Estimation of Protection Distance between Digital TV Signals in Adjacent Channel on Terrestrial Television

Abstract

The Office of the National Broadcasting and Telecommunication Commission (NBTC) of Thailand initiated the transition to digital broadcasting. The implementation process requires a broadcasting license and digital transmission testing, which was carried out on channel 29 and channel 30—adjacent channels. Due to the 20 MHz spacing between these signals, adjacent channel interference is inevitable. This study experimentally evaluates the degradation caused by interference between digital television signals operating on adjacent channels in terrestrial television broadcasting.A novel aspect of this research is the use of field strength measurements to assess the impact of adjacent channel interference on digital TV signals within urban areas. The results demonstrate that most measured protection ratios (PR) align with the ITU-R recommended value of -11 dB. This confirms that the power ratio is affected by spectrum overlap rather than the distance from the trasmitter station.