Wardkein, Paramote

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Wardkein, Paramote
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Wardkein, P.
Wardkein, Pramote
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paramote.wa@kmitl.ac.th

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    Novel Double Slope Frequency Shift Chirp Symbol
    (2024-01-01)
    Kirasamuthranon, Lerson
    ;
    Wardkein, Paramote
    ;
    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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    Pulse Oximetry Based on Quadrature Multiplexing of the Amplitude Modulated Photoplethysmographic Signals
    (2023-07-01)
    Koseeyaporn, Jeerasuda
    ;
    Wardkein, Paramote
    ;
    Sinchai, Ananta
    ;
    Kainan, Pattana
    ;
    Tuwanut, Panwit
    In this research, a pulse oximeter based on quadrature multiplexing of AM-PPG signals is proposed. The oximeter is operated by a microcontroller and employs a simple amplitude modulation technique to mitigate noise interference during SpO<inf>2</inf> measurement. The two AM-PPG signals (RED and IR) are quadrature multiplexed using carrier signals with equal frequencies but a 90-degree phase difference. The study focused on noise interference caused by light intensity and hand movement. The experiment was conducted under three different levels of light intensity: 200 Lux, 950 Lux, and 2200 Lux. For each light intensity level, the SpO<inf>2</inf> level was measured under three scenarios: hand still, shadow movement over the hand, and hand shaking. A comparison between the proposed technique and the conventional method reveals that the proposed technique offers a superior performance. The relative error of the measured SpO<inf>2</inf> level using the proposed technique was less than 3.1% overall. Based on the study, the proposed technique is less affected by noise interference caused by light intensity and hand movement compared to the conventional method. In addition, the proposed technique has an advantage over contemporary methods in terms of computational complexity. Consequently, the proposed technique can be applied to wearable devices that include SpO<inf>2</inf> measurement functionality.
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    Coding and Coherent Decoding Techniques for Continuous Single Slope Cyclic Shift Chirp Signal
    (2023-06-01)
    Kirasamuthranon, Lerson
    ;
    Wardkein, Paramote
    ;
    Koseeyaporn, Jeerasuda
    Chirp signals are currently widely used in broad-band and spread spectrum communications due to their ad-vantageous features, such as immunity to fading noise, low power consumption, consistent long-range transmission, and constant bandwidth. As a result, they are applied at the physical layer of the Internet-of-Things (IoT). This study proposes two techniques for encoding and decoding 4-cyclic shift chirp symbols, based on addition and subtraction oper-ations. The proposed techniques have simple structures that can be easily implemented using analog circuits. The pro-posed encoding techniques reveal obviously the relationship between cyclic-shift chirp symbols and pulse modulating signals (PWM, PPM, and PAM), which is rarely discussed in prior research. Moreover, the circuit for encoding and decoding of the proposed technique is implemented by dis-crete commercial devices at low frequency (25–35 kHz) which is suitable for sonar and communication under water; however this proposed technique is not limited to only low frequency but is also capable of being used in high frequency band as well which experimental and simulation result show agreeing well with each other.
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    Simplified Derivative-Based Carrierless PPM Using VCO and Monostable Multivibrator
    (2025-06-01)
    Koseeyaporn, Jeerasuda
    ;
    Wardkein, Paramote
    ;
    Sinchai, Ananta
    ;
    Kaew-in, Chanapat
    ;
    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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    SAGC circuit design and implementation for FSK modem through radio channel
    (2021-05-19)
    Sutam, Apichat
    ;
    Magkeethum, Apiwat
    ;
    Wardkein, Paramote
    ;
    Koseeyaporn, Jeerasuda
    ;
    Sae-Chia, Sukkharak
    In this research, the sinusoidal automatic gain control circuit (SAGC) has been fabricated by using differentiator circuits, multiplier circuits, a summation circuit, a square root circuit and a division circuit. By using an Operational amplifier (Op amp) and 2 capacitors, the differentiator circuit has been constructed An Op amp and IC AD633 used as a multiplier are combined for fabricating the square root circuit [1]. Apart from evaluating the SAGC characteristics, the FSK recovery process for transmitting the (Global Positioning System) GPS coordinates through radio channel has been improved via the proposed SAGC circuit. The results show that the proposed circuits and its implementation operate perfectly and agree well with the conventional theory.