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DSSZ-SM: A Simplified Chirp Coding Scheme with Inherent Clock Synchronization
(2026-06-01)
Kirasamuthranon, Lerson
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Koseyaporn, Jeerasuda
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Wardkein, Paramote
This study proposes a novel double-slope chirp symbol, termed double-slope start zero stop minimum (DSSZ-SM), for efficient data communication. Unlike conventional chirp coding, which often involves complex generation and synchronization, the DSSZ-SM provides a simpler structure with inherent clock synchronization using a PWM-based generator. System performance is evaluated through analysis and simulations over additive white Gaussian noise (AWGN) and Rayleigh fading channels. Two asynchronous decoding methods, with and without an integrator, are compared. Results show that the non-integrator approach achieves lower error rates under both channel conditions. The proposed DSSZ-SM offers a simplified and robust alternative for efficient data communication.
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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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A Cyclic Shift Chirp Modulation Scheme for Analog Message with Simplified PPM Demodulation
(2026-01-01)
Kaew-In, Chanapat
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Wardkein, Paramote
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Chatchaiphat, Nisukan
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Chodkaveekityada, Peeramed
In this work, a cyclic shift chirp modulation scheme with an analog message signal is presented. The demodulation process is carried out by converting the cyclic shift chirp into pulse position modulation (PPM), followed by three demodulation approaches: (i) direct LPF filtering of the PPM pulses, (ii) inversion of the PPM pulses prior to LPF filtering, and (iii) integration driven by the PPM pulses. The recovered signal in these cases corresponds to the differentiated form of the original message signal. However, when the message signal is preintegrated before PPM modulation, the subsequent demodulation via integration directly yields the original message signal, eliminating the need for an additional integration stage at the receiver. This results in a simplified and less complex receiver compared to conventional PPM schemes without input pre-integration. Analytical and experimental results are in close agreement, validating the effectiveness of the proposed method.
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Simplified Derivative-Based Carrierless PPM Using VCO and Monostable Multivibrator
(2025-06-01)
Koseeyaporn, Jeerasuda
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Wardkein, Paramote
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Sinchai, Ananta
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Kaew-in, Chanapat
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Tuwanut, Panwit
This study proposes a derivative-based, carrierless pulse position modulation (PPM) scheme utilizing a voltage-controlled oscillator (VCO) and a monostable multivibrator. In contrast to conventional PPM systems that rely on reference carriers or complex demodulation methods, the proposed architecture simplifies signal generation by directly modulating the time derivative of the message signal. The modulated signal, when processed through standard analog demodulators, inherently yields the derivative of the original message. This behavior is first established through theoretical derivations and then confirmed by simulations and circuit-level experiments. The proposed method includes a differentiator feeding into a VCO, followed by a monostable multivibrator to generate a carrierless PPM waveform. Experimental validation confirms that, under all tested demodulation approaches—integrator-based, PLL-based, and quasi-FM—the recovered output aligns with the differentiated message signal. The integration of this output to retrieve the original message was not performed to maintain focus on verifying the modulation principle. Additionally, the study aimed to ensure the consistency of derivative recovery. Signal-to-noise ratio (SNR) expressions for each demodulator type are presented and discussed in the context of their relevance to the proposed system. Limitations and directions for further study are also identified.
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Development of a Phase-Locked Loop Circuit in Running Frequency Mode for Capacitance-to-Voltage Conversion
(2025-01-01)
On-Khong, Tada
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Sisuk, Noppadon
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Wardkein, Paramote
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Katman, Ratchanoo
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Prompak, Kriangsak
Capacitance-to-voltage conversion is essential for capacitive sensors in various industries, including touch interfaces, medical devices, and moisture measurement. However, circuit design faces challenges like non-linearity, noise, and small capacitance variations affecting voltage signals. This article proposes a phase-locked loop in free-running oscillator mode with a frequency-to-voltage converter to enhance accuracy and stability. Test results show a 97.9% measurement accuracy, demonstrating reduced noise and improved stability. The proposed circuit is ideal for high-precision applications in diverse environments, overcoming limitations of traditional methods.
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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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DEVELOPMENT OF AN EMBEDDED EXERCISE POSTURE PREDICTION SYSTEM FOR OFFICE SYNDROME USING MACHINE LEARNING
(2024-12-01)
Sisuk, Noppadon
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Onkhong, Tada
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Kaewpoonsuk, Anucha
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Wardkein, Paramote
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Prompak, Kriangsak
Office syndrome is a condition with a high prevalence among people of working age and an upward tendency. In this study, a wearable device implant based on machine learning will be created for exercise of office syndrome. Developing a machine learning model that can distinguish 3 exercise postures for implantable devices was the objective of the study. The Edge Impulse online software was used for data collecting, preprocessing, training, and testing. After that, the model was successfully installed and tested on an Arduino Nano 33 BLE microcontroller. In addition to designing embedded systems, this work also developed applications through the App Inventor program for exercising properly. From testing the system, the model showed an average classification accuracy of 97.6% of exercise postures. The results of testing the embedded system in conjunction with the presented application on 10 subjects showed that the system was able to provide predictive accuracy for wrist exercises, shoulder exercises and stretch exercises with 95%, 97%, and 93%, respectively.
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Discrete Time Two-Frequency Shift Keying
(2024-01-01)
Wardkein, Paramote
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Kaew-In, Chanapat
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Wanprasert, Thanaree
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Philuek, Pandaree
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Moonthongnoi, Nateekan
In this article, two-frequency shift keying is used to modify the time for generating the Time-Frequency Shift Keying (TFSK). Which both frequencies occupy different times and vary with a message. For this mechanism, it causes M-ary time-frequency pattern coding, where one pattern can code n bits if we have different 2n patterns, which overall code like a Pulse Width Modulation (PWM) combined with binary FSK. To confirm the proposed idea or technique, four-time-frequency coding is simulated with MATLAB, and an experiment is implemented with a commercial FSK IC. Both simulations and experimental results show that they are identical to predictions. Moreover, its bandwidth is predicted, and clock recovery is also implemented.
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Novel Double Slope Frequency Shift Chirp Symbol
(2024-01-01)
Kirasamuthranon, Lerson
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Wardkein, Paramote
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Koseeyaporn, Jeerasuda
One of the most significant concerns in serial digital communication is the synchronization of data bits between the transmitter and receiver. Therefore, the preferred coding symbols should contain an inherited clock signal. The cyclic-shift chirp, which is primarily used in long-range systems, employs a single slope in a symbol, which contains few information for synchronization. Hence, two new forms of cyclic-shift chirp symbols are proposed herein. The associated coding schemes are based on the use of a dual slope within one symbol. Synchronization is inherited in the coding symbol using a dual slope. Additionally, both proposed coding schemes utilize the same decoding technique. The decoded chirp symbol is in the form of a pulse width modulation signal, which can be used for synchronization and retrieving data bits from their duty cycle. The simulation results show that the coding and decoding processes of the proposed coding schemes align with those of a theoretical framework. The error performance analysis for the proposed detection scheme is given and the results of error probability analysis are consistent with the simulation results. Moreover, under a Rayleigh fading channel, the proposed coding schemes provide superior performance compared with other comparable coding schemes.
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Effects of hot air temperature on moisture reduction and drying time of turmeric in a closed-system herb dryer: kinetics and models
(2023-11-01)
Chindaruksa, Sirinuch
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Bongkaew, Haruethai
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Wardkein, Paramote
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Chantrawongphisal, Borisut
The primary objective of this research was to devise a model focused on the drying kinetics of turmeric, utilizing a closed-system herb dryer to facilitate energy conservation. Drying turmeric within this closed-system herb dryer involves a heat source—specifically, an electric coil heater powered at 3500 W and a humidity controller. The drying condition includes an air volume of 0.039 kg/s, the temperature at 40, 50, and 60 °C with initial moisture of the turmeric at 667.53 %db. The result of drying turmeric was analyzed using a thin-layer drying model for 8 models: Newton, Page, Logistic, Henderson and Pabis, Logarithmic, Two-Term, Approximation of Diffusion, Midill et al. The result shows that Midill et al. equation was the best model for predicting the drying behavior of turmeric. Therefore, this insinuates that the Midill model is superior to its contemporaneous counterparts in terms of accuracy. It offered the highest coefficient of determination R 2 (0.9998, 0.9996, 0.9999), the most root mean square error (RMSE) (3.39×10−9, 2.37×10−5, 3.10×10−5), the last chi-square χ 2 (3.39×10−9, 2.85×10−5, 3.99×10−5), and a temperature of 40, 50, and 60 °C, respectively. The study revealed that implementing a closed-system herb dryer could potentially manufacture high-value commodities while preserving their fundamental attributes. The closed-system herb dryer has been ingeniously designed as a proficient approach to diminish the drying time and improve the end product’s quality.

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