In this paper, a DTV interference test was performed in order to measure the affected ranges of the DTV service that result from the operating of a narrowband system as a DTV White Space Service under severe environmental conditions. The DTV coexistence testing was performed in order to review the degree of DTV signal degradation depending on the bandwidth of the secondary users. For this, the criteria of the testing evaluation were selected according to the general characteristics of the ATSC system and the terrestrial truncated radio (TETRA) system were targeted in a narrowband application of DTV White Space Service. In addition, the modified CDMA system was selected as the wideband system in order to demonstrate the usability of the narrowband application in DTV White Space Service by comparing the degree of the DTV system degradation based on the values of the signal to noise ratio (SNR) and error vector magnitude (EVM).