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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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Estimation of Cloud Attenuation over Bangkok, Thailand Based on an ITU-R Model
(2019-10-01)
Sookhawattako, Paphawarin
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Youngthongkham, Patamawadee
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Prasopbuchatham, Pannita
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Chodkaveekityada, Peeramed
We estimated satellite signal degradation by cloud. Cloud attenuation over Bangkok, Thailand, was estimated with an International Telecommunication Union Radiocommunication sector (ITU-R) model. The estimation was done at several high frequency bands: Ku, Ka and Q/V band with a variety of antenna elevation angles at the ground station of THAICOM satellite. According to the ITU-R model, the worst possible case of cloud attenuation over Thailand in Ku band would be 0.6 dB but in V band could be up to 9 dB. In the Ka band, cloud attenuation was the worst for Singapore, followed by Japan, Thailand and Italy. This estimation scheme may benefit new developers of satellites and their ground stations.
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Design and Development of Effective Radiosonde for Rainmaking Process in Thailand
(2018-07-02)
Chodkaveekityada, Peeramed
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Wardkein, Paramote
Weather information is very useful to many activities in every country such as aeronautical, meteorological and rainmaking. Thailand is located near the equator that makes the weather in this region vary a lot and more severe than in another areas. Thailand also exports a lot of agricultural products to serve people globally. Oftentimes, rain does not fall on an intended area like an area round a dam, hence there is not enough water to provide to farmers. This work is a part of a goal to design and develop a weather observation system suitable for rainmaking in Thailand.
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Cansat design and their applications
(2018-01-01)
Piatong, Atiwat
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Sirisestanun, Aonjira
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Chiangchin, Supachai
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Apisakulroj, Suwijak
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Suwat, Witsanu
CanSat is a simulation model used in actual satellite working in the space. It has been presented for almost 20 years. The development of CanSat is based on educational proposes, and its design can be multiple depending on associated educational attainments [1]-[2]. Most developed countries give priority to develop the literacy of space technology in their students since secondary school in which the CanSat design is utilized as one tool to acquire the understanding of the satellite operation. The main objective of this paper is to design the CanSat for competition in 2018. The mission of the competition has been changing over the year to challenge competitors in the field of space engineering. Normally, base requirements may limit certain design factors such as the total mass of the CanSat, the rate of transmission once per second, the use of XBEE for telemetry at 2.4 GHz or 900 MHz and the cost of the CanSat that should be under 1000 USD. However, the competitors are allowed to design other attributes of the CanSat to achieve a competent one. The body of the proposed CanSat will consist of sensors subsystem and power subsystem. We will choose appropriate sensors by considering the cost and main features of our design. Basically, sensors for satellite used to collect data relevant to its surrounding environment and our sensor subsystem consists of a temperature sensor, a humidity sensor, a pressure sensor, an altitude sensor, a GPS sensor, a magnetometer sensor and an additional camera module. Some sensors are integrated as one component to make the CanSat more lightweight and cost effective. Regarding the feature of a CanSat for collecting environment data which is very useful to apply for the weather observation system, we will develop a CanSat to operate similarly to a radiosonde. Hopefully, it can be used as a smart radiosonde for the rainmaking project in our country.
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Time correlation used to improve time diversity gain of rainfall prediction
(2018-01-01)
Chodkaveekityada, Peeramed
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Fukuchi, Hajime
Correlation of the rainfall rate with time depends on geography, environment, and the type of rainfall. In this letter, we consider the use of such a correlation to improve the time diversity gain of a system that predicts rainfall over Japan. From a rain may with 4 years of data, we selected 43 locations throughout mainland Japan, and from these data, we derived the cumulative time percentage, the diversity gain from a time diversity method using 10 to 120 min delays, and the correlation from a time series of rainfall. This information is used to improve the prediction of rainfall. Root-mean-square errors show an improvement in the diversity gain.

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