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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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Preliminary Analysis of the Impact of Rain Attenuation Around Reference Ground Station Using One-Minute Rainfall Data
(2025-01-01)
Supasirasatkul, Thanyaporn
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Chodkaveekityada, Peeramed
The current rapid and severe climate change is affecting rainfall patterns in terms of both intensity and frequency. This can have a significant impact on satellite communications, especially in high-frequency bands such as Ku-band. This research presents an analysis of rain attenuation effects, using KMITL as a reference station and rainfall data from surrounding stations collected at one-minute intervals over two years. The standard ITU-R model was used to calculate rain attenuation. The results show variations in attenuation among different stations, enabling analysis of rainfall amount, distance, and direction. This study can contribute to the development of a rain attenuation model for Thailand.
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Big Data Enhancement of R0.01Reliability for Rain Attenuation Model Optimization in Thailand
(2025-01-01)
Pa-In, Wetchaphat
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Chodkaveekityada, Peeramed
Rain attenuation prediction is crucial for satellite communication, particularly in tropical regions like Thailand. A key parameter in rain attenuation modeling is the rainfall rate exceeded for 0.01% of the time (R0.01). This study collects big data from rain gauges across Thailand, recorded at 1-minute intervals over three years (2022-2024), and analyzes the Data Reception Rate (DRR) by comparing annual rainfall rates. This analysis also monitors the development and quality of the rain gauge network. The results, showing a high DRR, indicate the reliability of R0.01. This reliable R0.01 can then be used to accurately calculate the predicted attenuation exceeded for 0.01% of the time (A0.01), derived from slant-path measurements following the ITU-R model, using existing satellites serving Thailand.
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IoT Modular Gateway Development for Multi-Standard Compatibility
(2025-01-01)
Kaiyarach, Kattiya
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Taprik, Sopita
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Buathong, Bantita
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Chodkaveekityada, Peeramed
Currently, IoT wireless communication technology plays a crucial role in connecting multiple devices. However, the diverse standards used limit their interoperability. To address the issue of incompatible communication protocols, this research presents a developed IoT system that seamlessly integrates various communication standards. The system comprises a central processing unit (Core Board) that functions as an IoT gateway. This core board connects local networks via LoRa and others, as well as public networks using 3G and Wi-Fi. The system utilizes the STM32H563ZI processor, which is based on the ARM Cortex M33 architecture. Additionally, it features expansion slots to accommodate future of others communication standards. The results show that the developed IoT system's effective support for a diverse range communication standards.
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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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Diversity Methods for Mitigating Tropospheric Attenuation in Thailand for Future Satellite Communication
(2022-01-01)
Chodkaveekityada, Peeramed
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Phongcharoenpanich, Chuwong
This paper aimed to propose diversity method for mitigating tropospheric attenuation in Thailand. Thailand experiences one of the strongest satellite attenuation conditions in the world. Three kinds of data - cloud calculation data, thaicom2&3 satellite beacon data, and rainfall data - indicate how severe tropospheric attenuation is at a moment, calling for some diversity methods to be applied Thailand's attenuation data to increase the efficiency of future satellite communication in Thailand, especially at high Ka band frequency and above.

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