| Summary: | 碩士 === 國立交通大學 === 電子工程系 === 88 === Taiwan formally adopted the ATSC Digital Television (DTV) system as its digital terrestrial broadcasting standard in May 1998. A simple DTV transmission station was set up in 1998 for conducting various tests. One important test item is the DTV indoor reception capability, which is the focus of this study.
For a given receiver, the indoor DTV reception, in general, depends on the test site building structure, its surrounding outdoor environment and the receiver antenna system. In this thesis, four antenna systems, consisting three types of antennas with or without pre-amplifier, have been tested. We conducted both DTV and NTSC receiving tests for comparison. We like to find out the impact of various environmental factors on DTV reception such as penetration loss due to different building material, indoor furniture, floor level, and the indoor and outdoor traffic. Therefore, thirty-five test sites were carefully selected, examined, and test data recorded.
From the communications system viewpoint, the DTV reception is decided by the field strength, signal-to-noise ratio (S/N), and multipath interference. A receiver system with low noise pre-amplifier and high-directional antenna is shown to have the best reception. In contrast, a typical (low-priced) commercial active antenna has an inferior performance, which may be due to its poor antenna directionality and wide-bandwidth amplifier with high internal noise. Our test data indicate that the DTV reception is typically better than that of NTSC on the same site when the penetration loss is low. However, in the high penetration loss cases, NTSC is somewhat superior to DTV although its CCIR picture quality rating is no better than 3.
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