-01-01)
Saechia, Sukkharak
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Koseeyaporn, Jeerasuda
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Wardkein, Paramote
A new human identification system based electrocardiogram (ECG) signal is introduced in this work. The human heart is considered to be a unique system of each person. ECG signal therefore represents as an impulse response of the system. The frequency response of the system (Fourier transform of the ECG signal) is employed to be a tool for feature extraction. In addition, the ECG signals employed in this paper, which may be derived from different heart rates from different subjects at the recording time, are normalized to a standard heart rate. Furthermore, not only the whole sequence of 1 period EC signal, containing P, QRS, and T waves, is processed but also its three subsequences, each respectively representing P, QRS, and T waves, is examined. The results of using neural network have demonstrated that subsequences technique is superior to whole period of ECG signal method.

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