7104 research outputs found
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Development Of Wideband Circularly Polarized Antennas For Remote Sensing Microsatellite
No full textChiba University is developing the GAIA-I microsatellite which makes use of the Global Navigation Satellite System (GNSS) Radio Occultation (RO) and the Electron Density - Temperature Probe (EDTP) sensors. The mission is to provide global coverage vertical resolution of pressure, temperature, refractivity, and water vapor in the atmosphere, also electron temperature and density in the ionosphere. The atmospheric parameters data will be used in numerical weather prediction (NWP) for climate modeling, while the ionospheric data will be beneficial to investigate the relationship between global land deformation and te electron density.In this research, two novel methods to generate wideband circularly polarized (CP) based on equilateral tringular ring slot (ETRS) antenna for the GNSS-RO receiver and command communication satellite of te GAIA-I are proposed. The first method is the introduction of a pair of slits to improve the CP bandwidth of equilateral tringular slot (ETS) antenna which technically is a wide slot but employs the ring slot CP excitation technique thanks to the basic shape. The small size antennas introduce chamfered corners, triangular perturbation patch and feed line with additional branches to produce wideband CP operation. A further 3-dB ARBW improvement close to its impedance bandwidth is obtained by attaching a pair of slits. It can be confirmed that the pair of slit has a significant impact to double the 3-dB ARBW and decrease te antenna size. A study on several parameters influencing the shape transformations to the impedance and axial ratio bandwidth is presented. The designed ETS antennas for both applications are fabricated to verify the simulated results. The measured antenna for communication satellite presents good agreement with the simulated one by presenting CP bandwidth of 52%. Meanwhile, the measured design for the GNSS-RO receiver performs 3-dB ARBW of 41,6%. A truncated come reflector manufactured using 3D printer offers unidirectional radiation pattern for the proposed antenna and improves te perfoemance by delivering a maximum gain of 11.9 dBic.The second method is the insertion of two diagonal line slots to improve CP bandwidth of ETS antenna. In this second antenna type, te linearly polarized (LP) ETRS is converted to circular by truncating only two slot corners and attaching grounded perturbation patch. Since tecnically become a wide slot, it is ten referred as ETS as well. However, it performs smaller 3-dB ARBW tahn its reflection coefficient bandwidth.Xii, 100 hlm. ; 28 c
Lapan-A3 Satellite Data Analysis For Land Cover Classification (Case Study: Toba Lake Area, North Sumatra)
No full textLAPAN-A3 is the 3rd generation satellite for remote sensing developed by National Institute of Aeronautics and Space (LAPAN). The camera provides imagery with 15 m spatial resolution and able to view a swath 120 km wide. This research analyzes the performance of LAPAN-A3 satellite data to classify land cover in Toba Lake area, North Sumatera. Data processing starts from the selection of region of interest up to the assessment of accuracy. Supervised classification with maximum likelihood approach and confusion matrix method was applied to classify and evaluate the assessment results. The land cover is classified into five classes; water, bare land, agriculture, forest and secondary forest. The result of accuracy test is 93.71%. It proves that LAPAN-A3 data could classify the land cover accurately. The data is expected to complement the need of the satellite data with medium spatial resolution.Hlm. 71-8
Detecting the Lava Flow Deposits From 2018 Anak Krakatau Eruption Using Data Fusion LANDSAT-8 Optic and Sentinel-1 SAR
No full textThe increasing volcanic activity of Anak Krakatau volcano has raised concerns about a major disaster in the area around the Sunda Strait. The objective of the research is to fuse Landsat-8 OLI (Operational Land Imager) and Sentinel-1 TOPS (Terrain Observation with Progressive Scans), an integration of SAR and optic remote sensing data, in observing the lava flow deposits resulted from Anak Krakatau eruption during the middle 2018 eruption. RGBI and the Brovey transformation were conducted to merge (fuse) the optical and SAR data. The results showed that optical and SAR data fusion sharpened the appearance of volcano morphology and lava flow deposits. The regions are often constrained by cloud cover and volcanic ash, which occurs at the time of the volcanic eruption. The RGBI-VV and Brovey RGB-VV methods provide better display quality results in revealing the morphology of volcanic cone and lava deposits. The entire slopes of Anak Krakatau Volcano, with a radius of about 1 km from the crater is an area prone to incandescent lava and pyroclastic falls. The direction of the lava flow has the potential to spread in all directions. The fusion method of optical Landsat-8 and Sentinel-1 SAR data can be used continuously in monitoring the activity of Anak Krakatau volcano and other volcanoes in Indonesia both in cloudy and clear weather conditions.Hlm. 157-16
Geometric Aspects Evaluation of GNSS Control Network for Deformation Monitoring in The Jatigede Dam Region
No full textMany factors led to dam construction failure so that deformation monitoring activities is needed in the area of the dam. Deformation monitoring is performed in order to detect a displacement at the control points of the dam. Jatigede Dam deformation monitoring system has been installed and started to operate, but there has been no evaluation of the geometry quality of control networks treated with IGS points for GNSS networks processing. Therefore, this study aims to evaluate the geometric quality of GNSS control networks on deformation monitoring of Jatigede Dam area. This research data includes the GNSS measurements of five CORS Jatigede Dam stations (R01, GG01, GCP04, GCP06, and GCP08) at doy 233 with network configuration scenarios of 12 IGS points on two quadrants (jat1), three quadrants (jat2), and four quadrants (jat3 and jat4). GNSS networks processing was done by GAMIT to obtain baseline vectors, followed by network processing using parameter method of least squares adjustment. Networks processing with least squares adjustment aims to determine the most optimal by precision and reliability criterion. Results of this study indicate that network configuration with 12 IGS stations in the two quadrants provides the most accurate coordinates of CORS dam stations. Standard deviations value of CORS station given by jat1 configuration are in the range of 2.7 up to 4.1 cm in X-Z components, whereas standard deviations in the Y component are in the range 5.8 up to 6.9 cm. An optimization assessment based on network strength, precision, and reliability factors shows optimum configuration by jat1.Hlm. 167-17
Pengembangan Sistem Pengukuran Kinerja Dan Analisis Karakteristik MPPT (Maximum Power Unit Tracking) Dalam Proses Charging Baterai Pada LSU (LAPAN Surveillance UAV) Bertenaga Surya
No full textPustekbang mengembangkan sistem kelistrikan LSU (LAPAN Surveillance UAV) bertenaga surya. Manajemen energi dibutuhkan untuk memenuhi dan mengatur daya yang dibutuhkan beberapa sistem yang ada pada pesawat. Mengendalikan energi yang diterima oleh panel surya saat pesawat terbang membutuhkan modul pengendali daya yang masuk ke dalam baterai. Hal tersebut berguna untuk mencegah kerusakan pada baterai saat proses charging. Panel surya hanya menghasilkan energi yang maksimum diwaktu tertentu. Diperlukan odul pengendali untuk mendapatkan energi listrik yang maksimum. Modul pengendali itu sering disebut sebagai MPPT (Maximum Power Point Tracking). Dalam makalah ini akan dilakukan pengembangan terhadap sistem pengukuran proses charging ke baterai Lithium Polymer (Lipo) 3S dengan Media MPPT. Dan Menganalisa kinerja dari MPPT yang dihitung dari nilai efisiensinya. Dan Kegiatan penelitian ini telah dibangun sistem pengukuran arus dan tegangan terhadap output divais MPPT. Analisis menunjukkan arus dan tegangan yang masuk ke MPPT. sangat berpengaruh terhadap durasi charging baterai. Perhitungan efisiensi divais MPPT dari pengukuran yang telah dilakukan didapatkan nilai sebesar 96%.Hlm. 1-1