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Author: search.filters.author.Saechia, SukkharakStart date: 2020

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    A Novel Multi-Slope Chirp Modulation and Demodulation with Instantaneous Chirp Rate Estimation
    (2026-05-01)
    Magkeethum, Apiwat
    ;
    Saechia, Sukkharak
    ;
    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
    ;
    Kaew-In, Chanapat
    ;
    Chatchaiphat, Nisukan
    ;
    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.