| Summary: | 碩士 === 大同大學 === 通訊工程研究所 === 94 === A beam-switching technique is proposed to improve the reception performance of the advanced television system committee (ATSC) digital television (DTV) in the multipath environment. The multipath produces notches to cancel the pilot signal in the DTV spectrum. In this situation, the picture can not be demodulated.
The beam-switching technique, which is consisted of four beamformers, is simpler and cheaper than adaptive array antenna and diversity antenna. In this thesis, the beam-switching technique does not need any algorithm. It uses the OP comparator and the switch to realize the beam-switching technique. The OP comparator is used to compare the voltage of signal. Then, the switch will pass the main signal to next stage.
The ATSC DTV reception needs a directive antenna with 100MHz bandwidth. We design the antenna based on slot antenna. The antenna has the characteristic of wideband by the multiband. By designing the array spacing, the Front to Back rate can achieve to 10dB. Experimental results show the technique can improve the performance in the multipath environment.
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