Kenpankho, Prasert

Preferred name

Kenpankho, Prasert

Alternative Name

Kenpankho, P.

Main Affiliation

School of Industrial Education and Technology

prasert.ke@kmitl.ac.th

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Estimation of the single GPS-receiver bias using the gradient descent algorithm
(2016-09-06)
Chiablaem, Athiwat
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Supnithi, Pornchai
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Klinngam, Somjai
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Panachart, Chaiwat
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Saekow, Apithep
The ionospheric Total Electron Content (TEC) can be obtained from processing measurements of the dual-frequency Global Positioning System (GPS) receiver. The main sources of errors in the TEC calculation are satellite and receiver biases. In this paper, we apply the gradient descent algorithm on the receiver bias estimation. The TEC is derived from measurements at 12 dual-frequency GPS stations in Thailand. The criterion of receiver bias estimation is based on the minimum sum of the vertical TEC (VTEC) standard deviation method. The results show that the maximum receiver bias value is approximately 3.69 ns at UDON station, while the minimum value is -5.91 ns at SRTN station. The accuracy of the receiver biases from this algorithm is compared with the reference method. The maximum percentage deviation is about 7.5% at SRTN station. The percentage deviation of the minimum sum of the VTEC between the reference method and the proposed method from all stations are less than 0.05%. Thus, the proposed algorithm is a viable option to estimate the receiver bias.
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Adaptive algorithm in space division multiple access with n users and m antenna elements
(2004-12-01)
Kenpankho, Prasert
The increasing number of wireless broadband access users in local and wide area networks is the principal expression of the need for flexible and omnipresent wireless connectivity. In order to satisfy users' requirements in the presence of the wireless medium, sophisticated multiple access, multiple elemental antenna and adaptation techniques are required. The use of multiple elemental antenna arrays at the base station allows intra cell channel reused by multiple spatially separable users through Space Division Multiple Access (SDMA). In this paper, I investigate the implement of three elemental antenna arrays and propose an adaptive algorithm to allocate channels to four users based on the number of users and elements of antenna, while appropriately adjusting to n users and m elemental antenna arrays. The unified consideration of such adaptive algorithm techniques yields significant through the benefits. © 2004 IEEE.
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Comparison of GPS TEC measurements with IRI TEC prediction at the equatorial latitude station, Chumphon, Thailand
(2011-01-01)
Kenpankho, P.
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Watthanasangmechai, K.
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Supnithi, P.
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Tsugawa, T.
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Maruyama, T.
We have analyzed the total electron content (TEC) derived from dual-frequency GPS receivers (GPS TEC) at the Chumpon station, Thailand, during the period 2004-2006. The diurnal, monthly, and seasonal variation in the measured TEC is compared with the TEC derived from the IRI-2007 model as well as the TEC obtained from the International GNSS service (IGS). To date, TEC data at equatorial latitudes are limited. The Chumphon station (10.72 °N, 99.37°E) is located at the equatorial latitude and the dip latitude of 3°N. The TEC from the IRI-2007 model is based on the actual F<inf>2</inf> plasma frequency (f<inf>o</inf>F<inf>2</inf>) measurement. The results of our study show that the TEC derived from the IRI-2007 model agrees with the GPS TEC data mostly in the morning hours, but that it generally underestimates the GPS TEC. The maximum differences are about 15 TECU during the daytime and 5 TECU during the nighttime. The underestimation is more evident at daytime than at nighttime. The noon-bite out phenomena are clearly seen for the IRI-2007 TEC, but not on the IGS TEC and GPS TEC. The general underestimation of the IRI-2007 model can be explained from the exclusion of the plasmasphere, whereas the large difference during noon bite-outs is caused by the difference in the slab thickness in the ionosphere between the IRI-2007 model and the actual measurement. When compared with the TEC from the IGS model, the TEC measurements at Chumpon appear to be quite similar. Copyright © The Society of Geomagnetism and Earth.
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The Study of GPS Total Water Vapor Content over Ubon Ratchathani
(2025-01-01)
Wongsak, Pattawut
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Kraisi, Prasert
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Kenpankho, Prasert
The research paper focused on learning and investigating water vapor in the atmosphere over Ubon Ratchathani, Thailand. Water vapor can be measured by using total water vapor content (TWVC) which is calculated by Global Positioning Satellites known as GPS which are over Thailand and receives signals passively which can be extracted by BG2s receiver. In this research study, Ubon Ratchathani is selected and installed BG2s receiver according to the weather and environment conditions where are among mountains, rivers, and lands with large population and agriculture occupation. TWVC can be obtained by GPS signals which are in Receiver Independent Exchange (RINEX) format. For calculating TWVC, the used altitude in troposphere over Ubon Ratchathani is five kilometers. The period of this research study was from August-October 2024 over Ubon Ratchathani. GPS datasets were analyzed and processed to Total Electron Content (TEC) estimation, converted it as ionospheric delay and estimated it as the zenith tropospheric delay (ZTD). Then, personnel at the Thai Meteorological Department (TMD) were trained and investigated the TWVC values from GPS with the TWVC values from measurement by TMD. As the results, we found that the maximum TWVC was recorded at Ubon Ratchathani in September 2024, with an average of 15.30 mm and the minimum TWVC was in October 2024, with average of 7.39 mm. The pretest and posttest were different values, which pretest score is smaller than the posttest score at 13.39. In addition, the investigation TWVC values from GPS underestimated the TWVC values from measurement by TMD at 1.5 times.
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Global Navigation Satellite System (GNSS) Low-Cost Robotics Platform for Competition Game
(2025-01-01)
Sumniang, Patiphan
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Putthong, Burin
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Namniwong, Thapanan
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Kenpankho, Prasert
In this research, the Global Navigation Satellite System (GNSS) low-cost robotics platform for competition game was designed, including the development of competition rules and field. The competition rules are specifically tailored to GNSS low-cost robot, highlighting the essential components required to build robots based on GNSS low-cost robotic platform. This research aims to promote learning and skill development in robots and GNSS, with a focus on affordable resources to ensure accessibility for students and independent developers. In research methodology, a total of 58 teams with 116 participants took part in the GNSS low-cost robotics platform competition game, including 47 high school level teams (94 participants), 6 vocational level teams (12 participants), and five undergraduate level teams (1 0 participants). As the results, the competition game was successfully developed by the GNSS low-cost robotic platform, with over 70% of participants demonstrating a solid understanding of GNSS navigation, robot, and game design. Participants rated innovation-focused activities highly (4.55), highlighting the competition game role in inspiring creativity in GNSS and low-cost robot. In term of rule for competition game, participants gave the rates on fairness (4.23) and consistency (4.28) which were well received, although rule clarity received the lowest score (3.84), suggesting the need for clearer guidelines. In addition, the pre- and posttest assessments on participants' knowledge, understanding, and inspiration in GNSS navigation, robot, and game design, further confirmed the effectiveness of GNSS low-cost robotics platform competition game by giving the improved mean score from 23.06 to 27.01.
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Complex Ionospheric Irregularity Echoes Observed by Low Latitude Long Range Ionospheric Radar
(2026-01-01)
Li, Yuxiao
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Hu, Lianhuan
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Li, Guozhu
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Ning, Baiqi
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Dai, Guofeng
Using the Low lAtitude long Range Ionospheric raDar (LARID) at Dongfang (19.2°N, 108.8°E), Hainan Island, China, we report a unique case of complex ionospheric irregularities observed on 9 June 2024. The most interesting aspect is the first-time long-range (∼2,000 km) detection of daytime ionospheric irregularities and post-sunset band-like irregularity structures by HF radar at low latitudes. By incorporating VHF radar and global navigation satellite system (GNSS) rate of total electron content index (ROTI) observations, the radio wave propagation modes of the ionospheric irregularity events observed by LARID and evolution of these ionospheric irregularities were analyzed. The daytime ionospheric irregularity echoes observed by LARID over the Indian Ocean exhibited westward drift, evident in both echo patterns and Doppler velocities. These ionospheric echoes were likely backscattered from E region field aligned irregularities by the “downleg” of the 1-hop HF ray path. The post-sunset irregularity echoes observed by LARID over Indian Ocean manifested as a band-like structure. This structure was closely attached to the bottom of ground/sea scatter echoes and showed the same range variation as the ground/sea scatters. GNSS ROTI observation revealed that irregularities primarily appeared south of the magnetic equator and drifted eastward across the eastern longitudes in later hours. Analysis indicates that the displacement of small-scale irregularities within the equatorial plasma bubble event along the magnetic field likely contributed to the band-like irregularity structure observed by LARID and the asymmetric irregularity distribution observed by GNSS.
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Study on the relationship between Global Positioning System Total Electron Content Anomalies and Earthquake Events in Thailand during Solar Cycle 24
(2025-10-29)
Pansong, Chollada
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Kenpankho, Prasert
This study investigates ionospheric Total Electron Content (TEC) anomalies in relation to earthquake events in Thailand from 2007 to 2020, encompassing Solar Cycle 24. TEC data were obtained from three sources: the Global Positioning System (GPS), the International GNSS Service (IGS), and the International Reference Ionosphere (IRI), and were compared to 473 earthquakes (Mw ≥ 3.0). While earthquake magnitudes below Mw 5.0 did not exhibit a clear correlation, earthquake events of Mw 5.0 or higher reflected in moderate negative correlation coefficients for GPS TEC, IGS TEC, and IRI TEC (-0.495,-0.501, and-0.303, respectively). Furthermore, a positive correlation coefficient (0.611) was found between Mw ≥ 5.0 earthquakes and geomagnetic storms with the Kp index. However, focusing specifically on geomagnetic storms and TEC variations on the day of an earthquake, no significant relationship was detected across GPS, IGS, and IRI data. Nevertheless, further research is needed to clarify the link between seismic activity and TEC fluctuations, potentially through alternative approaches or targeted case studies. This is especially important given the limited number of earthquakes above a magnitude of 5.0 in our study area, which restricts the available sample size.
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Comparison of observed TEC values with IRI-2007 TEC and IRI-2007 TEC with optional foF2 measurements predictions at an equatorial region, Chumphon, Thailand
(2013-11-15)
Kenpankho, P.
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Supnithi, P.
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Nagatsuma, T.
In this research, as part of working towards improving the IRI over equatorial region, the total electron content (TEC) derived from GPS measurements and IRI-2007 TEC predictions at Chumphon station (10.72 N, 99.37 E), Thailand, during 2004-2006 is analyzed. The seasonal variation of the IRI-2007 TEC predictions is compared with the TEC from the IRI-2007 TEC model with the option of the actual F2 plasma frequency (foF2) measurements as well as the TEC from the GPS and International GNSS service (IGS). The Chumphon station is located at the equatorial region and the low latitude of 3.22 N. For a declining phase of the solar cycle (2004-2006), the study shows that the IRI-2007 TEC underestimates the IRI-2007 TEC with the foF2 observation at the nighttime by about 5 TECU. The maximum differences are about 15 TECU during daytime and 5 TECU during nighttime. The overestimation is more evident at daytime than at nighttime. When compared in terms of the root-mean square error (RMSE), we find that the highest RMSE between GPS TEC and IRI 2007 TEC is 14.840 TECU at 1230 LT in 2004 and the lowest average between them is 1.318 TECU at 0630 LT in 2006. The noon bite-out phenomena are clearly seen in the IRI-2007 TEC with and without optional foF2 measurements, but not on the GPS TEC and IGS TEC. The IRI TEC with optional foF2 measurements gives the lowest RMSE values between IRI TEC predicted and TEC measurement. However, the TEC measurements (GPS TEC and IGS TEC) are more correct to use at Chumphon station. © 2012 COSPAR. Published by Elsevier Ltd. All rights reserved.
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QZSS L1 Bandwidth Frequency Filter Design for QZSS Receiver
(2021-03-01)
Onanong, Narumol
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Pattameak, Julongkorn
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Mekpradab, Teerachet
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Chinnapark, Surachet
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Kenpankho, Prasert
We present the design of bandpass filter on the frequency of the QZSS satellite, by providing bandwidth at the cut-off frequency equally to the bandwidth of the QZSS L1 with selecting the response characteristic on Butterworth maximally flat amplitude. Bandpass filter design using frequency of the QZSS L1 with bandwidth is 24MHz. The design procedure involves two steps, the first step is to find the required order of the filter, which we use 3rd order, and the second step is to find the scale factor that must be applied to the normalized parameter values. The Band-Pass Butterworth filler is a combination between low pass and high pass. For the Butterworth filter, the value of a resistor that has been used are 50Ω. Then go to find the capacitor and inductor and by using PSpice as the tools for the simulation. The results of the output of bandpass filter at-3dB was between 1563 and 1587MHz. And was bandwidth around 24MHz. The combination of the lowpass filter and high pass filter is to perform as the bandpass filter. Therefore, there are two combinations also in designing bandpass filter. The aim of this combination is to have an influence on the performance of bandpass filter. As a conclusion, this designed filter on the frequency of QZSS L1.
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The study on the relationship between ionospheric delay and low-cost localizing robots
(2025-03-01)
Sumniang, Patiphan
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Sittichai, Wishapol
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Kenpankho, Prasert
The dispersive and anisotropic nature of the ionosphere above certain regions particularly on Thailand's low − nearly equatorial − latitude, positioning accuracy is seriously affected when using a precision limited model. Change in ionospheric delay is a key factor impacting the Global Navigation Satellite Systems (GNSS) positioning and navigation accuracy. We studied the effect of ionospheric delay on localizing low-cost robots. We investigated the positioning error using ionospheric delay from a GNSS receiver, IRI and our campus, KMITL, in Bangkok, to guide our ‘G-LOC’ robot. There were eight target points, set from 3 to 50 m at the same meridian with varying latitudes. Impacts on a robot moving on low solar activity days, high solar activity days, daytime, and nighttime were measured over 12 months in 2023. We found that high solar activity day impacts a robot moving on highest accuracy error up to 363 cm at high speed. In addition, we found that daytime impacts a robot moving on highest accuracy error up to 154.05 cm at high speed as well. Ionospheric delay according to high and low solar activities, and daytime, and nighttime effects on the GNSS interference transmitted to a low-cost localizing robot was expected to affect moving errors, but it did not seem to lead to a significant difference in error between the low and high solar activity days.

Kenpankho, Prasert

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