數位電視工程測試及研究

Abstract

我國即將於本年底開始數位電視廣播試播，為使電視數位化能順利推動，電信總局已進行第一期DTV廣播工程測試。完成VHF及UHF電波傳播損失之特性研究及實測，及研究多重路徑傳播對數位廣播信號之影響。第二期DTV工程測試著重DTV與NTSC所造成同、鄰頻干擾效應之研究，並對DTV頻道指配最佳化進行研究。由於第二期工程測試將有DTV實驗台之新建發射設備，並配合專業級的解調變器與MPEG-2解碼器，具備分析DTV數位信號位元錯誤率(SER)的測試功能，可以針對數位電視實驗台信號進行實測，詳細驗證美國FCC相關規範，這些結果將能充實我國「數位電視無線電台設置使用暫行管理辦法」規定之工程參數。此外，由於計畫進行中隨時與各電視台工程人員相互討論，技術交流，對彼此的相關工程技術水準提昇應有所幫助，並可研擬我國數位電視電波信號之測試規範。本計畫完成之測試結果，將對我國數位電視廣播之順利推動，奠定重要的基石，主管單位藉此可訂定適當的工程規範，落實頻率規劃;而營運者技術之提昇，對數位廣播系統將能提出更合理、適當之規劃，提昇頻率效益及播放品質。

A national program to build up a DTV station will be finished at the end of this year and it will also start to broadcast some test programs. To help the DTV service growing strong in Taiwan, DGT has completed the first phase of DTV field test to clarify some engineering issues, such as radio coverage, transmitting power of the base station, multipath fading effect, and propagation characteristics difference between VHF and UHF channels. In this project, the second phase, the goal is to investigate the effects of co-channel or adjacent-channel interference on the received signal, and to optimize the channel assignment for DTV channels. With the help of the test results like SER, field strength distribution, and interference protection ratio, the interim rules to regulate the operation of terrestrial broadcasting stations will be solidified. The measurement or test procedures of DTV signal in field will also be determined in the project after going through and detail field measurement and analyses. These results may lay a solid foundation in promotion DTV services in our country.