Browsing by Author "Yang, Ru-Muh"

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1-Bit High Accuracy Carrier Phase Discriminators
(2013-01-01)
Chang, Chieh-Fu
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Yang, Ru-Muh
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Kao, Ming-Seng
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電信工程研究所
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Institute of Communications Engineering
Asymptotic derivation of traditional 1-bit arctangent phase discriminator (APD) is derived, even though neighboring quantized samples are dependent. The results reveal that high accuracy can be achieved by an APD in low signal-to-noise ratio (SNR) applications using sufficient samples. For high-SNR applications a novel phase discriminator called noise-balanced digital phase discriminator (NB-DPD), which has a complementary asymptotic performance of APD, is proposed to achieve high accuracy. The threshold SNR 2.6 dB that is suggested to identify either APD or NB-DPD is adopted in a specific application. Finally the sampling, quantization, and environmental noise effects on convergence of the asymptotic performance are discussed, and the simulations are provided to verify the analytical results.
A Compact Design of Antenna Feed for 6 M S/X-Bands Mono-Pulse Auto-Tracking Ground Station
(2015)
Lee, Yun-Jui
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Huang, Vincent
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Yang, Ru-Muh
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Hsu, Ti-Hsiang
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Chen, Ming-Hui
A compact S-band auto-tracking antenna feed for 6 m mono-pulse auto-tracking ground station is presented. It is designed to reduce the effect of blockage of the antenna systems and modify the orientation angle of the main reflector to align antenna boresight with a satellite. A circular waveguide is designed to connect to the septum polarizer for communication between the earth and LEO satellite. Based on the circular waveguide as an inner metal, a cylindrical metal is added as an outer metal to form a coaxial line for tracking LEO satellite. The uplink band of the antenna feed is from 2.025 to 2.12 GHz and the downlink band is from 2.2 to 2.3 CHz. The results show that the antenna gain of 6 m reflector is about 39.7 dBic and the 1-dBbeamw idth is 1 degree. The polarization isolation between sum and difference patterns is larger than 30 dB, and the axial ratio is lower than 1.1 dB within +/- 0.5 degree range.
A Small Satellite C-band SAR Mission Payload Definition for Disasters Management
(2013)
Yaung, James Yu-Chen
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Chen, Kun-Shan
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Chung, Shyh-Jong
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Yu, Shiann-Jeng
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Hung, Hao-Lun
Taiwan is an island with various high mountains created by tectonic plate collision where continent building is still active with numerous earthquake activities. Taiwan is also in one of the most prevalent monsoon and typhoon areas and they can bring along heavy precipitation that produce great threat of mud slide and land slide in the mountains. Remote mountain areas can only rely on satellite monitoring before, during, and after heavy rains where the optical monitoring satellites won\'t be able to provide the timely data or information. SAR satellites, with their advantages of all-weather capability, repeat pass, fine spatial resolution and wide swath, can provide coverage at disaster locations in the island, disaster assessment and resource survey provided the operating frequency to be lower enough as indicated in the low cost C-band SAR satellite payload defined in this paper. Based on the payload technology tradeoff analysis, the C-band system with GaN SSPA power amplifier was selected by comparing it with the X-band system with the TWTA technology which was described in our early stage of mission definition and analysis.
Design of Antenna Feed for Mono-pulse Auto-Tracking Ground Station
(2014)
Lee, Yun-Jui
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Chen, Wei-Lin
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Yaung, Shan-Kuo
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Yang, Ru-Muh
;
Chen, Ming-Hui
An S-band auto-tracking antenna feed for mono-pulse ground station is presented. The uplink band is from 2.025 to 2.12 GHz and the downlink band is from 2.2 to 2.3 GHz. The feed is utilized to modify the orientation angle of the antenna to align antenna boresight with a satellite. According to the mono-pulse radar theory, the system structure can be divided into two parts, sum and difference channels. Sum channel is used for data transmission and the key component is a septum polarizer which generates circularly polarized electric fields. Difference channel is used to modify the antenna angle and the key component is a TE21 tracking coupler with signal combining circuits. The results show that the polarization isolation is larger than 40 dB, and the axial ratio is smaller than 1.4 dB.