Efficient use of digital TV spectrum is becoming one of global issues when the transition to DTV is completed. Various wideband services including spectrum sensing application are mainly discussed currently. However, there are critical issues with broadcasters as incumbent users in the DTV band. Therefore, the narrowband applications should also be considered for practical use of White Space for more efficient use of DTV spectrum. In this paper, TETRA release 1 was considered as a narrowband application for DTV White Space. Through the computing, the interoperable range of TETRA system was reviewed according to their operating modes and power classes.