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A Simplified Analog Implementation of Cyclic Shift Chirp Encoding and Decoding for LoRa Communications
(2026-06-01)
Saelim, Nopparut
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Tuwanut, Panwit
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Pornavalai, Chotipat
Currently, LoRa wireless communication technology has become widely adopted in IoT systems due to its long-range capability and low power consumption. However, LoRa is a technology developed by Semtech, which does not disclose the details of the Cyclic Shift Chirp encoding process, a core component of LoRa signals. This lack of transparency prevents users from accessing the physical-layer structure of the signal or freely customizing key parameters such as bandwidth and spreading factor. Although such customization can enhance system flexibility, there is currently no officially disclosed method to achieve it. This research proposes a Cyclic Shift Chirp encoder/decoder circuit built from basic analog components, including adders, subtractors, comparators, and ramp generators, based on a Pulse Width Modulation (PWM) principle. This approach enables researchers and developers to generate LoRa-like signals independently and customize various parameters without introducing limitations. Moreover, the proposed circuit is simple, low-cost, and easy to understand, making it suitable for advanced research, educational experiments, and the design of communication systems that require high flexibility at the LoRa PHY layer.
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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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OTA-based independently adjustable pulse width modulator
(2015-01-01)
Kaewpoonsuk, Anucha
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Suklek, Niparat
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Rerkratn, Apinai
A pulse width modulation (PWM) based on operational transconductance amplifiers (OTAs) is presented in this paper. The proposed circuit provides a simple configuration and employs only OTAs as the active elements. In addition, the duty cycle of the output signal can be adjusted independently with the frequency and the amplitude. The performances of the proposed circuit are discussed in detail and confirmed by the PSPICE simulation results.
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An improved Three-Level Zero-Voltage and Zero-Current Switching PWM DC-DC converter for battery charger
(2014-01-01)
Jangwanitlert, A.
This paper describes a 2-kW Three-Level Zero-Voltage and Zero-Current Switching (TL-ZVZCS) PWM dc-dc converter for battery charger. To solve the disadvantages from TL-Zero-Voltage Switching (ZVS) such as a circulating primary current and parasitic voltage ringing on the dual diodes rectifier, a proposed simple auxiliary circuit is composed of a small capacitor with two small diodes is put on the transformer secondary side to achieve ZVZCS conditions of primary switches and to clamp secondary voltage rectifier. The auxiliary circuit does not give any losses in components and additional active switches, which provides the proposed circuit converter more effective and efficient. Moreover, this paper describes the key operation waveforms, operational modes and design considerations. The concept idea is verified by the MATLAB simulation. © 2014 IEEE.
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AC power load controlling by using PWM based on phase locked loop
(2009-10-22)
Kitipongwatana, A.
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Koseeyaporn, P.
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Koseeyaporn, J.
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Wardkein, P.
This paper proposes power load controlling by using PWM signal to on-off an electronic switch. With this technique, load current can be easily adjusted. For PWM signal, it is derived by using PLL. With the property of PLL, PWM signal whose frequency is synchronized with that of load power is generated. Consequently, phase of signal which is fed to load can be controlled all range of 360 degrees or 180 degrees. In addition, the experiment results show that linear relation between phase of signal and DC voltage. ©2009 IEEE.
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A novel monostable multivibrator circuit
(2005-01-01)
Tuwanut, Panwit
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Koseeyaporn, Jeerasuda
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Wardkein, Paramote
This article represents a novel monostable multivibrator circuit in which width and height of the pulse output can be independent electronically adjusted. In addition, the pulse width of output is not restricted to be wider or narrower than that of input pulse as conventionally employed. Namely, there is no restriction on the width of input and output pulse, the circuit's implementation is thus more convenient. The proposed circuit is composed of three OTAs, two resistors and one capacitor, basically constructed a simple pulse generator (Schmitt-trigger circuit). Therewith the compactness of the circuit, It Is thus suitable to be fabricated for integrated circuit. The results of circuit simulation is accordance well with theoretical analysis.
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A simple and low cost of delta modulator for static PWM inverter
(2004-12-01)
Choochuan, C.
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Kinnares, V.
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Pirajnanchai, V.
The problem of switching frequency over the fundamental period of the modulation signal in fixed band delta modulation is improved by adding a triangular carrier wave to the sinusoidal reference and forcing the integrator output to follow the sum of these two signals is proposed in this paper. The proposed method is applied to the voltage source inverters for variable-speed three-phase induction motor drives applications(VSD).
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A Fully Independently Adjustable, Integrable Simple Current Controlled Oscillator and Derivative PWM Signal Generator
(2003-01-01)
Siripruchyanun, Montree
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Wardkein, Paramote
A simple circuit scheme, able to generate square/triangular wave, is proposed. Its advantages are that oscillation frequency and amplitudes of the proposed circuit do have a small range of temperature drift. Electronic adjustments of them can be obtained with a wide sweep range and DC offset adjustment available. In addition, the proposed scheme can produce frequency-constant derivative of PWM signal without an additional device requirement. It is very appropriate for, with simple circuit details, not only circuit implementation but also monolithic fabrication. The PSPICE simulation results through bipolar technology are given here, they show good performance of the proposed circuit.
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Influence of PWM characteristics on the core losses due to harmonic voltages in PWM fed induction motors
(2000-01-01)
Khomfoi, S.
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Kinnares, V.
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Viriya, P.
The paper focuses on mechanisms of harmonic core losses due to PWM characteristics. The influence of PWM characteristics such as switching frequency, modulation depth and PWM strategy on core losses has been examined. The investigation into harmonic core losses based on no-load input power measurement with minimized rotor copper loss and rotational loss has been made. The experimental results show that the increment of core losses due to PWM harmonic voltages is significant compared to a sinusoidal supply and the modulation depth has significant effect on machine core losses.
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Quick torque controlled SPIM using PID controller based on PLL technique
(2000-01-01)
Tipsuwanporn, V.
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Charean, A.
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Piyarat, W.
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Kittisiam, T.
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Thepsatorn, P.
This paper proposes the PERM technique by using the phase locked loop (PLL) and binary rate multiplier (BRM) techniques combined together to control the speed of a single-phase induction motor (SPIM). The system simulation is based on utilizing a discrete signal and the root locus technique to analyze the stability of the system before design. It is an easy method to determine the result response of the system. The PERM can adjust the circle criterion in the digital loop by considering a K ratio value between 0.179 to 1.85. This PERM technique can also control response signals back to steady state in less than 1.7 second during variable load or no load.

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